Microleakage of silorane- and methacrylate-based class V composite restorations.

The marginal integrity of class V restorations in a silorane- and a group of methacrylate-based composite resins with varying viscosities was tested in the present study. Different adhesives (OptiBond FL, KerrHawe; AdheSE One, Vivadent; or Silorane System Adhesive, 3M ESPE) were applied to 168 standardized class V cavities. The cavities (n = 12) were filled with a wide range of different viscous composite resins: Filtek Silorane, 3M ESPE; els and els flow, Saremco; Tetric EvoCeram and Tetric EvoFlow, Vivadent; Grandio, Voco; and Ultraseal XT Plus, Ultradent. Microleakage of the restoration was assessed by dye penetration (silver staining) on multiple sections with and without thermocycling and mechanical loading (TCML: 5,000 × 5-55°C; 30 s/cycle; 500,000 × 72.5 N, 1.6 Hz). Data were statistically analyzed with the Mann-Whitney U test and the Error Rates Method (ERM). The silorane-based composite resin yielded the lowest dye penetration after TCML. Microleakage of methacrylate-based composite restorations, in general (ERM), was statistically significantly influenced by the adhesive system, Moreover, dye penetration at enamel margins was significantly lower than dye penetration at dentin margins. The chemical basis of composite resins and adjacent tooth substance seems to strongly influence marginal sealing of class V restorations for methacrylate-based materials. Moreover, the steps of dental adhesives used affected marginal integrity. The silorane-based composite resin evaluated in the present study exhibits the best marginal seal. The three-step adhesive yielded better marginal sealing than the one-step adhesive for methacrylate-based class V composite restorations.