Stawarczyk Bogna, Lümkemann Nina, Eichberger Marlis, Wimmer Timea
Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336 Munich, Germany.
Dent J (Basel). 2017 Dec 19;5(4):36. doi: 10.3390/dj5040036.
The purpose of this investigation was to analyze the accuracy of digitally fabricated wax trial dentures and conventionally finalized complete dentures in comparison to a surface tessellation language (STL)-dataset. A generated data set for the denture bases and the tooth sockets was used, converted into STL-format, and saved as reference. Five mandibular and 5 maxillary denture bases were milled from wax blanks and denture teeth were waxed into their tooth sockets. Each complete denture was checked on fit, waxed onto the dental cast, and digitized using an optical laboratory scanning device. The complete dentures were completed conventionally using the injection method, finished, and scanned. The resulting STL-datasets were exported into the three-dimensional (3D) software GOM Inspect. Each of the 5 mandibular and 5 maxillary complete dentures was aligned with the STL- and the wax trial denture dataset. Alignment was performed based on a best-fit algorithm. A three-dimensional analysis of the spatial divergences in -, - and -axes was performed by the 3D software and visualized in a color-coded illustration. The mean positive and negative deviations between the datasets were calculated automatically. In a direct comparison between maxillary wax trial dentures and complete dentures, complete dentures showed higher deviations from the STL-dataset than the wax trial dentures. The deviations occurred in the area of the teeth as well as in the distal area of the denture bases. In contrast, the highest deviations in both the mandibular wax trial dentures and the mandibular complete dentures were observed in the distal area. The complete dentures showed higher deviations on the occlusal surfaces of the teeth compared to the wax dentures. Computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated wax dentures exhibited fewer deviations from the STL-reference than the complete dentures. The deviations were significantly greater in the vicinity of the denture teeth area and the bases. The conventional transfer of CAD/CAM-fabricated wax dentures into acrylic resin leads to the highest deviations from the STL-reference.
本研究的目的是将数字化制作的蜡型试戴义齿和传统最终完成的全口义齿与表面细分语言（STL）数据集进行比较，分析其准确性。使用生成的义齿基托和牙槽窝数据集，将其转换为STL格式并保存为参考。从蜡块铣削出五个下颌和五个上颌义齿基托，并将义齿蜡型固定到牙槽窝中。检查每个全口义齿的贴合度，将其蜡型固定到石膏模型上，并用光学实验室扫描设备进行数字化处理。全口义齿采用注射法常规完成、修整并扫描。将得到的STL数据集导出到三维（3D）软件GOM Inspect中。将五个下颌和五个上颌全口义齿中的每一个与STL和蜡型试戴义齿数据集对齐。对齐基于最佳拟合算法进行。3D软件对x、y和z轴上的空间差异进行三维分析，并以彩色编码图示进行可视化。自动计算数据集之间的平均正负偏差。在上颌蜡型试戴义齿和全口义齿的直接比较中，全口义齿与STL数据集的偏差高于蜡型试戴义齿。偏差出现在牙齿区域以及义齿基托的远中区域。相比之下，下颌蜡型试戴义齿和下颌全口义齿的最高偏差均出现在远中区域。与蜡型义齿相比，全口义齿在牙齿咬合面上的偏差更大。计算机辅助设计/计算机辅助制造（CAD/CAM）制作的蜡型义齿与STL参考相比偏差较少。在义齿牙齿区域和基托附近，偏差明显更大。将CAD/CAM制作的蜡型义齿常规转换为丙烯酸树脂会导致与STL参考的偏差最大。
