Microtensile bond strength of a filled vs unfilled adhesive to dentin ...

Microtensile bond strength of adhesive to dentin using self-etch and total-etch technique 287
Figure 2 (A) Scanning electron micrograph of the resin–
dentin interface bonded with One-Step Plus with selfetch
technique after argon ion etching. Thickness of the
hybrid layer (3.5 mm) was similar to the One-Step Plus
total-etch group (Fig. 1(A) and (B)) and the adhesive
layer was 10 mm thick. c, composite; fa, filled adhesive;
h, hybrid layer; d, dentin. (B) Scanning electron
micrograph of the resin–dentin interface bonded with
One-Step Plus with self-etch technique subjected to
sequential acid–base treatment. Thickness of the hybrid
layer (3.5 mm) and the adhesive layer (17 mm) were
similar to the One-Step Plus total-etch group (Fig. 1(B)).
Resin penetration into dentinal tubules were observed
(arrow) c, composite; fa, filled adhesive; h, hybrid layer;
d, dentin; g, gap induced between hybrid layer and
adhesive.
created with the filled One-Step Plus and the
unfilled One-Step adhesives using the total-etch
technique were approximately 3 mm (Figs. 1(A) and
(B), 3(A) and (B)), and when using self-etch
technique, the hybrid layers of both adhesives
were also a similar thickness of 3.5 mm (Figs. 2(A)
and (B), 4(A) and (B)). The adhesive layers achieved
with the filled adhesive One-Step Plus both with
total-etch and self-etch techniques were thicker
(12–17 and 10–17 mm, respectively; Figs. 1(A) and
(B), 2(A) and (B)) than the unfilled adhesive One-
Step (2 mm) (Figs. 3(A) and (B), 4(A)). Fillers were
Figure 3 (A) Scanning electron micrograph of the resin–
dentin interface bonded with One-Step with total-etch
technique after argon ion etching. The hybrid layer was
3 mm thick and the adhesive layer was 2 mm thick.
Adhesive layer (a) created with the unfilled adhesive
was very thin (compare Fig. 1(A) and (B)). c, composite;
h, hybrid layer; d, dentin. (B) Scanning electron
micrograph of the resin–dentin interface bonded with
One-Step with total-etch technique subjected to sequential
acid–base treatment. The hybrid layer was 3 mm thick
and the adhesive layer was only 2 mm thick. Resin-tags
(arrow) were penetrated deeply into dentinal tubules.
Adhesive layer (a) created with the unfilled adhesive
was very thin (compare Fig. 1(A) and (B)). c, composite,
h, hybrid layer, d, dentin.
uniformly dispersed in the adhesive layers (Figs.
1(A) and (B), 2(A)) and were evident around the
tubular orifices and into some dentin tubules
(Fig. 1(A)) with the total-etch technique.
Failure modes of the specimens in various
groups are shown in Table 4. SEM of the
representative debonded specimens are shown
in Figs. 5–8. Chi-squared analysis revealed that
One-Step Plus self-etch group, which provided
the lowest mTBS among the all groups, was
significantly different from the other groups
(p!0.05) and 85% of the specimens showed