Impact of Calcium Hydroxide, Sodium Ascorbate, and Sodium Thiosulfate on the Bond Strength of Composite Restorations to Bleached Dentin.

This article investigates the impact of calcium hydroxide and antioxidant agents—specifically 10% sodium ascorbate and 5% sodium thiosulfate—on the bond strength of composite resin restorations to dentin following nonvital tooth bleaching. Using an artificial pulp chamber model and bovine teeth subjected to bleaching with sodium perborate and 20% hydrogen peroxide, the study compared immediate versus delayed (7 days) restoration protocols with or without surface treatments. Results showed that delaying the final restoration by 7 days after bleaching significantly improved bond strength to levels comparable to nonbleached controls, regardless of the surface treatment applied. Immediate restoration, even after antioxidant application for 10 minutes, resulted in significantly lower bond strength, indicating that these antioxidants did not effectively reverse the compromised adhesion when used in this manner. The findings support clinical recommendations to postpone adhesive restorations for at least 7 days following nonvital bleaching to ensure satisfactory bonding outcomes.