Study On Forensic Identification By The Characteristics Of Teeth、Palatal Rugae And Craniofacial Skeleton

Identification using oral radiographic image materials is one of the important study directions in forensic dentistry medicine The characteristic index of maxillofacial for forensic identification were chosen according to anatomical structures,pathological changes and dental interventions of teeth and maxillofacial bone by the X-ray orthopantomography or X-ray lateral cephalogram.However,the methods and items of personal identification using radiographic image materials should be more objectified and standardized.But in recent years, the progress of dental health and treatment have resulted in a gradually decrease in dental caries. As a result of that the forensic identification only by characteristics dental caries and interventions cannot fully adapt to the new situation. Therefore, it is necessary to explore new index for identifying the free dental treatment to solve the forensic identification.Palatal rugae is mediated by genetic genes, showing various characteristics among population and retains unchanged in each individual.In the human lifetime,the length of palatal rugae may change but the location maintains unchanged,it never alters by disease, trauma or chemical corrosion.Due to unique and diverse features, human palatal rugae attract increasing attention as a new marker in the forensic identification.All of the the digital X-ray orthopantomogram were comprehensively observed, including200samples with dental interventions,600samples(treatmen or treatmenless) randomly selected.in this study indexes were selected for dentition patterns according to the characters of dental alignment,dental pathological changes and intervention patterns.Two hundreds X-ray lateral cephalogram were selected.Facial pattern were classified by sagittal and vertical features. Maxillofacial sagittal features is divided into9categories in accordance with the relationship between SNA and SNB, According to the ratio of S-Go and N-Me,vertical facial pattern were classified into3categories.Eight identification indexes were identified to code the identification indexes for craniofacial morphology.It will provide a theoretical basis for the use of lateral cephalogram in Forensic Identification Indexes. The figures of palatal rugae of200study models were depicted. The classification was followed based on form、quantity、position and distribution to assess the individuality of rugae pattern,and expected to construct a forensic identification system for oral palatal rugae.we simultaneously collected the information of rugae images under standard conditions, and used Rugae Image Identification System (RIIS) in various ways including collection, noise reduction, augmentation, segmentation, feature extraction, edge detection, and information matching, with each a corresponding algorithm. Together with the processing of Matlab, we succeeded in obtaining a more rapid and accurate way of rugae image identification. We also suggested a standard and unified process for the collection, documentation, and computer analysis of rugae patterns, hoping this will offer an effective method for forensic identification. The findings:(1) The group with randomly selected with or without therapy had544kinds of dental pattern in600samples,thus its diversity of full dentition patternswas90.67%.The diversity was74.84%in maxillary and74.33%in mandible.The group with dental interventions had198kinds of dental pattern in200samples,thus its diversity of full dentition patterns was99.0%.The diversity was98.0%in maxillary and98.5%in mandible.(2) In600samples,the diversity in anterior regions is24.33%,which was lower than the samples with dental interventions(59.50%).Both of these groups showed a tendency of the diversity in posterior regions was higher than anterior regions.(3) Facial pattern were classified into27categories.According to9sagittal and3vertical facial pattern.All eight quantitative variables had comparatively high CV value.The difference of classification index between both sexes has statistical significance(p<0.05).(4) Among the involved200models, palatal rugae types varied among individuals,the diversity of palatal rugae types is100%.Palatal rugae pattern was different between men and women, even between two sides in the same individual. The curve type accounted for the higher percentage (23.03%), while the trifurcated type occupied the lowest proportion (0.74%).The sinuous and curve types were dominant in men and women (women:sinuous22.7%, curve18.28%; men:sinuous24.11%, curve21.43%)(5) Image Identification in various ways including collection, noise reduction, augmentation, segmentation, feature extraction, edge detection, and information matching, with each a corresponding algorithm. Together with the processing of Matlab, we succeeded in obtaining a more rapid and accurate way of rugae image identification.Base on these findings, it is concluded that the group with dental interventions had very good full dentitiondiversity in full dentition involved the posterior regions.Thus the method of full or part dentition coding was valuable in the group. Initial identification by the Facial pattern classification of Maxillofacial sagittal features followed with coding the craniofacial morphology with8indexes is likely a novel approach for forensic identification of in X-ray lateral cephalogram.the study shows the characteristic index of maxillofacial for forensic identification were chosen according to soft-sclerous tissues morphologic characteristic...