Comparative evaluation of self-etching primers with fourth and fifth generation dentin-bonding systems on carious and normal dentin substrates: An in vitro shear bond strength analysis

AIM: The aim of this study was to test the hypothesis that bonding to caries-affected dentin would yield strengths that are lower than bond strengths achievable when bonded to normal dentin. Dentin-bonding systems used in this study were fourth and fifth generation as well as self-etching primers. MATERIALS AND METHODS: Forty-eight freshly extracted mandibular and maxillary molars were selected of which 24 were caries-affected teeth and the remaining were noncarious teeth. Random sampling was done with eight teeth in each group based on the bonding system used. In caries-affected teeth, the soft, stainable, caries-infected dentin was excavated using a caries detector dye whereas the hard, caries-affected, nonstainable dentin was retained. All the teeth were subsequently mounted in a suitable acrylic mould. Prepared teeth were restored with a single composite resin, using three different dentin bonding systems. These prepared specimens were transferred to a Hounsfield tensometer to measure the shear bond strength. The results obtained were analyzed using Anova, Student's unpaired t-test, and Student Neuman Keulis test. RESULTS: The results showed that the self-etching primer required the highest mean shear load compared to the fifth and fourth generation dentin-bonding systems in both normal dentin and caries-affected dentin. CONCLUSION: Bond strength to dentin depends on whether the dentinal tubule is open or occluded. Within the limitations of this study, it was observed that bond strength to caries-affected dentin was low compared to normal dentin.