Morphological Study Of Dental Arches Evolution During6000Years In Shaanxi District

【Introduction】Shaanxi is a prestigious place in ancient Chinese as one of the “JiuZhou”.Millions years ago, there were some prints of primitive human life along both sides ofBaHe. Six or seven thousand years ago, the civilization of matriarchal society quietlynurtured with the time slowly developed in Banpo. Five thousand years ago, HuangDi andYanDi lead their tribes to create a Chinese civilization in the Loess Plateau area ofinflammation. After the farming civilization been established and the Chinese charactersbeen invented, there had been many emperors build their own power here. Those differentkinds of history are all marked the splendid and glorious ancient civilization of Shaanxi.The rapid development of these five thousand years of Chinese civilization, theenvironment changed rapidly and the social becomes complex. The type of food and theeating habits has changed, so a longitudinal study of masticatory organs not only helpsreveal the evolution of social history, but also helps us to explore human evolution in adeeper way, what is more, we could understand how the human physiological process ofgrowth and development of the structure changes in multiple dimensions. Morphology andsize of the dental arches, teeth and dentition arch crowding closely related in some way.By studying more than one group’s arches, in addition to help we better understanding of the changes occurring in the arch of human evolution, but also as a secondary reference,so we will be more familiar with the human living environment, and cultural background.【Objective】 To observe and measure the samples from different times, we canexplore the human evolution trend arch forms in the past6,000years in Shaanxi; this is foraccumulating of relevant data of the study of human craniofacial morphology and foraccumulating the data of the human physique study.【Materials and Methods】The experimental method adopted longitudinal study, atotal of223cases of adults’ jaw bone specimens were measured on, including94casesfrom the group of6,000years ago,63cases from the group of2,000years ago, and66cases from the modern group; and220cases of adult mandible specimens, including98cases from the group of6,000years ago,58cases from the group of2,000years ago,64cases from the group of modern ones. It also measured the group of people from4,000years ago,3,000years ago and1,000years ago. Sample inclusion criteria were: wellpreserved and after restored which although there were still some defects but does notaffect the data measured maxillary and mandible specimens; second molars intact, theremaining teeth to keep at least one tooth of the same name; aged18years or older.The measurement methods of model from the book written by Fu Minkui and thearch measurement method from “Anthropometric Handbook” written by Shao Xiangqingare the standard of the measure indicators of this study. Each data must been measuredtwice, taking the average of all measurements done by the same person. The arch formshould been observed and follow the standard of “Oral Anatomy and Physiology”. Theresearchers observed the same judgment on the dental arch form of each specimen.Each group separately in the maxillary and mandibular arch measure analysis ofvariance, observe whether the measure differences between different groups, whether thedifference was statistically significant, and between different generations indicatorspairwise comparisons (LSD-t test; P<0.05) for analysis.【Results】1. Respectively reported the maxillary and mandible dental arch form from differentperiods. 2. Respectively reported a group of people from different years, the measurementdata of the maxillary and mandibular arch of length, width, height and angle.3. Through223cases of maxillary specimens and specimens of220cases ofmaxillary and mandibular arch comparative study we found that:Arch form study:①In maxillary arch, elliptical arch form is in the highest flight,then is the square round form and tip round arch form. In mandibular arch, elliptical archform is still in the highest flight,males’ square round arch form occupied the second placeand females’ tip round arch form is in the second place.②Different groups of people inShaanxi regions, the proportion of the maxillary and mandibular arch various forms ofsmall-scale changes.③In the maxillary arch form, the oval and square arch formproportions over time became smaller, the proportion of rounded tip gradually increasing;in the mandibular arch, the ratio of oval gradually become smaller over time, sharp roundand square round proportion gradually increased, there was not statistically significant inbetween genders.Arch size study: Through the different generations of people, the maxillary andmandibular arch length, width, height and angle were been compared and we found itemssuch as:①in the maxillary specimens, whether male or female, in addition to the archangle, the rest of the measure was gradually narrowing, the arch angle was graduallyincreasing, which indicated that the segment arch over time tend to be straight, thedifference was statistically significant;②mandibular specimens, except forthe anteriorand posterior dental arch length of women, the rest of the measurement are either male orfemale was gradually narrowing trend.In summary, the maxillary and mandibular dental arches6000years to come inShaanxi except for a few segment of arch length and width, others showed differentdegrees of narrowing and arches overall are decreased gradually.【Conclusion】In summary, in this study we observed and measured the dental archfrom6000years ago,2000years ago and modern human groups of the maxillary andmandibular arches, to understand the morphological characteristics of different periods ofhuman dental arch, the evolutionary trends of arch over time, provide relevant information and accumulated according to morphology of the human maxillary and mandible.