- 學位論文
國人恆齒齒冠形態之牙科人類學研究
Dental Anthropological Study of Permanent Crown Morphology in Taiwan
摘要
人類牙齒不易毀壞變形，演化保守穩定，有堅實遺傳基礎與豐富形態表現，易於觀察比較，是人類演化與族群研究的理想工具．牙齒形態之人類學研究，主要目的在增加人類體質特徵之族群資料庫，建立族群間時空上之關聯．國人相關之研究，多為零星之形態項目式偏重大小之測量，缺乏較完整之形態觀察與分類．本研究以較大量標本數，較穩定之年齡層，較嚴謹之分類，較簡單之方法，從人類學角度探討在台灣中國人?齒齒冠形態特質之表現程度與頻度，建立國人之本土資料． 本研究以1984至1996年間台北醫學院牙醫學系學生，年齡20至2l歲，男生706名，女生207名，合計913名之上下顎齒列模型，依美國亞利桑那州立大學牙科人類學系統之分類與參考模板，觀察上下顎之門齒、犬齒、大臼齒與下顎小臼齒之24項形態特質．每一個體總計記錄45項牙齒與特質之組合，以個體計數法統計各項特質與各等級程度表現之頻數，並就有關國人形質研究之其他報告做一檢討． 數據分析顯示，國人上顎左右中門齒排列大多平直，雙側翼轉(中門齒近心舌側迴轉)也並非少見．上顎中、側門齒幾全為舌面鏟形，但表現程度多屬中等型；下顎前齒部近三分之一無舌面鏟形，有則多屬微弱型．上顎門齒雙鏟形(唇面鏟形)多屬微弱型，半數側門齒與三分之一中門齒不具雙鏟形．三分之二中門齒有唇面曲度，皆屬微凸表現．舌面溝較多見於上顎側門齒之舌面中央或近心側，中門齒少見舌面溝．舌面結節表現強弱依次為犬齒、側門齒、中門齒．錐形門齒約2%左右．上顎犬齒邊緣脊大都對稱分離，不具布希曼犬齒型．犬齒遠心副脊較多見於上顎，且大多為輕度發育． 下顎第一小臼齒具橫脊頻數遠大於第二小臼齒之近乎不具橫脊．第二小臼齒約半數為雙側二咬頭型，且多見H型咬面溝，U型次之；雙側三咬頭型雖未達半數，Y型咬面溝仍為最多數之溝型．下顎第二小臼齒近心舌咬頭大於遠心舌咬頭之頻數極高． 上顎第一大臼齒具四咬頭之頻數很高，遠心舌咬頭無顯著退化；第二大臼齒則顯現較高度之遠心舌咬頭退化，五分之一不具四咬頭．上顎大臼齒遠心頰咬頭均極顯著，第二大臼齒較第一大臼齒稍退化，但無完全消失者．第五咬頭頻數不高，在第二大臼齒稍退化．第一大臼齒卡拉貝利氏特質之頻數不高，然咬頭型並非少見；第二大臼齒僅極少數卡拉貝利氏特質，多為小窩呈現．上顎大臼齒幾乎部無頰側副咬頭，僅有一、二例． 下顎第一大臼齒大多第五咬頭顯著而有高頻數之五咬頭數與Y型咬面溝，保有森林猿之原始類型Y5型．第二大臼齒則多為四咬頭與高頻數之十型咬面溝，以十4型最常見，X型溝亦有不低之比率．半數以上第一大臼齒呈現迴脊，第二大臼齒則少見．下顎大臼齒第六咬頭皆較第七咬頭常見，且第一大臼齒之頻數皆較高，第二大臼齒僅1%有第七咬頭．頰側副咬頭在下顎大臼齒都不明顯，但不窩與溝型之頻數不低，且第一大臼齒較多見．
並列摘要
Few of the dental studies were focused on the non-metric morphologic traits of Chinese in Taiwan which also lack of some traits especially concerning anthroplogic significance. The objectives of this study are using a more definite classification with standard reference plaque, and with large samples in a more fixed age group, to understand the ranked natures of Taiwanese dental variation from a dental anthroplogical view. The final purpose serves to establish the database of Chinese dentition in Taiwan for student teaching and clinical use. Twenty four crown morphologic traits were investigated on plaster casts of 913 dental students from Taipei Medical College during 1984 to 1996, aged 20 to 21 years, 706 males and 207 females but sex pooled. By suing the Arizona State University Dental Anthropolgoy System and reference plaques provided by Turner and Dahlberg, with some other classifications, the ranked trait expression on lower premolars and incisors、canines、molars of both arches were observed, and total 45 tooth-trait combination data were recorded. The frequency percentage of each trait and every graded expression within the trait were compared to other studies using the same ranked classification system. On the basis of Mongoloid dental trait, the dentition of Chinese in Taiwan exhibit the characters by high frequency of shoveling, labial convexity, canine distal accessory ridge, metacone, hypocone, transverse ridge of lower first premolar, hypoconulid, deflecting wrinkle, protostylid, Dryopithecus pattern of lower first molars, +typed groove pattern and four cusp number of lower second molar. Relative high frequency as winging, double shoveling, Y groove pattern of lower second premolar. Moderate frequency of tuberculum dentale, Carabelli's trait, entoconulid, and three cusp number of lower second premolar. Low frequency to interruption groove, canine mesial ridge, metaconule, parastyle, and metaconulid. Although frequency distribution of the dental trait in the modern Taiwanese were very similar to Mongoloid racial stock, it did not follow a strict Sinodont/Sundadont divisions of Mongoloid dental complex classified by Turner. They have high Sinodont component with some effects of Sundadont admixture. Winging, shoveling, double shoveling, deflecting wrinkle and protostylid are consistent with Sinodont variation, but four cusps of lower second molar resembles Sundadont groups. Some traits with high total frequencies but moderate to low expression shows it may be some clinal variation from Sinodont. In general, the pattern of dental morphologic variation in Taiwan corresponds closely to the migration from mainland China, but they also have some Southeast Asian characters. They form the modern Chinese in Taiwan some called Taiwanese.