Objective To analyze the effects on the morphology of temporomandibular joint (TMJ) of the adult with the low angle Class II malocclusions before and after orthodontic treatment comparatively. To provide the references for the orthodontic treatment of the adults. Methods 19 adult patients with low angle Class Ⅱ malocclusions were chosen and treated with Damon self-ligating braces. The examinations of 16-slice spiral CT were taken before and after the orthodontic treatment. The parameters of skeletal morphology of TMJ were measured in the multiplanar reconstruction (MPR) images. The results were analysed statistically. Results The rate of condyles in a center position in the glenoid fossa after the treatment was 52.6% (20/38), and the rate of retrodisplacement was 31.6% (12/38). The position of the condyles before and after the orthodontic treatment had significant differences (P＜0.05, x2=4.41, x2=5.32). The mean value of the anterior oblique angle of condyle decreased by 2.32°±1.78° after treatment, meanwhile the average height of the condylar head increased by (1.07±0.29) mm. There were significant differences in both results before and after treatment (P<0.05). Conclusion The orthodontic treatment can make the TMJ structures stable and beneficial to relieve the symptoms by moving the condyle forward, increasing the height and reconstructing the anterior oblique angle of condyle on adult patients with low angle Class Ⅱ malocclusions.%目的 比较分析低角型Ⅱ类错(牙合)成年患者正畸治疗前、后颞下颌关节位置及形态结构的变化,为成人正畸治疗提供参考.方法 选取19名成年低角型安氏Ⅱ类错(牙合)患者,采用自锁托槽矫治技术,于正畸治疗前、后,利用16层螺旋CT,进行颞下颌关节扫描,采用多层面重建(MPR)技术对颞下颌关节进行三维重建及参数测量,对结果进行统计学分析.结果 治疗后有20侧髁突处于关节窝内中性位,占52.6％ (20/38);而处于关节窝后位的髁突减少至31.6％ (12/38),二者与治疗前比较差异均有统计学意义(P＜0.05,x2分别为4.41和5.32).髁突前斜面倾角测量值在治疗后减小了2.32°±1.78°,髁突头高度则增加了(1.07±0.29) mm,与治疗前比较均有统计学意义(P＜0.05).结论 成年低角型安氏Ⅱ类错(牙合)患者正畸治疗后,髁突位置及髁突部分骨性结构发生一定程度改变,改变结果使关节结构趋于协调和稳定.
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