Dissertation Research: Secular Change of Japanese Occlusion: The Frequency of the Overbite and its Association with Food Preparation Techniques and Eating Habits

直到200多年前，正常的人类咬合是边到边的。也就是说，当磨牙紧握在一起时，上下门牙的切边相互交汇，而不是像现在认为的正常情况下重叠。这一变化发生在18世纪末欧洲人采用餐叉和饮食习惯的变化之后。由于美国独立战争导致旧世界交往的中断，这种变化直到19世纪30年代才开始在美国发生。在食物准备方法发生变化后，亚洲也应该发生类似的变化，允许筷子、中国的桂子和日本的哈希作为日常饮食用具。《中国》的初步研究表明，宋代中国上层社会出现了现代覆牙合现象。宋文化的影响对日本的生活产生了深远的影响，这个项目的目的是测试以筷子为代表的中式烹饪和饮食习惯的采用，是否伴随着第一批日本农民及其后裔在大和日本从边咬到边咬的变化，这紧接在中国的第一次重大影响之前。这些研究将有助于阐明饮食、饮食行为、食物准备技术和牙列正常咬合之间的关系。

Until just over 200 years ago, the normal human bite was edge-to-edge. That is, when the molars were clenched together, the cutting edges of the upper and lower incisors met each other rather than overlapping as is now considered normal. The change took place in Europe following the adoption of the dinner fork and the changes in eating habits it indicated late in the 18th century. Because of the hiatus in Old World contacts caused by the American Revolution, that change did not begin to take place until the third decade of the 19th century in America. A similar change should have occurred in Asia following the change in food preparation methods that allowed chopsticks, kwai-zi in China and hashi in Japan, to be used as everyday eating utensils. Preliminary work in China indicates that the modern overbite occurred in upper class Chinese in the Song Dynasty. Song cultural influences had a profound effect on life in Japan, and the purpose of this project is to test whether the adoption of Chinese food preparation and eating habits exemplified by the use of chopsticks was accompanied by a change from the edge-to-edge bite of the first Japanese farmers and their descendants in Yamato Japan which immediately preceded the first major influences from China. These investigations will help clarify the relationships between diet, eating behavior, food preparation technology and normal occlusion of the dentition.