Bond Strength to Intact/caries-affected Dentin after Caries Indicator Application
Objective: to evaluate the effect of caries indicator application to intact or caries-affected dentin on shear bond strength (SBS) of an etch&rinse and a self-etch adhesive Methods: Occlusal surfaces of 60 extracted human molars with coronal dentin caries extending approximately halfway through the dentin and 60 caries free molars were ground perpendicular to the long axis of the tooth to expose a flat surface. The intact dentin (G1) and caries-affected dentin (G2) specimens were randomly divided into 6 subgroups according to the application of caries indicators and adhesive systems (n=10): a: untreated surface+ two step self-etch adhesive (Clearfil SE/ Kuraray); b: untreated surface+acid etching+etch&rinse adhesive (Clearfil Photo Bond/ Kuraray); c: Caries detector (Kuraray)+two step self-etch adhesive; d: Caries detector+acid etching+etch&rinse adhesive; e: Expose caries indicator (Centrix)+two step self-etch adhesive; f: Expose caries indicator+acid etching+etch&rinse adhesive.A nano-composite (Majesty Esthetics/ Kuraray) was applied using a special jig and SBS test was performed with a universal testing machine. Failure modes were determined under a stereomicroscope. SEM investigations were performed for the qualitative evaluation of resin-dentin hybridization. The data were subjected to statistical analysis using Kruskal-Wallis and Mann Whitney-U tests(p=0.05). Results: SBS test results revealed significant differences among subgroups of G1 (p<0.05). No significant difference was observed among the subgroups of G2 (p>0.05). The pair-wise comparisons of G1 and G2 subgroups showed significant differences (p<0.05). The SBS of G2c was higher than G1c and G2e showed higher SBS than G1e (p<0.05). The failure modes for all groups were mainly adhesive. SEM examinations supported the SBS results. Conclusion: Caries indicator application to intact dentin could hamper the SBS of self-etch adhesive, although its use on intact and caries-affected dentin prior to bonding procedure with etch&rinse adhesive was possible without impairing the performance of the final restoration.