Fracture resistance of teeth undergoing postendodontic bleaching: Comparison of four treatment modalities - An in vitro study

Abstract

Aims: The aims of the study were: (1) to evaluate the fracture resistance of endodontically treated teeth restored with microhybrid composite following combination bleaching and (2) to assess the antioxidizing effect of 10% sodium ascorbate hydrogel. Settings and Design: This was a randomized control trial in a tertiary care setting. Subjects and Methods: Endodontic treatment was performed on 40 freshly extracted human mandibular premolars. Following removal of gutta-percha 2 mm apical to cementoenamel junction and application of resin-modified glass ionomer as cervical barrier, all teeth were embedded in acrylic resin using cylindrical molds. Specimens were divided into five groups: Group 1 (n = 8): Specimens subjected to inside and outside bleaching using 10% hydrogen peroxide followed by composite restoration. Group 2 (n = 8): Specimens subjected to inside-outside bleaching with 10% hydrogen peroxide and sodium perborate followed by composite restoration; Group 3 (n = 8): Specimens subjected to conditioning with 10% sodium ascorbate after inside-outside bleaching using 10% hydrogen peroxide followed by composite restoration; Group 4 (n = 8): Specimens subjected to conditioning with 10% sodium ascorbate after inside-outside bleaching with 10% hydrogen peroxide and sodium perborate followed by composite restoration; and Group 5 (negative control) (n = 8): After endodontic treatment specimens were restored with composite. Finally, all the specimens were subjected to fracture resistance test using Universal Testing Machine. Statistical Analysis Used: ANOVA test followed by post hoc comparison of groups taken together by Tukey's analysis was performed. Results: Statistically significant difference in fracture resistance was present between Group 5 and Group 1 and also between Group 5 and Group 2. Unpaired t-test showed statistically significant difference between Group 1 and Group 3 and also between Group 2 and Group 4. Conclusion: The use of 10% sodium ascorbate antioxidant gel was effective in compensating for the decreased fracture resistance following combination bleaching.