计算机辅助设计与辅助制作氧化锆全瓷冠的临床效果初探

Preliminary evaluation of clinical effect of computer aided design and computer aided manufacture zirconia crown

目的评价计算机辅助设计与辅助制作氧化锆全瓷冠的临床修复效果，为其临床应用提供参考。方法选择于北京大学口腔医学院·口腔医院修复科就诊的磨牙牙体缺损患者60例。30例患者共计35颗患牙用三维激光扫描仪获取工作模型、对拾模型及咬合记录的三维数据；用软件的全冠设计程序设计有咬合关系及邻牙接触关系的全解剖形态氧化锆全瓷单冠；用数控机床和氧化锆块制作、终烧结并上釉完成最终修复体，临床试戴并粘固（全瓷冠组）。30例患者共计30颗患牙制作金合金铸造单冠（铸造冠组）。参考改良的美国公共卫生署评价标准，戴冠后即刻、3、6、12、24个月临床观察和评价修复体外形、颜色、自身和对验牙磨耗及修复体破损情况。结果35件氧化锆全瓷冠均未出现崩瓷及折裂，修复后24个月5例患者5件全瓷冠对拾牙出现I级磨耗，1例患者1件全瓷冠对猞牙由修复后即刻的Ⅰ级磨耗变为Ⅱ级磨耗，全瓷冠抛光后对验牙磨耗未进展。30件金合金铸造冠无磨穿等破损现象，对袷牙无明显磨耗。结论用氧化锆全瓷冠修复磨牙牙体缺损，美观程度较好、不易破损、磨耗，但氧化锆全瓷冠可在一定程度上磨耗其对拾天然牙，应严格把握临床适应证。

Objective To evaluate clinical effects of computer aided design and computer aided manufacturing （CAD/CAM） milled zirconia crown in three aspects： aesthetic, contact wear and fracture. Methods Sixty patients were devided into two groups. In one group, 35 full contour CAD/CAM zireonia crown were made on molars of 30 patients. The manufacturing process of zirconia crown was as follow. First, the three dimensional（3-D） data of working models, antagonist impression and check records were acquired by 3-D laser scanning Dentalwings S50. Then full contour zirconia crowns, which had functional occlusal contacts with antagonistic teeth, and appropriate contact with adjacent teeth were designed with Zeno-CAD （ V4. 2. 5.5. 12919 ） software. ZENOSTAR Zr pure zireonia material was milled in digital controlled machine WIELAND 4030 M1. In the end, the zirconia crown were completed with the method of second sintering and polishing. After clinical try-in, the crown was cemented. In the control group, thirty gold alloy full crown were made and cemented on molars of 30 patients. According to the modified U S Public Health Service Criteria（USPHS） evaluation standard, all crowns were evaluated on the same day, at three months, half a year, one year and two years following delivery. There were three aspects we were focusing on in the evaluation ： aesthetic, contact wear （ restoration and antagonist ） , and fracture. Results In all the prosthesis we evaluated during the 24 months, no fracture was found. Contact wear of crowns varies according to different antagonist teeth. Conclusions The zirconia crowns show privilege in aesthesis, toughness and anti-wearing. However, there is contact wear on antagonistic natural teeth. Thus it is a good choice when full zirconia crowns are indicated on two antagonistic teeth in both jaws.