Song Doo-Bin, Han Man-So, Kim Si-Chul, Ahn Junyong, Im Yong-Woon, Lee Hae-Hyoung
Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandaero, Cheonan 31116, Korea.
Department of Dental Laboratory Technology, Daejeon Health Institute of Technology, Daejeon 34504, Korea.
Materials (Basel). 2021 Mar 13;14(6):1401. doi: 10.3390/ma14061401.
This study investigated the fitting accuracy of titanium alloy fixed dental prostheses (FDP) after sequential CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) fabrication. A three-unit FDP model connecting mandibular second premolars and molars was prepared and scanned to fabricate titanium FDPs by CAD/CAM milling. A total of six FDPs were sequentially milled in one titanium alloy disk using a new set of burs every time (n = 4). The fitting accuracy of FDPs was mesiodistally evaluated by a silicone replica technique and the measurement was triplicated at four different locations: MO (marginal opening), MG (marginal gap), AG (axial gap), and OG (occlusal gap). Data were statistically analyzed using ANOVA and Tukey's HSD test. The fitting accuracy of PMMA (polymethyl methacrylate) FDPs milled using the worn or new bur were evaluated by the same procedure (n = 6). The mean dimensions of titanium FDP for all measuring positions, except for AG, were significantly increased from the third milling. However, no difference was noted between the first FDP and the second FDP milled with the same set of burs. Severe edge chippings were observed in all milling burs. Detrimental effects of the worn burs on the fitting accuracy were demonstrated in the CAD/CAM-milled PMMA FDP. The results recommend proper changing frequency of cutting burs to achieve the quality of fit and predictable outcomes for dental CAD/CAM prostheses.
本研究调查了采用连续计算机辅助设计/计算机辅助制造（CAD/CAM）技术制作的钛合金固定义齿（FDP）的适合精度。制备了一个连接下颌第二前磨牙和磨牙的三单位FDP模型并进行扫描，通过CAD/CAM铣削制作钛FDP。每次使用一组新的车针在一个钛合金盘上依次铣削总共六个FDP（n = 4）。通过硅橡胶复制技术在近远中方向评估FDP的适合精度，并在四个不同位置重复测量三次：边缘开口（MO）、边缘间隙（MG）、轴向间隙（AG）和咬合间隙（OG）。使用方差分析和Tukey's HSD检验对数据进行统计学分析。采用相同程序评估使用磨损或新车针铣削的聚甲基丙烯酸甲酯（PMMA）FDP的适合精度（n = 6）。除AG外，所有测量位置的钛FDP的平均尺寸从第三次铣削开始显著增加。然而，使用同一组车针铣削的第一个FDP和第二个FDP之间未观察到差异。在所有铣削车针中均观察到严重的边缘崩裂。在CAD/CAM铣削的PMMA FDP中证明了磨损车针对适合精度的有害影响。结果建议适当改变车针的更换频率，以实现牙科CAD/CAM修复体的适合质量和可预测的结果。
