A prospective randomised clinical trial of one bis-GMA-based and two ormocer-based composite restorative systems in class II cavities: three-year results.

OBJECTIVES Ormocer composites, consisting of a silicon-based polymer, have been developed recently as a tooth-coloured restorative material. The purpose of this prospective randomised clinical trial was to evaluate the performance of two small-particle hybrid ormocer-based restorative systems (AD, Admira/Admira Bond, VOCO; DE, Definite/Etch & Prime 3.0, Dentsply) and one small-particle hybrid bis-GMA-based composite restorative system (TC, Tetric-Ceram/Syntac, Ivoclar-Vivadent) in occlusal stress-bearing restorations. METHODS One hundred and twenty-eight occlusal-proximal restorations (44 AD, 43 DE and 41 TC) were placed according to the manufacturer's instructions in thirty-two adult patients. Their clinical performance was scored according to the USPHS criteria and evaluation of bite-wing radiographs. RESULTS After 3 years, four AD, five DE and four TC restorations had failed due to fracture or marginal gap formation. Surface roughness improved significantly when compared to the baseline in AD and TC (Friedman test, p<0.05) during the first year but returned to baseline values after 3 years. DE had a significant tendency towards discolouration (p<0.05). Bite-wing radiographs showed two AD and one TC restorations with internal porosities. ANOVA showed that larger restorations (> or = 3 surfaces) showed significantly more degradation than smaller ones. CONCLUSIONS In a group of class II restorations, there was no significant difference in failures after 3 years between ormocer-based and bis-GMA-based restorative systems.