Clinical performance and wear characteristics of veneered lithia-disilicate-based ceramic crowns

Objectives. The objectives of this study were to characterize the clinical performance and wear characteristics of lithia-disilicate-based ceramic crowns. Methods. Thirty posterior crowns were made using the heat-pressing technique and lithia-disilicate-based core ceramic. Subjects were recalled annually. The quality of crowns and adjacent gingival tissues were examined using nine criteria for acceptability. All crowns were examined and ranked from 4 (Excellent) to 1 (Unacceptable) for each criterion. Impressions were made for replica models at each appointment. Wear characteristics of dental ceramic and enamel were obtained by comparing the surface of the original model with the follow-up model using a laser scanner. Results. Twenty-nine subjects returned for the 1-year recall examination. The maximum clenching force for the 30 subjects ranged from 125 to 815N. All clinical criteria were ranked good to excellent at the 1-year recall exam and no fractures were observed. The mean occlusal wear volumes for the ceramic crowns after 1 year were 0.19 (0.065) mm(3) for premolar sites and 0.34 (0.08) mm(3) for molar sites. The mean occlusal wear volumes of opposing enamel after 1 year were 0.21 (0.06) mm(3) for premolar teeth and 0.50 (0.22) mm(3) for molar teeth. The mean occlusal wear volume of ceramic molar crowns was significantly lower than the volume of enamel wear of the opposing teeth (p <= 0.05). Conclusions. The quality of the overall prostheses and the gingival tissues were acceptable after 1 year. The mean occlusal wear volume of ceramic molar crowns was significantly lower than the enamel wear volume of the opposing teeth. (C) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.