Abstract: In order to manufacture molar restorations accurately so that which can occlude well，it is necessary to partition molar restorations into some characteristic regions such as gouge，socket and ridge.This paper firstly expatiates how to fix the edge of characteristic regions by an interactive way with computer.Secondly an offsetting for edge rings is proposed and some problems such as “region connected by point”，“sharp-angled ring” and “self- intersect” are solved.Then the STL data of characteristic regions are extracted.Finally some extracting examples on the STL model of a molar restoration are provided.

Key words: occlusal region, offsetting, region extraction

摘要： 为精确加工出磨牙牙合面的几何形状，以保证磨牙修复体的咬合功能，需将磨牙的牙合面划分为一系列区内曲率相近的沟、窝、嵴等特征区域分别进行加工。介绍了在磨牙STL模型中，人机交互式确定特征区域边界的方法。提出了一种对边界线环进行偏置的算法，解决了偏置过程中的“点连通”、“尖角”以及“自相交”问题，实现了特征区域的STL数据的提取。最后给出了该方法在磨牙STL模型中的验证实例。

关键词: 牙合面, 边界环偏置, 区域提取