Effect of abrasion medium on wear of stress-bearing composites and amalgam in vitro.

Measurements of in vitro wear for several composite materials and an amalgam were conducted using a new device in which contact stress, moving speed, mutual slip, and third-body composition could be set. This preliminary study reports the results obtained with a fixed choice of contact stress, speed, and slip, but with different third-body media. With a Millet-seed/PMMA-beads mixture as a medium, the various types of restoratives showed a wear pattern and relative ranking comparable with that reported in clinical studies.