目的: 比较传统夹板式印模和利用预成刚性连接杆系统进行无牙颌种植固定修复印模制取的操作复杂程度及精度差异。方法: 制备带有6颗种植体替代体的下颌无牙颌标准模型,种植体植入位置平齐骨面,在种植体替代体上连接多牙修复基台。对照组采用传统开窗夹板式印模技术制取印模,在多牙修复基台上连接转移杆,使用聚甲基丙烯酸甲酯材料制作夹板,并制取开窗印模。试验组采用刚性连接杆系统制取开窗印模,在多牙修复基台上连接临时修复套筒,根据种植体间距,选择合适长度的预成刚性连接杆,使用少量聚甲基丙烯酸甲酯材料将套筒和预成刚性连接杆固定,制取开窗印模。实验组和对照组各重复6次印模制取,比较试验组和对照组的印模制取耗时差异。在制取的印模上连接基台替代体,灌制石膏模型,并使用模型扫描仪将石膏模型和标准模型转化为三角网格数据文件。将试验组和对照组模型分别与标准模型进行精度差异测量,比较两种印模方法获得模型的精度差异。结果: 在标准模型上进行印模制取,试验组用时显著低于对照组,两者差异有统计学意义[(984.5±63.3) s vs. (1 478.3±156.2) s, P<0.05]。与标准模型相比,在种植体基台处,试验组制取印模灌制模型均方根误差(root mean aquare,RMS)与对照组模型基本相同,两者差异无统计学意义[(16.9±5.5) μm vs. (20.2±8.0) μm, P>0.05]。结论: 预成刚性连接杆可以简化无牙颌种植即刻固定修复的印模流程,节约椅旁操作时间,获取的印模精度与传统印模技术无显著差异,值得在临床推广使用。

Objective: To compare the operation complexity and accuracy of traditional splint impression technique and impression technique with prefabricated rigid connecting bar system for full-arch implants-supported fixed protheses in vitro. Methods: Standard mandibular edentulous model with six implant analogs was prepared. The implants were placed at the bone level and multiunit abutments screwed into the implants. Two impression techniques were performed: the traditional splint impression technique was used in the control group, and the rigid connecting bar system was used in the test group. In the control group, impression copings were screwed into the multiunit abutments and connected with autopolymerizing acrylic resin. Open tray impression was fabricated with custom tray and polyether. In the test group, cylinders were screwed into the multiunit abutments. Prefabricated rigid bars with suitable length were selected and connected to the cylinders with small amount of autopolymerizing acrylic resin, and open tray impression was obtained. Impression procedures were repeated 6 times in each group. The working time of the two impression methods were recorded and compared. Analogs were screws into the impressions and gypsum casts were poured. The gypsum casts and the standard model were transferred to stereolithography (STL) files with model scanner. Comparative analysis of the STL files of the gypsum casts and the standard model was carried out and the root mean square (RMS) error value of the gypsum casts of the control and test groups compared with the standard model was recorded. The trueness of the two impression techniques was compared. Results: The work time in the test group was significantly lower than that in the control group and the difference was statistically significant [(984.5±63.3) s vs. (1 478.3±156.2) s, P<0.05]. Compared with the standard model, the RMS error value of the implant abutments in the test group was (16.9±5.5) μm. The RMS value in the control group was (20.2±8.0) μm. The difference between the two groups was not significant (P>0.05). Conclusion: The prefabricated rigid connecting bar can save the chair-side work time in implants immediate loading of edentulous jaw and simplify the impression process. The impression accuracy is not significantly different from the traditional impression technology. The impression technique with prefabricated rigid connecting bar system is worthy of clinical application.