Nakata Yoshiko, Ueda Hiroshi M, Kato Masaaki, Tabe Hideki, Shikata-Wakisaka Noriko, Matsumoto Eka, Koh Myongsun, Tanaka Eiji, Tanne Kazuo
Orthodontic Clinic, Hiroshima University Hospital, Hiroshima, Japan.
J Oral Maxillofac Surg. 2007 Mar;65(3):444-51. doi: 10.1016/j.joms.2005.12.071.
This study was designed to investigate the changes in stomatognathic function through orthognathic treatment in patients with mandibular prognathism.
Thirty-six patients with mandibular prognathism were tested and compared with 30 healthy controls with normal occlusion. For each subject, the occlusal contact area and occlusal force were measured during maximum voluntary clenching (MVC). Activities of the masseter and temporalis muscles were recorded during MVC and voluntary gum chewing. Jaw movement was analyzed during chewing on the left and right sides. For the analyses, 2 parameters, asymmetry index (AI) and error index (EI), were established to further investigate the nature of masticatory function. AI was used to evaluate the bilateral balance of masticatory muscle activity, and EI indicates the rate of abnormal jaw movement pattern.
In patients with mandibular prognathism, the occlusal contact area and maximum bite force decreased before surgery, and increased after surgery. The masseter and temporal muscle activities also decreased before surgery, but showed no substantial increase even after surgery. The occlusal and muscle efficiency exhibited significantly smaller values in the patient group than in the controls, irrespective of treatment stages. The AI decreased after surgery. The EI decreased significantly after surgery, but was still significantly greater in the patient group than in the controls.
It is suggested that masticatory muscles in the patients with mandibular prognathism may adapt to the new environment achieved with surgically corrected dentofacial structure, although the activities remain at lower levels as compared with the controls.
本研究旨在调查下颌前突患者经正颌治疗后口颌功能的变化。
对36名下颌前突患者进行测试，并与30名咬合正常的健康对照者进行比较。对每位受试者，在最大自主紧咬（MVC）时测量咬合接触面积和咬合力。在MVC和自主咀嚼口香糖时记录咬肌和颞肌的活动。在左右两侧咀嚼时分析下颌运动。为了进行分析，建立了2个参数，不对称指数（AI）和误差指数（EI），以进一步研究咀嚼功能的性质。AI用于评估咀嚼肌活动的双侧平衡，EI表示异常下颌运动模式的发生率。
下颌前突患者术前咬合接触面积和最大咬合力降低，术后增加。咬肌和颞肌活动术前也降低，但术后即使增加也不显著。无论治疗阶段如何，患者组的咬合和肌肉效率值均显著低于对照组。术后AI降低。术后EI显著降低，但患者组仍显著高于对照组。
提示下颌前突患者的咀嚼肌可能会适应通过手术矫正牙颌面结构所实现的新环境，尽管与对照组相比活动水平仍较低。
