下颌第三磨牙的外形特征及临床意义探讨

THE EXTERNAL FEATURES AND CLINICAL SIGNIFICANCE OF MANDIBULAR THIRD MOLAR

目的:为临床拔除下颌第三磨牙提供参考数据。方法:对207颗离体下颌第三磨牙的牙冠与牙根进行解剖学观察和比较,从中找出冠形、根形以及冠根配布规律。结果:①下颌第三磨牙的牙冠根据牙尖的数目可分为三尖型占2.41%,四尖型占31.4%,五尖型占53.14%,六尖型占12.08%,七尖型占0.97%;②下颌第三磨牙的牙根根据数目和形态可分为融合根型占34.3%,双根型占63.29%,三根型占2.41%;③冠根配布规律:三尖型者均为融合根,四尖型者以融合根为主,五尖及其以上者均为双根和三根。结论:根据牙冠与牙根的配布规律从牙冠的牙尖型可基本推出牙根类型和形态,为临床拔除此牙根提供参考。

Objective：To offer reference for tile extraction of mandibular third molar.Methods：,The corona and root of 207 teeth were observed and compared to find out the rule of the corona shape and root shape amt therelationship between them.Results： ①Aeeording to the number of the tips,the eoronae of mandibular third molar could be divided into five types：tri cuspid 2.41%,quadri cuspid 31.4%,quinque cuspid 53.14%,hexa cuspid 12.08% and hepta e.uspid 0.97%; ②Aeeording to the number and the shape,the root of mandibular third molareould be divided into three types：fused root 34.30%,two root 63.29%,three root 2.41%; ③the relationship between the corona and the root was that all tri cuspid teeth were fused root, most of quadri euapid teeth were fused root,teeth with live or more than five tips were two-root or three-root. Conclusion：According to the relationship between orona and root,we ean deduee the number and the shape of the root by observing the cuspid of the earona,whieh offers referenee for the extraetion of mandibular third molar.