In vivo wear pattern of experimental light-cured hybrid composite resins

This study evaluated the effect of various types of microfiller on the in vivo wear resistance of composite resins. Experimental light-cured composites with two different microfiller systems were prepared: (1) 56 wt % fine quartz filler, 21 wt% organic filler and 3 wt% colloidal silica filler (Hybrid type 1), and (2) 64 wt% fine quartz filler and 21 wt% colloidal silica filler (Hybrid type 2). The resin monomer consisted of 50 wt % Bis-GMA and 50 wt% TEGDMA. These materials were placed in 2 mm diameter cylindrical cavities located in the OCA (occlusal contact area) or the CFA (contact free area) in cast gold-silver-palladium alloy full coverage crowns, which were temporarily set in a volunteer patient's mouth. The crowns were removed at monthly intervals for SEM observation. Hybrid type 1, which contained organic fillers, showed bulk fractures in the OCA, by the second month of the experiment. However, reinforcement of the resin matrix by dispersion of microfiller provided Hybrid type 2 with superior wear resistance for up to two months.