ABSTRACT
Purpose: This study was to compare and evaluate the effect of home bleaching on the microhardness and flexural strength of microhybrid and nanohybrid composite resins. Materials and methods: The study samples were prepared using a custom-made silicon rubber mold. For microhardness evaluation, 40 disc-shaped specimens (4mm*2mm) were prepared and divided into 4 groups: GROUP A (n=10): microhybrid (GC Solaire X, GC Corporation) control group, GROUP B (n=10) nanohybrid (Tetric N Ceram, Ivoclar Vivadent) control group, GROUP C (n=10): microhybrid bleaching group, GROUP D (n=10) nanohybrid bleaching group. For flexural strength evaluation, 40 bar shaped specimens (25mm*2mm*2mm) were prepared. They were divided into 4 groups, GROUP 1 (n=10): microhybrid control group, GROUP 2 (n=10) nanohybrid control group, GROUP 3 (n=10): microhybrid bleaching group, GROUP 4(n=10) nanohybrid bleaching group. All the control groups were placed in artificial saliva and bleaching groups were exposed to home bleaching agent for 14 days according to manufacturer's instructions. The microhardness and flexural strength were evaluated for the respective specimens after 14 days and the data were statistically analyzed. Results: Home bleaching regimen decreased microhardness of both microhybrid and nanohybrid composites whereas there was no significant effect on the flexural strength. Nanohybrid composites showed greater microhardness values before and after bleaching. Conclusion: Bleaching agents, irrespective of their concentration can decrease the microhardness of the composite resin samples, which raises a concern about replacement of these restorations due to the effects on physical and mechanical properties.
ABSTRACT
INTRODUCTION: The aim of this retrospective study was to estimate the outcome of nonsurgical root canal treatment using matched single-cones with a calcium hydroxide-based sealer and to identify the various prognostic factors influencing the outcome. METHODS: This was a retrospective study that enrolled 272 patients who underwent routine endodontic therapy and were obturated with matched single-cones and Sealapex as sealer. This study involved 223 patients with 261 teeth meeting the selection criteria and recalled between 24 and 84 months. The outcome was categorized as success (healed/healing clinically and radiographically) or failure (not healed clinically and/or radiographically). Two calibrated examiners assessed the treatment outcomes. A binomial logistic regression model was performed to identify the effect of various prognostic factors. The χ2 test was used to find the association between sealer extrusion and the initial periapical index scores. RESULTS: The overall success rate was found to be 89.7% for a mean recall period of 39.18 (±11.05) months. An increase in age was associated with increased odds of success, whereas the success rates were reduced by an increase in the number of roots and negative pulp sensibility status. Initial periapical index scores, presence of preoperative sinus tract, number of visits, and sealer extrusion did not affect the outcome significantly (P > .05). CONCLUSION: Within the limitations of this study, it was found that teeth obturated with matched single-cone and Sealapex achieved substantial success rates. Sealer extrusion did not have any significant effect on the treatment outcome.
