Dental Asia March/April 2019

In Depth With
The first set of data is our baseline, the
second set is the test group, the third
set simulates a user new to using the
intraoral scanner. See the results of the
three comparisons.
Primescan results are very similar, so let’s
look at some numbers (unit in microns):
Positive Avg Negative Avg Absolute Avg Std Deviation
Omnicam (F) 48.0 -43.9 46.0 59.0
Primescan (F) 26.6 -21.8 24.2 41.1
Primescan (R) 26.2 -24.1 25.2 39.3
Since the above results come from the
same scanner twice (albeit with a different
method), you can think of it as a
very rough precision estimation.
More data is definitely required,
but from our very rough tests, the
Dentsply-Sirona claims of 30-ish
microns of trueness and precision
seem to hold up quite well.
The method shown in the above three
images, called superimposition, overlays
one model onto another and shows how
much they differ using a colour spectrum
(legend on the right). The green regions
are where the models match (within
50 microns), and thus are more accurate.
There is also a histogram attached to the
spectrum legend on the right showing the
distribution of deviations. In short, the
tighter and narrower the distribution, the
more accurate the overall result.
Just from visual inspection of the
preliminary results above, we can already
see that the results for the Primescans
are more accurate. Interestingly, the two
The absolute average values in the table
above indicates how much average
deviation there is between the intraoral
scans and the desktop scan. Lower
absolute average means better accuracy
(or more specifically, trueness). So within
the scope of this simple study, we can
draw some conclusions:
• Primescan scans are cleaner and less
noisy than those from the Omnicam.
• Primescan is able to preserve more
local details than the Omnicam.
• Primescan is able to achieve better
global trueness than the Omnicam even
with Framework Scanning, but both are
more than clinically acceptable results.
• There is no significant difference in
global accuracy between different
methods of using Primescan.
It would seem that, if the results above
are verified with a larger sample size, that
Primescan is considerably less techniquesensitive
than its predecessor. This is
definitely good news as it may reduce
the learning curve for new users. Out of
curiosity, I ran a comparison between
random scanning and Framework
Scanning with the Primescan:
Positive Avg Random vs Framework
Negative Avg 29.1
Absolute Avg -33.3 31.2
Std Deviation 45.1
For those of you who are interested, these
average values are calculated by sampling
between approximately 600,000 and
800,000 polygons per model.
Final Thoughts
The release of Primescan at this
time, along with its complementary
software, is intriguing as it signals
Dentsply-Sirona’s push to capture a
bigger DI (digital impression) market from
other intraoral scanners.
For dental professionals looking to
purchase their first intraoral scanner,
the ease of use and accuracy offers
immediate short-term benefits. At the
same time, the A.I., the optional modular
software, and great communities such as
CERECDoctors.com and CEREC Asia are
valuable assets for the longer term.
For current CEREC users, Primescan
offers an interesting alternative. But
assuming that the Omnicam will indeed
still get all the latest software updates,
current users will be just as satisfied with
either the Omnicam or the Primescan.
In reality, whether practitioners purchase
or upgrade to the Primescan will ultimately
depend on two factors: price and
long-term plan. If a practice needs
something that replaces traditional
impression and nothing else, it really
doesn’t matter whether it opts to get
the Primescan, the Omnicam, or any
other major brand for that matter. But
for practices that aim to undergo a
gradual conversion to the new digital
workflow in restoratives, implantology,
or orthodontics, then the DI-focused
Primescan is a great first step into the
CEREC ecosystem. DA
MARCH / APRIL 2019 DENTAL ASIA 79