The manufacturing characterization of zirconia core copings of CAD/CAM systems

Hiroaki Yamaguchi, DDS, Naho Hamano, DDS, PhD, Yuki Katsumata, DDS, PhD, and Satoshi Ino, DDS, PhD

Division of Removable Prosthetics, Department of Oral and Maxillofacial Rehabilitation, Kanagawa Dental College, Japan

Purpose: The purpose of the present study was to investigate the manufacturing characterization of zirconia copings for abutments. Comparative evaluation was made using five different CAD/CAM systems.
Materials and Methods: The abutment model was fabricated. Five zirconia copings were produced using Procera, Katana, Cercon, and Lava 0.5 and 0.6 by CAD/CAM system dealers. Silicone impression material was placed between the abutment model and a coping to observe the manufacturing characteristics and pressed. The abutment model with impression material was embedded in epoxy resin. The embedded model was cut buccolingually using an automatic precision cutter, and the thickness of silicone impression material was observed using an optical microscope with a scale.
Results: A significant difference was observed in the gap average between Procera and Lava 0.5 (p<0.01), and Procera and Lava 0.6 (p<0.05) in the buccal margin. For the buccal corner and occlusal chamfer, the gap was significantly larger in Procera compared with the other copings (p<0.01). In the palatal margin, the gap was significantly smaller in Lava 0.6 compared with Procera, Katana, and Cercon (p<0.01).
Conclusion: Marginal lines were smooth and coincided with abutments for all CAD/CAM systems. Although the gap size varied among the manufacturers, the thickness of impression material was smaller, and the processing quality was even in Lava compared with the other copings. These characteristics are considered to be related to the shape and size of drilling tools of each CAD/CAM system.(Asian Pac J Dent 2012; 12: 11-16.)

Key Words: CAD/CAM system, gap, manufacturing characteristics, zirconia copings