Qian K, Liu Y
Beijing Da Xue Xue Bao Yi Xue Ban. 2025 Jun 18;57(3):604-609. doi: 10.19723/j.issn.1671-167X.2025.03.027.
To analyze the fitness of zirconia and lithium disilicate glass-ceramic onlays fabricated with direct and indirect computer-aided design and computer-aided manufacturing (CAD/CAM) technology .
In the study, 48 standardised typodont left mandibular first molars received standardised onlay preparation. Then, all the specimens were randomly divided into 4 groups. There were 12 specimens in each group. The preparation quality was checked under the stereomicroscope. All the specimens were fixed in typodonts. Subsequently, the typodonts were fixed in the dental simulators to simulate the oral conditions. In groups A and B, the digital impressions were obtained by using the intraoral scanner. In groups C and D, conventional impressions of polyether impression material were obtained according to the instructions of the manufacturer using individual trays. The stone casts were made with type Ⅳ gypsum later. Then, all casts were digitized with the model scanner. Based on the data obtained from the scan, onlay restorations of all the groups were designed using the corresponding software, the simulated cement thickness was set to 50 μm. Then, the final onlays restorations of all the groups were machined with the milling machines in lab. The fabrication materials were different in groups. The specimens of groups A and C were fabricated with zirconia. While, the specimens of groups B and D were fabricated with lithium disilicate glass-ceramic. The marginal gap and internal gap of all restorations were analyzed by 3D replica technique, for each measurement, the specimen was digitised using the model scanner.
The marginal gap of the onlays fabricated with indirect digital impressions were smaller than that with direct digital impressions ( < 0.05). At the same time, the internal gap of the onlays fabricated with indirect digital impressions were smaller than that with direct digi-tal impressions ( < 0.05). The marginal gap was larger in distal gingival than that in the other regions in all the groups ( < 0.05). Different fabrication materials, zirconia or lithium disilicate reinforced glass-ceramic, had no effect on onlay marginal and internal fit (>0.05).
The marginal and internal adaptation of the onlays fabricated with indirect digital impressions was better than with direct digital impressions. Zirconia and lithium disilicate reinforced glass-ceramic had no effect on the onlay adaptation.
分析采用直接和间接计算机辅助设计与计算机辅助制造（CAD/CAM）技术制作的氧化锆和二硅酸锂玻璃陶瓷嵌体的适合性。
本研究中，48颗标准化的人工牙列左下颌第一磨牙接受标准化嵌体预备。然后，将所有标本随机分为4组。每组12个标本。在体视显微镜下检查预备质量。所有标本固定在人工牙列中。随后，将人工牙列固定在牙科模拟器中以模拟口腔条件。A组和B组使用口内扫描仪获取数字印模。C组和D组根据制造商的说明使用个别托盘获取聚醚印模材料的传统印模。随后用Ⅳ型石膏制作石膏模型。然后，用模型扫描仪对所有模型进行数字化处理。基于扫描获得的数据，使用相应软件设计所有组的嵌体修复体，将模拟粘结剂厚度设置为50μm。然后，在实验室用铣床加工所有组的最终嵌体修复体。各组的制作材料不同。A组和C组的标本用氧化锆制作。而B组和D组的标本用二硅酸锂玻璃陶瓷制作。采用三维复制技术分析所有修复体的边缘间隙和内部间隙，每次测量时，使用模型扫描仪对标本进行数字化处理。
采用间接数字印模制作的嵌体的边缘间隙小于采用直接数字印模制作的嵌体（<0.05）。同时，采用间接数字印模制作的嵌体的内部间隙小于采用直接数字印模制作的嵌体（<0.05）。所有组中，远中牙龈处的边缘间隙大于其他区域（<0.05）。不同的制作材料，氧化锆或二硅酸锂增强玻璃陶瓷，对嵌体边缘和内部适合性无影响（>0.05）。
采用间接数字印模制作的嵌体的边缘和内部适应性优于采用直接数字印模制作的嵌体。氧化锆和二硅酸锂增强玻璃陶瓷对嵌体适应性无影响。
