正畸治疗前后腭皱的法医同一认定研究

目的利用腭皱模型分析法评价腭皱形态的个体独特性及正畸治疗前后腭皱形态的稳定性,探索腭皱形态在法医齿科学个体识别应用中的可靠性。方法分别收集70例正畸治疗前、后的上颌模型。通过模型测量分析对腭皱形态及个体识别进行检测,包括数量、方向、形状及长度的变化和近、远中侧端点分别在近远中向及前后方向上的位移。同时对正畸治疗前、后及正畸治疗后与其复制后腭皱模型进行配对检测,计算其平均正确配对率(%)。结果 (1)正畸治疗后腭皱数量、方向、形状及长度均有变化,表现为长度变化(28.6%);分裂(4.3%);联合(2.9%);方向变化(1.4%);形状变化(1.4%)。并且治疗后腭皱远中端点的前后向位移变化占45.7%,近远中向位移占40%;而腭皱近中端在在前后向和在近远中向上位移变化分别为32.9%和17.1%。(2)正畸治疗前组及正畸治疗后组不同个体均未发现相同的腭皱模式。(3)正畸治疗前、后模型的腭皱平均正确配对率为92.19%。而治疗后模型与复制后模型的腭皱平均正确配对率是99.05%。结论腭皱形态具有高度的个体特异性,尽管正畸治疗后腭皱的形态有一定变化,但仍可作为一种新的方法应用于法医齿科的同一认定。     

应用数字图像识别系统研究正畸治疗前后腭皱形态变化

目的利用腭皱数字图像识别系统对正畸治疗前后腭皱形态匹配正确率的分析研究,为法医学中同一认定提供理论依据。方法利用正畸患者治疗前后腭皱形态数字图像,通过腭皱数字图像识别系统对图像的特征进行提取并收录到腭皱数字库,运用Matlab软件完成对腭皱形态数字图像的信息匹配处理。结果正畸治疗前后,个体性检测匹配正确率各自都达到100%。正畸治疗前后腭皱形态匹配正确率为95.67%,配对检验结果 P0.05,具有统计学意义。结论腭皱形态具有高度的个体特异性,正畸治疗后腭皱形态会发生多种变化,但对同一认定的影响不大。腭皱形态识别为法医学同一认定提供一种新的方法和途径。     

利用腭皱特征进行同一认定的指标体系构建

目的根据腭皱的形态图特征,进行口腔腭皱在法医学同一认定的指标体系构建。方法收集100例成年人腭皱模型,依据腭皱的形状、数量、位置分布等特征对腭皱形态图进行全面系统的编码。编码顺序采用英文字母按照先右侧再左侧,先前部再后部的顺序编码,并且右、左侧编码以破折号连接。最后依据编码,统计分析腭皱形态分布特征。结果 100例腭皱形态图中,个体间未见完全一致者,每个个体不论男性与女性均表现有独特的腭皱形态图;且同一个体左右侧单条腭皱的形态及分布亦不同。波浪形腭皱所占比例最大（23.03%）,三分叉形出现比例最小（0.74%）,不同性别的波浪形及曲线形腭皱所占比例均较大,女性波浪形（22.7%）及曲线形（18.28%）;男性波浪形（24.11%）及曲线形（21.43%）。结论口腔腭皱法医学同一认定的指标体系构建,将为法医学的同一认定提供一种新的方法。     

Morphological pattern of palatal rugae in children of Davangere

The aim of this study was to identify and compare the rugae pattern between males and females of two different communities in the city of Davangere, Karnataka, India, which may be an additional method of identification in cases of crimes or communal riots. Elastomeric impressions of the maxillary arch of 100 selected children were made; casts were poured in Type IV stone. The method of identification of rugae pattern followed was that of Lysell and Thomas and Kotze, which includes the number, shape, direction, and unification of rugae. The study revealed no significant difference in the total number or length of rugae between the two communities and sexes. However, with regard to shape and unification, females showed a significantly higher diverging rugae type while males had a significant number of circular and converging type of rugae. Also, discrimination function analysis allowed a moderate differentiation of the population. Hence, the rugae pattern can be an additional method of differentiation in conjunction with the other methods such as visual, fingerprints, and dental characteristics in forensic sciences.     

数字全口牙位曲面体层片的法医学同一认定指标

目的采用颌面全口牙位曲面体层片,针对牙齿无病变者筛选简洁实用的法医学同一认定识别指标并进行编码、统计分析及评估。方法随机选取170例牙齿无病变者的颌面数字全口牙位曲面体层片进行观测．根据牙齿的生理变异特征和牙齿的排列特征分别筛选全口牙型和牙列型识别指标。按设计的编码标准对全口牙型、牙列型逐一编码,统计分析编码的多样性,以评估两类识别指标的应用价值。结果170例中共有74种全口牙型编码,多样性为43．53％：170例中共有129种牙列型编码,多样性为75．88％;170例同时进行全口牙型和牙列型编码．则共有150种全口牙型／牙列型编码,多样性为88．24％。结论全口牙型编码多样性较低,单独使用尚不能满足法医学同一认定的要求。牙列型编码的多样性比较高,具有一定的法医学同一认定价值。如果同时进行全口牙型和牙列型编码,多样性明显提高,有较高的法医学同一认定价值。     

Forensic dental training in the dental school curriculum

This article reviews the literature regarding forensic education in the dental school curriculum and describes an exercise in forensic identification of victims of a mass casualty. Radiographs were made of dentate human cadavers in the gross anatomy laboratory at the Southern Illinois School of Dental Medicine. The jaws were then removed to provide "wet specimens" for the exercise. Several restorations were performed on the cadaver teeth, after which radiographs of the dissected jaws were made. One author wrote up mock dental records for each of the victims. These records included the first set or "premortem" radiographs. Students participating in the exercise were provided with a plane crash scenario, the dental records of the passengers on the manifest, the dissected jaws, and the second set or "postmortem" radiographs. Students were expected to form three teams. The first two teams evaluated the ante-mortem and postmortem dental records. The third team compared the ante-mortem and postmortem records to arrive at identification. The purpose of the exercise was twofold. It introduced dental students to forensic dentistry and emphasized the need for complete and accurate record keeping in the dental office. Several factors lessened the realism of the exercise and made it difficult to reproduce in the future. These included the uniformity of the dental records and the destruction of cadaver material following the exercise.     

Computer‐aided Dental Identification: An Objective Method for Assessment of Radiographic Image Similarity*

Abstract: A pilot study evaluated a computer‐based method for comparing digital dental images, utilizing a registration algorithm to correct for variations in projection geometry between images prior to a subtraction analysis. A numerical assessment of similarity was generated for pairs of images. Using well‐controlled laboratory settings, the method was evaluated as to its ability to identify the correct specimen with positive results. A subsequent clinical study examined longitudinal radiographic examinations of selected anatomical areas on 47 patients, analyzing the computer‐based method in making the correct identification based upon a threshold level of similarity. The results showed that at a threshold of 0.855, there were two false negative and two false positive identifications out of 957 analyses. Based on these initial findings, 25 dental records having two sets of full mouth series of radiographs were selected. The radiographs were digitized and grouped into six anatomical regions. The more recent set of films served as postmortem images. Each postmortem image was analyzed against all other images within the region. Images were registered to correct for differences in projection geometry prior to analysis. An area of interest was selected to assess image similarity. Analysis of variance was used to determine that there was a significant difference between images from the same individual and those from different individuals. Results showed that the threshold level of concordance will vary with the anatomical region of the mouth examined. This method may provide the most objective and reliable method for postmortem dental identification using intra‐oral images.     

An Unusual Case of Predation: Dog Pack or Cougar Attack?

Injuries produced by animals are capable of leaving severe patterns and in some cases may result in the death of the attacked individual. Law enforcement authorities may come to erroneous conclusions about the source of the bites based on their awareness of animals present and similarities of the injuries to the untrained eye, with dreadful consequences. Expertise of a carnivore biologist and an odontologist that indentifies the particularities of bite marks may be useful for identifying the attacking species. We present the investigation of a fatal dog pack attack involving a 43‐year‐old man in Bell Ville (Argentina) where the evidence provided by a forensic dentist and a biologist was categorical for establishing the animal species involved. Because of the unusual characteristics of the wounds and the initial hypothesis made by local authorities of a cougar attack, habits and specific patterns of both dog pack and cougar predation on humans are discussed.     

Yet another method for marking incisal edges of teeth for bitemark analysis

Over the years many methods have been proposed and presented for marking or "highlighting" the incisal edges of anterior teeth on a dental stone model -- one of the critical steps in production of transparent overlays for bitemark analysis. A method is presented here that is an extension and refinement of the "paint the edges" method shown at least as early as 1966 by Gustafson. This method uses "invisible ink" and ultraviolet illumination to produce a very high contrast image of the incisal edges of the teeth on the model. The advantages of this new method are that it is nondestructive, it does not leave visible marks on the models, operator subjectivity in selecting the portions of anterior teeth to be highlighted is reduced, and the author submits that this technique lends itself to easy construction of overlays using computer image-processing software such as Adobe Photoshop and ImageJ.     

Field capability of dogs to locate individual human teeth

Avulsed teeth can be difficult if not impossible to recover in the outdoor environment, yet are important for victim identification. This study assessed dog teams as a resource to locate human teeth in a field setting and related performance in training with field capability. Standardized, objective training data were recorded and analyzed followed by double-blind capability trials. In the double-blind trials, 10 teeth were placed in each of six (10 m(2)) plots. Search time per plot ranged from 27 to 50 min, and the proportion of teeth found by the teams varied between 0.20 and 0.79. Using 0.45 m as a distance criterion for a "find," the proportion of false positives ranged between 0.07 and 0.75. Results show that dog teams are capable of recovering individual human teeth in the field setting with high precision although capability varies. Training records support a team's expected field performance. Additional studies are needed.     

Antemortem dental records: attitudes and practices of forensic dentists

This study was designed to provide insight concerning the attitudes and practices of forensic dentists regarding antemortem dental records reviewed for purposes of dental identification. Forensic dentists were invited to participate in a 10 item survey. The majority of the respondents reported a considerable amount of experience in dental identifications of the deceased. Sixty-six percent reported having suspected dental negligence or fraud in their antemortem record reviews. Only 17% believe that a forensic dentist should report suspected dental negligence, while 31% agree that dental fraud should be reported. Their response to additional issues addressed in the study suggests diversity in the practices and attitudes of forensic dentists in the use of antemortem dental records. In conclusion, opening a dialogue among practicing forensic dentists may lead to a standardized set of recommendations by the appropriate societies in the forensic dental community.