超声及下颌骨X射线评估下颌角磨削去骨及隆颏前后的咬肌变化

Masseter muscle changes before and after angle-grinding ostectomy and chin augmentation : Evaluation by ultrasound and X-ray

背景：双下颌嚼肌肥大症患者，往往都存在着下颌角前切迹明显凹陷，从而不仅突出方型面容，还同时突出方型的颏部。目的：观察下颌角磨削去骨矫治下颌角肥大畸形后咬肌的变化。设计、时间及地点：自身前后对照，病例来自2005—06／2007—01南方医院整形科。对象：选择南方医院整形科治疗并有完整资料的外翻型下颌角肥大伴小颏形女性患者60例，年龄19～42岁。方法：应用下颌角磨削去骨矫治60例下颌角肥大畸形，并将所磨削的骨屑植入颏部，颏成形塑形后石膏托固定改善下颌整体形态。采用高频浅表超声成像技术，分别在治疗前、治疗后每隔4周，放松和用力咬合2种状态下测量双侧咬肌厚度，同时拍摄口腔全景X射线平片及下颌角X射线侧位平片。主要观察指标：患者的治疗情况：治疗前及治疗后24，32周下颌角度、下颌宽、咬肌厚度变化及下颌角X射线侧位平片表现。结果：60例患者治疗后无感染、神经损伤及出血，均无颏唇部感觉麻木。①随访1年，一般在治疗后第24周肿胀完全消退，磨骨后的下面部形态明显改善，55例患者对颏成形及下颌角磨削后脸型变化均表示满意。2例治疗后10d要求改变成形的颏部形状，给予调整后满意。3例分别于治疗后因外力使颏部变形，给予调整后恢复原来塑形形状。②与治疗前相比，治疗后双侧下颌角度明显增大、下颌宽度明显减小（P〈0．05）。在松弛和咬合2种颌位状态下，治疗后24周双侧咬肌厚度均明显小于治疗前（P〈0．05）。③口腔全景X射线平片及下颌角X射线侧位片示，下颔角明显变小，磨骨后的下颌角更加圆滑，颏部隆起，下面部弧度自然，角度〉110°，移植的骨屑与下颏骨融合好。结论：下颌角磨削去骨后24周内肥大的咬肌会出现自行萎缩，不需处理，24周后咬肌不再有变化。下颌角肥大者可行单纯磨削去骨，无需切除咬肌。

BACKGROUND： Hypertrophy of masseter muscle is commonly accompanied by obvious mandibular antegonial notch, which causes square face and mental region. OBJECTIVE： To observe the change of masseter muscle after the angle-grinding ostectomy for the treatment of the mild enlarged mandibular angle. DESIGN, TIME AND SETTING： Self-control. The cases were selected from Department of Plastic Surgery, Nanfang Hospital, Southern Medical University between June 2005 and January 2007. PARTICIPANTS： Sixty female patients with mandibular angle hypertrophy and microgenia, aged 19 42 years, were selected. METHODS： Angle-grinding ostectomy was performed for all patients, and the grinded skeletal fragment was implanted into mental region. After moulding, the mandible was fixed by plaster slab. The thickness of masseter of 60 patients was bilaterally measured under both resting and maximal contracted positions by high-frequency superficial ultrasonic imaging before and every 4 weeks postoperatively. The X-ray was used to observe the change of mandibular angle and the area of chin. MAIN OUTCOME MEASURES： Treatment condition; mandibular angle, width, and masseter muscle thickness and X-ray films of mandibular angle before and 24, 32 weeks after treatment, RESULTS： No infection, nerve injury or bleeding was found in any patient. During the one year follow-up, the swelling disappeared at week 24, and the face morphology was significantly improved. Fifty-five patients were satisfactory with their face. Two were satisfactory after the face was changed to mental region appearance on day 10. Three were restored to the moulding appearance. The mandibular angle and width were greatly decreased compared with before treatment （P 〈 0.05）. The mean thickness of masseter muscle of pre-operation became thinner markedly than that at 24 week postoperatively （P 〈 0.05）. The film of X-ray shows that the mandibular angle was above 110~and autogeous micromorselized bone graft was moulded easily. CONCLUSION： After the angle-grinding ostectomy, the hypertrophy masseter muscle can get atrophy itself during 24 weeks. But there was no change in masseter muscle. The patients can be treated with angle-grinding ostectomy only.