Developing the data-base and simulation model of tooth loss expansion.

我们研究了病人强迫拔牙的因素。首先，我们必须收集有关牙齿脱落扩展的数据。因此，我们列出了从2004年到2005年接受义齿治疗的844名患者，并研究了他们的医疗记录。分析结果表明，可摘局部义齿的基牙、上颌牙、磨牙、无髓牙、无磨牙咬合接触、同一颌内牙数较少与拔牙因素密切相关。在此基础上，我们构建了牙齿脱落扩展数据库，并定义了影响牙齿脱落扩展的因素。

We have studied factors which patients force to extract their teeth.At first, we had to collect data about tooth loss expansion. So, we listed up 844 patients who had been provided prosthetic dentures from 2004 to 2005, and researched their medical records.As the result of this analysis, abutment teeth of removable partial dentures, maxillary teeth, molar teeth, pulpless teeth, without molar occlusal contact, having fewer teeth in the same jaw, were closely related to factors of extraction.From this study, we constructed database of the tooth loss expansion, and defined some factors related to tooth loss expansion.