Study on arrising factors of TM disorders and food habits -Survey on the Central American Indian, whose origin are the same as Japanese-

本研究包括两个目的：一是对颞下颌症状（TMS）发生率的流行病学研究，二是利用干颅骨标本调查牙齿磨损与髁突形态变化的关系。为了进行调查，我们选择了一个主要由中美洲洪都拉斯和危地马拉的土著居民组成的人群，他们与日本人有着相同的激进根源，但他们的生活环境，特别是饮食习惯与日本人不同。至于后一项调查，我们收集了中美洲土著印第安人的数据。结果：TMS发病率从低到高依次为山区洪都拉斯土著印第安人[31.7%(20/63)]、危地马拉土著印第安人[42.1%(43/02)]、加勒比海沿岸洪都拉斯土著印第安人[46.8%(74/58)]和洪都拉斯首都特古西加尔巴居民[50.0%(26/52)]。采用磨损Broca(B)评价磨损程度，将所有经颅磁刺激患者分为1级或2级。牙磨蚀与髁突形态变化的关系，将b1 ~ b3轻度磨蚀组归为凸型，b2 ~ b4组归为凹凸型。本研究表明，随着磨耗从轻度到重度的进展，菲亚特型的病例数量增加。讨论：本研究结果提示经颅磁刺激患者处于适应性较差的状态；下颌髁有轻微的磨损和重塑。

The present study consists of two objectives: an epidemiological study of the incidence of temporomandibular symptoms(TMS) and an investigation to clarify the relationship between the dental attrition and morphological change of condyle using dried cranial bone samples.In order to conduct the survey, we selected a population consisting mainly of the native inhabitants of Honduras and Guatemala in Central America, who have the same radical roots as the Japanese and whose living environment, especially eating habits, are different from those of Japanese. As for the latter investigation, we collected data on native indians in Central America.Results: The ranking of incidence of TMS, from lowest to highest, was a Honduran native indians, living in the mountain[31.7%(20/63)], Guatemalan native indian[42.1% (43/02)], a Honduran native Indian on the Coasu of the Caribbean Sea[46.8%(74/58)] and the citizens of Tegucigalpa, the capital of Honduras[50.0%(26/52)].Attrition Broca(B)was used to evalvate the degree to attrition and all patients with TMS were classified as either class 1 or class 2.Regarding the relationship between dental attrition and the morphological change of mandibular condyle, the B1-B3 mild attrition group was classified as convex type, while the B2-B4 group was classified as fiat type. The present study demonstrated that the number of cases of fiat type increased as attrition progressed from a mild to severe degree.Discussion: The results obtained in this study suggested that the patients with TMS were in a state of poor adaptability character; zed by mild attrition and slight remodeling of the mandibular condyle.