Throckmorton G S, Ellis E, Sinn D P
Division of Oral and Maxillofacial Surgery, University of Texas Southwestern Medical Center, Dallas 75235-9109, USA.
J Oral Maxillofac Surg. 1995 Aug;53(8):898-908; discussion 908-9. doi: 10.1016/0278-2391(95)90277-5.
The purpose of this investigation was to compare morphologic parameters and functional performance between controls and a sample of patients with mandibular retrognathia prior to surgical correction, and to examine how oral motor function adapts after treatment.
Twenty-four retrognathic female patients were compared with 26 female controls before and up to 3 years after mandibular advancement surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way analysis of variance was used to compare the controls, the patients before surgery, and the patients after surgery.
Surgical lengthening of the mandible averaged 7.3 mm, bringing most skeletal measures into the normal range. There were no significant differences in jaw muscle mechanical advantage between patients and controls before surgery, but surgery significantly reduced mechanical advantage of the anterior temporalis and masseter muscles. Jaw hypomobility was apparent at 6 weeks after surgery, but returned to normal values within 12 to 24 months. Before surgery the patients had maximum isometric bite forces less than half those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite force were equivalent to those of controls or somewhat higher. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls.
The results of this study suggest that correction of mandibular retrognathia by mandibular advancement surgery produces some significant functional benefits.
本研究旨在比较手术矫正前下颌后缩患者样本与对照组之间的形态学参数和功能表现，并研究治疗后口腔运动功能如何适应。
24名下颌后缩女性患者与26名女性对照组在进行下颌前徙手术前及术后长达3年的时间里进行了比较。随时间推移，对所有受试者进行了骨骼形态测量、下颌运动范围、最大等长咬合力以及等长咬合时颞肌前束、颞肌后束和咬肌的肌电图活动水平测量。采用单因素方差分析比较对照组、术前患者和术后患者。
下颌手术延长平均7.3毫米，使大多数骨骼测量值进入正常范围。术前患者与对照组之间颌肌机械优势无显著差异，但手术显著降低了颞肌前束和咬肌的机械优势。术后6周出现下颌活动度降低，但在12至24个月内恢复到正常值。术前患者的最大等长咬合力不到对照组的一半。术后咬合力稳步增加，2年内接近正常值。术前患者每单位咬合力的肌肉活动水平与对照组相当或略高。术后部分患者每单位咬合力的肌肉活动水平明显低于对照组。
本研究结果表明，下颌前徙手术矫正下颌后缩可产生一些显著的功能益处。
