Dislodgement resistance of Biodentine and mineral trioxide aggregate as coronal barriers for revascularizing teeth after simulated "Walking bleach" technique: An ex-vivo study

Aim: The aim of this study was to compare the dislodgement resistance of Biodentine (BD) and mineral trioxide aggregate (MTA), when used as coronal barriers during revascularisation procedures, on exposure to a bleaching agent in a simulated "walking bleach" technique. Materials and Methods: The study used 100 human, maxillary central incisors. Root canals were enlarged up to size 6 Peeso drills. After coronal-barrier placement, either BD or MTA, specimens of each material were randomly divided into five subgroups (n=10) according to time and setting environment: For subgroups A, B and C, specimens were placed in contact with a saline-moistened cotton pellet in a pulp chamber for 1 day, 1 week or 2 weeks respectively. Subgroup D specimens were placed in contact with a saline-moistened cotton pellet for 1 day, then in contact with the bleaching agent for 1 week. For subgroup E the specimens were prepared as subgroup D, followed by a change of bleaching agent for the second week. Push-out bond strength was measured. ANOVA was used to compare means, followed by the Tukey post hoc test for pair-wise comparisons. The significance level was set at P = 0.05. Results: BD recorded higher dislodgement resistance than MTA after 1 day, 1 and 2 weeks of setting (P 0.05); BD retained its higher dislodgement resistance than MTA after bleaching for 1 week (P 0.05). After 2 weeks of bleaching, however, there was no significant difference between BD and MTA (P > 0.05). There was no significant difference in dislodgement resistance of BD with or without bleaching after 1 or 2 weeks and of MTA with and without bleaching after 1 week (P > 0.05). After 2 weeks, however, MTA showed higher dislodgement resistance with bleaching than without (P 0.05). Conclusions: BD seems to have better retention qualities than MTA as a coronal barrier for revascularising teeth providing a suitable alternative. The walking bleach technique can be safe to use in discoloured, immature teeth undergoing revascularisation, retention-wise. Keywords: Biodentine, bond strength, sodium perborate