A six-year prospective randomized study of a nano-hybrid and a conventional hybrid resin composite in Class II restorations

ObjectiveThe objective of this 6 year prospective randomized equivalence trial was to evaluate the long-term clinical performance of a new nano-hybrid resin composite (RC) in Class II restorations in an intraindividual comparison with its well-established conventional hybrid RC predecessor.MethodsEach of 52 participants received at least two, as similar as possible, Class II restorations. The cavities were chosen at random to be restored with an experimental nano-hybrid RC (Exite/Tetric EvoCeram (TEC); n = 61) and a conventional hybrid RC (Exite/Tetric Ceram (TC); n = 61). The restorations were evaluated with slightly modified USPHS criteria at baseline and then annually during 6 years.ResultsTwo patient drop outs with 4 restorations (2TEC, 2TC) were registered during the follow-up. A prediction of the caries risk showed that 16 of the evaluated 52 patients were considered as high risk patients. Eight TEC (2 P, 6M) and 6 TC (2P, 4M) restorations failed during the 6 years. The main reason of failure was secondary caries (43%; including the failure fracture + secondary caries it increases to 57.1%). 63% of the recurrent caries lesions were found in high caries risk participants. The overall success rate at six years was 88.1%. No statistical significant difference was found in the overall survival rate between the two investigated RC.SignificanceThe nano-hybrid RC showed good clinical performance during the 6 year evaluation, comparable to the well-established conventional hybrid RC.