Bond Strength of 10-MDP-Containing Adhesives Following Pre-Operative and Post-Operative Dental Bleaching: An In Vitro Study

Dental bleaching may compromise resin–tooth bonding, while functional monomers and post-bleaching strategies may influence adhesive performance. This study assessed the micro-tensile bond strength (µTBS) of a 10-MDP-containing versus a non-10-MDP-containing adhesive on enamel and dentine following hydrogen peroxide (HP) or carbamide peroxide (CP) bleaching performed before bonding or after restoration aging. Forty human molars yielded 400 beams for µTBS testing. For pre-operative bleaching, specimens received 32% HP or 35% CP and were bonded immediately, after a one-week delay, or immediately after sodium ascorbate (SA) application. For post-operative bleaching, bonded specimens were aged for three months before HP or CP bleaching; non-bleached specimens served as controls. Failure modes were assessed stereomicroscopically, and data were analyzed using four-way ANOVA. The tested 10-MDP-containing adhesive showed higher µTBS across experimental groups. HP produced higher µTBS in SA-treated and post-operative groups with the 10-MDP-containing adhesive, whereas CP produced higher µTBS after a one-week delay. Immediate bonding after bleaching produced the lowest µTBS values. Within the study conditions, bond strength was influenced by adhesive system, bleaching protocol, and bonding timing; SA after HP and delayed bonding after CP were associated with more favorable outcomes.