牙制备体形态对计算机辅助设计与辅助制作全瓷底层冠适合性的影响

目的　研究牙制备体形态对计算机辅助设计与辅助制作 (computeraideddesign computeraidedmanufacture ,CAD CAM )全瓷底层冠适合性的影响。方法　将牙制备体设计成不同的向聚合度和边缘形态 ,采用MC切削陶瓷经Cerec2CAD CAM系统加工制作成全瓷底层冠 ,粘结于制备体上。采用体视显微镜测试全瓷底层冠边缘、肩台、轴面和面的适合性。结果　当向聚合度为 2 0°时 ,全瓷底层冠的适合性最好 (10 1 7～ 12 7 9) μm ;边缘形态对底层冠边缘和肩台的适合性有影响 (P <0 0 5 ) ,凹面型者适合性较好。当牙制备体设计为 2 0°聚合度、边缘形态为凹面型时 ,全瓷底层冠的边缘适合性为 (40 1± 11 8) μm。 结论　临床制作CAD CAM全瓷底层冠时 ,建议牙制备体设计成 2 0°向聚合度及凹面型边缘形态

The effect of tooth preparation design on the CAD/CAM all-ceramic coping crown′s fitness

OBJECTIVE: To study the effect of tooth preparation design on fitness of CAD/CAM all-ceramic coping crown. METHODS: The tooth preparation comprised 2 types of occlusal convergence (10 degrees, 20 degrees), 2 margin forms (shoulder, chamfer). The MC coping were milled by Cerec 2 CAD/CAM system, cemented, embedded, sectioned, and measured at 10 sites to obtain the data of margin, shoulder, axial surface, occlusal surface fitness. RESULTS: The coping's fitness was influenced by convergence angle and margin form. The coping's fitness was very nice (101.7 approximately 127.9) microm when the coping with 20 degrees occlusal convergence angle. Those coping with 20 degrees occlusal convergence and chamfer margin in tooth preparation provided the best fitness, its cement film thickness in margin was (40.1 +/- 11.8) microm. CONCLUSIONS: The 20 degrees occlusal convergence and chamfer margin can be used for CAD/CAM all-ceramic crown in clinical application.