Occlusal Wear of Metal-Free Ceramic-Filled Polymer Crowns After 2 Years in Service

Purpose: Improvements in the physical properties of modern composites have led to continuous expansion of their field of application to include extensive, occlusion-bearing posterior restorations and even metal-free polymer crowns. The objective of this clinical study was to investigate the influence of gender, arch, and crown location on the occlusal wear of metal-free ceramic-filled polymer crowns and to compare their wear with the mean annual occlusal wear of enamel (15 to 38 µm). Materials and Methods: One hundred fourteen ceramic-filled polymer crowns made of Artglass (Heraeus Kulzer) were placed in 74 patients. After 1 year, 93 crowns were available for wear measurement. After 2 years, 76 crowns were available. Wear was determined by use of replicas. A 3-dimensional optical profilometer (Laserscan 3D, Willytec) was used to digitize and superimpose the occlusal surfaces of the baseline and recall replicas (occlusal matching). Results: After 1 year, median wear of the entire occlusal surface was 19 µm for anterior and canine teeth, 19 µm for premolars, and 21 µm for molars. After 2 years, median wear was 36 µm for anterior and canine teeth, 44 µm for premolars, and 84 µm for molars. The wear of the occlusal contact areas was significantly higher. Significant effects of crown location (premolar or molar) on the extent of wear of the occlusal contact areas were found. Conclusions: Ceramic-filled polymer crowns are subject to measurable occlusal wear that exceeds that of natural enamel.