Wear of prosthodontic materials--an in vivo study.

The aim of this investigation was to study quantitative and qualitative aspects of the wear process of some prosthodontic materials in three different persons in vivo. The in vivo models combined two methods: removable double crowns and a replica technique. The wear resistance of gold (types III and IV), porcelain and a microfilled resin was studied opposing metal ceramic crowns and in one person when opposing all four materials. All three persons had earlier histories of occlusal wear of teeth and/or restorations. The wear rate of gold and porcelain showed equal values antagonizing metal ceramic crowns in all three persons. The microfilled resin had a wear rate three or four times higher in the same situations. No significant difference in wear resistance could be found between type III and type IV gold alloys. The wear mechanism seemed to be a fatigue type in porcelain, and in gold a combined fatigue and abrasive type of wear. The microfilled resin showed mainly a fatigue type of wear but some observations indicating a tribochemical reaction were also made.