The Attachment of the Masseter Muscle Influences of the Craniofacial Morphology and Bite Force Distribution

本研究分为以下三个部分：1.咬肌与颅面形态的关系这一部分描述了有牙齿和无牙颌受试者咬肌浅层的附着、面积和方位及其与颅面形态的关系。主成分分析表明，下咬肌宽度与升支的大小有关，与肌肉前缘的位置有关。线性判别函数的结果表明，有齿和无牙颌之间的差异主要是由咬肌支宽度、冠状高度和咬肌前缘到下颌切迹之间的距离决定的。这项研究的结果表明，咀嚼功能的降低与咬肌附着点前缘的位置有关，也与升支大小的不同有关，即mos…。结论：1.冠突和性腺角的差异有统计学意义。咬合力与颅面形态的关系本部分的目的是通过比较斐济人和日本人的牙弓形态、颅面形态和咬合力来了解他们特定的颌骨器官，并估计颅面形态与咬合的关系。测量项目包括牙型、头影测量和牙体测量(咬合力分析、咬合面积、平均咬合力和咬合力)。在各个方向上，斐济人的牙弓都比日本人大。斐济人的腭长、下颌长、下颌体长均较大，呈双颌前突。斐济人下切牙的倾斜度比日语多。斐济人和日本人的杠杆臂长度存在显著差异。下颌骨垂直断面CT扫描的形态特征本研究的目的是比较下颌体纵断面的内部形态，评价其与下颌角的关系。作为主成分分析的结果，除颊皮质骨厚度外，每个断面的值都被归为相同的因子。尤其是联合颊皮质骨与前磨牙颊皮质骨相对。下颌角与第二磨牙切面的颊、舌侧皮质厚度相关，与联合和第二磨牙切面的高度相关。这些结果证实了下颌角与第二磨牙区下颌体部大小的关系。该区域位于附着性咀嚼肌的升支附近。较少

This research is divided into three sections as follows ;1. The relationship between masseter muscle and craniofacial morphologyThis section describes the attachment, the area and orientation of the superficial masseter muscle and its relationship with craniofacial morphology in dentate and edentulous subjects. A principal component analysis provided evidence that the lower masseter muscle width was associated with the size of ramus and was related to the position of the anterior margin of the muscle. The result of a linear discriminant function suggested that the ramus width, coronoid height and the distance between the anterior margin of masseter muscle and the mandibular notch contributed most to the observed difference between dentate and edentulous subjects. The results of this study indicated that a reduction of masticatory function was associated with the position of the anterior border of the insertion of the masseter muscle and also with differences in ramus dimension, the mos … More t significant of which were differences in the coronoid process and gonial angle.2. The relationship between bite force and craniofacial morphologyThe purposes of this section were to understand their specific jaw apparatus by comparing the dental arch morphology, craniofacial morphology and bite force and also to estimate the relationship between craniofacial morphology and bite in Fijians and Japanese. The measurements were taken on dental casts, cephalograms and dental prescale (bite force analysis ; occlusal area, average occlusal force and bite force). In every direction, the size of the dental arch in Fijians was larger than Japanese. And also Fijians had the large palatal length, mandibular length and mandibular body length and showed the bimaxillary protrusion. The inclination of the lower incisor in Fijians was more lingual than Japanese. There were significant differences in the lever armlength between Fijians and Japanese.3. The morpnhological characteristics of vertical sections of mandibles by CT scanningThe aims of this section were to compare the internal morphologies of vertical sections of the mandibular body and to evaluate the relationship between these morphologies and the gonial angle. As the result of the principal component analysis, each value of the sections was grouped into the same factor, except for the buccal cortical bone thickness. Especially the symphysis buccal cortical bone was opposite to the premolar buccal cortical bone. The gonial angle was associated with the buccal and lingual cortical bone thickness of the second molar section, and related to the height of the symphysis and the second molar section. These results confirmed the relationship between the gonial angle and the size of the mandibular body at the second molar region. This region was located near the ramus which had the attachment of masticatory muscles. Less