磨牙形态差异的X线测量研究

Study of morphological characteristics of molars by X-ray

目的探讨磨牙牙冠与牙根的形态特征,为磨牙的拔除与保留提供理论依据。方法利用曲面断层片对第一磨牙(简称为M1)、第二磨牙(简称为M2)、第三磨牙(简称为M3)的牙冠宽、牙冠高、牙根长、牙颈宽、根尖距五个指标进行测量,分别对M1与M2、M2与M3进行各项测量指标的比较,以揭示磨牙形态差异。结果男性上颌M1与M2在牙冠宽、牙根长、牙颈宽的差异具有统计学意义(P<0.05),M2与M3在牙根长、根尖距上的差异具有统计学意义(P<0.05);男性下颌M1与M2在牙冠宽、牙根长、根尖距上的差异具有统计学意义(P<0.05),M2与M3在牙冠高、牙根长上的差异具有统计学意义(P<0.05)。女性上颌M1与M2仅在牙冠高的差异具有统计学意义(P<0.05),M2与M3在牙冠宽、牙冠高、牙根长的差异均具有统计学意义(P<0.05);女性下颌M1与M2在牙冠高、牙根长、根尖距上的差异具有统计学意义(P<0.05),M2与M3在牙根长、根尖距上的差异具有统计学意义(P<0.05)。结论男性上下颌M3与M2的形态差异均小于M2与M1的差异;女性上颌M3与M2的形态差异较M2与M1的差异大,下颌M3与M2的形态差异较M2与M1的差异小。

Objective To discuss the morphological characteristics of the molar crown and the root of the third molar. and to offer the theoretical basis for whether extracting or keeping the third molar. Methods Using the panoramic film to measure the crown width, crown height, root length, tooth neck width and the distance of apex of the first molar （ M1 ）, second molar （M2） and the third molar （ M3）, and t test among them was performed to get the differences. Results In male, there were differences among the crown width, root length, neck width of the first molar and the second molar, and the differences between the second molar and the third molar existed in the root length and the distance of apex in the maxillary; there were differences among the crown width, root length and the distance of apex the of the first molar and the second molar, and there were statistically significances between the crown height and the root length in the second molar and the third molar; but in the female, the differences existed in the crown height in the M1 and the M2, there were differences among the crown width, crown height and the root length in the M2 and M3 in maxillary. In the mandibular, the differences existed in the crown width, the root length and the distance of apex between M1 and M2, and there are differences between the root length and the distance of apex in the M2 and the M3. Conclusion In female, the differences between M2 and M3 is more remarkable than the differences between the M2 and the M3 in the maxillary, and the differences between the M1 and the M2 is more notable than the differences between the M2 and the M3 ;but in male, the differences between the M2 and the M3 is less remarkable than the differences between the M2 and M1.