Contact- and contact-free wear between various resin composites

Objective
Nowadays direct and indirect resin composites are frequently applied to build up the occlusion when extensive tooth wear took place. To achieve long-lasting restorations it is essential to obtain knowledge about their interactions due to occlusal contacts. Therefore, the two- and three-body wear between frequently used direct and indirect resin composites was investigated.

Materials and methods
The two- and three-body wear of three direct resin composites and three indirect resin composites, with Clearfil AP-X, Filtek Z250, and Filtek Supreme XT as antagonists, were measured, using the ACTA wear device. The wear rates were determined and the surfaces were evaluated with SEM.

Results
The most remarkable outcome was that the two-body wear rate of the different composites opposing the Z250 wheel were significantly higher. Furthermore, it was shown that the three-body wear rate was independent on the antagonist and in general higher than the two-body wear rate.

Conclusions
To reduce abrasion of the opposing resin composite surface the resin composite fillers should consist of a softer glass, e.g. barium glass or in case of a harder filler the size should be reduced to nano-size.