Graduate student, Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Junior Associate Professor, Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
J Prosthet Dent. 2022 Oct;128(4):695-701. doi: 10.1016/j.prosdent.2020.12.049. Epub 2021 Mar 26.
Insufficient information is available regarding the trueness and precision of artificial teeth in computer-aided design and computer-aided manufacturing (CAD-CAM) milled complete dentures fabricated from custom disks, including prefabricated teeth.
The purpose of this in vitro study was to determine the trueness and precision of the position of the artificial teeth arranged in CAD-CAM milled complete dentures manufactured by using a custom disk method and to compare the trueness and precision of different tooth types and the occlusal surface and entire surface of the teeth.
The milling data were designed by using a CAD software program. Four types of artificial teeth (maxillary-left central incisor, mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar) were arranged concentrically in the disk with 3 corresponding teeth per disk. Five custom disks were milled based on the milling data. The sample size for maxillary-left central incisor, mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar was 15. The standard tessellation language data were obtained by scanning the milled disks with cone beam computed tomography. The obtained data were superimposed by using a CAD software program to assess the trueness and precision of the tooth positions. For the occlusal surface, the data were superimposed after trimming to assess the trueness and precision of the tooth position with respect to the entire tooth surface. After data superimposition, the deviation was analyzed by using a 3-dimensional analysis software program to obtain the mean absolute error values and color maps. The data were analyzed by using 2-way ANOVA and the Games-Howell post hoc test (α=.05).
Significant differences were found in the mean absolute error values of the position trueness of the entire surface between the different teeth, except for maxillary-left first premolar and maxillary-left first molar (P<.05). Moreover, significant differences in the mean absolute error values of the precision for the entire surface were observed between mandibular-left central incisor and maxillary-left first premolar, as well as between mandibular-left central incisor and maxillary-left first molar (P<.05). The mean absolute error values of the position trueness of the occlusal surface were significantly smaller than those for the entire tooth surface for mandibular-left central incisor, maxillary-left first premolar, and maxillary-left first molar (P<.05). Finally, the mean absolute error values of the position precision of the occlusal surface were significantly smaller than those for the entire tooth surface for mandibular-left central incisor and maxillary-left first premolar (P<.05).
The trueness and precision of the posterior teeth were higher than that of anterior teeth. The trueness of the movement of the artificial teeth during the manufacturing of dentures by using the custom disk method was found to be within a clinically acceptable range.
关于使用定制托盘制作的计算机辅助设计和计算机辅助制造（CAD-CAM）铣削全口义齿中人工牙的准确性和精度，可用的信息有限，包括预制牙。
本体外研究的目的是确定使用定制托盘方法制造的 CAD-CAM 铣削全口义齿中人工牙位置的准确性和精度，并比较不同牙型、牙合面和整个牙面的准确性和精度。
使用 CAD 软件程序设计铣削数据。将四种类型的人工牙（上颌左侧中切牙、下颌左侧中切牙、上颌左侧第一前磨牙和上颌左侧第一磨牙）同心排列在带有三个相应牙齿的托盘中。根据铣削数据铣削了五个定制托盘。上颌左侧中切牙、下颌左侧中切牙、上颌左侧第一前磨牙和上颌左侧第一磨牙的样本量为 15。使用锥形束计算机断层扫描扫描铣削盘获得标准 tessellation 语言数据。使用 CAD 软件程序对获得的数据进行叠加，以评估牙位的准确性和精度。对于牙合面，在修剪后对数据进行叠加，以评估整个牙面相对于牙位的准确性和精度。数据叠加后，使用三维分析软件程序分析偏差，以获得平均绝对误差值和彩色图谱。使用双向方差分析和 Games-Howell 事后检验（α=.05）对数据进行分析。
除上颌左侧第一前磨牙和上颌左侧第一磨牙外，不同牙齿的整个表面位置准确性的平均绝对误差值存在显著差异（P<.05）。此外，下颌左侧中切牙和上颌左侧第一前磨牙以及下颌左侧中切牙和上颌左侧第一磨牙的整个表面精度的平均绝对误差值存在显著差异（P<.05）。下颌左侧中切牙、上颌左侧第一前磨牙和上颌左侧第一磨牙的牙合面位置准确性的平均绝对误差值明显小于整个牙面的平均绝对误差值（P<.05）。最后，下颌左侧中切牙和上颌左侧第一前磨牙的牙合面位置精度的平均绝对误差值明显小于整个牙面的平均绝对误差值（P<.05）。
后牙的准确性和精度高于前牙。使用定制托盘方法制作义齿时，人工牙在制造过程中的移动准确性被发现处于临床可接受的范围内。
