Marginal Adaptation of Ormocer, Nanofilled, and Nanoceramic Class V Composite Restorations Subjected to Thermal and load Cycling

Abstract Background: The marginal integrity of resin composite restorations especially in class V cavities remains a challenge in operative dentistry. This study aimed to evaluate the effect of substrate and restorative system on the marginal adaptation of class V composite restorations. Methods: Standardized class V cavities were prepared in sound human molars with the cervical margin on dentin and the occlusal margin on enamel. An ormocer, nanofilled, nanoceramic and microhybrid composite were utilized. After finishing and polishing, marginal adaptation of the restorations was analyzed by metallographic microscope (T0) and the following parameters were recorded: width of maximum marginal gap (MG), percentage length of debonded margin relative to cavity periphery (DM), and marginal index (MI = MG × DM/100). After the first evaluation, the specimens underwent thermal cycling (2,000 cycles of 5ºC–55ºC ± 2ºC) and load cycling (50,000 cycles of 50 N and 1 Hz). Specimens were reanalyzed by metallographic microscope (T1). The recorded data were compared using multi-way analysis of variance (ANOVA) and Tukey’s test (ɑ < 0.05). Results: The type of restorative/adhesive system and margin location significantly affected marginal adaptation. Ormocer restorations exhibited the lowest MG, DM, and MI values, whereas microhybrid composite restorations exhibited the highest values. Relative to the baseline condition, the specimens showed higher gap measurements after thermal and load cycling. Conclusion: The margin location and restorative system have a substantial effect on the marginal adaptation of class V composite restorations. Clinical relevance statement:The cavity margin location and the restorative system have significant influence on the durability of cervical restorations.