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

Objective: The 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.
Methods: Each 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.
Results: Two 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.
Significance: The nano-hybrid RC showed good clinical performance during the 6 year evaluation, comparable to the well-established conventional hybrid RC.
(Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)