Talwar R M, Ellis E, Throckmorton G S
University of Texas Southwestern Medical Center, Dallas 75235-9109, USA.
J Oral Maxillofac Surg. 1998 Apr;56(4):430-9. doi: 10.1016/s0278-2391(98)90707-8.
The objective of this investigation was to evaluate the adaptations that occur in the masticatory system after treatment of bilateral fractures of the mandibular condylar process.
Twenty-two patients (15 men and seven women) with bilateral condylar process fractures treated by open reduction and rigid internal fixation (n = 6), closed therapy (n = 14), or a combination of these techniques (n = 2) were compared with 22 sex- and age-matched controls. Measures of mandibular range of motion, bite force, muscle activity, estimated joint forces, and skeletal morphology were determined at 6 weeks, 6 months, and 1, 2, and 3 years after treatment in all subjects. Various statistical tests were used for comparing differences between patients and controls.
There was no significant difference in the patients' morphologic measures for the open and closed reduction procedures; therefore, all of these patients were tested as a single group. After treatment, patients had significantly increased mandibular plane and gonial angles and decreased facial axis angles. They also showed a significant reduction in posterior facial height and moment arm length for the masseter and pterygoid muscles. Anterior and posterior temporalis muscle direction also was significantly different between patients and controls. Patients had significantly limited mobility during the first year after fracture. Bite forces were lower for patients at all times and tooth positions, with a significant difference at 6 weeks after treatment. Patients had a tendency to use proportionally higher temporalis muscle activity during maximum biting; however, the differences were not statistically significant, probably because of the small sample size. The estimated joint force magnitudes were essentially identical between patients and controls; however, the direction of the patients' joint forces were more posteriorly directed for both incisor and molar bites.
The results of this study suggest that early reduction in mandibular range of motion, bite force, and the distribution of masticatory muscle activity assist in preventing overloading of the bilaterally fractured mandibular condylar processes.
本研究的目的是评估双侧下颌髁突骨折治疗后咀嚼系统发生的适应性变化。
将22例双侧髁突骨折患者（15例男性和7例女性）与22例性别和年龄匹配的对照者进行比较，这些患者采用切开复位内固定术（n = 6）、闭合治疗（n = 14）或两种技术联合治疗（n = 2）。在所有受试者治疗后的6周、6个月以及1、2和3年时，测定下颌运动范围、咬合力、肌肉活动、估计的关节力和骨骼形态。采用各种统计检验比较患者与对照者之间的差异。
切开复位和闭合复位手术患者的形态学测量结果无显著差异；因此，所有这些患者作为一个单一组进行测试。治疗后，患者的下颌平面角和下颌角显著增加，面轴角减小。他们还表现出面部后份高度以及咬肌和翼内肌的力臂长度显著减小。患者与对照者之间颞肌前后方向也存在显著差异。骨折后的第一年患者的活动度明显受限。患者在所有时间和牙位的咬合力均较低，治疗后6周时差异显著。患者在最大咬合力时倾向于按比例使用更高的颞肌活动；然而，差异无统计学意义，可能是因为样本量较小。患者与对照者估计的关节力大小基本相同；然而，患者的关节力方向在切牙和磨牙咬合时均更向后。
本研究结果表明，早期下颌运动范围、咬合力及咀嚼肌活动分布的减小有助于防止双侧骨折的下颌髁突过载。
