Dr. Gordon Christensen The Dangers of - Glidewell Dental Labs
Dr. Gordon Christensen The Dangers of - Glidewell Dental Labs
Dr. Gordon Christensen The Dangers of - Glidewell Dental Labs
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Chairside®<br />
A Publication <strong>of</strong> <strong>Glidewell</strong> Laboratories • Volume 6, Issue 1<br />
<strong>Dr</strong>. <strong>Gordon</strong> <strong>Christensen</strong><br />
<strong>The</strong> <strong>Dangers</strong> <strong>of</strong> “Gray-Market”<br />
and Counterfeit <strong>Dental</strong> Products<br />
Page 14<br />
Monolithic Versus<br />
Bilayered Restorations<br />
<strong>Dr</strong>. Gregg Helvey Takes a Closer Look<br />
Page 21<br />
Detecting Computer-<br />
Enhanced Dentistry:<br />
How to Spot Digitally Edited Photos<br />
Page 46<br />
One-on-One Interview<br />
<strong>Dr</strong>. David Hornbrook Discusses<br />
Esthetics, Lasers and Digital Dentistry<br />
Page 32<br />
<strong>Dr</strong>. Michael DiTolla’s<br />
Clinical Tips<br />
Page 9
Contents<br />
9 <strong>Dr</strong>. DiTolla’s Clinical Tips<br />
Featured in this issue is the IOS FastScan ® , a new<br />
digital impression system that has been clinically<br />
tested at <strong>Glidewell</strong> over the past three years. Also<br />
highlighted are Clear-Lock Retainers for Life and<br />
the aveoTSD ® Health Pr<strong>of</strong>essional Patient Sizing Kit,<br />
both from <strong>Glidewell</strong> Laboratories. Finally, we have<br />
what may be a way to predictably bond BruxZir ®<br />
restorations: OptiBond XTR.<br />
14 Are You Using “Gray-Market” or<br />
Counterfeit <strong>Dental</strong> Products?<br />
It’s no secret that dentists love to save money. But, as<br />
<strong>Dr</strong>. <strong>Gordon</strong> <strong>Christensen</strong> discusses, purchasing steeply<br />
discounted dental materials when looking to cut<br />
costs may be a gray area you want to avoid. Learn<br />
the dangers <strong>of</strong> purchasing gray-market and counterfeit<br />
dental products. Plus, <strong>Dr</strong>. <strong>Christensen</strong> explains<br />
how to spot gray-market and counterfeit products<br />
and outlines measures you can take to avoid falling<br />
victim to this illegal, yet lucrative, business.<br />
21 Monolithic Versus Bilayered<br />
Restorations: A Closer Look<br />
Advancements in dental ceramics have forever<br />
changed dentistry. Monolithic restorations, such as<br />
IPS ® e.max and BruxZir, are one such game changer.<br />
<strong>Dr</strong>. Gregg Helvey compares IPS e.max monolithic<br />
crowns to bilayered PFM restorations and highlights<br />
the characteristics <strong>of</strong> each.<br />
32 One-on-One with <strong>Dr</strong>. Michael DiTolla:<br />
Interview <strong>of</strong> <strong>Dr</strong>. David Hornbrook<br />
Esthetic dentistry authority <strong>Dr</strong>. David Hornbrook is<br />
one <strong>of</strong> my clinical mentors and has been ever since I<br />
took his courses at LVI. I checked in with him to see<br />
which modern-day materials he considers the gold<br />
standard for anterior restorations and to gauge his<br />
thoughts on digital impressions, monolithic restorations<br />
and diode lasers. Does this esthetic dentistry<br />
expert believe in same-day dentistry, with crowns<br />
milled chairside in the dental <strong>of</strong>fice? I got the answer.<br />
Contents 1
Contents<br />
NEW! Read Chairside on the go using your smartphone.<br />
Thanks to a simpler design, you can now<br />
enjoy your favorite recurring columns from virtually<br />
anywhere. Visit www.chairsidemagazine.com from<br />
your smartphone to see just how easy it is.<br />
46 Detecting Computer-Enhanced<br />
Dentistry<br />
When it comes to dental photography and pictures<br />
<strong>of</strong> products, patients and medical conditions, many,<br />
if not all, pictures have been edited. Maybe it’s done<br />
to hide a crack or whiten a smile, but how can<br />
you be sure what you are seeing is real? <strong>Dr</strong>. Ellis<br />
Neiburger and Yehonatan Frandzel discuss the many<br />
ways to detect digital photo enhancement. <strong>The</strong>y<br />
reveal that, despite recent developments in digital<br />
imaging in dentistry, there are telltale signs a photo<br />
has been edited.<br />
53 Periodontal Photo Essay:<br />
Is Closed-Flap Crown Lengthening a<br />
Biologically Sound Procedure?<br />
In this photo essay, <strong>Dr</strong>. Daniel Melker discusses his<br />
feelings on closed-flap crown lengthening. With the<br />
drop in prices <strong>of</strong> hard tissue lasers, this procedure will<br />
no doubt become more popular among GPs. Rather<br />
than laying a flap and directly observing the bone<br />
that is being reshaped, closed-flap crown lengthening<br />
relies strictly on feel, hence the controversy.<br />
63 <strong>Dr</strong>. DiTolla’s Patient Product Review<br />
In the last issue <strong>of</strong> Chairside magazine, I discussed<br />
how men and flossing don’t belong in the same sentence.<br />
Touching again on this topic, I introduce you<br />
to a unique toothpick by Ultradent called Opalpix .<br />
While Opalpix doesn’t replace the benefits <strong>of</strong> flossing,<br />
it is my best hope for men who appear to be<br />
allergic to floss.<br />
2<br />
www.chairsidemagazine.com
Publisher<br />
Jim <strong>Glidewell</strong>, CDT<br />
Editor-in-Chief<br />
Michael DiTolla, DDS, FAGD<br />
Managing Editors<br />
Jim Shuck<br />
Mike Cash, CDT<br />
Creative Director<br />
Rachel Pacillas<br />
Clinical Editor<br />
Michael DiTolla, DDS, FAGD<br />
Senior Copy Editor<br />
Melissa Manna<br />
Copy Editors<br />
Jennifer Holstein, Eldon Thompson<br />
Magazine Coordinator<br />
Teri Arthur<br />
Graphic Designers/Web Designers<br />
Jamie Austin, Deb Evans,<br />
Joel Guerra, Phil Nguyen, Ty Tran<br />
Photographers/Clinical Videographers<br />
Sharon Dowd, Kevin Keithley,<br />
James Kwasniewski, Sterling Wright<br />
Illustrators<br />
Wolfgang Friebauer, MDT<br />
Ad Representative<br />
Teri Arthur<br />
(teri.arthur@glidewelldental.com)<br />
If you have questions, comments or complaints regarding<br />
this issue, we want to hear from you. Please e-mail us at<br />
chairside@glidewelldental.com. Your comments may be<br />
featured in an upcoming issue or on our website:<br />
www.chairsidemagazine.com.<br />
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Chairside ® Magazine is a registered trademark <strong>of</strong> <strong>Glidewell</strong> Laboratories.<br />
Editor’s Letter<br />
I have been hearing about the death <strong>of</strong> PFMs for the past<br />
15 years. In fact, the PFM department managers here at the<br />
lab always have a good laugh when I show them a dental<br />
journal with an article by a metal-free clinician predicting<br />
the demise <strong>of</strong> PFMs within the next three to five years.<br />
While a metal-free style <strong>of</strong> practice can certainly work for<br />
dentists who passionately believe in metal-free dentistry,<br />
the numbers at the lab tell another story: PFMs aren’t dead.<br />
Most dentists are satisfied with PFMs and continue to prescribe<br />
them in large numbers. After all, PFMs are versatile<br />
and can be used for single units, multiple units and even<br />
roundhouse bridges. Those who want to pretty it up can<br />
always cut a facial shoulder for a porcelain margin or use<br />
an esthetic PFM, such as Captek , in the esthetic zone.<br />
PFMs have long been the workhorse restoration, but then<br />
one day something happened … and that something was<br />
BruxZir ® Solid Zirconia. For 10 years I begged R&D for<br />
a cast gold crown in a shade A2. Jim <strong>Glidewell</strong> was bugging<br />
them to make a full-contour zirconia crown, just to<br />
see what it would look like. BruxZir got both <strong>of</strong> us <strong>of</strong>f<br />
their backs.<br />
From the day it launched, BruxZir was a niche product. It<br />
was meant to be an esthetic replacement for cast gold and<br />
metal occlusals, but I started using it to replace broken<br />
PFMs (because those patients had already destroyed<br />
that type <strong>of</strong> restoration). All <strong>of</strong> a sudden, dentists started<br />
placing BruxZir everywhere, showing preference for<br />
this high-strength, cementable, monolithic, tooth-colored<br />
material, despite it being “more brawn than beauty.”<br />
<strong>The</strong> popularity <strong>of</strong> BruxZir continues to grow, with a recent<br />
sales record totaling 7,300 crowns & bridges in one week!<br />
That makes BruxZir the fastest growing product in the<br />
40-year history <strong>of</strong> <strong>Glidewell</strong> Laboratories.<br />
So while PFMs are not dead, the PFM department no longer<br />
laughs at these jokes. We can use BruxZir to do virtually<br />
anything that can be done with a PFM, including<br />
roundhouse bridges. <strong>The</strong>se monolithic restorations seem<br />
poised to replace their bilayered brethren; however, the<br />
change may be measured in decades, rather than years.<br />
Yours in quality dentistry,<br />
<strong>Dr</strong>. Michael C. DiTolla<br />
Editor- in-Chief, Clinical Editor<br />
mditolla@glidewelldental.com<br />
Editor’s Letter 3
Letters to the Editor<br />
Dear <strong>Dr</strong>. DiTolla,<br />
I have really enjoyed your articles and<br />
video presentations over the years. <strong>The</strong>y<br />
are very informative and helpful.<br />
I have a question regarding your success<br />
rate with the Milestone Scientific<br />
STA System. I have been using it now for<br />
more than a year, and it seems to be hit or<br />
miss, just like the mandibular block. I love<br />
it when it works, but I find it very annoying<br />
when I have to go back and do a block.<br />
I wonder what you might be doing differently.<br />
I use 4 percent articaine with<br />
1:100,000 EPI and usually deposit the<br />
anesthetic for 15 seconds after I have<br />
reached the PDL (about one-third <strong>of</strong> a<br />
carpule). I have tried both buccal and<br />
lingual placement, as well as mesial and<br />
distal. Many times it does not even get<br />
to three bars on the graph LED. Any<br />
thoughts you may have as to why this is<br />
happening would be greatly appreciated.<br />
– Jeffrey Olson, DDS<br />
Irving, Texas<br />
Dear Jeffrey,<br />
Thanks for the kind words! I did<br />
have a period <strong>of</strong> time where my<br />
effectiveness with the STA System<br />
went down, albeit very slowly.<br />
My initial enthusiasm for the unit<br />
4<br />
www.chairsidemagazine.com<br />
slowly waned and then, luckily, the<br />
unit stopped working completely. I<br />
sent it back to Milestone Scientific,<br />
and they sent me a loaner to use in<br />
the interim. It was like magic! I was<br />
getting the PDL alert on every single<br />
tooth! I was in heaven. I realized<br />
that the problem was with my unit.<br />
When my STA System came back I<br />
was reluctant to return the loaner.<br />
I kept it in the <strong>of</strong>fice for a week, until<br />
I verified that my old one was working.<br />
My suggestion is that you send<br />
your unit in for some maintenance to<br />
ensure it’s working properly.<br />
I usually start in the buccal furcation<br />
with an extra-short needle, and if I<br />
get the PDL alert there I am usually<br />
good. If there is perio involvement, I<br />
usually go to the ML corner, where it<br />
is the norm to get the PDL alert, and<br />
then I also go to the DL corner. If the<br />
patient is phobic or sensitive, I do all<br />
four corners. Sometimes I have to go<br />
back in with a little more in the PDL,<br />
but I have never had to go back and<br />
give a block. I usually see patients<br />
whose last dentist couldn’t get them<br />
numb with a block, and I’m able to<br />
with the STA System.<br />
Keep me apprised <strong>of</strong> your experience<br />
because I recommend the<br />
STA System to everyone.<br />
– Mike<br />
Dear <strong>Dr</strong>. DiTolla,<br />
I recently discovered your Rapid Anesthesia<br />
Technique on YouTube, and I have tried<br />
it a few times. What are some <strong>of</strong> the postop<br />
complaints, and how do you address<br />
them? Thank you for your help.<br />
– Seada Damiano, DDS<br />
Cicero, N.Y.<br />
Dear Seada,<br />
I don’t get that many side effects now<br />
that I use the STA System to deliver<br />
the Septocaine ® . When I was doing<br />
the Rapid Anesthesia Technique using<br />
a hand syringe, I used too much<br />
pressure, which caused some tearing<br />
<strong>of</strong> the PDL and resulted in the tooth<br />
being sensitive to percussion or biting<br />
in some cases. <strong>The</strong> STA System<br />
has eliminated the speed and pressure<br />
issues, so I don’t see that anymore.<br />
Post-op complaints are almost<br />
nonexistent now — nowhere near<br />
where they used to be when I was<br />
routinely giving lower blocks.<br />
– Mike<br />
Dear Mike,<br />
Thank you for your prompt reply. I really<br />
appreciate it. I have tried the technique<br />
(manually) about six times. Yesterday a<br />
patient I had seen about a week ago for<br />
an occlusal on tooth #31 came back and<br />
complained <strong>of</strong> pain in the gingival area.<br />
<strong>The</strong> tooth was fine on percussion. Maybe<br />
I used too much pressure or too much<br />
solution. I think this technique is fantastic,<br />
and I will look into the STA System.<br />
Thanks again, and have a great day!<br />
– Seada<br />
Dear Seada,<br />
I’m not an STA System salesman,<br />
but when I started using it my confidence<br />
with the technique really<br />
took <strong>of</strong>f. I had a patient come in last<br />
week who left her dentist <strong>of</strong> 15 years<br />
because he couldn’t get her lower<br />
molar numb on two consecutive<br />
appointments to finish a crown prep.<br />
I used to dread these types <strong>of</strong> patients,<br />
but I actually look forward to<br />
them now because I have been able<br />
to anesthetize all <strong>of</strong> them so far. In<br />
those cases, I inject in the furcation<br />
and the buccal and lingual sulcus,<br />
but it has always worked. You truly<br />
become their hero.<br />
– Mike
Dear <strong>Dr</strong>. DiTolla,<br />
I wanted to thank you for the excellent<br />
veneer video you made. I learned a lot:<br />
putty-wash index, the Rapid Anesthesia<br />
Technique and fixing alignment before<br />
depth cutting! Those were big, and I feel<br />
like I became a better dentist from watching<br />
your presentation.<br />
One question: When you use a putty-wash<br />
index <strong>of</strong> the wax-up, do you use lubricant?<br />
I broke a few wax-up teeth (glued them<br />
back easily though) when I took my putty<br />
index. <strong>The</strong> impression material sucked up<br />
all the moisture from the model and adhered<br />
to certain waxed teeth on the model.<br />
– Ruslan Korobeinik, DDS<br />
White Plains, N.Y.<br />
Dear Ruslan,<br />
I have done that as well, although<br />
once the putty-wash matrix is done,<br />
I really don’t need the wax-up anymore.<br />
Of course, you could always<br />
have the lab make a duplicate stone<br />
model <strong>of</strong> the wax-up, making it easier<br />
to work with. I hope that helps!<br />
– Mike<br />
Dear <strong>Dr</strong>. DiTolla,<br />
As usual, I read Chairside magazine cover<br />
to cover as soon as I received it (I can’t say<br />
the same for some <strong>of</strong> the other periodicals<br />
I receive). In the most recent issue, I was<br />
glad to see that you mentioned <strong>Glidewell</strong><br />
Laboratories is a CEREC ® Connect laboratory.<br />
(I don’t think it has been properly<br />
advertised, and <strong>Glidewell</strong> is very good at<br />
advertising.) This might be a good topic<br />
for a future article.<br />
I wrote an article on the subject that has<br />
not yet been published, and I am attaching<br />
it for your opinion. I hope you find the time<br />
to send me some feedback.<br />
– Carlos Boudet, DDS, DICOI<br />
West Palm Beach, Fla.<br />
Dear Carlos,<br />
Thanks for the kind words. I would<br />
love to review the article you sent.<br />
Our only requirement is that it is accompanied<br />
by outstanding clinical<br />
photography! I look forward to reading<br />
it.<br />
– Mike<br />
Dear <strong>Dr</strong>. DiTolla,<br />
Congratulations on your latest issue <strong>of</strong><br />
Chairside. I very much enjoyed the article<br />
“Simplifying Lab Communication: <strong>The</strong><br />
<strong>Dental</strong> Midline Position, Incisal Cant and<br />
Incisal Horizontal Plane” by <strong>Dr</strong>. Leendert<br />
Boksman. <strong>The</strong> article seems uniquely appropriate<br />
when one looks at the front cover<br />
and observes and absolutely beautiful<br />
young lady with her upper midline at least<br />
half a tooth to the left <strong>of</strong> her facial midline<br />
and her left eye fully 6 mm higher than<br />
her right eye. Literally everyone has some<br />
facial asymmetry, including <strong>Dr</strong>. Boksman<br />
whose glasses have a pronounced uphill<br />
slant to the left. <strong>The</strong> point is that our stepbrothers,<br />
the cranial osteopaths, and the<br />
rather few practicing cranial orthodontists<br />
have shown that they are able to produce<br />
dramatic improvement and, occasionally,<br />
correction <strong>of</strong> these asymmetries. <strong>The</strong><br />
others simply say that such asymmetry is<br />
“acceptable” (which it must be if one does<br />
not know or understand how to correct it).<br />
I don’t know if this information would be<br />
<strong>of</strong> interest to Chairside magazine, as it is<br />
more <strong>of</strong> an orthodontic concern, but the<br />
article in your magazine was absolutely<br />
fascinating to me, and I intend to order<br />
several Onebite facial plane relators<br />
immediately. Thank you so much!<br />
– Gerald W. Spencer, DDS<br />
Sedalia, Mo.<br />
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Letters to the Editor 5
Contributors<br />
Michael C. DiTolla, DDS, FAGD<br />
<strong>Dr</strong>. Michael DiTolla is a graduate <strong>of</strong> University <strong>of</strong> the Pacific Arthur A. Dugoni School <strong>of</strong> Dentistry.<br />
As Director <strong>of</strong> Clinical Education & Research at <strong>Glidewell</strong> Laboratories in Newport Beach, Calif.,<br />
he performs clinical testing on new products in conjunction with the company’s R&D Department.<br />
<strong>Glidewell</strong> dental technicians have the privilege <strong>of</strong> rotating through <strong>Dr</strong>. DiTolla’s operatory and<br />
experiencing his commitment to excellence through his prepping and placement <strong>of</strong> their restorations.<br />
He is a CR evaluator and lectures nationwide on both restorative and cosmetic dentistry. <strong>Dr</strong>. DiTolla has<br />
several clinical programs available on DVD through <strong>Glidewell</strong> Laboratories. For more information on<br />
his articles or to receive a free copy <strong>of</strong> <strong>Dr</strong>. DiTolla’s clinical presentations, call 888-303-4221 or e-mail<br />
mditolla@glidewelldental.com.<br />
<strong>Gordon</strong> J. <strong>Christensen</strong>, DDS, MSD, Ph.D<br />
<strong>Dr</strong>. <strong>Gordon</strong> <strong>Christensen</strong> is a practicing prosthodontist in Provo, Utah. His degrees include DDS,<br />
University <strong>of</strong> Southern California; MSD, University <strong>of</strong> Washington; and Ph.D, University <strong>of</strong> Denver. He<br />
is a Diplomate <strong>of</strong> the American Board <strong>of</strong> Prosthodontics; Fellow and Diplomate <strong>of</strong> the International<br />
Congress <strong>of</strong> Oral Implantologists; Fellow <strong>of</strong> the Academy <strong>of</strong> Osseointegration, American College <strong>of</strong><br />
Dentists, International College <strong>of</strong> Dentists, American College <strong>of</strong> Prosthodonists and Royal College <strong>of</strong><br />
Surgeons <strong>of</strong> England; Honorary Fellow <strong>of</strong> the AGD; and Associate Fellow <strong>of</strong> the AAID.<br />
<strong>Dr</strong>s. <strong>Gordon</strong> and Rella <strong>Christensen</strong> are c<strong>of</strong>ounders <strong>of</strong> the nonpr<strong>of</strong>it <strong>Gordon</strong> J. <strong>Christensen</strong> CLINICIANS<br />
REPORT ® (formerly CRA ® Newsletter). Contact <strong>Dr</strong>. <strong>Christensen</strong> at 801-226-6569 or info@pccdental.com.<br />
Yehonatan L. Frandzel, FPH<br />
Yehonatan Frandzel is an architect and designer based in Haifa, Israel. He is a graduate <strong>of</strong> Technion-<br />
Israel Institute <strong>of</strong> Technology, where he studied in the Faculty <strong>of</strong> Architecture and Town Planning.<br />
Yehonatan is head <strong>of</strong> Architectural Visualization, 3-D Modeling and Computer Rendering for<br />
Mochly-Eldar Architects, where he lends his extensive experience with the creation and detection <strong>of</strong><br />
virtual imaging. Contact him at kaizer@gmail.com.<br />
Gregg Helvey, DDS, MAGD<br />
<strong>Dr</strong>. Gregg Helvey graduated from Georgetown University School <strong>of</strong> Dentistry in 1976. He is part <strong>of</strong> an<br />
elite group <strong>of</strong> dentists who are also skilled ceramists. This combination <strong>of</strong> experience as a dentist and<br />
laboratory technician has aided him in the development <strong>of</strong> unique restorative and laboratory procedures,<br />
many <strong>of</strong> which have been published in peer-reviewed journals. <strong>Dr</strong>. Helvey serves on the editorial<br />
board <strong>of</strong> Inside Dentistry, Compendium <strong>of</strong> Continuing Education in Dentistry and Inside <strong>Dental</strong><br />
Technology. An AGD Master since 1997, he is an adjunct associate pr<strong>of</strong>essor at Virginia Commonwealth<br />
University School <strong>of</strong> Dentistry and teaches in the AEGD residency program emphasizing all-ceramic restorations.<br />
<strong>Dr</strong>. Helvey continues to lecture nationally and internationally and maintains a private practice<br />
in Middleburg, Va. Contact him at 540-687-5855, www.gregghelveydds.com or phident@gmail.com.<br />
6<br />
www.chairsidemagazine.com
David S. Hornbrook, DDS, FAACD<br />
<strong>Dr</strong>. David Hornbrook graduated from UCLA School <strong>of</strong> Dentistry and currently practices in San Diego,<br />
Calif. A leading educator in esthetic dentistry, he has been a guest faculty member <strong>of</strong> the postgraduate<br />
programs in cosmetic dentistry at Baylor, Tufts, SUNY at Buffalo, UMKC and the UCLA Center <strong>of</strong> Cosmetic<br />
Dentistry. <strong>Dr</strong>. Hornbrook has also consulted with numerous manufacturers in product development<br />
and refinement and is on the editorial board <strong>of</strong> many dental journals. He is a past editor <strong>of</strong> the Journal<br />
<strong>of</strong> the American Academy <strong>of</strong> Cosmetic Dentistry and an accredited member and Fellow <strong>of</strong> the AACD.<br />
Founder and past director <strong>of</strong> P.A.C.~live and the Hornbrook Group, <strong>Dr</strong>. Hornbrook continues to lecture<br />
internationally. Contact him at www.davidhornbrook.com.<br />
Daniel J. Melker, DDS<br />
<strong>Dr</strong>. Daniel Melker graduated from Boston University School <strong>of</strong> Graduate Dentistry in 1975 with specialty<br />
training in periodontics. Since then, he has maintained a private practice in periodontics in<br />
Clearwater, Fla. <strong>Dr</strong>. Melker lectures at the University <strong>of</strong> Florida periodontic and prosthodontic graduate<br />
programs on the periodontic-restorative relationship. He also presents at UAB, University <strong>of</strong> Houston,<br />
Baylor University and LSU’s graduate periodontal program. <strong>Dr</strong>. Melker has published several articles<br />
in national dental magazines, as well as <strong>The</strong> International Journal <strong>of</strong> Periodontics & Restorative Dentistry,<br />
and has twice been honored with the Florida Academy <strong>of</strong> Cosmetic Dentistry Gold Medal. Contact<br />
him at 727-725-0100.<br />
Ellis J. Neiburger, DDS<br />
<strong>Dr</strong>. Ellis “Skip” Neiburger graduated from University <strong>of</strong> Illinois at Chicago College <strong>of</strong> Dentistry in 1968.<br />
He practices general dentistry in Waukegan, Ill. A former vice president <strong>of</strong> the American Association <strong>of</strong><br />
Forensic Dentists, <strong>Dr</strong>. Neiburger has been the association’s journal editor since 1978. His other experience<br />
includes publisher/editor for <strong>Dental</strong> Computer Newsletter (the journal that introduced computing<br />
to the dental field) and consultant for Apple Computer Inc. In addition to a background in computer<br />
technology and dentistry, <strong>Dr</strong>. Neiburger also has practical knowledge <strong>of</strong> law enforcement and was Lake<br />
County, Ill., deputy coroner for many years. Contact him at 847-244-0292 or eneiburger@comcast.net.<br />
Contributors 7
A toothpick<br />
is the object most <strong>of</strong>ten choked on by<br />
Americans. Since 1900, 17,000 people<br />
have died from choking on toothpicks,<br />
including novelist Sherwood Anderson.<br />
80%<br />
<strong>The</strong> percentage<br />
<strong>of</strong> metal-based<br />
fixed restorations<br />
prescribed in 1997.<br />
by the<br />
Numbers<br />
43%<br />
<strong>The</strong> percentage<br />
<strong>of</strong> metal-based<br />
fixed restorations<br />
prescribed in 2010.<br />
1 out <strong>of</strong> 3<br />
<strong>of</strong> the last<br />
2,000,000 shades<br />
prescribed were<br />
A2 and A3.<br />
8 days<br />
<strong>The</strong> amount <strong>of</strong><br />
time sharks’<br />
teeth last before<br />
being replaced<br />
by the next row.<br />
1 out <strong>of</strong> 2<br />
dentists in Massachusetts sent<br />
a case to <strong>Glidewell</strong> in 2010.<br />
7,300<br />
BruxZir crown & bridge<br />
units were ordered the week<br />
<strong>of</strong> Dec. 13, 2010, making it<br />
the fastest-growing product<br />
in lab history.<br />
8<br />
www.chairsidemagazine.com<br />
1 out <strong>of</strong> 142<br />
<strong>of</strong> the last<br />
2,000,000 shades<br />
prescribed<br />
were D4.<br />
Six feet<br />
<strong>The</strong> recommended<br />
distance to keep<br />
your toothbrush from<br />
your toilet to avoid<br />
airborne particles<br />
from the flush.
<strong>Dr</strong>. DiTolla’s<br />
CLINICAL TIPS<br />
PRODUCT........ aveoTSD ® Health Pr<strong>of</strong>essional<br />
Patient Sizing Kit<br />
SOURCE........... <strong>Glidewell</strong> Laboratories<br />
Newport Beach, Calif.<br />
800-334-1979<br />
www.getaveo.com<br />
One <strong>of</strong> the most common questions I field from<br />
dentists is: “Does that aveoTSD thing actually work?”<br />
Yes, it does, but I understand why they ask. It is a<br />
simple appliance (especially compared to other antisnoring<br />
appliances) with no moving parts that looks<br />
too good to be true. It anteriorizes the tongue directly<br />
without involving the teeth or jaws, hence there is no<br />
need for straps or hinges.<br />
<strong>The</strong> aveoTSD Health Pr<strong>of</strong>essional Patient Sizing<br />
Kit is now available to dentists for helping patients<br />
achieve a perfect fit <strong>of</strong> the device. <strong>The</strong> extra-oral<br />
titration rings come in 4 mm and 7 mm thicknesses<br />
to accommodate patients with<br />
longer-than-average tongues. And although<br />
the medium size aveoTSD fits<br />
90 percent <strong>of</strong> patients, the sizing<br />
kit also contains a small and a<br />
large aveoTSD for patient<br />
sizing. Additionally, the<br />
components can be<br />
placed back into the<br />
blue kit for sterilization<br />
between<br />
appointments.<br />
<strong>Dr</strong>. DiTolla’s Clinical Tips 9
<strong>Dr</strong>. DiTolla’s<br />
CLINICAL TIPS<br />
PRODUCT........ OptiBond XTR<br />
SOURCE........... Kerr Corporation<br />
Orange, Calif.<br />
800-537-7123<br />
www.kerrdental.com<br />
Since the introduction <strong>of</strong> BruxZir ® Solid Zirconia,<br />
I have been looking for a way to bond these monolithic<br />
restorations into place whether using totaletch,<br />
self-etch or conventional cementation. Zirconia<br />
is notoriously tough to bond to, but OptiBond XTR<br />
provides a solution. It also has helped me reduce<br />
post-op sensitivity. And due to its film thickness <strong>of</strong><br />
5 to 10 microns, I am able to light cure OptiBond<br />
XTR prior to placing restorations without worrying<br />
about them seating all the way. I simply apply the<br />
OptiBond XTR Primer to the inside <strong>of</strong> the BruxZir<br />
restoration, air thin and light cure. To bond to the<br />
tooth, I apply the primer with a scrubbing motion<br />
and then air thin. <strong>The</strong>n I apply the OptiBond XTR<br />
Adhesive to the tooth, air thin and cure. Finally, I fill<br />
the BruxZir restoration with the cement <strong>of</strong> my choice,<br />
seat it on the tooth, and I’ve got a virtually unbreakable<br />
crown or bridge with a high-strength bond.<br />
10 www.chairsidemagazine.com
<strong>Dr</strong>. DiTolla’s<br />
CLINICAL TIPS<br />
PRODUCT........ Clear-Lock Retainers for Life <br />
SOURCE........... <strong>Glidewell</strong> Laboratories<br />
Newport Beach, Calif.<br />
866-497-3700<br />
www.glidewelldental.com<br />
I <strong>of</strong>ten get asked to make retainers for patients who<br />
don’t want to bother going back to their orthodontic<br />
<strong>of</strong>fice five years after their first appliance was made.<br />
Most <strong>of</strong> the time the patient’s teeth have slightly relapsed,<br />
and while he or she doesn’t care enough to<br />
have more ortho, the patient doesn’t want his or her<br />
teeth to get any worse. Thanks to Invisalign ® , patients<br />
now prefer clear retainers to the old pink acrylic<br />
and wire Hawley retainers many <strong>of</strong> us grew up with.<br />
<strong>Glidewell</strong> started making clear retainers for dentists<br />
a few years ago. With the advent <strong>of</strong> CAD/CAM, the<br />
lab realized we could make multiple sets <strong>of</strong> retainers.<br />
This is especially practical when the patient loses or<br />
damages his or her retainer, which always happens.<br />
<strong>The</strong> lab now <strong>of</strong>fers Clear-Lock Retainers for Life, a<br />
service in which we send you either three single-arch<br />
retainers (three uppers or three lowers) or one set <strong>of</strong><br />
three upper and three lower retainers to give to the<br />
patient. When all the retainers are lost or damaged,<br />
contact us and we will send you three more from our<br />
digitally stored data. It’s a great service that even your<br />
orthodontist doesn’t provide!<br />
<strong>Dr</strong>. DiTolla’s Clinical Tips11
<strong>Dr</strong>. DiTolla’s<br />
CLINICAL TIPS<br />
PRODUCT........ IOS FastScan ®<br />
SOURCE........... IOS Technologies Inc.<br />
San Diego, Calif.<br />
858-202-3360<br />
www.ios3d.com<br />
I will readily admit that digital impressions are the<br />
future <strong>of</strong> dentistry. But as <strong>of</strong> today, the ROI <strong>of</strong> digital<br />
systems leaves a lot to be desired. Enter IOS FastScan.<br />
<strong>Glidewell</strong> Laboratories has been the main clinical testing<br />
facility for IOS Technologies’ IOS FastScan, and I<br />
have spent a lot <strong>of</strong> time with it in my hands over the<br />
last three years. Besides the fact that it might be the<br />
fastest scanner for digital impressions, I think ROI<br />
will be the feature dentists love most. For any monolithic<br />
IPS e.max ® or BruxZir ® IOS FastScan digital file<br />
you send to the lab, you will save $27 — that’s comprised<br />
<strong>of</strong> $7 savings on inbound shipping, $10 savings<br />
on impression material, and $10 <strong>of</strong>f the restoration<br />
list price because it can be digitally fabricated without<br />
making a model. No other scanning system gives you<br />
the ability to save this much on every crown you scan.<br />
In fact, many digital systems actually cost you more.<br />
Technology, Inc.<br />
12 www.chairsidemagazine.com
Are You Using<br />
“Gray-Market”<br />
or Counterfeit<br />
<strong>Dental</strong> Products?<br />
– ARTICLE by<br />
<strong>Gordon</strong> J. <strong>Christensen</strong>, DDS, MSD, Ph.D<br />
14 www.chairsidemagazine.com
Most people find it difficult to pass up a bargain, and<br />
dentists and dental staff members who select and order<br />
products are no exceptions. It is relatively common to see<br />
dental products <strong>of</strong>fered in dental magazines and journals<br />
at discounts <strong>of</strong> 10 percent to 50 percent.<br />
Are you using products purchased at significant discounts?<br />
As staff members typically handle the ordering <strong>of</strong> supplies<br />
in most dental <strong>of</strong>fices, do you, the dentist, even know if you<br />
are using such products?<br />
A key question to ask is: How can some dental retailers sell<br />
dental supplies at deeply discounted prices, while others<br />
continue to sell at the recognized market level? Deeply discounted<br />
products may not be legitimate ones produced by the<br />
manufacturer from which you think you are buying. You may<br />
be using “gray-market” or even counterfeit products without<br />
knowing it.<br />
Gray-market products include branded goods intended by the<br />
brand owner for one national market that are diverted and<br />
resold by unauthorized distributors to another market. Counterfeit<br />
products, on the other hand, never originate from the brand<br />
owner. Counterfeiters simply pass <strong>of</strong>f fake materials under the<br />
guise <strong>of</strong> a well-known product. <strong>The</strong>re is a surprising lack <strong>of</strong> published<br />
information on this subject. However, a few related articles are<br />
interesting. 1–4<br />
A key question to ask is: How can<br />
some dental retailers sell dental<br />
supplies at deeply discounted<br />
prices, while others continue to<br />
sell at the recognized market<br />
level? Deeply discounted<br />
products may not be legitimate<br />
ones produced by the<br />
manufacturer from which you<br />
think you are buying. You<br />
may be using “gray-market”<br />
or even counterfeit products<br />
without knowing it.<br />
Large dental companies, such as 3M ESPE (St. Paul, Minn.), DENTSPLY (York, Pa.) and Kerr (Orange, Calif.), deal<br />
with gray-market and counterfeit products regularly, and some find it difficult to estimate what percentage they<br />
represent <strong>of</strong> products sold. Kirsten Edwards, director <strong>of</strong> clinical affairs for Kerr, estimated that approximately<br />
5 percent to 8 percent <strong>of</strong> apparent Kerr products are gray-market or counterfeit (oral communication, Feb. 23,<br />
2010). <strong>The</strong>se products are sold under the pretense <strong>of</strong> being brand-name items.<br />
Purchasing discounted dental products saves money, but is it worth the potential hazards <strong>of</strong> buying and using<br />
such products? For example: Say you gross $600,000 per year with a 60 percent overhead before taxes, and your<br />
supply expenses are equivalent to about 5 percent <strong>of</strong> your gross income, or about $30,000 for the year. Assuming<br />
you save 10 percent <strong>of</strong>f your supply cost, you’ll save $3,000 in a year, or $250 per month. However, what if<br />
these discounted products are expired, altered or even counterfeit, and you have a material failure — such as<br />
postoperative tooth sensitivity — in a group <strong>of</strong> patients? Additionally, the legal liability associated with using<br />
a dental material that is not approved for sale in the U.S. or cannot be tracked back to its origin <strong>of</strong> sale is a<br />
significant threat. Even if you determine the cause <strong>of</strong> the problem, have you really saved anything? Is it worth<br />
the $250 per month savings? To whom do you go when the product does not meet its expressed purpose or<br />
you have problems with patient complaints?<br />
In this article, I discuss the prevalence <strong>of</strong> gray-market and counterfeit products and manufacturers’ concerns<br />
about them; the need for communication between the dentist and the staff member(s) ordering the dental<br />
products; how to identify gray-market and counterfeit products; and, most importantly, what to do to avoid<br />
the problem.<br />
Are You Using “Gray-Market” or Counterfeit <strong>Dental</strong> Products?15
<strong>The</strong>re are other reasons I<br />
prefer to purchase from these<br />
major distributors. By doing<br />
so, I know that in spite <strong>of</strong><br />
<strong>of</strong>ten paying somewhat more<br />
for some items, I have their<br />
repair support. Additionally,<br />
I can ask their local sales<br />
representatives about the<br />
properties <strong>of</strong> specific products<br />
and the acceptance or<br />
rejection that products are<br />
receiving in my community.<br />
DENTAL INDUSTRY’S CONCERNS<br />
REGARDING GRAY-MARKET AND<br />
COUNTERFEIT PRODUCTS<br />
<strong>The</strong> U.S. Food and <strong>Dr</strong>ug Administration (FDA) regulates<br />
the dental industry, ensuring that dental medical devices —<br />
or the dental products used and placed in patients’ mouths<br />
— meet accepted standards. <strong>The</strong> FDA also approves manufacturers’<br />
claims and inspects manufacturing facilities for<br />
ongoing compliance.<br />
Manufacturers’ concerns about gray-market and counterfeit<br />
products are about more than financial loss. <strong>The</strong>y also center<br />
on potential health risks for patients and negative brand<br />
perception among clinicians who might use a gray-market or<br />
counterfeit product and not get the expected clinical result.<br />
3M ESPE Global Director <strong>of</strong> Channel Sales Kathy Gaertner<br />
stated that the company sees the presence <strong>of</strong> unauthorized<br />
intermediaries selling products that are not authorized for<br />
sale in the U.S. (written communication, Feb. 23, 2010). <strong>The</strong>se<br />
items <strong>of</strong>ten are products intended for sale in developing countries<br />
that have been repackaged and sent back to the U.S. for<br />
sale to American dentists. When products not cleared for sale<br />
in the U.S. are repackaged, you cannot be guaranteed that you<br />
are buying the product you think you are buying. Warning and<br />
traceability information may be missing, and the products may<br />
no longer comply with regulatory requirements. Oftentimes, these<br />
repackaged products are outdated or expired with a fraudulent<br />
extended expiration date. <strong>The</strong> gray-market product may have been mishandled,<br />
resulting in compromised product efficacy.<br />
“<strong>The</strong> only way to know you’re getting the 3M ESPE product quality you trust is to purchase [products] through<br />
certified 3M ESPE distributors,” stated Gaertner.<br />
DENTSPLY Chief Clinical Officer <strong>Dr</strong>. Linda Niessen described the company’s concerns about gray-market and<br />
counterfeit products not providing the clinical outcomes that dentists have come to expect from DENTSPLY<br />
brands (written communication, Feb. 23, 2010). Company personnel routinely see examples <strong>of</strong> discounted<br />
noncompliant, expired or repackaged DENTSPLY products. <strong>The</strong>y have seen cases in which early generations <strong>of</strong><br />
products, no longer registered with the FDA, are acquired in developing markets. <strong>The</strong>se products are imported<br />
illegally into the U.S. and resold to U.S. dentists as the newest product under different brand names. <strong>The</strong> primary<br />
packages are labeled clearly as the early-generation product, while the directions for use and the invoice<br />
falsely claim the product to be the newest-generation product. Gray-market activity not only creates a clinical<br />
risk exposure for dentists, but also deprives their dealer partners <strong>of</strong> the opportunity to supply a quality product<br />
behind which the manufacturer will stand. DENTSPLY has 22 authorized dealer partners; <strong>Dr</strong>. Niessen said<br />
that if a DENTSPLY product comes from anyone else, it is likely to be counterfeit or altered.<br />
Kirsten Edwards <strong>of</strong> Kerr stated that counterfeit OptiBond ® Solo Plus , Herculite ® and other popular Kerr<br />
brands have been sold through unauthorized dealers (oral communication, Feb. 23, 2010). To the naked eye,<br />
the packaging appears to be identical to the <strong>of</strong>ficial company packaging. This includes lot codes that match<br />
16 www.chairsidemagazine.com
legitimate codes for lots sold to authorized dealers. <strong>The</strong> company cautions dentists that if the price <strong>of</strong> a Kerr product<br />
is significantly below standard U.S. or Canadian pricing, the product is likely to be gray-market or counterfeit and<br />
could violate civil and criminal laws. Kerr also has filed a citizen petition with the FDA seeking action against several<br />
unauthorized dealers that have been found distributing gray-market or counterfeit Kerr products. As <strong>of</strong> the publication<br />
<strong>of</strong> this article, no action has been taken by the FDA to stop this activity.<br />
It is obvious that unscrupulous, pr<strong>of</strong>it-motivated distributors can find many ways to simulate popular products and<br />
sell them to dentists at discounted prices. <strong>The</strong> Internet has made this easier.<br />
HOW DO GRAY-MARKET OR COUNTERFEIT<br />
PRODUCTS GET INTO YOUR OFFICE?<br />
How can we identify gray-market and counterfeit products before they arrive at our <strong>of</strong>fice? In order to reduce or<br />
eliminate this problem, dentists must change their behaviors.<br />
Who in your <strong>of</strong>fice orders and purchases dental supplies? If you are a typical dentist, dental supplies are ordered,<br />
purchased, shelved and placed in the operatory by a competent, knowledgeable dental assistant or, in some <strong>of</strong>fices,<br />
by the <strong>of</strong>fice manager. <strong>The</strong>se loyal staff members are eager to please you by making inexpensive supply purchases.<br />
Bargain rates <strong>of</strong> 10 percent or more <strong>of</strong>f standard prices are as attractive to them as they are to you.<br />
How many relatively unknown companies vie for your supply business? Advertisements come through your <strong>of</strong>fice<br />
on a daily basis, and staff members collect these ads to make choices about the company from which to order.<br />
Do you routinely meet with the staff member in charge <strong>of</strong> ordering to review and confirm the brands and prices<br />
<strong>of</strong> the products? Does this staff member know the necessity <strong>of</strong> confirming that the distributor is an authorized<br />
dealer? It is doubtful that in an organized <strong>of</strong>fice, in which the dentist has delegated responsibility to staff members,<br />
that the dentist and the staff member who orders supplies meet to discuss product ordering. In my opinion,<br />
such a meeting would reduce or eliminate the problem <strong>of</strong> gray-market and counterfeit product proliferation.<br />
It is time for every dentist to hold these meetings.<br />
I suggest that on a scheduled basis, the dentist and the staff member ordering supplies meet to determine<br />
desired brands and needed quantities <strong>of</strong> these brands <strong>of</strong> products. Before the meeting, the staff member can<br />
collect information about the various companies from which specific categories <strong>of</strong> products are available and<br />
have the information ready for the dentist’s review at the meeting. This preparation will reduce the time needed<br />
for the meeting, which can be brief.<br />
Manufacturers sell their products either directly to you or through their authorized distributors and dealer<br />
partners. Ordering only from known, authorized retailers will ensure that the products are legitimate and from<br />
respected manufacturers.<br />
All major manufacturers have lists <strong>of</strong> authorized distributors available. If you have a question about the legitimacy<br />
<strong>of</strong> a discounting distributor, you can verify that the distributor is an authorized retailer by contacting the<br />
product’s manufacturer.<br />
Purchasing from the major U.S. distributors such as Benco <strong>Dental</strong>, Burkhart <strong>Dental</strong> Supply, Darby <strong>Dental</strong><br />
Supply, Goetze <strong>Dental</strong>, Henry Schein and Patterson <strong>Dental</strong> helps ensure that the supplies are legitimate, and<br />
covered by warranties and manufacturer support. <strong>The</strong>re are other reasons I prefer to purchase from these<br />
major distributors. By doing so, I know that in spite <strong>of</strong> <strong>of</strong>ten paying somewhat more for some items, I have<br />
their repair support. Additionally, I can ask their local sales representatives about the properties <strong>of</strong> specific<br />
products and the acceptance or rejection that products are receiving in my community.<br />
Are You Using “Gray-Market” or Counterfeit <strong>Dental</strong> Products?17
HOW DO YOU IDENTIFY GRAY-MARKET<br />
OR COUNTERFEIT PRODUCTS?<br />
<strong>The</strong>re are several ways to identify potentially gray-market or counterfeit dental supplies.<br />
Low price. <strong>The</strong> product is selling for significantly below the known market price. You may determine the market<br />
price by looking in the online or printed catalogs <strong>of</strong> the major dental retailers noted earlier.<br />
Unknown distributor name. You know the major retailers, and you know the major private-label independent<br />
companies that do not sell via the major retailers. If the company selling the product does not have a recognizable<br />
name, you have reason to be suspicious. Do some homework to learn about the supplier, particularly if you are<br />
purchasing online, before you make a purchase decision.<br />
Suspicious packaging. If you attend a dental meeting and see a significantly discounted apparently identifiable<br />
product, you should consider the following relatively easily observable characteristics. Examine the printing on<br />
the package. Is it smeared, irregular, uneven or not <strong>of</strong> the quality you have previously observed on packaging<br />
<strong>of</strong> products with the same brand name? Is the product name current or a previous name you remember from an<br />
earlier version <strong>of</strong> the product? Is the bar code or any aspect <strong>of</strong> the product description blocked out? Is the product<br />
marked “For export only” or “Not registered for sale in the European Union or United States”? Be sure the label on<br />
the product matches the product name on the directions for use. Is the language on the package something other<br />
than English?<br />
Check the expiration date. Is the product expired? Does it appear that the expiration date has been changed?<br />
If you become suspicious <strong>of</strong> a product while attending a convention, go to a known authorized distributor <strong>of</strong> the<br />
brand in question, examine its packaging and ascertain the price <strong>of</strong> the product. You may see an immediately<br />
apparent difference.<br />
ACTIONS TO TAKE RELATIVE TO<br />
GRAY-MARKET AND COUNTERFEIT SUPPLIES<br />
I suggest the following preventive actions to avoid the problems potentially related to purchasing gray-market<br />
or counterfeit products.<br />
Use authorized distributors. If you have any question about the legitimacy <strong>of</strong> a distributor, call the manufacturer<br />
and request a verification <strong>of</strong> the distributor’s authenticity.<br />
Expect to pay a fair market price for products. Authorized distributors <strong>of</strong>fer occasional price reductions as<br />
specials. However, brand-name products have an expected fair price that does not vary significantly among<br />
distributors.<br />
Avoid deeply discounted prices. If the price is too good to be true, you probably are looking at a suspect<br />
product.<br />
Investigate. If you have questions about any product, have your staff investigate the retailing company by<br />
visiting the manufacturer company’s website and comparing the image and description <strong>of</strong> the product in<br />
question with the manufacturer’s information. Most manufacturing companies feature images <strong>of</strong> their products<br />
on their websites.<br />
In addition, dental manufacturers themselves are taking steps to prevent gray-market or counterfeit products.<br />
18 www.chairsidemagazine.com
<strong>The</strong>y are using new types <strong>of</strong> labeling to facilitate the identification <strong>of</strong> gray-market and counterfeit products. When these<br />
products are identified, the manufacturers are taking action against the vendors to remove them from the market.<br />
SUMMARY<br />
As verified by dental manufacturers, there is no question that gray-market and counterfeit products are being<br />
distributed and sold on the U.S. dental market. “Buyer-beware” policies should prevail in dental <strong>of</strong>fices. Dentists<br />
should meet with and assist <strong>of</strong>fice staff members in selecting products and identifying authorized product distributors.<br />
Questionable products and unknown, unauthorized distributors should be avoided. Although discounted dental<br />
products are available, the cost <strong>of</strong> overcoming the potential problems for patients caused by inferior products can<br />
be far greater than the amount saved. CM<br />
<strong>Dr</strong>. <strong>Gordon</strong> <strong>Christensen</strong> is the director <strong>of</strong> Practical Clinical Courses and c<strong>of</strong>ounder <strong>of</strong> the nonpr<strong>of</strong>it <strong>Gordon</strong> J. <strong>Christensen</strong> CLINICIANS REPORT ® . Contact him at<br />
801-226-6569 or info@pccdental.com.<br />
REFERENCES<br />
1. Santerre P, Conn A, Teitelbaum B. Toronto Academy <strong>of</strong> Dentistry winter clinic panel discussion on gray-market and counterfeit dental materials.<br />
J Can Dent Assoc. 2008;74(3):233–35.<br />
2. Lewis K. China’s counterfeit medicine trade booming. Can Med Assoc J. 2009;181(10):E237–38.<br />
3. Gautam CS, Utreja A, Singal GL. Spurious and counterfeit drugs: a growing industry in the developing world. Postgrad Med J. 2009;85(1003):251–56.<br />
4. Schweim JK, Schweim HG. Internet pharmacies and counterfeit drugs (in German). Med Klin (Munich). 2009;15;104(2):163–69.<br />
<strong>Christensen</strong> GJ. Are you using “gray-market” or counterfeit dental products? JADA. 2010;141(6):712–15. Copyright ©2010 American <strong>Dental</strong> Association.<br />
All rights reserved. Reprinted by permission.<br />
Are You Using “Gray-Market” or Counterfeit <strong>Dental</strong> Products?19
Monolithic Versus<br />
Bilayered Restorations:<br />
A Closer<br />
– ARTICLE and CLINICAL PHOTOS by<br />
Gregg Helvey, DDS, MAGD<br />
Abstract<br />
<strong>The</strong> all-ceramic crown was developed in the early 20th century when Charles H. Land patented the allporcelain<br />
“jacket” crown to improve esthetics. This procedure consisted <strong>of</strong> rebuilding the missing tooth<br />
with a porcelain covering, or “jacket” as Land called it. To solve the product’s strength problems, Abraham<br />
Weinstein in the late 1950s introduced a metal core to which porcelain was fused, thus creating the<br />
ceramo-metal crown. Throughout the years, the metal has been substituted with different materials to<br />
achieve a more esthetic result. Problems have been reported with the fusion between the ceramic and the<br />
core, which have resulted in debonding <strong>of</strong> the veneered ceramic. Further investigations in dental material<br />
science have produced tremendous advances in unveiling aspects that have been taken for granted, such<br />
as the bond strength between different materials that comprise the crown restoration. Recently, a lithium<br />
disilicate material that was once used solely as a core material was introduced as an all-ceramic alternative.<br />
This article discusses the strength factors that comprise a monolithic and bilayered ceramic restoration.<br />
Monolithic Versus Bilayered Restorations21
Advances in the field<br />
<strong>of</strong> dental ceramics<br />
can take time to find<br />
acceptance in the dental<br />
community. Ceramic materials<br />
are usually employed in<br />
higher-end procedures, and<br />
the clinician is compelled to<br />
deliver a product that has a<br />
proven durable and esthetic<br />
track record. Materials and<br />
procedures must have the<br />
science behind them and<br />
the endorsement <strong>of</strong> leading<br />
clinicians before being introduced.<br />
Only then can these<br />
materials become part <strong>of</strong><br />
the dentist’s restorative armamentarium.<br />
For years, the ceramo-metal<br />
restoration has been the<br />
gold standard in crown &<br />
bridge procedures. Although<br />
durable and time-tested, this<br />
type <strong>of</strong> restoration may not<br />
be the most esthetic. For<br />
years, patients have asked<br />
for metal-free restorations,<br />
and the industry has accommodated<br />
this request with<br />
various resin composite and<br />
ceramic systems.<br />
<strong>The</strong>se newer systems have an effect on the actual fabrication<br />
methods. Traditionally, the ceramo-metal restoration<br />
is constructed by casting a metal coping and applying<br />
a porcelain opaque layer followed by layering veneering<br />
porcelain. Newer methods have bypassed the coping<br />
fabrication step. Using a vacuum-pressing system, allceramic<br />
restorations are waxed to full contour and<br />
invested, wax burnt out and hot-pressed, creating a solid<br />
ceramic restoration. <strong>The</strong> question remains if these allceramic<br />
monolithic forms can endure the rigors <strong>of</strong> an<br />
intraoral restoration as well as the bilayered porcelain-tometal<br />
kind.<br />
All-Ceramic Crowns: Bilayered Versus Monolithic<br />
Numerous bilayered crown systems that are supported<br />
by a substructure core are available. Various materials are<br />
used to create these substructures, e.g., metal alloys, alumina<br />
and zirconia. Often, ceramo-metal crowns have been<br />
used because <strong>of</strong> their strength, biocompatibility and esthetics.<br />
1 Patient demand for more esthetic restorations has<br />
Figure 1: For several decades, the ceramo-metal crown<br />
has been the “workhorse” restoration.<br />
Figure 2: Anterior ceramo-metal crowns display the less<br />
esthetic opacity that is sometimes evident in metal-substructure<br />
restorations.<br />
gradually increased, leading<br />
to greater use <strong>of</strong> nonmetallic,<br />
high-strength core materials.<br />
<strong>The</strong>se esthetic core materials<br />
include alumina, zirconia,<br />
zirconia-toughened alumina,<br />
magnesium aluminate spinel<br />
and lithium disilicate. Once<br />
the cores are fabricated, the<br />
laboratory technician applies<br />
veneering porcelain to create<br />
the final esthetic restoration.<br />
2,3 Yet all <strong>of</strong> these porcelain-laminated<br />
systems share<br />
a common mode <strong>of</strong> failure:<br />
fracture <strong>of</strong> the veneering<br />
ceramic from its core.<br />
<strong>The</strong>re are three basic configurations<br />
for restorative<br />
crowns: bilayered ceramometal,<br />
bilayered ceramozirconia<br />
and monolithic<br />
lithium disilicate. While numerous<br />
studies are cited<br />
in the literature, specific<br />
comparative tests uniformly<br />
conducted on all three<br />
systems are difficult to find.<br />
<strong>The</strong> testing methods, sample<br />
sizes and the instrumentation<br />
used in the studies are<br />
variables that must be considered.<br />
<strong>The</strong>refore, strength comparisons <strong>of</strong> different<br />
studies can be misleading. However, after reviewing the<br />
body <strong>of</strong> literature, a different perspective may be gained<br />
as to the overall strength <strong>of</strong> each system, rather than one<br />
particular asset.<br />
Ceramo-Metal Restorations<br />
Through the years, replacement and reinforcement<br />
<strong>of</strong> the human tooth has evolved from a monolithic design<br />
(gold crown) to a bilayered design (ceramo-metal<br />
and ceramo-zirconia) and again to a monolithic design<br />
(lithium disilicate/full zirconia). In the past several<br />
decades, the workhorse restoration is the ceramo-metal<br />
crown: a metal substructure in which ceramic material<br />
is layered or pressed to form the anatomic shape <strong>of</strong><br />
the restoration (Figs. 1, 2). <strong>The</strong> weakest point is the<br />
ceramo-metal interface. <strong>The</strong> exact mechanism <strong>of</strong> porcelain-to-metal<br />
fusion is unknown; however, at least four<br />
theories have been discussed.<br />
22 www.chairsidemagazine.com
1. <strong>The</strong> theory <strong>of</strong> van der<br />
Waals forces 4 refers to the<br />
bonding <strong>of</strong> materials created<br />
by the attraction <strong>of</strong> charged<br />
atoms that do not exchange<br />
electrons. <strong>The</strong>se secondary<br />
forces are generated more<br />
by a physical attraction between<br />
charged particles than<br />
by an actual sharing or exchange<br />
<strong>of</strong> electrons in primary<br />
(chemical) bonding. 5<br />
2. <strong>The</strong> theory <strong>of</strong> mechanical<br />
retention <strong>of</strong> ceramic to<br />
a metal coping is derived<br />
from the microscopic irregularities.<br />
<strong>The</strong> contribution <strong>of</strong><br />
micromechanical bonding<br />
may be relatively limited because<br />
ceramic does not require<br />
a roughened area to<br />
bond. 5 Lacy 4 has shown that<br />
ceramic will fuse to a wellpolished<br />
metal surface; however,<br />
some surface roughness<br />
does contribute to an<br />
increased bond. 6–8 <strong>The</strong>refore,<br />
mechanical retention alone<br />
is probably not sufficient to<br />
entirely explain how dental<br />
ceramic adheres to a metal<br />
substrate. 5<br />
3. Bonding <strong>of</strong> porcelain to metal by means <strong>of</strong> compression<br />
is the third theory. <strong>Dental</strong> porcelain, like most brittle<br />
materials, is strong in compression but relatively weak<br />
when subjected to tensile stresses. Its tensile strength<br />
is approximately 4 percent <strong>of</strong> its compressive strength. 9<br />
Compressive stress in the layering porcelain reinforces<br />
the fracture strength. A thermal mismatch between<br />
the coping and the porcelain leads to compressive or<br />
tensile stress depending on whether the coefficient<br />
<strong>of</strong> thermal expansion <strong>of</strong> the porcelain is higher or<br />
lower than that <strong>of</strong> the coping. 10 <strong>The</strong> expansion <strong>of</strong> the<br />
porcelain must be lower than that <strong>of</strong> the coping to<br />
generate compressive stress during cooling. 11 <strong>The</strong><br />
development <strong>of</strong> compressive forces in the porcelain and<br />
tensile forces in the metal is due to the difference in contraction<br />
rates.<br />
4. Chemical bonding is the final generally accepted theory<br />
as the primary mechanism <strong>of</strong> ceramic-to-metal attachment.<br />
12–14 <strong>The</strong> mode <strong>of</strong> bonding involves the metal surface<br />
Figure 3: Ceramo-metal failures are multifactorial and<br />
can be related to a combination <strong>of</strong> reasons.<br />
<strong>The</strong> literature cites studies<br />
observing various ceramometal<br />
failures. Failure<br />
rates range between<br />
5 percent and 10 percent<br />
over 10 years.<br />
oxides dissolved by the applied<br />
ceramic opaque layer.<br />
This results in an atomic contact,<br />
whereby shared electrons<br />
form ionic and covalent<br />
bonds between the oxide layer<br />
on the metal surface and<br />
the ceramic opaque layer. 12,13<br />
Ceramo-Metal Failures<br />
<strong>The</strong> literature cites studies<br />
observing various ceramometal<br />
failures. Failure rates<br />
range between 5 percent and<br />
10 percent over 10 years. 15<br />
Strub et al. found failure<br />
rates <strong>of</strong> ceramo-metal restorations<br />
as high as 3 percent<br />
over five years. 16 Hankinson<br />
and Cappetta 17 and Kelsey<br />
et al. 18 found a failure rate<br />
between 2 percent and<br />
4 percent that occurred after<br />
two years. <strong>The</strong>y also<br />
found that, due to a repetition<br />
<strong>of</strong> consistent occlusal<br />
contacts, after four to five<br />
years the failure rate rose to<br />
20 percent to 25 percent.<br />
A ceramo-metal failure is a<br />
multifactorial problem related<br />
to a combination <strong>of</strong> reasons 1 (Fig. 3). Some studies<br />
attribute failures to environmental factors, particularly<br />
moisture. A moist environment was found to reduce the<br />
ceramo-metal strength by 20 percent to 30 percent. 19 In<br />
the presence <strong>of</strong> moisture, the silicon-oxygen bond between<br />
metal and ceramic weakens and promotes failure<br />
because <strong>of</strong> water propagation at the crack tip. 20 Most<br />
frequently, ceramic failures are related to the cracks in<br />
the ceramic. 1 Small scratches on the ceramic surface can<br />
act as notches where the concentration <strong>of</strong> stress can exceed<br />
the theoretical strength <strong>of</strong> the ceramic. As the crack<br />
propagates through the material, the stress concentration<br />
is maintained at the crack tip until the crack moves<br />
completely through the material. 21<br />
Technical errors in the laboratory can also account for<br />
ceramo-metal failures. A void or pore that remains after<br />
the fabrication can be the site <strong>of</strong> weakness and eventual<br />
failure. 22 Porosity does occur between ceramic particles<br />
during the ceramic application, and the technician should<br />
make every effort to minimize this.<br />
Monolithic Versus Bilayered Restorations23
Diaz-Anold et al. found several<br />
reasons for failure, including<br />
faulty metal structure<br />
design and incompatible coefficients<br />
<strong>of</strong> thermal expansion<br />
between the metal and<br />
the ceramic material. 23<br />
Another reason was insufficient<br />
metal support for the<br />
ceramic, leading to unsupported<br />
excessive thickness<br />
<strong>of</strong> ceramic, technical flaws<br />
in the porcelain application,<br />
and occlusal forces or trauma.<br />
Ceramic material properties,<br />
including microstructure,<br />
crack length, fracture<br />
toughness and applied stress<br />
intensity, also contribute to<br />
failure. 23<br />
Usually, a catastrophic failure<br />
is the result <strong>of</strong> crack<br />
initiation and propagation.<br />
Llobell et al. described reasons<br />
for intraoral ceramic<br />
failure: impact load, fatigue<br />
load, improper design and<br />
microdefects within the material.<br />
<strong>The</strong>y also found that<br />
masticatory repetitive forces,<br />
including parafunctional<br />
occlusion, created alternating<br />
forces, contributing to<br />
the fatigue <strong>of</strong> ceramo-metal<br />
restorations. 24 Typically, one<br />
factor alone does not cause<br />
ceramo-metal catastrophes;<br />
rather, the cumulative effect<br />
<strong>of</strong> a large number <strong>of</strong> comparatively<br />
small loadings<br />
leads to failure. 1<br />
Bond Strength <strong>of</strong><br />
Porcelain to Metal<br />
<strong>The</strong> ideal test to determine the bond strength between<br />
ceramics and metal does not exist, although several<br />
methods have been used. 25 Several tests have been employed<br />
to evaluate the ceramo-metal bond strength 26 :<br />
shear test (maximum stress that a material can withstand<br />
before failure in shear), 27 planar shear test (opposing forces<br />
are applied parallel to the cross-sectional area under<br />
test), 25 tensile, 28 flexural 29 and torsional strength. 30 Chong<br />
Figure 4: Before the zirconia substructure is placed on<br />
a solid working model, the separating medium has been<br />
applied prior to wax application.<br />
Sufficient bond strength<br />
between veneering<br />
ceramic and zirconia<br />
framework substructures<br />
is a concern for longterm<br />
success. Chipping<br />
<strong>of</strong> the veneering ceramic<br />
constitutes clinical failure<br />
and has been reported<br />
to occur at a rate <strong>of</strong> 13<br />
percent during a threeyear<br />
observation.<br />
and Beech 27 proposed the<br />
circular-planar surface shear<br />
test, which provided standardization<br />
and ease in specimen<br />
fabrication. 31<br />
Scolaro et al. 26 tested different<br />
ceramics that were<br />
bonded to a palladium-silver<br />
alloy (Pors-On 4; DENTSP-<br />
LY Ceramco; Burlington,<br />
N.J.). <strong>The</strong>y used Ceramco<br />
(DENTSPLY), Noritake Super<br />
Porcelain EX-3 (Cincinnati,<br />
Ohio) and VITA VMK ®<br />
68 (Vident; Brea, Calif.).<br />
<strong>The</strong> shear bond strength<br />
results were: Noritake<br />
(28.96 MPa ± 6.92 MPa),<br />
Ceramco (28.20 MPa ±<br />
8.65 MPa) and VITA VMK 68<br />
(24.11 MPa ± 6.27 MPa).<br />
Akova et al. 32 compared the<br />
bond strength <strong>of</strong> layering<br />
porcelain to cast Ni-Cr and<br />
Co-Cr alloys to laser-sintered<br />
Co-Cr alloy. In this study, the<br />
mean shear bond strength<br />
was the highest for the base<br />
metal Ni-Cr (81.6 MPa ±<br />
14.6 MPa) and slightly less for<br />
the Co-Cr base metal<br />
(72.9 MPa ± 14.3 MPa). <strong>The</strong><br />
shear bond strength <strong>of</strong> the<br />
laser-sintered Co-Cr metal<br />
was 67 MPa ± 14.9 MPa.<br />
Joias et al. 31 tested the shear<br />
bond strength <strong>of</strong> a ceramic<br />
to five commercially available<br />
Co-Cr alloys. <strong>The</strong> same<br />
ceramic (VITA Omega 900,<br />
Vident) was bonded to<br />
each alloy. <strong>The</strong> shear bond<br />
strength test was performed<br />
in a universal testing machine with a crosshead speed <strong>of</strong><br />
0.5 mm/min. <strong>The</strong> ultimate shear bond strength ranged<br />
from 61 MPa to 96 MPa.<br />
According to Powers and Sagaguchi, 26 an adequate bond<br />
occurs when the fracture strength or fracture stress<br />
(the stress at which a brittle material fractures) is above<br />
25 MPa. Other studies also have accepted a sufficient bond<br />
for metal-ceramics when the fracture stress is greater<br />
24 www.chairsidemagazine.com
than 25 MPa. 1,33–35 Because<br />
this value represents the<br />
limit <strong>of</strong> the test, it could be<br />
argued whether this were a<br />
true representation <strong>of</strong> adequacy.<br />
36 As previously noted,<br />
some ceramo-metal systems<br />
in other studies have tested<br />
higher.<br />
A recently introduced laboratory<br />
method <strong>of</strong> ceramic application<br />
to metal is the use<br />
<strong>of</strong> the lost-wax technique, in<br />
which a pressable ceramic is<br />
applied to an opaque metal<br />
or zirconia core (Figs. 4–7).<br />
This is a simpler and quicker<br />
method than the conventional<br />
technique and eliminates<br />
the need for the 20 percent<br />
shrinkage compensation with<br />
traditional porcelain firing. 37<br />
Venkatachalam et al. 38 compared<br />
the debond/crack<br />
initiation strength <strong>of</strong> a leucite-based<br />
low-fusing ceramic-pressed-to-metal<br />
and<br />
feldspathic porcelain-fusedto-metal.<br />
<strong>The</strong> metal specimens<br />
included gold-palladium<br />
alloy and chrome-cobalt<br />
base metal alloy divided into<br />
two groups <strong>of</strong> 20 samples.<br />
<strong>The</strong> mechanical testing method<br />
used in this study was the<br />
Schwickerath crack-initiation<br />
three point bending test standardized<br />
by the International Organization for Standardization<br />
(ISO), 39 which is now considered the gold standard<br />
for examining metal-ceramic bond strength. 38 <strong>The</strong>ir<br />
findings showed a mean debond strength for feldspathic<br />
porcelain to the base metal alloy <strong>of</strong> 36.11 MPa ± 2.31 MPa,<br />
while the feldspathic porcelain to the gold-palladium<br />
alloy demonstrated a mean bond strength <strong>of</strong> 42.64 MPa<br />
± 1.94 MPa. For the ceramic-pressed-to-metal specimens,<br />
the mean debond strength <strong>of</strong> the base metal combination<br />
was 37.47 MPa ± 6.02 MPa and 47.94 MPa ± 3.92 MPa for<br />
the gold-palladium samples.<br />
Ceramo-Zirconia Failures<br />
<strong>The</strong> actual mechanism <strong>of</strong> bonding ceramic to zirconia<br />
substructures is not completely understood, nor is the<br />
Figure 5: After wax is injected onto the zirconia substructure,<br />
the margins are refined on the removable die.<br />
Figure 6: <strong>The</strong> undersurface <strong>of</strong> a single zirconia-based<br />
crown after the waxing phase is completed<br />
manipulation <strong>of</strong> surface<br />
treatment <strong>of</strong> zirconia in the<br />
quality <strong>of</strong> the bond. 40–42 Sufficient<br />
bond strength between<br />
veneering ceramic and zirconia<br />
framework substructures<br />
is a concern for long-term<br />
success. 10 Chipping <strong>of</strong> the<br />
veneering ceramic constitutes<br />
clinical failure and has<br />
been reported to occur at<br />
a rate <strong>of</strong> 13 percent during<br />
a three-year observation. 43<br />
In a follow-up study, Sailer<br />
et al. found the failure rate<br />
increased to 15.2 percent<br />
during a five-year period. 44<br />
One approach to enhancing<br />
ceramic-to-zirconia bond<br />
strength is sandblasting,<br />
which increases the surface<br />
roughness and provides<br />
undercuts. 38–40 Conversely,<br />
Kosmac et al. 45 and Guazzato<br />
et al. 46 found sandblasting<br />
adversely affects the mechanical<br />
strength <strong>of</strong> the zirconia<br />
by initiating a phase transition<br />
(tetragonal to monoclinic<br />
form) and probably has<br />
a detrimental effect on the<br />
bonding capacity. This phase<br />
transition <strong>of</strong> tetragonal zirconia<br />
to monoclinic zirconia<br />
results in a significantly<br />
lower coefficient <strong>of</strong> thermal<br />
expansion.<br />
Fischer et al. 47 investigated the effect <strong>of</strong> different surface<br />
treatments on the bond strength <strong>of</strong> veneering ceramics<br />
to zirconia. <strong>The</strong>ir study assessed the influence <strong>of</strong> treating<br />
the zirconia surface by polishing, sandblasting, silica<br />
coating and applying a liner. <strong>The</strong>y also studied the impact<br />
<strong>of</strong> regeneration firing, which entails firing the zirconia<br />
framework for 15 minutes at 1,000 degrees Celsius<br />
prior to veneering. This re-establishes the tetragonal lattice<br />
after sandblasting or grinding to obtain better bond<br />
strength. 48 Five different layering ceramics were used.<br />
<strong>The</strong> shear strength <strong>of</strong> all the types <strong>of</strong> surface conditions<br />
was 23.5 MPa ± 3.4 MPa to 31 MPa ± 7.1 MPa. In all specimens,<br />
the fracture started at the core-veneer interface<br />
and continued into the veneering ceramic, which<br />
remained on the core. <strong>The</strong> weakest link was not the<br />
Monolithic Versus Bilayered Restorations25
interface, but the veneering<br />
ceramic itself. This study<br />
concluded that increased<br />
surface roughness did not<br />
enhance shear strength, the<br />
application <strong>of</strong> a liner did not<br />
improve shear strength, and<br />
regeneration firing decreased<br />
the shear strength. <strong>The</strong> recommendation<br />
to realize the<br />
benefit <strong>of</strong> high-strength zirconia<br />
as a framework was<br />
to strengthen the veneering<br />
ceramic.<br />
Although the zirconia substructure<br />
is fracture-resistant,<br />
a high percentage <strong>of</strong> failures<br />
<strong>of</strong> the ceramo-zirconia restoration<br />
are found in ceramic<br />
chipping and delamination.<br />
49–51<br />
A randomized, controlled<br />
clinical trial showed the performance<br />
<strong>of</strong> 3-unit posterior<br />
prostheses using three ceramo-metal<br />
fabrication methods<br />
and five major companies’<br />
zirconia technologies. 52<br />
<strong>The</strong> researchers evaluated<br />
the framework and the veneering<br />
ceramics. <strong>The</strong> report<br />
showed veneering ceramic<br />
fractures were five times<br />
more prevalent with ceramic<br />
formulations used on zirconia<br />
versus those employed<br />
on metal.<br />
In another study, Taskonak<br />
et al. 53 determined the site<br />
<strong>of</strong> crack initiation and the<br />
causes <strong>of</strong> fracture in failed<br />
zirconia-based ceramic fixed<br />
partial dentures. Fractures<br />
that had origins on the ceramic<br />
veneer surface had<br />
failure stresses between 31<br />
MPa and 38 MPa.<br />
Figure 7: Facial view <strong>of</strong> the finished restoration<br />
Aboushelib et al. 54 stated that the bond strength between<br />
veneer ceramic and the zirconia framework is the weakest<br />
component in the layered structure. To enhance the final<br />
esthetics <strong>of</strong> layered zirconia-based restorations, colored<br />
<strong>The</strong> lithium disilicate<br />
microstructure has<br />
numerous small<br />
interlocking plate-like<br />
crystals … This crystal<br />
size and orientation<br />
causes cracks to deflect,<br />
branch or blunt, which can<br />
account for the increase<br />
in flexural strength and<br />
fracture toughness<br />
compared to leucitereinforced<br />
ceramics.<br />
pigments are incorporated<br />
into the surface <strong>of</strong> the zirconia<br />
framework (Fig. 8).<br />
<strong>The</strong> objective <strong>of</strong> this study<br />
was to investigate the effect<br />
<strong>of</strong> zirconia type (white or<br />
colored) and its surface finish<br />
on the bond strength to<br />
two veneer ceramics. <strong>The</strong>y<br />
found the addition <strong>of</strong> coloring<br />
pigments resulted in a<br />
significantly weaker bond<br />
strength compared to the<br />
white zirconia frameworks.<br />
In a comparative study,<br />
Guess et al. 55 evaluated the<br />
shear bond strength between<br />
various commercial zirconia<br />
core and veneering ceramics<br />
and the effect <strong>of</strong> thermocycling.<br />
Using the Schmitz–<br />
Schulmeyer test method,<br />
they evaluated the coreveneer<br />
shear bond strength<br />
<strong>of</strong> Cercon ® base to Cercon<br />
Ceram S; VITA In-Ceram ®<br />
YZ cubes to VITA VM9; and<br />
DC-Zirkon to IPS e.max ®<br />
Ceram (Ivoclar Vivadent;<br />
Amherst, N.Y.). As a control<br />
specimen, they used<br />
a ceramo-metal system,<br />
DeguDent U94 (DeguDent,<br />
a DENSTPLY Company)<br />
to VITA VM13. Half <strong>of</strong><br />
each specimen group was<br />
thermocycled at 5 degrees<br />
Celsius to 55 degrees Celsius<br />
for 20,000 cycles. <strong>The</strong>ir<br />
results demonstrated the<br />
shear bond strength values<br />
<strong>of</strong> 12.5 MPa ± 3.2 MPa for<br />
VITA In-Ceram YZ Cubes/<br />
VITA VM9, 11.5 MPa ±<br />
3.4 MPa for DC-Zirkon/<br />
IPS e.max Ceram and 9.4 MPa ± 3.2 MPa for Cercon<br />
base/Cercon Ceram S. <strong>The</strong> specimens that were thermocycled<br />
did not show any significant differences.<br />
<strong>The</strong> control ceramo-metal specimen showed a higher<br />
shear bond strength, regardless <strong>of</strong> thermocycling, <strong>of</strong><br />
27.6 MPa ± 12.1 MPa.<br />
26 www.chairsidemagazine.com
Monolithic Restorations:<br />
Lithium Disilicate<br />
<strong>The</strong> first all-ceramic restorative<br />
system was introduced<br />
in 1903 by Charles Land. 56<br />
<strong>The</strong> so-called porcelain<br />
“jacket” crown was fabricated<br />
with high-fusing feldspathic<br />
porcelain. Although it was<br />
noted for natural esthetics,<br />
the failure rate was high,<br />
probably due to the low<br />
strength <strong>of</strong> the porcelain.<br />
57 Interest in all-ceramic<br />
restorations has grown<br />
throughout the years.<br />
Developments have included<br />
several bilayered systems consisting <strong>of</strong> a ceramic-type substructure<br />
interfaced with a veneering ceramic.<br />
Recently, a monolithic approach was introduced using<br />
lithium disilicate glass ceramic (e.g., IPS e.max Press and<br />
IPS e.max CAD). This material has two forms: a homogeneous<br />
ingot with various degrees <strong>of</strong> opacity used with<br />
hot-pressed technology and a pre-crystallized block used<br />
with CAD/CAM technology. Both forms can be used in a<br />
full anatomical contour method with the application <strong>of</strong><br />
stain and glaze or a cutback and layering technique.<br />
<strong>The</strong> CAD milling blocks are produced for distribution<br />
using a glass technology. This process prevents the<br />
formation <strong>of</strong> defects and voids throughout the block and<br />
allows for an even distribution <strong>of</strong> the pigmentation. This<br />
partial crystallization process forms lithium-metasilicate<br />
crystals, which provide sufficient strength for milling.<br />
According to the manufacturer, the partially crystallized<br />
milling block has a microstructure consisting <strong>of</strong> 40 percent<br />
lithium-metasilicate crystals, which are embedded<br />
in a glassy matrix. <strong>The</strong> grain size <strong>of</strong> these crystals<br />
ranges from 0.2 μm to 1 μm. At this point, the lithium<br />
metasilicate block has a flexural strength <strong>of</strong> 130 MPa,<br />
which is comparable to leucite-reinforced CAD/CAM<br />
blocks (ProCAD, Ivoclar Vivadent) and feldspathic<br />
CAD/CAM blocks (Vitablocs ® Mark II, Vident). 58 After<br />
milling, the pre-crystallized restoration is placed in the<br />
mouth and adjusted, if necessary. <strong>The</strong> restoration is then<br />
crystallized during a 20-minute firing cycle using a twostep<br />
ceramic furnace. Because the restoration can be<br />
milled to full contour, there is no ceramic infiltration<br />
process or veneering process. <strong>The</strong> restoration shrinks<br />
0.2 percent during crystallization, which the computer<br />
s<strong>of</strong>tware accounts for during the milling process. During<br />
the crystallization cycle, the lithium-metasilicate restoration<br />
reaches a temperature <strong>of</strong> 840 degrees Celsius to<br />
Figure 8: A shade base stain is applied to the zirconia<br />
framework and fired prior to application <strong>of</strong> the veneering<br />
porcelain.<br />
850 degrees Celsius. During<br />
the temperature rise, a<br />
controlled growth <strong>of</strong> lithium<br />
disilicate crystals occurs,<br />
producing a transformation<br />
<strong>of</strong> the microstructure that<br />
results in an increase <strong>of</strong> the<br />
final flexural strength <strong>of</strong> 360<br />
MPa. This flexural strength is<br />
approximately three to four<br />
times stronger than leucitereinforced<br />
glass ceramics. 59<br />
This glass ceramic is comprised<br />
<strong>of</strong> 70 percent prismatic<br />
lithium disilicate crystals (0.5<br />
μm to 5 μm long) dispersed<br />
in a glassy matrix. 26 <strong>The</strong> lithium<br />
disilicate microstructure has numerous small interlocking<br />
plate-like crystals randomly oriented. This crystal<br />
size and orientation causes cracks to deflect, branch<br />
or blunt, which can account for the increase in flexural<br />
strength and fracture toughness compared to leucite-reinforced<br />
ceramics. 60<br />
<strong>The</strong> manufacturer’s internal testing (Ivoclar Vivadent,<br />
unpublished data, 2005) states the fracture toughness<br />
(single-edge, V-notched beam testing) to be 2 MPa to 2.5<br />
MPa m ½ and a modulus <strong>of</strong> elasticity <strong>of</strong> 95 GPa ± 5 GPa.<br />
Bindl et al. 61 studied the fracture strength and fracture<br />
pattern <strong>of</strong> three monolithic posterior crowns (lithium<br />
disilicate, leucite glass and feldspathic ceramic) that have<br />
a uniform thickness <strong>of</strong> 1.5 mm. <strong>The</strong>y conventionally<br />
cemented one half <strong>of</strong> the specimens while adhesively cementing<br />
the other half on dies. For the conventionally<br />
cemented crowns, load to fracture was 2,082 N, which<br />
was significantly higher than that <strong>of</strong> the leucite glass or<br />
feldspathic ceramic. When the specimens were adhesively<br />
cemented to the die, the fracture load for the lithium<br />
disilicate rose to 2,389 N, which was comparable to the<br />
two other specimens. This study showed the strength <strong>of</strong><br />
the lithium disilicate when conventional cementing techniques<br />
are employed. A manufacturer’s internal study comparing<br />
the difference in failure load for monolithic and<br />
bilayered crowns showed adhesively retained monolithic<br />
lithium disilicate restorations had the highest load<br />
to failure numbers. 66,67<br />
<strong>The</strong> pressed form <strong>of</strong> the lithium disilicate has been shown<br />
to have a modulus <strong>of</strong> elasticity ranging from 91 GPa 64<br />
to 95 GPa ± 5 GPa (Ivoclar Vivadent, unpublished data,<br />
2009). <strong>The</strong> flexural strength varies depending on the testing<br />
method used. Using biaxial flexural strength tests<br />
under dry and wet conditions, Sorenson et al. 65 found a<br />
flexural strength ranging from 411.6 MPa to 455.5 MPa.<br />
Monolithic Versus Bilayered Restorations27
Albakry et al. 64 measured<br />
the biaxial strength with a<br />
universal testing machine.<br />
Twenty standardized disc<br />
specimens (14 mm by 1.1<br />
mm) were supported on<br />
three balls and loaded with a<br />
piston at a crosshead speed <strong>of</strong><br />
0.5 mm/min. until fracture.<br />
<strong>The</strong> mean biaxial strength for<br />
the lithium-disilicate specimen<br />
was 440 MPa ± 55 MPa.<br />
Depending on the testing<br />
method, fracture toughness<br />
<strong>of</strong> the lithium disilicate has<br />
been shown to be at least or<br />
greater than 3 MPa m ½ . Using<br />
the indentation strength<br />
technique, Guazzato et al. 66<br />
found a fracture toughness<br />
<strong>of</strong> 3 MPa m ½ . Albakry et<br />
al. 67 measured the fracture<br />
toughness <strong>of</strong> the pressed<br />
lithium disilicate using two<br />
different techniques: indentation<br />
fracture and indentation<br />
strength. <strong>The</strong>y reported<br />
a fracture toughness <strong>of</strong><br />
3.14 MPa and 2.5 MPa m ½ ,<br />
respectively.<br />
Veneering Ceramic for<br />
Lithium Disilicate<br />
<strong>The</strong> coefficient <strong>of</strong> thermal<br />
expansion <strong>of</strong> feldspathic<br />
glass is closely matched to<br />
alumina-based core material<br />
(~7 ppm/degrees Celsius to<br />
8 ppm/degrees Celsius) and,<br />
consequently, can be used as<br />
a veneering ceramic. Leucite<br />
layering ceramics have the<br />
same coefficient <strong>of</strong> thermal<br />
expansion as the leucite core<br />
material, therefore, posing<br />
no problems in coefficient<br />
mismatch. However, the coefficient<br />
<strong>of</strong> thermal expansion<br />
<strong>of</strong> lithium disilicate is<br />
greater than 10 ppm/degrees<br />
Celsius. As a result, a new<br />
compatible layering ceramic<br />
Comparison <strong>of</strong> the Flexural Strength <strong>of</strong> Pressed Ceramics<br />
Figure 9: Comparison <strong>of</strong> different crown combinations<br />
using different materials and monolithic lithium disilicate<br />
during a cyclic loading test.<br />
Restorative dentistry is<br />
the science and art <strong>of</strong><br />
replacing human tooth<br />
structure. <strong>The</strong> tooth is<br />
comprised <strong>of</strong> enamel and<br />
dentin, which individually<br />
are low-strength materials<br />
but, when combined,<br />
their bond is unique and<br />
can survive a lifetime.<br />
Technology has not been<br />
able to replicate nature’s<br />
bioengineering.<br />
was developed. 26 <strong>The</strong> layering<br />
material (IPS e.max<br />
Ceram) is a low-fusing nan<strong>of</strong>luorapatite<br />
glass ceramic. It<br />
can be used with either the<br />
pressed or CAD/CAM version<br />
<strong>of</strong> the lithium disilicate<br />
core and does not contain<br />
feldspar or leucite.<br />
<strong>The</strong> light refraction gives the<br />
lithium disilicate material<br />
a natural appearance and<br />
can be used in a monolithic<br />
form. In this state, the flexural<br />
strength remains throughout<br />
the entire restoration.<br />
Surface colorants are available<br />
to obtain the final shade<br />
and characterization.<br />
When in-depth characterization<br />
is desired, a partiallayering<br />
technique can also<br />
be employed. At this point,<br />
it can no longer be considered<br />
monolithic because it<br />
still comprises a majority<br />
<strong>of</strong> the structure compared<br />
to the zirconia-based restoration,<br />
in which the bulk<br />
<strong>of</strong> the restoration is the<br />
veneered ceramic. A manufacturer’s<br />
internal long-term<br />
cyclic loading study compared<br />
various restorative<br />
dental materials for crowns<br />
with monolithic lithium disilicate<br />
crowns with and without<br />
layered veneering porcelain.<br />
68 After 300,000 cycles,<br />
only the monolithic lithium<br />
disilicate restorations —<br />
regardless <strong>of</strong> whether layering<br />
veneer porcelain had<br />
been applied — did not<br />
show any breakdown (Fig. 9).<br />
Conclusion<br />
Restorative dentistry is the<br />
science and art <strong>of</strong> replacing<br />
human tooth structure. <strong>The</strong><br />
tooth is comprised <strong>of</strong> enamel<br />
and dentin, which individu-<br />
28 www.chairsidemagazine.com
ally are low-strength materials but, when combined, their bond is unique and can survive a lifetime. Technology has<br />
not been able to replicate nature’s bioengineering. For many decades, the ceramo-metal crown has been the mainstay<br />
<strong>of</strong> restorative dentistry. Recently, the zirconia-based ceramic restoration was introduced with better esthetics and core<br />
strength. Both systems are bilayered restorations with the bulk <strong>of</strong> the restoration consisting <strong>of</strong> a veneered feldspathic<br />
ceramic or a leucite-reinforced, low-fusing pressed ceramic. In either case, the strength is dependent on the bond<br />
strength at the interface between the core and its ceramic veneer. A new approach has been described in which a<br />
ceramic with excellent optical properties and high flexural strength can be used in a monolithic design. <strong>The</strong> resulting<br />
restoration possesses these qualities throughout its entirety as opposed to a restoration based on a bond between two<br />
dissimilar materials — the layering ceramic and the core — in which bond strength is less than the individual parts <strong>of</strong><br />
the crown. Because nature’s bilayered tooth structure cannot be replicated, a monolithic approach may be the future. CM<br />
Acknowledgments<br />
<strong>The</strong> author would like to thank Ruth Egl, RDH, for her editorial contribution and to acknowledge Kramer Helvey for<br />
his support.<br />
<strong>Dr</strong>. Gregg Helvey is an AGD Master and part <strong>of</strong> an elite group <strong>of</strong> dentists who are also skilled ceramists. Contact him at 540-687-5855, www.gregghelveydds.com or<br />
phident@gmail.com.<br />
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67. Albakry M, Guazzato M, Swain MV. Fracture toughness and hardness evaluation <strong>of</strong> three pressable all-ceramic dental materials. J Dent. 2003;31(3):181–88.<br />
68. Guess PC, Zavanelli R, Silva NR, Thompson VP. Clinically relevant testing <strong>of</strong> dental porcelains for fatigue and durability with an innovative mouth motion simulator.<br />
Presented at: 39th Annual Session <strong>of</strong> the American Academy <strong>of</strong> Fixed Prosthodontics. February 2009; Chicago, IL.<br />
Reprinted by permission <strong>of</strong> AEGIS Publications. Helvey G. Monolithic versus bilayered restorations: a closer look. Vistas Complete & Predictable Dentistry.<br />
2010;3(2 Supplement):16–23.<br />
30 www.chairsidemagazine.com
32 www.chairsidemagazine.com
Interview with <strong>Dr</strong>. David Hornbrook<br />
– INTERVIEW <strong>of</strong> David S. Hornbrook, DDS, FAACD<br />
by Michael C. DiTolla, DDS, FAGD<br />
It was my pleasure to interview one <strong>of</strong> my clinical mentors, <strong>Dr</strong>. David<br />
Hornbrook, for this issue <strong>of</strong> Chairside magazine. David is someone whom<br />
I have followed since I graduated from dental school, when I started taking<br />
his courses at Las Vegas Institute for Advanced <strong>Dental</strong> Studies (LVI),<br />
PAC~live and the Hornbrook Group. Over the years, I’ve continued to<br />
follow David and look up to him as a clinician and friend.<br />
Interview with <strong>Dr</strong>. David Hornbrook33
<strong>Dr</strong>. Michael DiTolla: Good morning, David, it’s wonderful to have you here<br />
with us.<br />
<strong>Dr</strong>. David Hornbrook: Thanks, it’s great to be included.<br />
IPS e.max has filled an<br />
existing void in dentistry.<br />
It is a highly esthetic<br />
material — as you mentioned,<br />
it approaches the<br />
esthetics <strong>of</strong> anything we<br />
have in dentistry right<br />
now — and it’s amazingly<br />
strong. We now have a<br />
ceramic that’s four times<br />
stronger than the ceramic<br />
we’ve put on PFMs for<br />
the last 60 years.<br />
MD: People always say, “Now is the best time to be a dentist.” (With perhaps the<br />
exception <strong>of</strong> the 1960s, before the air-driven handpiece was invented and everything<br />
was belt-driven.) But as I reflect on my more than 20 years in practice, it seems<br />
that things just continue to get better. Do you feel that 2011 is a great time to be<br />
practicing dentistry?<br />
DH: Absolutely. <strong>The</strong>re are two things we need to look at. One is, obviously,<br />
that the economy has changed a little bit. <strong>The</strong>re may be people reading this<br />
who say, “I’m not doing what I was doing two years ago in smile designs and<br />
discretionary dentistry.” But if we eliminate that aspect <strong>of</strong> it, this is the best<br />
time to be a dentist.<br />
<strong>The</strong> advantage <strong>of</strong> where we are now is that we are no longer faced with the<br />
many limitations and compromises we’ve historically faced during treatment<br />
planning. Materials are more esthetic, and adhesive dentistry has allowed us<br />
to be more conservative. Today, the only limitations we face are those <strong>of</strong> the<br />
clinician’s imagination.<br />
MD: Well, let’s back up to what you said about the economic slowdown. I can tell<br />
you that, at least from the lab’s perspective, the economic slowdown over the past<br />
two years did happen — you are right on the money. If we look at our veneer sales,<br />
they definitely decreased over that time period. No one is imagining that. This isn’t<br />
a rumor running rampant through dentistry; there was a serious cutback in the<br />
number <strong>of</strong> elective cosmetic procedures.<br />
Over the past two years here at the lab, only a couple <strong>of</strong> products have grown.<br />
One <strong>of</strong> them is an esthetic product (in the sense that it’s a great-looking product):<br />
IPS e.max ® (Ivoclar Vivadent; Amherst, N.Y.) crowns. IPS e.max veneers have grown<br />
as well. People obviously still need full-contour restorations, so those may not be<br />
elective. At any rate, IPS e.max has continued to show an impressive growth curve<br />
over the last couple years. I’m guessing you’re a pretty big fan <strong>of</strong> this product. Tell<br />
me a little bit about the impact IPS e.max has had on your practice.<br />
DH: You are absolutely right to say that I’m a big fan <strong>of</strong> IPS e.max. It’s an<br />
unbelievable material. For those readers who aren’t familiar with this product,<br />
IPS e.max is a lithium disilicate material that can be waxed and pressed or<br />
fabricated using CAD/CAM.<br />
When waxed and pressed, kind <strong>of</strong> like we’ve done with IPS Empress ® (Ivoclar<br />
Vivadent) and leucite-reinforced ceramics for the past 20 years, we use the<br />
lost-wax process (just like we’d cast gold). It can also be made using CAD/<br />
CAM technology, whether in the <strong>of</strong>fice with CEREC ® (Sirona <strong>Dental</strong> Systems;<br />
Charlotte, N.C.) or E4D (D4D Technologies; Richardson, Texas), or in the dental<br />
laboratory.<br />
IPS e.max has filled an existing void in dentistry. It is a highly esthetic material<br />
— as you mentioned, it approaches the esthetics <strong>of</strong> anything we have in<br />
dentistry right now — and it’s amazingly strong. We now have a ceramic that’s<br />
four times stronger than the ceramic we’ve put on PFMs for the last 60 years. I<br />
mentioned earlier about options in treatment planning: Now I can look at even<br />
a second molar on a bruxer that has decreased vertical dimension and give the<br />
patient a restoration that is esthetic, conservative and strong.<br />
34 www.chairsidemagazine.com
MD: I distinctly remember placing my first IPS e.max crown.<br />
It was on a friend’s wife, and it was at the end <strong>of</strong> a two-year<br />
period in which I did nothing but zirconia-based restorations.<br />
We were struggling to blend the zirconia restorations<br />
with the adjacent teeth because we were dealing with coping<br />
shade issues and with dentists under-reducing teeth, especially<br />
in the gingival third.<br />
When lithium disilicate came out, I must admit I was a little<br />
suspect. Ivoclar was releasing this material for the third time,<br />
and I wondered if it would work. <strong>The</strong> first IPS e.max crown<br />
I put in was so beautiful that it blew me away. It was the<br />
kind <strong>of</strong> thing you looked at and said, “Wow. If this is going<br />
to stand up to the types <strong>of</strong> wear and tear we see in the mouth,<br />
this material is going to be successful.”<br />
How neat is it that a material can be used for almost any clinical<br />
indication — inlays, onlays, crowns and even veneers?<br />
I recently heard a rumor that some <strong>of</strong> the esthetic institutes<br />
were thinking <strong>of</strong> switching over to IPS e.max veneers. What<br />
are you teaching in your clinical course now, and how do<br />
you feel about IPS e.max veneers?<br />
DH: Well, by the time this article is published, my opinion<br />
may change based on the fact that Ivoclar is introducing<br />
even better ingot and block shades. I know some people<br />
will read this and say: “IPS e.max? It’s kind <strong>of</strong> gray. It’s<br />
kind <strong>of</strong> opaque. It doesn’t look as good as IPS Empress …”<br />
That was the IPS e.max <strong>of</strong> a year and a half ago, when<br />
Ivoclar didn’t have available the many translucent and<br />
esthetic ingots that are now <strong>of</strong>fered for CAD/CAM or for<br />
pressing. And now they’ve introduced ingots that mimic<br />
what we’ve always seen with Empress, which is what I<br />
would call my standard for anterior esthetics. To answer<br />
your question, today I’m still a fan <strong>of</strong> IPS Empress in the<br />
anterior and it is still my “go to” material. If you came into<br />
my <strong>of</strong>fice or into my teaching center and you were going<br />
to do six, eight, 10 veneers, IPS Empress would still be my<br />
first choice. I just think it interacts with light a little better<br />
than lithium disilicate. But as we get more experience<br />
with the new Value ingots, that preference may change. I<br />
seated 10 maxillary anterior veneers this week using the<br />
new V1 ingot, and the case was beautiful.<br />
We are also now doing prepless and very minimal-prep<br />
IPS e.max veneers, because at 0.2 mm or 0.3 mm thin,<br />
this material exhibits incredible marginal integrity. Even<br />
being this thin, they are very high strength and very easy<br />
for the laboratory to finish down at the margins. We’re<br />
doing anterior 3-unit bridges in IPS e.max, and we’re getting<br />
esthetics that approach IPS Empress. So we’re still<br />
teaching IPS Empress. But, then again, three months from<br />
now when you ask me this question I might say, “Who’s<br />
using IPS Empress anymore? Not me.” This is what makes<br />
dentistry so exciting and fun!<br />
MD: My personal viewpoint is that if I’ve got to do a veneer<br />
on tooth #9, and tooth #8 is a virgin tooth, I am going to use<br />
IPS Empress. Like you, I don’t think there’s anything as lifelike<br />
as IPS Empress somewhere between 0.3 mm and 0.6 mm<br />
thick. It just looks more like natural tooth structure than anything<br />
else. But I’ve started to change a little bit — and I’m<br />
not as demanding esthetically as you are. When I get to an<br />
8-unit veneer case, I like the idea — and we can see from<br />
the numbers that dentists liked the idea, too — <strong>of</strong> having a<br />
veneer material that’s three times as strong as IPS Empress.<br />
Dentists have had problems with chipping and they’ve had<br />
some breakage. Maybe it was due to poor prep design or not<br />
checking the occlusion close enough, but dentists seem to like<br />
the idea <strong>of</strong> having a stronger material. And, <strong>of</strong> course, when<br />
you have six, eight, 10 veneers lined up next to each other, it’s<br />
not the same kind <strong>of</strong> thing as it is with a single tooth. Do you<br />
think that’s a reasonable approach for the average dentist?<br />
DH: Absolutely. Not even for the average dentist — every<br />
dentist. If we can deliver a restoration that is two to three<br />
times stronger than anything else we can <strong>of</strong>fer and it<br />
doesn’t compromise esthetics, I think that’s definitely the<br />
way to go. We’re looking at this material very seriously. I<br />
mentioned that Ivoclar just introduced its IPS e.max Press<br />
Impulse Value ingots. I did another case recently using<br />
these V ingots — two cantilever bridges replacing laterals<br />
<strong>of</strong>f the canine and then eight other veneers — and it<br />
was absolutely beautiful. I actually had the lab make two<br />
sets: one IPS Empress and one IPS e.max. After trying in<br />
both cases, I chose IPS e.max. Needless to say, we’re very<br />
excited about this material.<br />
MD: I agree, and dentists are certainly voting here at the<br />
laboratory with their wallets, as well.<br />
I remember one morning about a year ago, I opened a journal<br />
and there was <strong>Dr</strong>. David Hornbrook doing a no-prep<br />
veneer case! I wasn’t sure if this was a hostage situation in<br />
which you had a gun to your head, but I was caught so <strong>of</strong>f<br />
guard that I spilled my c<strong>of</strong>fee; I didn’t know what might have<br />
prompted this. I have a feeling it’s material advancements.<br />
And, <strong>of</strong> course, as somebody who performs such esthetic services<br />
as yourself, the abuse <strong>of</strong> the no-prep veneer concept was<br />
probably something that bothered you a little bit. But I really<br />
thought it was a great sign. And you — being so open-minded<br />
to go forward and try one <strong>of</strong> these cases, and then publish<br />
the case! It was a gorgeous case, by the way.<br />
DH: Well, thank you. I think prepless or very minimalprep<br />
veneers are a technique that every dentist needs<br />
to explore. Obviously, it’s public-driven because a major<br />
dental manufacturer markets prepless veneers to the public,<br />
so now patients are asking for this procedure. But I<br />
think it’s been abused. We see very compromised results<br />
with this technique more <strong>of</strong>ten than not. You work with<br />
a dental laboratory, so you understand the importance <strong>of</strong><br />
the communication process. <strong>The</strong> communication between<br />
the ceramist and the dentist is so crucial. I think a lot <strong>of</strong><br />
Interview with <strong>Dr</strong>. David Hornbrook35
dentists were, and still are, doing these prepless veneer<br />
cases without really understanding the indications and<br />
contraindications <strong>of</strong> this procedure, and we see some really<br />
ugly and even unhealthy cases, especially tissue-wise.<br />
I practice dentistry three to four days a week, and my<br />
patients were asking about these prepless veneer cases.<br />
And I really wanted to explore this more closely: Was it<br />
the material itself, the lack <strong>of</strong> case planning or the technique?<br />
So I went back and worked with laboratories and<br />
materials and ideal cases. Together we established some<br />
planning protocols that have yielded some surprisingly<br />
unbelievable results, esthetically and functionally, with<br />
prepless veneer cases. It’s an opportunity available for<br />
patients and doctors. As I teach, I find that a lot <strong>of</strong> doctors<br />
refuse to prep virgin enamel. This refusal limits their ability<br />
to <strong>of</strong>fer their patients some beautiful smiles. Prepless<br />
veneer cases, when planned properly, are a viable alternative<br />
to prepped veneers.<br />
MD: That’s interesting. I’ve never heard a dentist say, I refuse<br />
to prep virgin enamel. If somebody were to make that argument,<br />
I would have to assume they were probably doing lots<br />
<strong>of</strong> inlays and onlays. We certainly see lots <strong>of</strong> virgin enamel<br />
on very healthy cusps being prepped in the name <strong>of</strong> insurance-approved<br />
crown & bridge. I don’t know why they would<br />
find it to be different just because it was in the anterior. You<br />
know what I mean?<br />
DH: I totally agree. But I hear and see it all the time. I see<br />
dentists who will prep a full crown instead <strong>of</strong> an inlay. Or<br />
they’ll prep virgin teeth on each side <strong>of</strong> a missing tooth to<br />
place a 3-unit bridge, but they won’t do a 0.5 mm depth<br />
cut on an anterior tooth. It amazes me.<br />
MD: To me, no-prep veneers really are a great finishing<br />
technique. I do hardly any no-prep cases where all eight or<br />
10 units are no-prep veneers. But I do see cases where we<br />
will replace, say, old PFMs on tooth #7 through tooth #10<br />
with some IPS e.max crowns. And then I will place no-prep<br />
veneers on the cuspids and the bicuspids and finish out the<br />
whole smile without having to do any additional preparation.<br />
That’s what I mean by a finishing technique: It is a<br />
great way to finish out a smile when it’s done in conjunction<br />
with other restorations.<br />
DH: I agree, especially in this baby boomer age. A lot<br />
<strong>of</strong> these people went through ortho as a teenager and<br />
had their first bicuspids extracted. Now their posterior<br />
quarters are collapsing and they want a nicer looking<br />
anterior smile because <strong>of</strong> wear or discoloration. You<br />
can do veneers, or you can replace existing crowns and<br />
then place very conservative veneers on the premolars<br />
and develop a beautiful smile.<br />
MD: When I first learned about esthetic techniques in your<br />
courses (back in 1995), we were doing fairly aggressive<br />
preparations in the dentin when placing IPS Empress<br />
veneers. And, as time has gone on, I have found that because<br />
<strong>of</strong> improvements in ceramic materials, we can achieve similar<br />
results with less reduction, assuming that the tooth is not<br />
way out <strong>of</strong> an ideal arch form and it’s just an esthetic issue.<br />
I like the idea <strong>of</strong> minimal-prep veneers, which, to me, is<br />
something that has all the margins still in enamel. I like the<br />
idea <strong>of</strong> bonding to enamel and keeping it intact. Do you<br />
find that minimal-prep veneers, where you’re not necessarily<br />
exposing dentin, are something that you are using more on<br />
a day-to-day basis?<br />
DH: When I first started teaching, around the time you<br />
went through my courses, I think it was also the inexperienced<br />
ceramist who established some <strong>of</strong> the “ideals” <strong>of</strong><br />
veneer preparation. IPS Empress was new to ceramists. It<br />
was a monolithic material. <strong>The</strong>y didn’t really understand<br />
how to use the different opacities and translucencies in a<br />
very thin environment. So they said, give us some more<br />
room because we just don’t get it. And we would prep<br />
0.7 mm to 1 mm, and they would want the contacts<br />
broken. It was a new concept to them. We were teaching<br />
very aggressive preps in the mid 1990s. In the last four<br />
or five years, we’ve really done an about face. And what<br />
we recommend now is 0.3 mm to 0.5 mm depth cuts,<br />
assuming that the tooth is ideally positioned in the arch.<br />
So, unlike in the past, when most <strong>of</strong> my preparation for a<br />
veneer was in dentin, most <strong>of</strong> it’s now in enamel.<br />
MD: Do you find that you enjoy bonding to enamel more<br />
than dentin, or is it not a big issue for you? I hear from dentists,<br />
whether it’s postoperative sensitivity or not being sure<br />
how much they’re supposed to dry the tooth <strong>of</strong>f, that they<br />
really like the idea <strong>of</strong> etching enamel. Being able to dry it<br />
to your heart’s content, see that nice frosty look. For those<br />
<strong>of</strong> us who are kind <strong>of</strong> old-school dentists, it feels comfortable<br />
in a sense. It’s something that we grew up with.<br />
DH: Personally, I don’t really have a problem bonding<br />
to dentin. We’ve been doing it for almost 15 years, and<br />
I feel the predictability is there. But, I agree: I think that<br />
dentists still struggle, even to this day, with this whole<br />
total-etch and how wet is wet and how dry is dry concept.<br />
Most clinicians feel a little more comfortable being able to<br />
etch, rinse and dry as much as they want and get success.<br />
I think we’re going to see increased predictability, less<br />
standard deviation and less failure when the restoration<br />
is primarily in enamel.<br />
MD: I actually think that we’ll see more <strong>of</strong> these restorations<br />
diagnosed. Obviously, there’s talk <strong>of</strong> over-diagnosis <strong>of</strong><br />
veneers, but I think that’s by a small percentage <strong>of</strong> dentistry.<br />
Many dentists still don’t talk about this type <strong>of</strong> esthetic dentistry<br />
because they’re not totally confident in their ability to<br />
get a great non-sensitive result doing it completely on dentin.<br />
<strong>The</strong>y seem to like the idea <strong>of</strong> bonding to enamel, and<br />
they know it works, and they get less post-op sensitivity. As a<br />
36 www.chairsidemagazine.com
esult, they’re going to be more confident in their procedures.<br />
DH: I agree with you.<br />
MD: Speaking <strong>of</strong> total-etch versus self-etch, for your direct-placed restorations in<br />
the posterior, are you using self-etch at all? Or are you still a total-etch guy?<br />
DH: I’m definitely a total-etch guy! In fact, I’ve actually gone back to fourth<br />
generation dentinal adhesive systems. So, I etch, and then utilize a separate<br />
solution for the hydrophilic primer and a separate solution for the hydrophobic<br />
adhesive.<br />
MD: So you’re back to the regular two-bottle system. What are you using?<br />
DH: I’m using ALL-BOND 3 ® (Bisco Inc; Schaumburg, Ill.). I like Bisco products<br />
and respect <strong>Dr</strong>. Byoung Suh and the research being done at his company.<br />
If I look back historically, what I would consider the gold standard would be<br />
ALL-BOND 2 and OptiBond ® FL (Kerr Corporation; Orange, Calif.). And the<br />
only problem, at least that I saw, primarily as an educator, was that ALL-BOND<br />
2 was acetone-based, so it was a little more finicky. What Bisco did a few years<br />
ago was change the hydrophilic carrier to alcohol. Now we have what I would<br />
consider a new gold standard. It’s alcohol based, and you can use it for every<br />
type <strong>of</strong> restoration you place in your <strong>of</strong>fice. Too many clinicians have too many<br />
bonding agents in their refrigerator. Unless they can get an adequate amount<br />
<strong>of</strong> light to polymerize the material, anything but a fourth-generation adhesive<br />
will lead to a compromised result.<br />
MD: It really is kind <strong>of</strong> funny. I don’t know how many times in dentistry we’ve seen<br />
dentists take a step backward from what the latest and greatest is, with maybe the<br />
exception <strong>of</strong> digital impressions, which tend to be more difficult and more timeconsuming<br />
than conventional impressions. You look at the way things went to one<br />
bottle and then all <strong>of</strong> a sudden we have self-etching in one bottle. It began to look<br />
like, “Wait a minute. Are we doing this for us, are we doing this for the quality, or<br />
are we doing this for our patients?” So it’s interesting to hear that you’ve gone back<br />
to something that’s time tested and proven. It does take a little more time, but you<br />
feel it’s better. I know you’re not going to go back to a self-cure composite instead <strong>of</strong><br />
light-cure composites or a belt-driven handpiece. You must really feel in your heart<br />
that this is the right thing to do.<br />
DH: I do. I have not seen the sensitivity that a lot <strong>of</strong> people saw with the<br />
total-etch. Obviously, we’re isolating and controlling that surface moisture, not<br />
over-etching the dentin. But it’s something where I have predictability; I have<br />
success; I don’t have much postoperative sensitivity; I don’t see premature<br />
failure; and I can look back and show you 15 years <strong>of</strong> clinical experience, as<br />
well as excellent research.<br />
<strong>The</strong> problem with today’s bonding agent chemistry is that it changes too fast.<br />
You’ll see a study on a self-etching primer that bonds to enamel that was carried<br />
out over a period <strong>of</strong> 36 months, and that material has changed chemistry<br />
since the article came out. So we can’t look at these and say this is going to<br />
have long-term success, where we can with total-etch systems.<br />
I hear and see it all the<br />
time. I see dentists who<br />
will prep a full crown<br />
instead <strong>of</strong> an inlay. Or<br />
they’ll prep virgin teeth<br />
on each side <strong>of</strong> a missing<br />
tooth to place a 3-unit<br />
bridge, but they won’t<br />
do a 0.5 mm depth cut<br />
on an anterior tooth.<br />
It amazes me.<br />
What we recommend<br />
now is 0.3 mm to 0.5 mm<br />
depth cuts, assuming<br />
that the tooth is ideally<br />
positioned in the arch.<br />
So, unlike in the past,<br />
when most <strong>of</strong> my preparation<br />
for a veneer was in<br />
dentin, most <strong>of</strong> it’s now<br />
in enamel.<br />
MD: Does this mean that you have not played with any <strong>of</strong> the self-etching flowable<br />
composites yet?<br />
DH: I’ve played with them, but I haven’t used them clinically except to alleviate<br />
sensitivity in gingival abfraction lesions.<br />
Interview with <strong>Dr</strong>. David Hornbrook37
MD: Yeah, I get it. If they work, it seems like a huge step forward for a dentist to be<br />
able to place things this quickly. But you always have to ask yourself: Is this about<br />
what’s convenient for me or is it about what’s better for the patient? And it may be<br />
different in the hands <strong>of</strong> the average dentist than it is for you.<br />
<strong>The</strong> problem with today’s<br />
bonding agent chemistry<br />
is that it changes too<br />
fast. You’ll see a study<br />
on a self-etching primer<br />
that bonds to enamel<br />
that was carried out over<br />
a period <strong>of</strong> 36 months,<br />
and that material has<br />
changed chemistry since<br />
the article came out. So<br />
we can’t look at these<br />
and say this is going to<br />
have long-term success,<br />
where we can with totaletch<br />
systems.<br />
DH: Again, I personally think the problem with some <strong>of</strong> the self-etching resins,<br />
and even the resin cements, is that the manufacturer can show us this great<br />
data, but what does it really do clinically in an environment on a live, vital<br />
tooth? I won’t name names, but there’s a product that is highly touted by the<br />
manufacturer as the best self-etching resin cement on the market. When zirconium<br />
oxide first came out, we had a lot <strong>of</strong> failures because we were using the<br />
wrong layering material, until it failed. So I cut <strong>of</strong>f 45 zirconium oxide crowns<br />
utilizing this cement that supposedly bonded excellently to dentin. And every<br />
single one I cut <strong>of</strong>f, the cement just peeled away in large sheets. <strong>The</strong>re was<br />
zero bond. So we have got to ask ourselves: Are the materials that show great<br />
benchtop success on non-vital teeth done in a controlled environment giving<br />
us the same clinical success in the mouth in a very hostile environment?<br />
MD: Right. And there is always going to be a disconnect between the two. I<br />
think you may be in second place behind me for the number <strong>of</strong> zirconia restorations<br />
cut <strong>of</strong>f. I know I’ve cut <strong>of</strong>f more than that. Some <strong>of</strong> the zirconia crowns<br />
I’ve cut <strong>of</strong>f have actually been our new BruxZir ® material. BruxZir is a monolithic<br />
zirconia restoration that, shockingly, dentists are prescribing in record<br />
numbers. Believe it or not, BruxZir actually passed IPS e.max in sales volume<br />
in November 2010. <strong>The</strong> ongoing wear studies at a couple <strong>of</strong> universities look<br />
encouraging, but you can imagine, having cut <strong>of</strong>f zirconia-based crowns, what it<br />
might be like cutting <strong>of</strong>f a full-contour zirconia crown! I have always thought this<br />
is something we need to talk about a little bit more. In fact, I remember you calling<br />
me once and saying, “Well, what if you have to do endo through one <strong>of</strong> these<br />
zirconia-based crowns?” And, at the time, we didn’t have a good set <strong>of</strong> diamonds.<br />
But now we’ve found some good diamonds to be able to cut those <strong>of</strong>f. Are you<br />
using many zirconia-based restorations right now in your day-to-day practice?<br />
DH: Lithium disilicate has replaced my zirconium oxide-supported crowns in<br />
the posterior. At one <strong>of</strong> my most recent lectures, a ceramist said IPS e.max has<br />
destroyed his Lava (3M ESPE; St. Paul, Minn.) market, which makes sense!<br />
I still use zirconium oxide-supported crowns for posterior bridges and three<br />
units in the anterior. I do pride myself on trying to be metal-free as much as<br />
possible, and that’s the only option I have. But single units, whether it be full<br />
zirconium oxide or zirconium oxide-supported with layering ceramic, I rarely<br />
ever do those. I do IPS e.max.<br />
MD: If you look at the history <strong>of</strong> indirect restorations in dentistry, <strong>of</strong> course cast<br />
gold was the first material out there — a monolithic material. <strong>The</strong>n, porcelain<br />
jacket crowns, which left a lot to be desired in terms <strong>of</strong> strength, but it was still just<br />
one material. Even back in the 1960s, there became this need to have something<br />
that was more esthetic than gold. We can talk about the current esthetic desires<br />
in Southern California, but even back in the 1960s there became a need to take a<br />
metal coping and fuse it to porcelain.<br />
<strong>The</strong> PFM has been the workhorse <strong>of</strong> dentistry for the last 40 years. It’s driven American<br />
dentistry, this laboratory, and almost all laboratories, for that matter. But<br />
PFMs have always suffered from the problem <strong>of</strong> having porcelain bonded onto the<br />
metal substructure. And with this bilayered restoration, there is always a chance<br />
that something can go wrong. In fact, it’s rather amazing that a lot <strong>of</strong> the times<br />
nothing did go wrong with the bond between the two. But, by nature, a bilayered<br />
restoration is going to have more problems than a monolithic restoration. I think<br />
38 www.chairsidemagazine.com
we finally saw that with the ceramic-bonded-to-zirconia<br />
market. Whether because <strong>of</strong> the coefficient <strong>of</strong> thermal expansion<br />
or the way people were fusing the two parts in the oven,<br />
there was going to be issues with compatibility and chipping.<br />
So, we’ve seen the same thing: IPS e.max, a monolithic<br />
material, and the monolithic BruxZir material introduced<br />
after it have destroyed the zirconia market. Again, the<br />
average dentist appears to be doing the same as you, at least<br />
in that respect.<br />
You’ve always struck me as a guy who would probably have a<br />
CEREC ® (Sirona <strong>Dental</strong> Systems; Long Island, N.Y.) machine<br />
in his practice. I’ve seen some <strong>of</strong> the artful direct composites<br />
and killer temporaries you’ve done, and you’ve always work<br />
with the best ceramists to get great results on your final restorations.<br />
You really are as much <strong>of</strong> a lab tech as any GP I<br />
know, but I don’t know that you ever fully embraced CEREC.<br />
Do you have a unit now that I don’t know about?<br />
DH: Actually, I do! But I’ve only had it for two weeks. I’ve<br />
done only four crowns. I was waiting for the camera to<br />
be better and for the s<strong>of</strong>tware to be a little more intuitive<br />
before I took the plunge. It has been worth the wait.<br />
When the 3M ESPE Paradigm Block came out several<br />
years ago, I was lecturing a lot on inlays and onlays. And<br />
3M said: “Hey, we’ll send you a CEREC. Start doing the<br />
Paradigm Block and when you love it, you’ll talk about<br />
it.” Well, I hated the CEREC machine. It was so counterintuitive.<br />
After three weeks, I sent it back and said, “I’m<br />
not using this!”<br />
MD: When was that?<br />
DH: Maybe seven years ago? Whenever CEREC 3 came<br />
out. But now I’m looking at the s<strong>of</strong>tware and looking at<br />
the camera, looking at the whole technology <strong>of</strong> digital<br />
impressions (which is obviously the future <strong>of</strong> dentistry),<br />
and it makes sense. You’re right in the fact that I do like<br />
to play with ceramics, but I’m not nearly to the level <strong>of</strong><br />
expert ceramists. I can’t make a veneer or an anterior<br />
crown look the way they can. But the fact is we’re using<br />
monolithic IPS e.max in the posterior where I’m not<br />
having to cutback or layer because I want strength. I’m<br />
getting good esthetics with monolithic material. After all,<br />
the lab was just waxing and pressing or milling it to full<br />
contour and superficially staining it. I thought, why am I<br />
not doing that?<br />
MD: I wasn’t praising you so much for veneers; I was complimenting<br />
your anterior direct temporaries. I would never<br />
take an impression and send it to you and say, “Hey, make<br />
my veneers.”<br />
DH: I wouldn’t either!<br />
MD: But I’ve seen what you can do on posterior teeth with<br />
direct composite, and it did seem like you are the kind <strong>of</strong><br />
guy who would mill IPS e.max restorations in the posterior.<br />
You’ve always <strong>of</strong>fered such great services to your patients.<br />
At <strong>Glidewell</strong>, we’ve now got six CEREC machines and probably<br />
10 additional MC XL mills. I’ve got a CEREC AC in the<br />
operatory and I am convinced — here I am practicing in a<br />
lab, but regardless — I am convinced that one-appointment<br />
dentistry is better than two-week dentistry.<br />
DH: I’ve only done four <strong>of</strong> these, so I’m not great at it<br />
yet. It’s like, how do I schedule it? One to two hours for a<br />
single unit? How long is it going to take me? But for the<br />
people who are great at it, I think it’s a huge advantage.<br />
I see this technology as an advantage for even a three- or<br />
four-day turnaround versus two weeks. Yes, we’re good<br />
at making temporaries; that’s what we’ve always done,<br />
and we’re good at it. But if we use this technology, we get<br />
reduced lab costs, improved turnaround time (whether<br />
that be 1.5 hours or three days) and total control.<br />
Let me give you an example. On the third CEREC crown<br />
that I did, an IPS e.max crown, I decided to try it in and<br />
adjust occlusion in the blue block state before it was sintered.<br />
And the patient bit down and broke the crown! In<br />
the past, had I sent that crown to <strong>Glidewell</strong> and it was<br />
IPS e.max or IPS Empress, I would have made a temporary,<br />
sent it back, and you would have made me a new<br />
one. Well, the cool thing about CEREC is that it was in my<br />
library. All I had to do was go back to the library, click<br />
it again, and in eight minutes I had a new crown! That’s<br />
where there is a huge advantage. Or say you have a material<br />
that you put in and there is a marginal discrepancy.<br />
Instead <strong>of</strong> taking a new impression, you can take a new<br />
digital impression and do it in three minutes.<br />
MD: I agree. That’s a better way to say it. I mean, it’s true:<br />
I do believe that one-appointment dentistry is better than<br />
two-week dentistry. But I also believe that three- or four-day<br />
dentistry is better than two-week dentistry. And I believe twoweek<br />
dentistry is better than six-week dentistry! <strong>The</strong> shorter<br />
period <strong>of</strong> time between prep and seat the better because <strong>of</strong><br />
bacterial leakage, teeth shifting and factors like that.<br />
DH: And also the fact that today we are doing more conservative<br />
dentistry. <strong>The</strong> primary complaint with some <strong>of</strong><br />
the crazy little single-cusp replacement onlays that we do<br />
is, how do you keep temporaries in? It’s a pain! If you<br />
plan to see this patient in three weeks, more than likely<br />
you’re going to see them twice in the next three weeks<br />
to re-cement the temporary. And if I can do it as either a<br />
single visit or get it back in two or three days because I<br />
milled it myself, we’re not going to have problems with<br />
provisionalization.<br />
MD: Right, because patients don’t want to come in three<br />
times. And, frankly, you’ve blown any pr<strong>of</strong>it you might have<br />
made on that case after three visits.<br />
Interview with <strong>Dr</strong>. David Hornbrook39
It’s funny you mention reduced lab costs because here at the<br />
lab we are all for that. We want to reduce lab costs. I mean,<br />
<strong>of</strong> course we'd like to work with more dentists, but primarily<br />
we’d like to reduce lab costs. We’re getting ready to release,<br />
most likely at the Chicago <strong>Dental</strong> Society Midwinter Meeting,<br />
a digital impression system that we will sell to dentists for<br />
their practice. We’re looking at it as an IPS e.max/BruxZir<br />
wand, if you will. So, for monolithic restorations, a dentist<br />
would take a digital impression, which we realize is more<br />
work than a regular impression. To me, to take a digital<br />
impression if it’s not hooked to a mill is kind <strong>of</strong> silly, unless<br />
it’s going to save you money. And some <strong>of</strong> the other digital<br />
impression systems actually cost you money. It’s very difficult<br />
for you to get any ROI with those systems.<br />
With the <strong>Glidewell</strong> system, we’re talking about taking a digital<br />
impression and sending it to the lab. Submitting the digital<br />
impression this way saves the dentist $27 on the cost <strong>of</strong> the<br />
restoration. <strong>The</strong>re is no one-way shipping cost ($7 savings),<br />
no cost for impression material ($10 savings), and the lab<br />
discounts $10 because it can be digitally fabricated. So, we<br />
do want to reduce lab costs to dentists by cutting out some <strong>of</strong><br />
the steps by making these model-free crowns.<br />
You and other CEREC users have proven that model-free<br />
crowns can be made, and Sirona has 25 years <strong>of</strong> experience<br />
doing it. We know it works. Have you used many <strong>of</strong> the other<br />
digital impression systems, such as Cadent iTero (<strong>The</strong> Cadent<br />
Company; Carlstadt, N.J.) or Lava C.O.S.?<br />
DH: I haven’t used Cadent clinically. I’ve played with it<br />
chairside and it seems like one <strong>of</strong> the easier systems to<br />
use. I know a lot <strong>of</strong> laboratories prefer it. And I like the<br />
technology <strong>of</strong> the Lava C.O.S. system, but it’s very time<br />
consuming. We looked at it, we were going to buy it, and<br />
then we decided not to. As we talked to colleagues, some<br />
<strong>of</strong> my friends that are excellent dentists, a lot <strong>of</strong> them<br />
had sent it back. It’s not that it wasn’t accurate or that its<br />
technology wasn’t cool. But if it takes 40 minutes to take<br />
an impression, it’s not pr<strong>of</strong>itable.<br />
You mentioned the cost savings <strong>of</strong> shipping, and that’s<br />
something that a lot <strong>of</strong> dentists don’t look at. If they say,<br />
oh, I only save $10 by doing that, what they don’t take<br />
into account is the money saved in outgoing shipping.<br />
<strong>The</strong>y will also get a better turnaround time because instead<br />
<strong>of</strong> taking two and a half days to get it to you, the<br />
case arrives at the lab instantly.<br />
MD: Exactly. I don’t like it when dentists are kind <strong>of</strong> force-fed<br />
technology or when dentists are told they are not doing great<br />
dentistry if they’re not using this technology. For example: On<br />
your polyvinylsiloxane impressions, do you perceive that you<br />
have a big problem with them day in and day out?<br />
DH: Not a major problem, but I think that if you really<br />
looked at the weakest link in the chain <strong>of</strong> restorative<br />
dentistry, it would be the impression and the pour-up in<br />
crummy dental stones. But is that going to keep my restorations<br />
from lasting 10 years or more? No. We have more<br />
accurate materials today than we did 20 years ago, when<br />
dentists were doing gold crowns that were in the mouth<br />
for 40 years. So, I totally agree with you on that.<br />
MD: That’s why I feel that if the digital impression system<br />
is not tied to a mill, where you can do same-day dentistry<br />
or three- or four-day dentistry and save nearly $20 per IPS<br />
e.max crown through a lab, what’s the point <strong>of</strong> going through<br />
the extra effort to do something like this?<br />
What are you using for a diode laser these days? And I’m<br />
guessing you have a hard-tissue laser, as well?<br />
DH: I use a diode every single day in my practice; we<br />
have one in each operatory. As far as hygiene, I personally<br />
think that use <strong>of</strong> a laser is standard <strong>of</strong> care. Dentistry<br />
as a whole will realize that in a few years.<br />
<strong>The</strong> advantages <strong>of</strong> present-day diodes compared to the<br />
ones we used are that they are affordable and smaller.<br />
You can get a good laser for less than $5,000; all <strong>of</strong> a sudden,<br />
lasers are very affordable.<br />
We’re also doing closed-flap osseous using an Erbium:YAG<br />
laser (AMD LASERS, LLC; Indianapolis, Ind.), which is<br />
very cool. So we’re performing crown lengthening without<br />
laying a flap, and we’re getting unbelievable results.<br />
Lasers, just like digital technology, are going to change<br />
the way we practice dentistry as they become more<br />
affordable and more dentists adopt the technology.<br />
MD: Do you feel pretty confident with closed-flap crown<br />
lengthening? I know it drives some periodontists crazy — it’s<br />
hard to treat what you can’t see. But I have to say that biologic<br />
width violations are a real problem. As you walk through the<br />
laboratory and look at anterior models, you see interproximal<br />
violations left and right. You know the crowns probably<br />
look pretty good, but the tissue is purple interproximally<br />
because the prep outline doesn’t follow the gingival outline.<br />
Are you doing most <strong>of</strong> these in the anterior or posterior?<br />
DH: I do it just in the anterior because I can tactfully feel<br />
the bone and make sure I’m not troughing or creating an<br />
artificial biologic width. Because posterior bone is thicker,<br />
I don’t do it. I refer that out if it needs to be done. I<br />
was keeping track <strong>of</strong> repercussions up to 2,500 teeth, and<br />
then I stopped, but we’ve had zero repercussions. I’ve<br />
done it in all my courses since 2004, and we’ve seen no<br />
problems. <strong>The</strong> cool thing is that unlike traditional crown<br />
lengthening, where a flap is laid and a diamond bur is<br />
used on the bone and then you wait 12 to 16 weeks,<br />
we’re prepping and impressing and provisionalizing on<br />
the same day that we do our osseous. We’re doing some<br />
fun, really cool things with that.<br />
40 www.chairsidemagazine.com
MD: Maybe in a perfect world every patient would be flapped and you’d see directly<br />
what you were doing. But the reality is that most <strong>of</strong> these cases have biologic<br />
width violations and dentists aren’t doing anything. <strong>The</strong>y’re taking the old crown<br />
<strong>of</strong>f and putting a new crown on. If anything, the margin gets dropped just a little<br />
bit further as the doctor goes in and cleans the cement <strong>of</strong>f the prep, so the biologic<br />
width violation gets a little bit worse. I think you’re seeing good results because it’s<br />
a step in the right direction. It may not be 100 percent perfect, but maybe the patient<br />
wouldn’t have had it done surgically anyway. I think that some treatment to<br />
improve biologic width is better than no treatment at all.<br />
DH: That’s right.<br />
MD: You mentioned that you do closed-flap crown lengthening procedures during<br />
your courses. Tell me a little about the courses that you’re putting on today.<br />
DH: <strong>The</strong> best source for those who are interested in where I’m going to be as<br />
far as a lecture or hands-on course is to visit www.davidhornbrook.com. Click<br />
on “Calendar,” and it will go through the things we’re doing. I still do a lot <strong>of</strong><br />
full-day lectures across the country, and that’s actually ramped up because <strong>of</strong><br />
all the new materials. People are obviously not getting trained in dental school<br />
on IPS e.max, prepless veneers and lasers. Now they’re hearing about it and<br />
getting excited. It’s good for me because I’m getting out there more, and I enjoy<br />
that aspect <strong>of</strong> my career.<br />
We are still doing some live patient courses. As you mentioned, you went to<br />
my esthetic courses when I was teaching at LVI. <strong>The</strong>n I formed P.A.C.~live<br />
and the Hornbrook Group, which were also live-patient, hands-on treatment<br />
courses. Now we’re doing it through a series called Clinical Mastery. Doctors<br />
can go to www.clinicalmastery.com and see a list <strong>of</strong> the courses we’re <strong>of</strong>fering,<br />
including occlusion courses and full-mouth and anterior live patient courses,<br />
in which dentists will bring their patients and their team.<br />
We’re doing these courses primarily in Mesa, Ariz., at the new dental school<br />
A.T. Still University – Arizona School <strong>of</strong> Dentistry and Oral Health (ATSU).<br />
This is just a phenomenal dental school. It’s so different from where I went to<br />
dental school. <strong>The</strong> faculty is very embracing, very technologically advanced.<br />
In fact, I was talking to the school’s dean, <strong>Dr</strong>. Jack Dillenberg, and the school’s<br />
recommendation for posterior restorations is composite, not amalgam. <strong>The</strong><br />
school only teaches amalgam so its students can get through the boards. It’s<br />
very interesting how different it is. <strong>The</strong> faculty is teaching veneers, implant<br />
placement, lasers. Students actually go through an entire laser curriculum. <strong>The</strong><br />
students are learning some very cool things.<br />
MD: That’s a real education! That’s pretty impressive.<br />
DH: It’s not that I’m pushing this particular school, but if a doctor who reads<br />
this has children, relatives or friends who are thinking about going to dental<br />
school, I would look at ATSU. <strong>The</strong>y only have one specialty program in the<br />
school — orthodontics — which means that graduating seniors leave dental<br />
school having placed an average <strong>of</strong> 15 to 20 implants because there is no<br />
periodontal program. <strong>The</strong> students are doing perio full-mouth surgery and<br />
impacted wisdom teeth — they’re just doing some really cool things.<br />
If you really looked<br />
at the weakest link in<br />
the chain <strong>of</strong> restorative<br />
dentistry, it would be the<br />
impression and the pourup<br />
in crummy dental<br />
stones. But is that going<br />
to keep my restorations<br />
from lasting 10 years or<br />
more? No. We have more<br />
accurate materials today<br />
than we did 20 years ago,<br />
when dentists were doing<br />
gold crowns that were in<br />
the mouth for 40 years.<br />
MD: <strong>The</strong> better part <strong>of</strong> having no specialty programs is that there are no specialists<br />
there to tell them that this stuff is too difficult for them to do, and they probably<br />
shouldn’t try it. That was my dental school!<br />
DH: Exactly, same with me. So we’re doing some cool things at ATSU. Again,<br />
Interview with <strong>Dr</strong>. David Hornbrook41
dentists can find out more about those courses by visiting my website<br />
www.davidhornbrook.com or www.clinicalmastery.com.<br />
MD: I want to close by telling you a story. I’m not sure if I’ve told you this before,<br />
but when we were together at LVI, I brought a patient …<br />
DH: I remember the case! When you left retraction cord in there?<br />
MD: Whoa, whoa, whoa, I didn’t leave retraction cord in there. What happened<br />
was that the two IPS Empress crowns on tooth #8 and #9 were deeply subgingival.<br />
We weren’t doing much s<strong>of</strong>t tissue recontouring back then, and certainly no hard<br />
tissue. But that’s really what this case needed. You said, “Let’s put some retraction<br />
cord in to contain the gingival fluids when we bond these crowns into place.” Well,<br />
I guess I was a little sloppy. I pulled the retraction cord out from tooth #8 after curing<br />
the cement, but when I went to pull out the retraction cord on tooth #9, I had<br />
bonded it into place. I tried to get it out and you tried to get it out. <strong>The</strong> good news<br />
is that it was size 00. <strong>The</strong> bad news is that it was black, and I’d bonded it between<br />
the crown and the tooth. You could see it through the patient’s thin tissue, and<br />
you said to me, “Congratulations. You are the first dentist in history to do an allceramic<br />
crown that has a gray margin like a PFM.” I’ve always been proud <strong>of</strong> that.<br />
Later, that patient went snow skiing with his wife and she fell getting <strong>of</strong>f the lift and<br />
smacked him in the face with a ski pole. And he called me in a panic and said,<br />
“My wife broke one <strong>of</strong> my front crowns <strong>of</strong>f.” I asked which one and he answered,<br />
“<strong>The</strong> one on the left (tooth #9).” I thought to myself, Hallelujah! <strong>The</strong>n he asked if he<br />
should look for it. “Hell no!” I didn’t want to have to explain what the black string<br />
was hanging <strong>of</strong>f the crown.<br />
So, your course and that experience were really instrumental in teaching me to pay<br />
attention and really do things right. Dentistry has been a learning experience for<br />
me, with this average set <strong>of</strong> hands I have.<br />
David, I want to thank you for being there every step <strong>of</strong> the way and being very<br />
generous with your time, especially for an interview like this.<br />
DH: Thank you, Mike! It’s always great to hear your voice because I haven’t<br />
talked to you in so long. You certainly have done so much for our pr<strong>of</strong>ession,<br />
and I consider you a mentor, a great friend, and I appreciate being asked. CM<br />
<strong>Dr</strong>. David Hornbrook is a leading educator in esthetic dentistry. For information on his upcoming lectures and<br />
hands-on courses, visit www.davidhornbrook.com or www.clinicalmastery.com.<br />
42 www.chairsidemagazine.com
Detecting<br />
Computer-Enhanced<br />
Dentistry<br />
– Article and Clinical Photos by<br />
Ellis J. Neiburger, DDS and<br />
Yehonatan L. Frandzel, FPH<br />
46 www.chairsidemagazine.com
A digital photo or radiograph may show a virtual<br />
reality that is considerably different than actual<br />
reality. <strong>The</strong>refore, there is a need for the practitioner<br />
to know how to detect virtual images and<br />
distinguish them from reality.<br />
Recent developments in digital imaging in dentistry and<br />
easy-to-use editing s<strong>of</strong>tware present many occasions for<br />
altering or fraudulently changing digital images <strong>of</strong> products,<br />
patients and their dental conditions, treatments and<br />
radiographs. Though seemingly impossible to detect when<br />
carefully done, there are numerous clues <strong>of</strong> digital editing<br />
that can be detected by the observant practitioner.<br />
Introduction<br />
In the last few years, more dentists and publications have<br />
increasingly switched from standard film photography<br />
and radiography to computer-generated digital techniques.<br />
1–4 Digital photography (DP) and digital radiography<br />
(DR) are produced by an electronic sensor linked to<br />
a computer, which generates and manipulates the virtual<br />
image either by light or X-ray exposure. Sophisticated<br />
editing s<strong>of</strong>tware can magnify, shade, duplicate and<br />
infinitely change the image. 1–4<br />
Image modification is not new. Since the 1870s, images<br />
on photographic film have been manipulated to show desired,<br />
artificial changes. 5,6 <strong>The</strong> creation <strong>of</strong> “spirit images,”<br />
burning, dodging, airbrushing, cropping, reverse printing<br />
and adding new subjects (e.g., a filled endodontic<br />
canal or whiter teeth) on an existing photo image has<br />
always been possible with photographic film. <strong>The</strong> famous<br />
disappearances <strong>of</strong> “vanishing commissars” in photos from<br />
Stalinist Russia, fantasy motion pictures (e.g., “Titanic” or<br />
“Harry Potter”), TV shows and the “retouched” photos <strong>of</strong><br />
the many tabloid newspapers are prime examples. 4–6<br />
Until recently, these changes were technologically demanding<br />
and expensive to do. 6 Often they were done<br />
poorly, showing obvious signs <strong>of</strong> manipulation. However,<br />
with the advent <strong>of</strong> DP, DR and inexpensive, easy-to-use<br />
editing s<strong>of</strong>tware, quality changes are as simple and inexpensive<br />
to achieve as pressing a computer key or pointing<br />
a mouse. 4–6 Most photographers and publications will<br />
use editing s<strong>of</strong>tware to “clean up” images: from cropping<br />
and eliminating red eye in portraits to repositioning the<br />
Egyptian pyramids (National Geographic) in order to fit<br />
the page better. 5 Many dentists and dental publications<br />
do the same.<br />
Today, a digital photo or radiograph may show a virtual<br />
(false) reality that is considerably different than actual<br />
reality. <strong>The</strong>refore, there is a need for the practitioner to<br />
know how to detect virtual (computer-generated) images<br />
and distinguish them from reality. 7 <strong>The</strong> quality <strong>of</strong> treatment<br />
and research, the descriptions <strong>of</strong> commercial products<br />
and the desire for honest cosmetic predictions for<br />
our patients depend on these skills.<br />
Detecting Computer-Enhanced Dentistry47
What Digital Photography<br />
Can Do<br />
Figures 1, 1f: Computer-generated extraction <strong>of</strong> deciduous tooth and creation <strong>of</strong> two restorations<br />
Figures 2, 2f: Virtual endodontics, periapical healing and four restorations<br />
Figures 3, 3f: Computer-created crown and three carious lesions (molars)<br />
Popular s<strong>of</strong>tware such as Adobe ®<br />
Photoshop ® (San Jose, Calif.), Corel ®<br />
PaintShop Photo ® Pro (Mountain<br />
View, Calif.), Apple iPhoto (Cupertino,<br />
Calif.), Google Picasa 3 (Mountain<br />
View, Calif.), and hundreds <strong>of</strong><br />
bundled digital camera photo programs<br />
have found their way into<br />
many <strong>of</strong>fices and homes. 6 If one<br />
buys a digital camera, it most likely<br />
comes with a functional editing program<br />
that allows the manipulation <strong>of</strong><br />
photos. Using these programs, one<br />
can cut, paste, erase, combine, overlay,<br />
reshade and otherwise retouch<br />
any photo taken. Patient photos can<br />
be enhanced to show better-shaped,<br />
positioned or whiter teeth and then<br />
used as a marketing tool or prognostic<br />
inducement for additional treatment.<br />
1–4,7<br />
Alternately, this means one can also<br />
create decay, cracks and abscesses on<br />
DR images <strong>of</strong> normal teeth in order<br />
to mislead other pr<strong>of</strong>essionals, thirdparty<br />
payers and the courts. 1–4,7,8<br />
DP and DR s<strong>of</strong>tware allows the operator<br />
to change the presence, shade,<br />
color saturation, brightness and contrast<br />
<strong>of</strong> bone or tooth structure in a<br />
digital image. 4–6 Restorations, teeth<br />
and pathology can be virtually created,<br />
removed or modified in the<br />
digital image. In some cases, this<br />
activity may approach the level <strong>of</strong><br />
fraud, where images <strong>of</strong> restorations<br />
or treatments (e.g., endodontics or<br />
extractions) can be created by computer<br />
and submitted as evidence in<br />
trials or sent to third-party payers as<br />
pro<strong>of</strong> <strong>of</strong> actual diseased conditions<br />
or previously billed treatments. 1–4,7<br />
Figures 4, 4f: Virtual removal <strong>of</strong> root, bone healing and creation <strong>of</strong> a 3-unit fixed bridge<br />
Virtual Examples<br />
Figures 1–6 are digital images <strong>of</strong> actual<br />
radiographs. Figures 1f–6f are<br />
corresponding digital images that<br />
have been edited to show pathologic<br />
changes, healing and restorations<br />
that have not actually occurred. <strong>The</strong>y<br />
48 www.chairsidemagazine.com
are computer simulations.<br />
Figure 1f shows computer enhancements<br />
to Figure 1 where a tooth has<br />
been virtually extracted, the bone <strong>of</strong><br />
the extraction socket partially healed<br />
and two virtual restorations placed.<br />
Note the root fragment left in Figure<br />
1f’s extraction.<br />
Figure 2f shows a re-edited Figure 2<br />
where virtual endodontic treatment<br />
was performed, the periapical radiolucency<br />
partially healed (smaller<br />
size) and four restorations placed.<br />
Nothing was really done except for<br />
computer simulations.<br />
Figure 3 shows distal decay in the<br />
upper second premolar and no other<br />
decay. Figure 3f demonstrates a virtual<br />
crown that “restored” distal caries<br />
in the upper second premolar;<br />
also note the virtual decay on the<br />
upper second (distal) and third (mesial)<br />
molars and mesial decay on the<br />
lower second molar.<br />
Figure 4f presents virtual treatment<br />
<strong>of</strong> Figure 4 where a root appears to<br />
have been extracted, partial healing<br />
<strong>of</strong> the socket accomplished and a<br />
3-unit fixed bridge made — all within<br />
a few minutes <strong>of</strong> computer work.<br />
Figure 5f shows the addition <strong>of</strong> an<br />
extra endodontic filling and crown<br />
on the first bicuspid <strong>of</strong> the perfectly<br />
natural tooth in Figure 5.<br />
Figure 6f shows whiter teeth than<br />
what actually appears in Figure 6.<br />
This can be used as pro<strong>of</strong> <strong>of</strong> the<br />
power <strong>of</strong> “Virtual Product X,” which<br />
bleached the patient’s teeth in a few<br />
seconds — except the active ingredient<br />
came from the computer.<br />
How to Detect Computer-<br />
Enhanced Images<br />
Sophisticated photos <strong>of</strong> dental products<br />
and techniques are appearing in<br />
dental literature in the form <strong>of</strong> advertisements<br />
or research treatment<br />
results. Many <strong>of</strong> these images are<br />
computer-generated and retouched.<br />
Figures 5, 5f: Computer-generated endodontics and crown on first premolar<br />
Figures 6, 6f: Virtual tooth whitening<br />
Sophisticated photos <strong>of</strong> dental<br />
products and techniques are<br />
appearing in dental literature in the<br />
form <strong>of</strong> advertisements or research<br />
treatment results. Many <strong>of</strong> these<br />
images are computer-generated<br />
and retouched.<br />
Detecting Computer-Enhanced Dentistry49
If it looks too good to be true, it probably is. Wild<br />
claims that defy your own experience can indicate<br />
potential computer editing. Perfect margins, shading,<br />
alveolar bone regrowth and other signs <strong>of</strong> perfection<br />
should raise questions.<br />
<strong>The</strong> discriminating practitioner must be able to identify<br />
the virtual from the real so that he or she can view the<br />
material presented on a sound, accurate scientific basis,<br />
rather than a virtual basis. <strong>The</strong>re are a number <strong>of</strong> classic<br />
techniques one can use to detect computer enhancements<br />
in digitally produced photos and radiographs.<br />
If it looks too good to be true, it probably is. Wild<br />
claims (supported by impressive photos) that defy<br />
your own experience can indicate potential computer<br />
editing. Perfect margins, shading, alveolar bone<br />
regrowth and other signs <strong>of</strong> perfection should raise<br />
questions. Whether it is seen in a lecture on clinical<br />
dentistry or in a magazine or journal touting whitening,<br />
etc., one must be cautious. In the real world,<br />
nothing is perfect. Any photo that is becomes suspect.<br />
5–8<br />
Computers are made to make straight lines and perfect<br />
angles. This seldom occurs in real life and is<br />
a dead giveaway for deception. <strong>The</strong> straight edges<br />
and perfect angle <strong>of</strong> the virtual molar mesial occlusal<br />
restoration in Figure 1f is a very good example.<br />
Compare the irregular shape <strong>of</strong> real restorations in<br />
Figure 3 with the straight, even artifacts in<br />
Figure 1f. <strong>The</strong> four virtual restorations in Figure 2f<br />
are another example. <strong>The</strong>y are too perfectly rounded<br />
and <strong>of</strong> similar size and shape — a rarity in real life.<br />
Close examination <strong>of</strong> the margin <strong>of</strong> the virtual crown<br />
in Figure 3f reveals a jagged border. This is an unrealistic<br />
attempt to eliminate a straight line, and thus<br />
detection that the image has been modified. 2,5,6<br />
Many digitally enhanced DR restorations appear as<br />
one solid color. Most natural restorations will show<br />
various degrees <strong>of</strong> radiopaqueness (density), as the<br />
restoration becomes thinner or thicker when placed<br />
on or in a real tooth. Actual restorations are seldom<br />
all one color or shade. Compare the real crown in<br />
Figure 5 or the restorations in Figure 3 to the restoration<br />
images <strong>of</strong> Figures 1f, 2f and 3f. <strong>The</strong>re are<br />
subtle differences in each real restoration’s peripheral<br />
density.<br />
Look for “Frankenstein” images where, in many<br />
photos, the head <strong>of</strong> a subject appears to be stitched<br />
onto the body or a virtual tooth is inserted into a jaw.<br />
Changes in shading, angles and seams can identify<br />
this kind <strong>of</strong> manipulation. Relative uniform lighting<br />
requires that shadows appear in the same direction<br />
and on all areas <strong>of</strong> the photo. If they do not, then<br />
editing should be suspect. Look at the reflections<br />
<strong>of</strong> light on the skin <strong>of</strong> the patient in Figure 6 as<br />
compared to virtual Figure 6f. In Figure 6f, there are<br />
more highlights on the skin around the lips, indicating<br />
that the shade <strong>of</strong> the entire photo was lightened<br />
in order to make the teeth appear whiter. 1–8<br />
Look for imperfections in geometry and whether<br />
the vanishing point is “<strong>of</strong>f.” Check if the quality <strong>of</strong><br />
the image is the same throughout the photo. If it is<br />
not, then something may have been added. Look for<br />
reoccurring patterns and objects, as well as discontinuities<br />
in the background. A lazy image editor may<br />
use standard shapes to fake restorations rather than<br />
spend the time to draw each restoration individually.<br />
Figure 2f shows virtual restorations <strong>of</strong> similar size<br />
and perfect shape. <strong>The</strong>se were digitally enhanced. 5,6<br />
Often, enhancements to images can become apparent<br />
if you use “false color image” editing. Radically<br />
changing the contrast and brightness can also be telltale<br />
signs. Using your computer to radically change<br />
the colors (false coloring) <strong>of</strong> the suspected photo<br />
will serve to identify otherwise subtle changes. This<br />
process can be done in just a few seconds with most<br />
photo editing s<strong>of</strong>tware. 5–8<br />
Look for artifacts <strong>of</strong> the editing process. <strong>The</strong>se may<br />
include tracks, brush marks, cavities and unnatural<br />
compression. Rough texture transitions and uneven<br />
pixilation (the small dots that make up the image)<br />
across the image is strong evidence <strong>of</strong> editing. 6<br />
50 www.chairsidemagazine.com
Look at the reflections <strong>of</strong> light on the skin <strong>of</strong> the patient<br />
in Figure 6 as compared to virtual Figure 6F. In Figure<br />
6F, there are more highlights on the skin around the<br />
lips, indicating that the shade <strong>of</strong> the entire photo was<br />
lightened in order to make the teeth appear whiter.<br />
Experienced image editors can detect metadata, short<br />
digital fingerprints formed on every digital image. In<br />
addition to storing information on the exact date <strong>of</strong><br />
creation and the modification <strong>of</strong> a file, metadata can<br />
link the photo to the camera used, ownership (e.g.,<br />
watermarking) and a variety <strong>of</strong> manipulations that<br />
may have been used to modify the raw image. Unfortunately,<br />
an image editor bent on deception can<br />
remove this data and thus play an infinite cat-andmouse<br />
game <strong>of</strong> detecting and hiding or scrubbing<br />
evidence <strong>of</strong> image manipulation. Unless you wish<br />
to spend considerable sums <strong>of</strong> time and money for<br />
this service, this level <strong>of</strong> detective work is seldom<br />
practical in dentistry. 5,6,8<br />
Look at the size (megabytes) <strong>of</strong> the image file. Enhanced<br />
images will have a considerably larger file<br />
size than those that have no changes.<br />
References<br />
1. Calberson F, Hommez G, DeMoor R. Fraudulent use <strong>of</strong> digital radiographs.<br />
Rev Belge Med Dent. 2005;60(1):58–67.<br />
2. Guneri P, Akdeniz B. Fraudulent management <strong>of</strong> digital endodontic images.<br />
Int Endod J. 2004;37(3):214–20.<br />
3. Boscolo F, et al. Fraudulent use <strong>of</strong> radiographic images. J Forensic Odontostomatol.<br />
2002;20(2):25–30.<br />
4. Wadkins P. Digital radiographs. JADA. 2000;131(1):18,20.<br />
5. Henshall J. Beware false reality. Photographer. 1998 Feb:28–30.<br />
6. Casimiro S. Seeing is not believing. Popular Science. 2005 Oct:71–79.<br />
7. Tsang A, Sweet D, Wood R. Potential for fraudulent use <strong>of</strong> digital radiography.<br />
JADA. 1999;130(9):1325–29.<br />
8. Gaylord C. Digital detectives discern Photoshop fakery. Christian Sci Monitor.<br />
2007 Aug 29. Accessed 15 Dec 2007.<br />
Reprinted with permission from the Journal <strong>of</strong> the Massachusetts <strong>Dental</strong><br />
Society, Vol. 57/No. 2, Summer 2008.<br />
Conclusion<br />
Because digital imaging has become so popular in dentistry,<br />
images <strong>of</strong> photos and radiographs may be edited<br />
to show different conditions than what is seen in reality.<br />
Photos can be enhanced to show whiter and straighter<br />
teeth, smoother skin or a well-blended margin on a<br />
crown. Digital radiographs can be changed to show additional<br />
pathology or treatment. <strong>The</strong>re are numerous signs<br />
<strong>of</strong> this manipulation, which an informed practitioner can<br />
detect. CM<br />
Acknowledgment<br />
<strong>The</strong> authors wish to thank Andent Inc. for permission to<br />
republish the photos in this article.<br />
<strong>Dr</strong>. Ellis Neiburger is a general practitioner in Waukegan, Ill. Contact him at<br />
847-244-0292 or eneiburger@comcast.net.<br />
Yehonatan Frandzel is a forensic photography consultant based in Haifa, Israel.<br />
Detecting Computer-Enhanced Dentistry51
Periodontal Photo Essay:<br />
Is Closed-Flap Crown Lengthening<br />
a Biologically Sound Procedure?<br />
– ARTICLE and CLINICAL PHOTOS by Daniel J. Melker, DDS<br />
Objective<br />
<strong>The</strong> objective <strong>of</strong> this article is to discuss the biological aspects <strong>of</strong> bone and the changes that occur when it is infringed<br />
upon either through disease or during the correction <strong>of</strong> certain periodontal conditions. It will discuss the correction <strong>of</strong><br />
osseous defects and why these procedures are necessary to create a long-term stable environment. When a comparison<br />
is made between certain periodontal problems stemming from either biologic width invasion or periodontal disease<br />
with closed-flap crown lengthening, similarities suggest that closed-flap crown lengthening is an unsound biologic<br />
procedure.<br />
Periodontal Photo Essay53
Case 1<br />
Figure 1<br />
Figure 2<br />
Figure 1: In order to change the length <strong>of</strong> the clinical crowns for<br />
a new restorative commitment, crown lengthening was advised.<br />
When doing closed-flap crown lengthening, marks are made on<br />
the laser tip to determine the amount <strong>of</strong> bone that needs to be<br />
removed to create space for a new crown. S<strong>of</strong>t tissue can also<br />
be removed when necessary. <strong>The</strong> major problem with such a procedure<br />
is the inability to remove the troughs created by the vertical<br />
removal <strong>of</strong> bone.<br />
Figure 2: <strong>The</strong> restorative doctor and periodontist discussed<br />
the case and determined that 1 mm <strong>of</strong> length would be needed<br />
on the incisal edges. An appropriate formula was used for the<br />
surgical procedure: biologic width, approximately 3 mm; clinical<br />
crown length, 10 mm; added porcelain, 1 mm. <strong>The</strong> total length<br />
needed from the existing incisal edge to the bone = 13 mm.<br />
Note: Six weeks postoperatively, it will be determined if touchup<br />
surgery will be necessary to correct any biologic changes.<br />
Figure 3: During crown lengthening, troughs in the bone occur that<br />
are similar to the periodontal vertical defects caused by endotoxins<br />
released by bacteria. Notice the significant defect caused between<br />
tooth #7 and #8; this is unavoidable.<br />
Figure 3<br />
54 www.chairsidemagazine.com
Case 1<br />
Figure 4 Figure 5<br />
Figure 4: A probe reveals the trough created in the bone due to<br />
crown lengthening. <strong>The</strong> probe shows the vertical defect involving<br />
line angles caused by the crown lengthening. <strong>The</strong> thicker the bone,<br />
which is common in the interproximal, the greater the resulting defect.<br />
Herein lies the problem with closed-flap crown lengthening:<br />
Without the ability to remove the troughs created by lengthening<br />
the teeth, serious long-term consequences can occur due to the<br />
lack <strong>of</strong> uniformity between bone and s<strong>of</strong>t tissue. It is critical for<br />
bone to mimic s<strong>of</strong>t tissue when contouring. <strong>The</strong> surgeon must<br />
create a parabolic architecture. Note: Horizontal access and<br />
visibility are necessary to remove the troughing caused by<br />
crown lengthening.<br />
Figure 5: Crown lengthening is completed on tooth #7 and #8.<br />
Figure 6: Notice how the bone and s<strong>of</strong>t tissue mimic each other.<br />
<strong>The</strong> existing length <strong>of</strong> tooth #8 and #9 is now 13 mm from the bone<br />
to the incisal edge. This allows for 3 mm <strong>of</strong> biologic width and<br />
10 mm for the clinical crown, with the new crown adding 1 mm to<br />
the incisal edge.<br />
Figure 6<br />
Periodontal Photo Essay55
Case 1<br />
Figure 7 Figure 8<br />
Figure 7: <strong>The</strong> tissue is sutured into place using a 5-0 chromic gut.<br />
Referring back to the original discussion on biologic width and<br />
clinical crown length, the tissue is placed where the remaining tooth<br />
structure is 10 mm. Notice there is an abundance <strong>of</strong> connective<br />
tissue remaining. Without the ability to remove the troughing created<br />
by the vertical removal <strong>of</strong> bone, the author finds closed-flap crown<br />
lengthening to be biologically unsound. Horizontal access and<br />
visibility are needed to create a sound biologic surgical procedure.<br />
Figure 8: Day <strong>of</strong> impression. Notice the tissue is slightly red. Due to<br />
her teaching schedule, the patient could not accommodate normal<br />
postoperative appointments. (<strong>The</strong> author and case surgeon would<br />
have preferred to see her several weeks before her impressions<br />
to reduce any inflammation, as this is the doctor’s responsibility.<br />
Subgingival chlorhexidine would be used to reduce minor inflammation.)<br />
Figure 9: Final restorations with mild gingival irritation. Over time,<br />
the author expects the tissue to improve, although reducing inflammation<br />
prior to impression taking is the preferred method.<br />
Figure 9<br />
56 www.chairsidemagazine.com
Case 2<br />
Figure 1<br />
Figure 2<br />
In this case, you will notice that the defect, which is<br />
caused by biologic width invasion, mimics the defect<br />
caused by closed-flap crown lengthening in the first<br />
case. Both are biologically unsound.<br />
Figure 1: Below tooth #5, the existing crown is violating the biologic<br />
width.<br />
Figure 2: Reflection <strong>of</strong> a flap exposes a created defect on the<br />
buccal <strong>of</strong> tooth #5, where biologic width invasion has occurred. To<br />
correct the defect, horizontal removal <strong>of</strong> bone is necessary, as well<br />
as the creation <strong>of</strong> bone architecture that mimics the s<strong>of</strong>t tissue.<br />
Figure 3: This shows the ideal osseous and s<strong>of</strong>t tissue architecture<br />
after proper bone contouring to remove the troughs. <strong>The</strong> crown is<br />
violating the biologic width. This crown will be removed and a core<br />
and a provisional will be placed.<br />
Figure 3<br />
Periodontal Photo Essay57
Case 3<br />
Figure 1<br />
Figure 2<br />
Figure 1: Crown lengthening is necessary to create a space for<br />
the biologic width. <strong>The</strong> author believes that visibility is critical for<br />
properly treating bone. A flap is required to see the underlying<br />
structures for crown lengthening.<br />
Figure 2: Regardless <strong>of</strong> the instrument — bur or laser — used when<br />
crown lengthening is performed, bone is removed. Unless the tip<br />
<strong>of</strong> the bur or laser is exactly the same dimensions as the bone to<br />
be removed, a trough will be created when there is a greater thickness<br />
<strong>of</strong> bone than tip diameter. This is a biologically unsound result.<br />
<strong>The</strong> bur is left in place to show the crater that is created as the<br />
bone is removed.<br />
Figure 3: Using the bur or laser horizontally allows the crater to be<br />
removed and an ideal osseous architecture to be created. Notice<br />
that the bone and s<strong>of</strong>t tissue mimic each other.<br />
Figure 3<br />
58 www.chairsidemagazine.com
Case 4<br />
Figure 1<br />
Figure 2<br />
Figure 1: <strong>The</strong> existing crown on tooth #28 violates the biologic<br />
width. <strong>The</strong>re are periodontists who say that if the biologic width is<br />
invaded, the bone will remodel to accommodate the infringement<br />
on this area. In 35 years <strong>of</strong> treating biologic width invasion, the<br />
author has consistently seen osseous defects associated with such<br />
violations. No remodeling is noted.<br />
Figure 2: Upon reflection <strong>of</strong> the tissue, a cratered defect is noted,<br />
presumably associated with the biologic width invasion. This type<br />
<strong>of</strong> defect must be removed to create an environment for the bone<br />
and s<strong>of</strong>t tissue to closely adapt for minimal probing depth.<br />
Figure 3: <strong>The</strong> defect is removed and the osseous support will now<br />
conform to the parabolic architecture <strong>of</strong> the s<strong>of</strong>t tissue as it heals.<br />
Thus, the bone mimics the s<strong>of</strong>t tissue and minimal pocket depth<br />
will be present upon complete healing.<br />
Figure 3<br />
Periodontal Photo Essay59
Case 5<br />
Figure 1 Figure 2<br />
Figure 1: With the tissue reflected, the ravages <strong>of</strong> periodontal<br />
disease on the bone can be seen clearly. A reverse architecture<br />
is visible. This means that rather than the bone conforming to<br />
the contours <strong>of</strong> the tissue, it is irregularly shaped, thus causing a<br />
discrepancy between the s<strong>of</strong>t tissue and the bone, resulting in a<br />
periodontal pocket.<br />
Figure 2: After osseous contouring to remove the pocket in the<br />
bone, the present configuration will mimic the s<strong>of</strong>t tissue upon<br />
healing. A minimal probing depth will remain, allowing for better<br />
long-term maintenance.<br />
Summary<br />
Without the ability to remove the troughing created by the vertical removal <strong>of</strong> bone, closed-flap crown lengthening is<br />
biologically unsound. Horizontal access and visibility are needed to create a sound biologic surgical procedure. CM<br />
<strong>Dr</strong>. Daniel Melker is in private practice in Clearwater, Fla., and lectures nationwide. Contact him at 727-725-0100.<br />
60 www.chairsidemagazine.com
Patient Product Review<br />
<strong>Dr</strong>. DiTolla’s<br />
In my experience, men love toothpicks. It has also been my experience that men don’t floss. Traditionally, dental<br />
pr<strong>of</strong>essionals have been conditioned to persuade male patients to routinely floss. (Ask your hygienist how this educational<br />
approach is going, if you aren’t sure.)<br />
I instead prefer to give men a tool they will use regularly, even if it isn’t as effective as flossing: the toothpick. Wooden<br />
toothpicks, which are freely available in all restaurants, have some limitations that make them a less than ideal choice<br />
for routine use. However, Opalpix toothpicks by Ultradent are flat and tapered to allow good interproximal access with<br />
minimal trauma to the papilla. I’ve seen patients do a pretty good job <strong>of</strong> getting them under fixed bridgework, as well.<br />
It’s a great option for the floss-phobic men (read: all men) who come to your practice. CM<br />
Opalpix is a trademark <strong>of</strong> Ultradent Products Inc. To purchase this product, contact your local dental dealer or visit https://store.ultradent.com.<br />
<strong>Dr</strong>. DiTolla's Patient Product Review63
<strong>The</strong> Chairside® PHOT Hunt<br />
How many differences between<br />
the two pictures can you find?<br />
Circle the differences on the version<br />
labeled NEW below. <strong>The</strong>n,<br />
write down how many differences<br />
you found, tear out this whole<br />
page and send it to:<br />
<strong>Glidewell</strong> Laboratories<br />
ATTN: Chairside magazine<br />
4141 MacArthur Blvd.<br />
Newport Beach, CA 92660<br />
Or scan your entry and e-mail it to<br />
chairside@glidewelldental.com.<br />
One entry per <strong>of</strong>fice. Participation<br />
grants Chairside magazine permission<br />
to print your name in a future<br />
issue or on its website.<br />
<strong>The</strong> winner <strong>of</strong> the Vol. 6, Issue 1,<br />
Chairside Photo Hunt Contest will<br />
receive $500 in <strong>Glidewell</strong> credit<br />
or a $500 credit toward his or<br />
her account. <strong>The</strong> second- and<br />
third-place winners will each receive<br />
$100 in <strong>Glidewell</strong> credit or a<br />
$100 credit toward their accounts.<br />
ORIGINAL<br />
Entries must be received by<br />
March 31, 2011. <strong>The</strong> winners will<br />
be announced in the spring issue<br />
<strong>of</strong> Chairside magazine.<br />
______________________________<br />
Name<br />
______________________________<br />
City/State <strong>of</strong> Practice<br />
______________________________<br />
Phone<br />
Total Found:___________________<br />
64 www.chairsidemagazine.com<br />
NEW
“With the current price <strong>of</strong> gold,<br />
dentists have begun mining.”<br />
Jeri C<strong>of</strong>fey, DDS<br />
Riverside, Ill.<br />
1st place winner <strong>of</strong> $500 lab credit<br />
“No, he doesn’t need crown<br />
lengthening. It’s only 12 mm<br />
subgingival.”<br />
Stephen L. Kirkpatrick, DDS, PLLC<br />
Olympia, Wash.<br />
2nd place winner <strong>of</strong> $100 lab credit<br />
“That’s not the nerve …<br />
It’s a Chilean miner!”<br />
Gregory L. Jovanelly, DMD<br />
Aliquippa, Pa.<br />
3rd place winner <strong>of</strong> $100 lab credit<br />
Honorable Mention<br />
“<strong>The</strong>se OSHA requirements are getting more strict every day!”<br />
Ernest Johnson, DDS<br />
Phoenix, Ariz.<br />
“No, but I did stay at a Holiday Inn Express last night.”<br />
James Tagliarini, DMD<br />
Danbury, Conn.<br />
<strong>The</strong> Chairside ®<br />
Caption Contest Winners!<br />
Congratulations to <strong>Dr</strong>s. Jeri C<strong>of</strong>fey, Stephen Kirkpatrick and Gregory Jovanelly, winners <strong>of</strong> the Vol. 5, Issue 4, Chairside Caption Contest.<br />
<strong>The</strong> winning captions were chosen from hundreds <strong>of</strong> entries e-mailed and submitted online to Chairside magazine when readers were<br />
asked to caption the above photo. Entries were judged on humor and ingenuity.