下颌第三磨牙牙冠形态与牙根形态的关系

Correlation Research of Mandibular Third Molars' Crown and Root

目的:通过观测牙冠形态探索其牙根形态,为下颌第三磨牙拔除的难易度估计提供参考。方法:200例有明确年龄、性别记录的下颌第三磨牙,使用齿规测量牙冠高和牙根长、同时清点记录牙冠牙合面牙尖数和区分记录牙根形态,最后统计出该牙的平均冠高和根长、聚类分析冠长与牙根数的关系、牙尖数与牙根数间的相关关系。结果:①下颌第三磨牙平均冠高6.5 mm和平均根长11.2 mm,当牙冠增高时其根长度相对变短;②牙冠越高其牙根分叉及根数增加的可能性就越大;③牙尖数增多时,其牙根的数目也就越多。结论:通过观察下颌第三磨牙的牙冠高度和牙合面牙尖数目的改变,可间接推导该牙的根形态及数目,这有助于在拔除该牙时减少并发症的发生。

Objective： Study the morphology of mandibular third molars. Methods： 200 specimens of the molars was studied on the crown height and the root length with clamp ruler, and the relationship between the numbers of dental cusp and the roots＇ shapes, and relationship between the increasing crown height and the roots changing complexities. Results： The crown average is 6.5 mm and root is length 11.2 mm in the mandibular third molars. The numbers of dental cusp increased possibley according to the height of the crown or the numbers of the cusps. Conclusion： The resuits suggest that the height of the crown and the numbers of the cusps should be checked care-fully before the mandibular third molars are extracted.