Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns

Statement of problem. Tooth wear is a complex process, which, if not prevented, may adversely affect the integrity of the stomatognathic system. Different restorative dental materials may affect the amount of wear on natural enamel antagonists. Purpose. The purpose of this in vivo study was to evaluate and compare the wear of enamel opposing natural enamel, zirconia, and metal ceramic crowns after 1 year. Material and methods. Ten participants between 18 and 35 years of age requiring 2 complete crowns, 1 on either side of maxillary or mandibular molar region, and having healthy natural teeth in the opposing arch were selected. For each participant, 1 monolithic polished zirconia crown and 1 glazed metal ceramic crown were fabricated and cemented. To evaluate the wear of the antagonistic natural enamel (premolar and molar), polyvinyl siloxane impressions were made immediately (baseline) and at 1 year after cementation. The wear of natural enamel against natural enamel was evaluated as the control. The resulting casts were scanned (using a 3D white light scanner), and 3D software was used to calculate the maximum amount of linear wear. Results. One-way repeated measures ANOVA was conducted to analyze data. Mean +/- SD occlusal wear of the antagonistic enamel 1 year after the cementation of metal ceramic crowns was 69.20 +/- 4.10 mu m for premolar teeth and 179.70 +/- 8.09 mu m for molar teeth, whereas for zirconia crowns, it was 42.10 +/- 4.30 mu m for premolar teeth and 127.00 +/- 5.03 mu m for molar teeth. Occlusal wear of natural enamel opposing natural enamel was 17.30 +/- 1.88 mu m in the premolar region and 35.10 +/- 2.60 mu m in the molar region. The Bonferroni post hoc test revealed that the occlusal wear of antagonistic enamel 1 year after the cementation of a metal ceramic crown was significantly higher (P<.001) than that of an opposing zirconia crown or natural enamel. Conclusions. Zirconia crowns led to less wear of antagonist enamel than metal ceramic crowns, but more than natural enamel.