Kawanaka M
Department of Dental Technology, Osaka University Faculty of Dentistry, Japan.
Osaka Daigaku Shigaku Zasshi. 1990 Jun;35(1):206-39.
Studies have been undertaken to apply CAD/CAM system to Dentistry and to make prosthetic appliances with this system automatically. Specimens are 4 times large plaster models. For the inside of the crown, the plaster model of prepared tooth is measured with laser displacement meter then the numerical data is obtained. After modification of this data for the concave cutting, the modeling machine works with this numerical data. For the outside of the crown, the typical colonal figure data (= CAD Data Base) is prepared. And this data is modified with computer to fit the prepared tooth margin and proximal or antagonical tooth (= CAD). This CAD Data Base was obtained with 3 dimensional point digitizer (3DPD). Because this measuring method with 3DPD is to be able to select points, the CAD Data Base could be consists of characteristic points. When this data base is really used, it is interpolated with s-spline. Spline interpolation is indispensable to the CAD/CAM system. Further understanding of this system, explanation is divided into three parts which are 3D measurement, CAD and CAM. (3D measurement) Two types of 3D measurement is dealed with this system. One is for the CAD data base and another is for the prepared tooth model. 3D measurement of the prepared tooth model is equivalent of the impression takings in the routine method. For the clear marginal line and for the uniform distribution of measuring points, the prepared tooth model is tilted and rotated on the working table when it is measured with laser. (CAD) The CAD Data Base can be extended, contracted, parallel translated and rotated with the Affine transformation. For putting the individual margin data on the CAD Data Base, the prepared tooth margin is re-digitized with 3DPD. Occlusal data is taken from F.G.P. core. (CAM) The application of the spline interpolation to the tool offset theory, which is effective at the groove especially, makes easy to calculate the tool path. When the prepared tooth model is manufactured, it is tilted and rotated on the table like the measurement with laser-scan.
已经开展了将计算机辅助设计/计算机辅助制造（CAD/CAM）系统应用于牙科并使用该系统自动制作修复体的研究。标本是放大4倍的石膏模型。对于牙冠内部，用激光位移计测量预备牙的石膏模型，然后获取数值数据。对该数据进行凹面切割修改后，造型机根据此数值数据进行工作。对于牙冠外部，准备典型的结肠形状数据（= CAD数据库）。然后用计算机对该数据进行修改，以适配预备牙边缘以及邻牙或对颌牙（= CAD）。此CAD数据库是通过三维点数字化仪（3DPD）获取的。由于这种使用3DPD的测量方法能够选择点，所以CAD数据库可以由特征点组成。当实际使用该数据库时，用s样条进行插值。样条插值对于CAD/CAM系统是必不可少的。为了进一步理解该系统，解释分为三个部分，即三维测量、CAD和CAM。（三维测量）该系统涉及两种三维测量。一种用于CAD数据库，另一种用于预备牙模型。预备牙模型的三维测量等同于常规方法中的取印模。为了获得清晰的边缘线和测量点的均匀分布，在用激光测量预备牙模型时，将其在工作台上倾斜和旋转。（CAD）CAD数据库可以通过仿射变换进行扩展、收缩、平行平移和旋转。为了将个体边缘数据添加到CAD数据库上，用3DPD对预备牙边缘重新数字化。咬合数据取自F.G.P. 核。（CAM）将样条插值应用于刀具补偿理论，这在凹槽处尤其有效，使得刀具路径易于计算。当制造预备牙模型时，它在工作台上倾斜和旋转，就像激光扫描测量时一样。
