MTBS of Various Bonding Systems to Normal & Caries Dentin

Objective: In order to simplify clinical procedures, one-step system has been developed. MTBS are used for evaluation of adhesives. Clinically, the bonding substrate is caries-affected (CA) dentin. Very little has been published on that clinically relevent substrate. This study tested the hypothesis that bonding to CA would yield bond strengths lower than bonds made to non-caries dentin (NCA). To compare gap & fracture analysis. Methods: Eighty human molars (CA & NCA)used. After caries excavated in CA, class I was prepared in both CA & NCA and bonded with OptiBond FL (OB), Prime & Bond NT (PB, Clearfil SE Bond (CF), & Prompt L-Pop (PLP). Cavities restored with composite. Slabs 1mm were sectioned, impressions taken & replicas produced. Marginal quality was calculated as % of gap viwed under SEM. Specimens were prepared for MTBS & debonded until failure. Fractured surfaces were evaluated using SEM. ANOVA & Tukey's post-hoc (P<0.05) were used. Results: There was significant effect of bonding (p=0.000) & dentin substrates (p=0.001). However there were no statistically significant differences between bonds made to NCA & CA for all adhesives, except for CF (p=0.002). SEM showed no gap in OB & CF of CA group, both PB & PLP showed gap in both dentin conditions. Most of the failures occurred in the adhesive, regardless of the adhesive used nor dentin substrate. Conclusions: The findings support the hypothesis that bonding to CA with all tested adhesives produces bond strengths lower than these achieved to NCA. However, the difference was not statistically significant except for CF. PLP had the highest gap amongst all systems regardless of the dentin substrates. The selection of an adhesive in a clinical setting should be based on undestanding the biology of the tooth substrate and consider certain factors in selecting one adhesive system over the other.