Utility of Dental Operating Microscopes in Assessing Microleakage of Nanohybrid Resin Restorations Using Different Placement Techniques.

Background Composite resin has become a material of choice due to its aesthetic potential and durability. It is at a lower cost compared to ceramic restorations. But it has a tendency to shrink during polymerization, leading to the formation of gaps at the margins. Placement techniques of restoration can be modified to reduce stress shrinkage. A dental operating microscope will help in the precise and thin layering of composite against the cavity wall and the matrix band. Methodology Class I cavities were prepared in 30 human permanent premolars. All cavity surfaces were dried and acid-etched. A bonding agent was applied and they were light-cured. Specimens were divided into three groups: I, II, and III, where restorations were performed using horizontal layering, oblique layering, and split-increment horizontal layering techniques respectively. Samples were then submerged in silver nitrate solution and were examined under a stereomicroscope after a longitudinal section and graded for dye penetration. Results The dye penetration scores were subjected to a statistical analysis using Analysis of variance (ANOVA) with post hoc Tukey's test with the statistical software Statistical Package for Social Sciences (SPSS version 12). The level of significance was set at 0.05 for all statistical inferences. Conclusion The split-increment horizontal layering technique under the dental operating microscope showed less microleakage when compared to other methods and is the preferred method for composite restorations.