上颌第三磨牙牙冠最大周径、牙尖与牙根相互关系的探讨

目的 通过上颌第三磨牙牙冠最大周径与牙尖型推断牙根型。方法 观察100颗离体上颌第三磨牙的牙冠最大周径、牙尖型和牙根型,列表总结并作统计学处理。结果1.上颌第三磨牙的牙冠最大周径均值为32.21mm,牙尖以三尖型占多数（48％）,牙根以融合根型或单根型占多数（52％）;2 影响上颌第三磨牙牙根型的主要因素是牙冠最大周径,而不是牙尖型;牙尖型与牙根型的关系属间接联系。结论 建议临床通过上颌第三磨牙的牙冠最大周径并同时参考牙尖型推断牙根型。

The Reserch of Relationship Between the Largest Circumference of Crowns,Cusps and Roots of the Maxillary Third Molar Tooth

Objective To understand the types of roots by the latest circumference of crowns and the types of cusps of the maxillary third molar tooth. Methods The largest ciucumference of crowns, types of cusps and types of roots of 100 extracted maxillary third molar tooth were observed and summed up by forms, and then statisticaly treated. Results 1. The average value of the largest circumference of crowns of the maxillary third molar tooth was 32.21mm.3 cusps(48%) was more than others. 1 root was more then others.2.The main fact to influence the types of roots of Maxillary third molar was the largest circumference of crown, not the types of cusps. The relationship between the types of cusps and the types of roots was indirect contact. Conclusion Clinically we can infer the types of roots by the largest circumference of crowns of the maxillary third molar and by consulting the types of cusps.