Morphological Study Of Mandible Dental Arch Evolution During 3000 Years In Xi'an District

【Introduction】Reviewing the evolutionary history of human during thousands years, we can find that in the struggle with nature the ancestor of human beings gradually adapted to the nature, while strengthening the body, developing the language and learning to make tools; The production of agriculture and animal husbandry solve the problem of human survival. The changes of environment and society result in the human constant self-adjustment and corresponding changes in human masticatory organ. So, changes in human masticatory organs in large part reflect the alteration of human living environment and development of education. Studying the human specimens from different eras has a great help and significance to our understanding of human evolutionary history and the degradation process of the human masticatory organs.【Objective】By studying the dental arch form of human mandible specimens respectively provided by Xi Zhou tomb 3000 years ago unearthed in Xi'an Chang'an Region, Qin Shi Huang Mausoleum mountains 2,000 years ago unearthed in Lintong District, Tang Dynasty resident relics 1000 years ago unearthed in Xi'an Chang'an Region and the mandible specimens of modern people from the Department of Anatomy of our school, to accumulate relevant data for our physical anthropology and evolution of the human stomatognathic system.【Methods】Respectively measured the size and the shape of the dental arch with linear and nonlinear methods. According to the fifth edition of―Orthodontics‖and the fifth edition of―Oral Anatomy and Physiology‖and using the digital vernier caliper (accurate to 0.01mm)provided by GunLin GuangLu corporation and spring divider with the maximum value of 200mm provided by ShangHai AiPuSu corporation, we measured the length and width of mandible dental arch with linear methods. According to the criteria of dental arch form from the fifth edition of―Oral Anatomy and Physiology‖, we surveyed the dental arch form. All the measurements were operated by the same person.【Results】1. Respectively reported the mandible dental arch form from different periods.2. Through comparing the mandible dental arch form of 157 cases, we find that the change of mandible dental arch form during 3000 years in X i'an district is not obvious and no statistical significance. The proportion of tip round, elliptical, square round are respective 26%,44%,30%.The main arch form are elliptical and square round, followed by tip round. However, there's little difference between different periods and it doesn't change with ages.3. Respectively reported the data of mandible dental arch lengths and widths from different periods.4. Through comparing the lengths and widths of dental arch from different periods, we find that the available dental arch length and the posterior dental arch width are gradually reducing. The data of 3000 years ago group is the largest, while the modern group is the smallest data. There is statistically significant difference. There are some differences between others groups, but it's no statistical significance.【Conclusion】In summary, we can get some understanding to the mandible dental arch form by measurement and analysis the mandible dental arch during 3000 years in Xi'an district and accumulate relevant data for our physical anthropology and evolution of the human stomatognathic system.