后牙残冠、残根的定义与缺损程度分类的探讨

The definitions of residual roots and crowns of molars and the classification of the defect degrees

本文根据离体牙生物力学实验研究结果以及残冠、残根临床疗效评价的客观需要对目前临床常见的牙体组织缺损——后牙残冠、残根进行了新的定义和缺损程度分类。分别根据牙冠咬合面缺损面积、缺损牙面数目以及牙面残留健康牙体组织高度等将残冠、残根进行定义和分类。将后牙咬合面缺损面积达到5/9的牙冠定义为残冠,将咬合面完全缺损且4个牙面中有1个牙面龈上残存健康牙体组织不足2 mm的残冠定义为残根。然后,再按缺损牙面分别将残冠、残根分为4类(Ⅰ、Ⅱ、Ⅲ、Ⅳ类)。对后牙残冠、残根进行定义和缺损程度分类便于客观地评定残冠、残根牙体缺损程度,提高其临床疗效评估的科学性,指导临床医师选择合适的修复方式和修复材料。

According to the experimental research results of the tooth-in-vitro biomechanics and the objec- tive needs of the clinical curative effect evaluation the residual crown and residual root of molars were definited and the tooth tissue defect degrees wer classified. The definitions and the classification are based on the respective researches of the defect area of tooth crown occlusal surface, the number of defected tooth surfaces, and the height of residual healthy tooth tissues. A molar tooth crown is defined as a residual crown when the defect area covers five ninths of its occlusal surface. A molar tooth is defined as a residual root when the occlusal surface is completely defected and the remaining healthy tooth tissues in one of its four tooth surfaces is shorter than 2 mm. And then, according to the defect of the mo lar tooth surfaces, the residual crowns and residual roots are classified into four degrees： I , Ⅱ ,Ⅲ, and IV. The definitions of residual crowns and roots of molars and the classification of the defect degrees can be used easily to evalu ate defect degree, so as to help the dentists to choose the appropriate restoration approaches and restorative materials.