Changes in Occlusal Contacts upon the Cementation of Zirconia Crowns with Different Cement Spacers

Occlusion plays a crucial role in the long-term success and functionality of dental restorations. The purpose of this study was to investigate the changes in occlusal contacts upon the cementation of zirconia crowns with different cement spacer settings in computer-aided design and computer-aided manufacturing (CAD-CAM) software (3Shape Dental System version 2.102.1.0). Methods: A master model of a prepared abutment for a crown on the right maxillary first molar was scanned, and 30 sets of sample casts and zirconia crowns were fabricated with varying cement spaces (70 μm and 120 μm). These casts were mounted in maximal intercuspation (MIP) on a semi-adjustable articulator. Pre-cementation adjustments were made to fit the crowns and maintain the existing occlusion. Occlusal records were taken before and after cementation using polyvinyl siloxane impression material. These records were analyzed using a DC light box and image analyzer to measure changes in contact area, intensity, and patterns. Paired sample t-tests were used to compare pre- and post-cementation occlusal contact areas of each sample (α = 0.05). Results: Significant differences in occlusal contact areas were found between pre- and post-cementation in both groups (p < 0.001). The mean post-cementation contact surface area for the 70 μm group was 6281 ± 3310 μm², compared to 2339 ± 1206 μm² before cementation. For the 120 μm group, the post-cementation area was 5545 ± 3491 μm², compared to 2071 ± 909 μm² before cementation. An increase in contact intensity was also observed after cementation. Conclusions: This study demonstrates that cementation increases occlusal contact surface area and intensity in both cement space groups.