THE JOURNAL OF - Dentsply

Latta
Table 1 Mean shear bond strength (SBS) for each group (in MPa)
Bonding Agent Mean SBS to dentin (MPa) Mean SBS to enamel (MPa)
Optibond Solo plus 26.5 ± 2.9 28.3 ± 4.8
XP Bond 25.8 ± 2.6 28.3 ± 4.7
Adper Scotchbond 1 XT 24.2 ± 3.4 26.5 ± 4.9
Syntac Classic (15-s etch) 13.2 ± 3.7* 21.6 ± 5.8*
* Significantly different compared to the other groups (p < 0.05)
mens in air or water, at room temperature and pressure, and
without destroying the specimen.
A new etch-and-rinse adhesive called XP Bond has been
developed that has several unique compositional components.
It is hypothesized that these components will allow
the adhesive formula to be less sensitive to residual dentin
moisture and allow full resin penetration under a wide range
of dentin conditions. Second, this adhesive contains phosphate
esters that may chemically interact with the mineral
apatite component of dentin and enamel. The purpose of
this study was to evaluate the shear bond strength of composite
to dentin and enamel using this new adhesive system.
In addition, micro-Raman spectroscopy was performed to
determine if there was a chemical interaction between the
resin adhesive and dentin and enamel.
MATERIALS AND METHODS
Shear Bond Strength
Flat bonding sites were prepared on the buccal surfaces of
96 extracted human teeth by grinding the teeth on a watercooled
abrasive wheel (Ecomet III Grinder, Lake Bluff, IL,
USA) to a 600-grit surface exposing dentin on 48 specimens
and enamel on 48 specimens. Twelve specimens each for
enamel and dentin for each adhesive were prepared. The adhesives
and conditions of use were:
• Group 1: XP Bond (lot 0503004020) cured for 10 s with
the SmartLite LED curing light.
• Group 2: Optibond Solo Plus (lot 437041) cured for 10 s
with the SmartLite LED curing light.
• Group 3: Adper Scotchbond 1 XT (lot 230270) for 10 s
with the SmartLite LED curing light.
• Group 4: Syntac Classic (lot G06551) using phosphoric
acid etch 15 s and cured for 10 s with the SmartLite LED
curing light.
DeTrey tooth conditioner (Dentsply Detrey; Konstanz, Germany;
lot 0403000687) was used to condition all surfaces
prior to placement of the adhesive. After the application of
the adhesive system, cylinders of composite resin (Spectrum
TPH Shade A2, lot 0411002236; Dentsply DeTrey; Konstanz,
Germany) were bonded to each dentin and enamel
bonding site. A gelatin capsule technique in which a resin
cylinder 4.5 mm in diameter is employed as a matrix was
used. Composite was loaded in the capsules approximately
two-thirds full, then cured in a Triad 2000 curing unit (Trubyte
Division, DENTSPLY International; York, PA, USA) for 1 min.
Additional composite was added to slightly overfill the capsules.
The capsules were firmly seated against the bonding
sites and excess resin removed with a dental explorer. The
resin was visible-light cured with three 20-s curing sequences,
each from opposite sides of the capsule at an angle
of 45 degrees to the tooth surface.
The specimens were stored in distilled water at 37°C for
24 h. Twelve specimens for each adhesive/tooth structure
combination were thermocycled between water baths of 5°C
and 55°C for 6000 cycles (dwell time 20 s). The specimens
were mounted in acrylic and loaded to failure in an Instron
Testing Machine (Model 1123, Instron; Canton, MA, USA)
equipped with a chisel-shaped rod. Each bonded cylinder
was placed under continuous loading at 5 mm per min until
fracture occurred. Shear bond strength was calculated in
MPa.
Raman Spectroscopy
Extracted third molars were prepared by grinding enamel
and dentin to a 600-grit surface. The experimental adhesive
was applied and composite resin placed over the adhesive
film. After water storage, the teeth were sectioned to expose
the tooth/adhesive interface and polished to 4000 grit with
silicon carbide paper. Specimens were placed on an X-Y
scanning stage in a Jasco 3100 laser Raman Spectrometer
(Jasco; Tokyo, Japan). The excitation was derived from a
785-nm source at an output level of 35 mW and focused
through an X100 near-IR lens to ~ 1 μm beam diameter.
Wavenumber calibration was determined by comparison of
spectra from pure silicon (520 cm -1 ).
RESULTS AND DISCUSSION
Shear Bond Strength
The mean shear bond strength (in MPa) for each group is displayed
in Table 1. A one-way ANOVA was done for the dentin
and enamel groups. The level of significance for dentin was
p < 0.0001, and for enamel p = 0.0168. A post-hoc LSD test
was done for pair-wise comparison. The group marked by an
asterisk was statistically different compared to the other
groups (p < 0.05).
246 The Journal of Adhesive Dentistry