Marginal quality of posterior microhybrid resin composite restorations applied using two polymerisation protocols: 5-year randomised split mouth trial.

OBJECTIVES: This randomised, split-mouth clinical study evaluated the marginal quality of direct Class I and Class II restorations made of microhybrid composite and applied using two polymerisation protocols, using two margin evaluation criteria. METHODS: A total of 50 patients (mean age: 33 years) received 100 direct Class I or Class II restorations in premolars or molars. Three calibrated operators made the restorations. After conditioning the tooth with 2-step etch-and-rinse adhesive, restorations were made incrementally using microhybrid composite (Tetric EvoCeram). Each layer was polymerised using a polymerisation device operated either at regular mode (600-650 mW/cm(2) for 20s) (RM) or high-power (1200-1300 mW/cm(2) for 10s) mode (HPM). Two independent calibrated operators evaluated the restorations 1 week after restoration placement (baseline), at 6 months and thereafter annually up to 5 years using modified USPHS and SQUACE criteria. Data were analyzed using Mann-Whitney U-test (α=0.05). RESULTS: Alfa scores (USPHS) for marginal adaptation (86% and 88% for RM and HPM, respectively) and marginal discoloration (88% and 88%, for RM and HPM, respectively) did not show significant differences between the two-polymerisation protocols (p>0.05). Alfa scores (SQUACE) for marginal adaptation (88% and 88% for RM and HPM, respectively) and marginal discoloration (94% and 94%, for RM and HPM, respectively) were also not significantly different at 5th year (p>0.05). CONCLUSION: Regular and high-power polymerisation protocols had no influence on the marginal quality of the microhybrid composite tested up to 5 years. Both modified USPHS and SQUACE criteria confirmed that regardless of the polymerisation mode, marginal quality of the restorations deteriorated compared to baseline.