The Developmental Mechanism and the Treatment of Malocclusion Accompanied with Progressive Muscular Dystrophy

本研究的目的是探讨错颌合伴进行性肌营养不良（PMD）的发育机制。本文对西别堡国立医院30例PMD患者的咀嚼肌活动变化与咬合形态的关系进行了研究。肌肉活动通过表面肌电图、肌肉微振动、舌唇压力和咬合力测量。通过口内和面部照片、头颅x线片和石膏模型进行形态学检查。1. 在PMD患者中观察到的开放咬合似乎是由于下颌顺时针旋转，下磨牙区外侧扩张和前牙舌尖的共同作用。2. 咀嚼肌的肌肉力量和身体的其他阳刚之气一样下降。3. 对于复咬合的变化，观察了两组，咬开组和复咬合稳定组。利用咬肌和二腹肌前腹肌电能谱绘制Lissajous图，分析下颌开闭肌平衡的变化。在咬开组中，明显存在改变图斜率的时间，该时间与血清肌酸激酶活性的快速下降相吻合。4. 分析了遗传和环境因素对单卵双生子生长发育的影响。肌肉功能下降、失衡和负复咬合增加的时间和程度不同。二者口面复合体形态和功能的差异可能与多基因遗传和DMD基因（XP21）的大尺寸有关。因此，为了分析基因的差异，目前从单核细胞提取的DNA中检测氨基酸的等级。

The purpose of the present research was to examine the developmental mechanism of malocclusion accompanied with Progressive Muscular Dystrophy (PMD).In 30 patients with PMD in the Nishibeppu national hospital, the relation between the changes of masticatory muscle activities and occlusal morphology was investigated. Muscle activities were measured by surface electromyography, microvibration of muscles, tongue and lip pressure and occlusal force. Mrophological examination were made by intraoral and facial photographs, cephalometric radiographs and plaster models.Results. 1. It seems that the open bite observed in PMD patients was due to the combination of clockwise mandibular rotation, lateral expansion in the lower molar region and lingual tipping of the anterior teeth. 2. The muscular strength of the masticatory muscles was decreased as well as the other masculature of the body. 3. Regarding the change of the overbite, two groups, bite opening and overbite stable group, were observed. Lissajous' figures were drawn from EMG power spectra of the masseter and the anterior belly of the digastric muscle to analyze the change of the jaw opening and closing muscle balance. In the bite opening group, the time to change the slope of the figure obviously existed, when was coincided with rapid decrease of the activities of serum creatine kinase. 4. The longitudinal materials of a monozygotic twin were analyzed on the influence of heredity and environmentupon the growth and development. The timing and degree of the decrease and imbalance of muscle function and the increase of negative overbite were different between them. Differences in form and function of orofacial complex between them might be cause by their polygene heredity and the large size of DMD gene (XP21). Therefore, for the analysis of the difference of gene, the ranks of the amino acid of DNA extracted from the monocyte are examined at present.