Friction and Wear Behaviors of Indirect Dental Restorative Composites

Under different simulated oral environments (distilled water, artificial saliva, and a cola soft drink) and with a small-amplitude reciprocating apparatus, the friction and wear behaviors of 5 types of indirect dental restorative composites relative to uniform Si3N4 balls were investigated. Test parameters were: normal load with 20 N, reciprocating amplitude (1,000 μm), and frequency (0.25 Hz). Tests lasting up to 5,000 cycles were conducted. The wear damage characteristics are discussed in detail based on an analysis of friction behaviors, SEM observations, and 2- and 3-D profile microscopy. The results indicated that the hybrid resin composites with high filler weight and well filler distributions, such as Filtek P60, possess better wear resistance than nano-filled composites, such as VITA ZETA and VITA LC, with relatively low filler weight. Artificial saliva and a cola soft drink could play important roles in lowering the friction coefficient and wear loss of dental composites. The cola soft drink displayed a better lubrication effect. The degree of sensitivity to changes in lubrication conditions varies with different dental composites. Abrasive wear is the main wear mechanism for the 5 composites, but brittle cracks and delamination are more common for VITA ZETA and VITA LC.