Effect of Bleaching Agents on the Sealing of Cervical Barrier in Intracoronal Bleaching Procedures

Abstract

Discoloration of nonvital teeth is an esthetic deficiency frequently requiring bleaching treatment. The purpose of this study was to evaluate in vitro the effect of bleaching agents on two different cervical barriers in order to minimize or prevent the leakage along the root canal filling in the intracoronal bleaching procedures. Ninety-six extracted human molars were used which were biomechanically prepared, filled and divided into eight groups. The cervical barriers tested were zinc phosphate cement (ZPC) and resin-modified glass ionomer cement (RMGIC) applied (3 mm of thickness) at the cementoenamel junction level. Forty-eight specimens were divided into four groups for each cervical barrier: (1) control group without bleaching agent, (2) a mixture of sodium perborate and distilled water, (3) a mixture of sodium perborate and 10% carbamide peroxide and (4) a mixture of sodium perborate and 35% carbamide peroxide. The bleaching agents were placed inside the pulp chamber for 7 and 14 days, and the access opening was sealed with Cimpat. After 21 days, microleakage evaluation of 2% rhodamine B dye solution at dentin-cervical barrier interface was performed by a stereomicroscope. Data were submitted to Kruskal-Wallis, Dunn's and Dunnett's tests, with a significance level of 0.05. The results demonstrated no statistically significant differences among the control group and the experimental groups for each cervical barrier (ZPC and RMGIC); there were no significant differences among the bleaching agents for the same barrier and RMGIC barrier provided better sealing than ZPC (p < 0.05). Therefore, the bleaching agents demonstrated similar performance when tested for the same cervical barrier and RMGIC barrier provided better sealing than the ZPC barrier, regardless of the association of bleaching agents used.