An In Vitro Exploration of Interaction Mechanisms of Intracoronal Bleaching on the Compressive Strength of Conventional and Calcium Silicate-Based Self-Adhesive Resins and Their Bonding to Composite Resin Restorative Material.

Objectives: The cervical resorption following intracoronal bleaching necessitates the application of impermeable cervical barriers. This study aimed to evaluate the effect of two bleaching agents on the compressive strength (CS) and shear bond strength (SBS) of two self-adhesive resins, TheraCem and Vertise Flow, to composite resin restorative material. Materials and Methods: Two hundred sixteen specimens from TheraCem and Vertise Flow were prepared in special molds and treated in three groups: nonbleached (control); sodium perborate-hydrogen peroxide (SP-HP) (sodium perborate +3% hydrogen peroxide); and HP gel (35% hydrogen peroxide gel). The CS of 72 specimens in the three groups was tested using a universal testing machine. For SBS test, 144 specimens from TheraCem and Vertise Flow in the three groups were bonded to Z250 composite using Single Bond Universal adhesive in self-etch and etch-and-rinse modes. SBS was measured using universal testing machine. Data were analyzed using two-way ANOVA and Tukey tests for CS and three-way ANOVA and Tukey tests for SBS. Results: Vertise Flow showed higher CS than TheraCem (p < 0.001), while none of the bleaching agents deteriorated its CS. HP gel significantly lowered the CS of TheraCem (p = 0.001). Bleaching agents increased the SBS of Vertise Flow while the SBS of TheraCem was not significantly affected. For both resin barriers, SBS was higher in the etch-and-rinse mode (p < 0.05), except in nonbleached Vertise Flow (p = 0.091). Conclusions: HP gel deleteriously affected the CS of only TheraCem during nonvital bleaching. The etch-and-rinse mode was preferred in terms of SBS for resin barriers.