Direct observation of in vivo wear of composite resins.

This study developed a simple method for in vivo evaluation of wear on composite resins and examined the role of filler particles in this process. Experimental light-cured composite resins with two different filler systems were prepared: (1) 81 wt% fine quartz filler (Conventional type) and (2) 73 wt% organic filler (Microfilled type). The resin monomer consisted of 50 wt% Bis-GMA and 50 wt% TEGMA. These materials were placed in cylindrical cavities 2 mm in diameter located in the OCA (occlusal contact area) or the CFA (contact free area) in Au-Pd crowns, temporarily set in a volunteer's mouth. The crowns were removed at monthly intervals for longitudinal SEM observation. Results showed that the newly developed method was useful for observing the in vivo wear-patterns of composite resins. The two experimental composite resins with different filler systems showed quite different wear-patterns.