Sol–gel materials: 2. Light-curing dental composites based on ormocers of cross-linking alkoxysilane methacrylates and further nano-components

Objectives The objective of this study was to investigate the use of ormocers, which were synthesized from amine or amide dimethacrylate trialkoxysilanes. Ormocers showed improved biocompatibility in dimethacrylate-diluent-free composite restoratives. Selected mechanical properties, such as flexural strength and flexural modulus of experimental composites containing ormocers were investigated. In addition, the influence of methacrylate-substituted ZrO2 clusters and SiO2 organosols on the mechanical properties of composites was studied. Methods The flexural strength and flexural modulus of elasticity were determined according to ISO 4049: 2000. For this purpose, test specimens (2 mm × 2 mm × 25 mm) of the composites investigated were prepared in stainless steel moulds and light-cured (150 mW/cm2, 2 × 180 s). The flexural strength and flexural modulus of elasticity were measured after the samples had been stored in water for 24 h at 37 °C. Results While visible light-cured dimethacrylate-diluent-free composite restoratives based on the investigated ormocers showed a similar flexural strength and flexural modulus of elasticity compared to composites that contain only dimethacrylates, their double bond conversion was considerable lower. The simultaneous addition of methacrylate-substituted ZrO2 clusters and SiO2 organosols to the ormocer composite improved the mechanical properties of the composites. Significance Ormocers of amine or amide dimethacrylate trialkoxysilanes enabled the preparation of dimethacrylate-diluent-free composite restoratives. Based on the lower cytotoxicity of the ormocers, the prepared restorative composites should show improved biocompatibility. With the addition of nanoparticles, such as methacrylate-substituted ZrO2 clusters or SiO2 organosols, the mechanical properties of composites can be improved.