SEM and microleakage evaluation of the marginal integrity of two types of class V restorations with or without the use of a light-curable coating material and of polishing

OBJECTIVES: To evaluate the marginal integrity of class V restorations through an SEM observation and a microleakage test. METHODS: Teeth with class V cavities were restored with either a flowable composite (n=20) or a glass ionomer cement (GIC) (n=20). Ten restorations in each group were immediately polished. A coating agent was applied on five polished and five non-polished restorations of each group. No coating was used on the remaining specimens. Epoxy resin replicas of the restorations were observed under a SEM and the percentage of marginal gaps was calculated. After immersion in a 2% methylene blue solution, three sections were obtained from each specimen and observed under a stereomicroscope. Occlusal and gingival microleakage were evaluated with a four-steps scoring system. The percentages of marginal gaps and the microleakage scores were analyzed with the Kruskal-Wallis ANOVA and the Mann-Whitney test with Bonferroni's correction. Occlusal and gingival microleakage were compared with the Wilcoxon test. RESULTS: No gaps were detected after coating. The restorative materials did not differ in interfacial gaps. Immediate polishing increased the gaps of uncoated restorations (p<0.05). The microleakage decreased with coating, except for occlusal wall of polished flowable composite restorations. After coating, the occlusal microleakage was higher than the gingival (p<0.05), except for non-polished flowable composite restorations. After polishing and coating, the flowable composite showed higher occlusal microleakage than the GIC. The polishing increased the occlusal microleakage of coated flowable composite restorations. CONCLUSIONS: The coating procedure is advisable for restoring marginal integrity and reducing gingival microleakage in class V restorations.