Influence of convergence angle and cement space on adaptation of zirconium dioxide ceramic copings.

Objective: The purpose of the present study was to evaluate the influence of total convergence angle and cement space on internal and marginal adaptation of posterior zirconium dioxide (zirconia) ceramic copings.

Material And Methods: Seventy-two standardized mandibular first molar zirconia copings were fabricated with nine parameters: three different total convergence angles (6 degrees , 12 degrees , and 20 degrees ) with three different computer-fixed cement spaces (10, 30, and 60 microm). Marginal adaptation was assessed to measure vertical discrepancy between the coping and abutment by direct viewing.

Marginal and internal adaptation of zirconium dioxide ceramic copings and crowns with different finish line designs.

The present study evaluated the marginal and internal adaptation of single-tooth zirconium dioxide (ZrO2) ceramic copings or crowns with three different finish line designs. Twenty-four steel dies were prepared for maxillary central incisor crowns with the following finish line designs: shoulder (S), rounded shoulder (RS), and chamfer (C) preparations. Twenty-four standardized ZrO2 ceramic copings were manufactured with a CAD/CAM system (Cercon Smart Ceramics), and the crowns were finalized by veneering with a feldspathic ceramic.