A study on factors have an effect on the tooth preparation

1. 颈线形状对全肩式预备终点线深度的影响当颈线最深部分较深时，在中相和远面线角周围也会出现预备不足，预备牙的操作难度增大。然后，面侧复位边缘暴露和近端牙间牙周组织炎症的病例在牙齿准备时就已经存在了。Dicor修复体（层压贴面、冠和嵌体）的预备牙体研究——人前磨牙的牙釉质厚度——为了使Dicor系统获得更高的附着力，牙釉质的存在是必不可少的。在这项研究中，测量了人类上第一前磨牙的牙釉质厚度，以揭示在预备层状贴面、冠和嵌体修复时牙本质暴露的潜在部位。固定义齿倾斜磨牙的牙齿制备-具有中斜第二磨牙的模拟模型的制备(*)-研究了固定义齿倾斜磨牙制备中的磨牙趋势。当*的冠轴在中向倾斜高达30个角时，结果与临床病例非常接近。在此倾斜度范围内，制备了4种右下磨牙中斜的第一磨牙（*）缺陷仿真模型。结果表明，*的中倾角对所制备基牙的形态特征有显著影响。

1. Influence of a shape of cervical line on the depth of finish line of full-shoulder-type preparationWhen the deepest part of the cervical line is deeper, insufficiency of preparation is seen also around the mesio and disto-facial line angle, and the aperation of teeth preparations becomes more difficult. And then the cases of margin exposure of restrations on the facial side and inflammation of periodontal tissue at the proximal interdentium would have already existed at teeth preparations.2. A study on the tooth preparation for the Dicor restorations (laminate veneer, crown and onlay) - Thickness of enamel of human premolar -In order to obtains higher adhesion for the Dicor system, the presence of enamel is indispensable. In this study, the thickness of enamel of the human upper first premolar was measured in order to reveal potential sites of dentine exposure in the preparation of laminate veneer, crown and onlay restorations.3. Tooth preparation of the inclined molar for fixed prosthodontics - Preparation of simulation model having the mesially inclined second molar( * )-A study was conducted to examining the grinding trend in preparations of inclined molars for fixed prosthodontics. A close simularity to clinical cases was obtained when a crown axis of * was inclined up to 30ﾟ in the mesial direction. Within this range of inclination, 4 types of simulation model of first molar( * ) defects having a mesially inclined lower right molar were prepared. As the result, an angle of mesial inclination of * had a significant influence on the morphological features of the prepared abutment.