正畸治疗中磨牙的拔除和保留(四十三)——上颌第三磨牙缺失或拔除后上颌结节骨量的对照研究

目的：对照研究上颌第三磨牙缺失或拔除后上颌结节骨量的差异,探讨第三磨牙的发生以及拔除第三磨牙对上颌结节骨量的影响。方法：全部病例均采用同一台西门子Orthophos3型牙科X线机拍摄口腔全景片,拍摄条件选择1．25倍恒定放大率模式。为排除生长发育因素,样本年龄均在18岁以上。选择上颌第三磨牙缺失病例21例,平均年龄26岁,上颌第三磨牙拔除2年以上病例18例,平均年龄28岁。测量上颌第二磨牙远中最突点与上颌结节后缘在上颌殆平面上的投影间距离作为上颌结节骨量。对比两组病例上颌结节骨量的不同。结果：上颌第三磨牙拔除组上颌结节骨量均值12．1mm,第三磨牙缺失组上颌结节骨量均值7．7mm,差异具有显著性。结论：上颌第三磨牙的发生对于上颌结节处牙槽骨的生长具有促进作用。在减数磨牙的矫治设计中,不必担心上颌第三磨牙拔除后上颌结节的改建吸收问题。即使是上颌第三磨牙先天缺失病例,上颌结节骨量与拔除前磨牙所提供的间隙相近,提示通过不拔牙矫治,可将全部牙齿向远中移动,解除前段牙弓问题,而有效保存28个牙齿。

The bone quantity study of maxillary tuberosity in cases of missing and extraction upper third molars.

Objective: Bone quantity of maxillary tuberosity were studied in contral when upper third molar is missing or extraction in order to discuss impaction of third molar on maxillary tuberosity. Method: Panoramic of all cases are taken by Siemens Orthophos3 type of dental X-ray machine and in choice of constant 1.25-fold magnification mode. All samples were aged over 18 years of age for the exclusion of growth. 21 cases of missing maxillary third molar were selected, the average age of 26 years old.18 cases of ...