Two-body sliding wear of a direct-filling silver alternative to amalgam

Objective: This study investigated the wear resistance of a mercury-free silver direct-filling material and a dental amalgam. Method and materials: A precipitated silver powder was rinsed with dilute fluoboric acid and consolidated into a cohesive solid. For tooth cavity restoration and flexural testing, the silver was consolidated with a dental amalgam plugger at a load of 15 N. For wear testing, because of the relatively large specimen size, the silver was pressed at a rpessure of 150 MPa, yielding a density similar to that obtained by hand consolidation. Results: The silver had a flexural strength twice that of amalgam. Pin-on-disk wear resulted in a smooth surface and hardening in silver, as measured by indentation inside the wea r tracks, in contrast to the damage that was found in amalgam. The wear track cross-sectional area (n = 12) at 10 to the sixth power revolutions was not statistically significantly different among amalgam, polished silver, and burnished silver. Conclusion: The consolidated silver exhibited work hardening and surface densification during wear and, as a result, was more resistant to wear-induced damage than amalgam.