The Study Of Teeth's Morphological Measure And Oral Diseases In The Population Excavated From The Changan County In Shaanxi Province About 1000 Years Ago

During the human evolution, with the improvement of instruments and the change of the diet structure,the tooth morphology has changed and the prevalence rate of oral disease has varied.In order to prevent the damage of the oral diseases to people's health, scholars researched the disease continually, so that they could find the rule of the appearance and development of the oral disease and control it. But the data about the development of oral disease and the tooth morphology was absent and insufficient. There were a few reports about the oral disease and tooth morphology of Chinese about 1000 years ago.Tang dynasty became the china's feudal society at the height of their power and splendor. Overseas Chinese today still regard themselves as the"descendants of the Tang"and the place where they live as the"street of the Tang"(China town). During the Tang dynasty, people led a relatively plentiful and stable life. Tang dynasty marked a golden era in china, which dates back 1000 years ago. By the samples,we can not only study the prevalence of the oral disease and dental morphological traits ,but also accumulate the social and ecological data at that time,which will help us to understand the people's working and living conditions at that time. This study aimed to find the rule and trend of oral diseases in the people at that time to prevent and control the incidence of oral diseases now.Our study used the method of cross-sectional study of descriptive epidemiology. The prevalence rate of the oral disease and dental morphological traits in the 62 skulls could be summarized in our detailed report. The study aimed to describe the status of oral diseases and dental morphological traits in people about 1000 years ago. Compared the epidemiologic data in different eras, we could found the rule and trend of oral disease in people.After collecting and cleaning up the whole objects, we numbered the skulls and labeled the position of all the teeth in the jaws. The dental samples examined in this study include 631 permanent teeth(328 upper teeth and 303 lower teeth) from Tang dynasty, referable to 62 individuals. Every data including height of dental crown,crown areas of the tooth, breadth of the dental crown, thickness of the dental crown, breadth of the dental neck and thickness of the dental neck was noted in detail by the standards and methods described in《Human Skeleton Measurement》and《Anthropometric Handbook》. Moreover Every kind of diseases was noted detailedly according to the latest and authoritative clinical diagnosis standards and method. In order to find the relation between the oral disease and age, the objects were divided into four groups according to their ages. The data were dealt with by statistical methods. The results were discussed and showed as follows:In the aspect of morphological measure study of teeth, Descriptive statistics of crown diameters: height of dental crown,crown areas of the tooth, breadth of the dental crown, thickness of the dental crown, breadth of the dental neck and thickness of the dental neck were reported. However, significant differences between the sexes were as fellowed: height of dental crown of upper M2,lower I1 and M1(malefemale); thickness of the dental crown of upper C,P1,M2,M3 ,and lower P1,M1(male>female); breadth of the dental neck of upper P1, P2,and lower C(male>female); thickness of the dental neck of upper P1,M3,and I1,C,P1 in the mandibular dentition(male> female).Though measuring the teeth of Tang dynasty about 1000 years ago,we can collect data for the study of Chinese teeth morphology.In the aspect of dental caries, The dental caries prevalence rate was 62.90%,and there were 92 caries teeth, which was 14.58% of the whole teeth. The proportion of patients and teeth having dental caries was ascending with the age in every group: 7.55%,10.13%,16.55% and 24.72%,respectively. Study from the distribution of caries cavity in the tooth surface,we found that the root caries(46.74%) was more than the occlusal caries(40.22%).There was no lingual caries found. Study from the relation of the dental caries and tooth position ,we found that the most frequent recorded caries was in the third molar, followed by the second molar, and the first molar. There was no significant difference between male and female(P >0.05). To learn the frequency, distribution, and characteristics of dental caries about 1000 years ago, which will be helpful to understand the people's working and living conditions at that time.In the aspect of periodontal disease, There were 529 teeth in 57 individuals suffering the periodontal disease, which was 83.84 per cent in the whole teeth. The prevalence rate of periodontal disease was 91.94 per cent. The proportion of patients and teeth having periodontal disease was ascending with the age in every group. The proportion of the canine was the highest and the proportion of the central incisor was lowest among the teeth which suffered the periodontal disease. The periodontitis in symmetrical tooth position between the maxilla and the mandibula was no significant difference (p>0.05). There was significant difference in the prevalence rate of periodontal disease between sexes(p<0.01) and the prevalence rate of males was higher than that of females.Learn the frequency, distribution, and characteristics of Periodontitis about 1000 years ago, which will be helpful to understand the people's working and living conditions at that time. In the aspect of tooth attrition, almost all of teeth wear away. In the whole attrited teeth, the proportion of score 2 was highest(36.80%).The first molar and the canine were attrited most seriously and the attrition of the third molar was the lightest. The tooth wear increased with age. The attrition in symmetrical tooth position between the maxilla and the mandibula was no significant difference (p>0.05). There was significant difference in the score of tooth attrition between sexes(p<0.05) and the score of males was greater than the score of females. Learn the frequency, distribution, and characteristics of tooth wear about 1000 years ago, which will be helpful to understand the people's working and living conditions at that time.As the above showed, 1000 years ago,many kinds of oral disease including dental caries, periodontal disease and tooth attrition were common and the morphological measure data of teeth was higher than that of modern humans .Not only the prevalence rate of dental caries and periodontal disease, but also the tooth attrition increased with age. The prevalence rate of dental caries in the people at that time was lower than the modern people. While the prevalence rate of periodontal disease at that time was higher than that of modern people. And the degree of tooth attrition in the people at that time was also worse than that of modern people. The heredity factor and environment factor were the most important factors affecting the evolvement of the jaw and tooth in the human, which also affected the clinical symptoms and development of the oral disease in different eras.