Mineral trioxide aggregate (MTA) has shown good biocompatibility in several studies. In the present study, the genotoxic and cytotoxic effects of calcium enriched mixture (CEM) were evaluated compared with MTA using MTT and single-cell gel (comet) assays with serial ascending concentrations (0 to 1,000 µg/mL) of tested materials. Cytotoxicity data indicated that there is no significant difference between CEM and MTA at all concentrations except for the full concentration (1,000 µg/mL); CEM had lower cytotoxicity. Genotoxic effects were more evident with CEM at concentrations of 15.6 and 250 µg/mL; however, was less than that of MTA at concentrations of 500 and 1,000 µg/mL. The cytotoxicity and genotoxicity effects of the two experimental groups generally increased with consistency. Under the conditions of this study, CEM is biocompatible in terms of cyto- and genotoxicity. It appears to be an alternative to MTA as an endodontic biomaterial offering several advantages.

Introduction: The aim of this study was to compare the cytotoxicity of Mineral Trioxide Aggregate (MTA) and a New Endodontic Cement (NEC) on L929 mouse fibroblasts.

Aim: The aim of this study was to compare the neutralizing effect of antioxidant agents on the microleakage of dental restorations in nonvital teeth after bleaching with carbamide peroxide. Also assessed was the correlation of the microleakage data between an electrochemical and a staining technique. Methods and Materials: Following root canal therapy, 40 sound and similar human maxillary central incisors were randomly divided into four groups of 10 specimens each (n=10). The groups were subjected to one of four treatments: Group 1, bleaching with 10 percent carbamide peroxide for periods of eight hours per day for one week without an antioxidant agent; Group 2, bleaching with 10 percent carbamide peroxide plus 10 percent sodium ascorbate gel; Group 3, bleaching with 10 percent carbamide peroxide plus 10 percent sodium ascorbate gel combined with a surfactant; and Group 4, no bleaching treatment (control group). In all groups, the access cavities were restored using the Single Bond Plus Adhesive system and Z100 resin-based composite. After 1,000 thermal cycles, the teeth were dried and three layers of nail varnish were applied over the entire surface area to within 1.0 mm of the restoration. A PVC-covered copper wire, with 3.0 mm of exposed bare wire, was inserted apically 5.0 mm into the canal, which was obturated with gutta-percha and sealed with sticky wax and varnish at the apex. Leakage was continuously monitored for 40 days using a conductimetric method. The teeth were immersed in 0.5 percent basic fuchsine for 24 hours, followed by sectioning for microscopic examination at 16x magnification. The data were analyzed using ANOVA and the Newman-Keuls multiple comparison, Kruskal-Wallis, Mann-Whitney, and Spearman's rho tests (p<0.05). Results: Based on the electrochemical results, cavities subjected to 10 percent sodium ascorbate gel combined with a surfactant displayed the least amount of microleakage while teeth that were bleached but not treated with an antioxidant exhibited significantly greater microleakage (p=0.007). These findings also were corroborated by the results of the staining experiments that showed a strong correlation between the electrochemical and staining findings (p=0.006) for the groups. Conclusion: After nonvital bleaching and the application of the antioxidant 10 percent sodium ascorbate, the addition of the surfactant 0.2 percent Tween 80 to the conventional antioxidant formulation significantly reduced microleakage. Clinical Significance: The addition of a surfactant to the antioxidant formulation significantly reduced microleakage when it was applied after bleaching. Citation: Moosavi H, Moghaddas MJ, Ghoddusi J, Rajabi O. Effect of Two Antioxidants on the Microleakage of Resin-Based Composite Restorations after Nonvital Bleaching. J Contemp Dent Pract [Internet]. 2010 December; 11(6):033- 040. Available from: http://www.thejcdp.com/ journal/view/volume11-issue6-moosavi