Selective masking for thin indirect restorations: Can the use of opaque resin affect the dentine bond strength of immediately sealed preparations?

Purpose: Evaluate the dentine bond strength using different methods of application of opaque resins to mask dentine discoloration. Materials and methods: Dentine was exposed on 21 extracted molars which were assigned to 3 groups: G1: immediate dentine sealing (IDS). G2: IDS + opaque. G3: IDS with adhesive resin mixed with opaque. After 1 week, teeth were restored and beams were fabricated for microtensile testing. Optical microscopy was used to analyse the failure mode. Results: Bond strength mean values were statistically different: G1 55.20 MPa > G2 45.79 MPa > G3 18.96 MPa. Failure modes were mostly adhesive for G1 and G3. G2 presented mostly mixed failures. Conclusion: The use of opaque resin to mask discoloured dentine results in a decrease of bond strength.