咬伤（痕）的检验及其应用

咬伤(痕)(biting injury,bite mark)是指人或动物上、下颌牙齿相对咬合、切磨、撕扯而形成的组织损伤[1]。不同个体的牙和牙弓具有不同的个体特征,其重复概率为5·67×10-12[2],因此咬伤(痕)可以反映咬者牙齿咬合面的形态特征,如牙的间距、牙的弧度,牙的排列形式、有无畸形和病变、有无修复脱落等。在强奸、抢劫、杀人等刑事案件中,常会发现被害人或犯罪嫌疑人将对方咬伤。咬伤(痕)的发现提取和检验鉴定,对侦察破案和证实犯罪者具有重要的意义。笔者近年来归纳整理了有关咬伤(痕)的检验思路及破案作用,仅供大家参考。1·3不同牙齿形成咬伤(…     

咬痕及其法医学鉴定

咬痕(ｂｉｔｅｍａｒｋ)是指某一个体的牙齿或牙齿与口腔其它部分一起作用于物体(人体、食物和其它物体),造成该物体在形态学上发生改变而留下的痕迹[1]。1874年,美国“防止虐待动物学会”报告了第一例儿童虐待案例———玛丽·艾伦案,其中首次涉及到咬痕证据[2]。咬痕多见于暴力案件和性犯罪案件,在受害人和加害人身上均可发现。许多学者认为,咬痕可以作为证据,因为咬痕特征具有明显的个体差异和相对稳定性,许多案件可以根据咬痕鉴定提供的线索和证据去破获或作正确的判决,由此可见,咬痕的法医学鉴定具有重要的实用价值。一、咬痕的发生情…     

咬痕个体识别的比对方法

目的 建立一个牙模数据库,为通过牙齿、咬痕进行个人识别的研究及其在法医实践中的应用提供一种新方法。方法 经过对400例牙模进行分析、计算,将牙齿的形状、排列转换成数字型(X,Y)坐标,通过计算出每颗牙关键点与坐标原点的相对位置,在DOS系统下运用Borland C++5.0语言编写程序,快速地计算出牙齿和牙弓的特征。结果 能对牙模进行自动识别,达到排除与认定。其比对精度长度为1.3mm,角度3°;可取的最少牙点位数目为12～14较为合理,大致需要5～7个完整的牙痕。结论 该方法是研究咬痕与牙模比对的基础。     

外温变化下小鼠肝细胞18s rRNA降解与死亡时间关系研究

目的探讨在外界环境温度变化条件下,小鼠肝细胞18s rRNA降解与死亡时间的关系。方法小鼠断颈处死后置于10℃、15℃、20℃、25℃、和30℃温度下保存;从死后6h至72h,每6h分别提取肝细胞组织中总RNA。利用实时荧光定量PCR检测18s rRNA循环阈值(Ct值)的变化。应用插值函数进行分析拟合,建立死亡时间推断方程。结果各温度组Ct值随死亡时间延长均呈上升趋势,对所得数据进行插值拟合,得到一定温度变化区间内(10℃~30℃),Ct值变化与PMI关系的三元五次曲面方程:f(x,y)=-426.9+30.82x+44.48y-1.297x~2-1.837xy-1.388y~2+0.034 38x~3+0.038 17x~2y+0.038 67xy~2+0.028 77y3-0.000 612 9x~4-3.897e~(-7)x~3y-0.001 223x~2y~2+0.000256 6xy3-0.000 537 4y~4+3.606e~(-6)x~5-2.846e~(-6)x~4y+1.009e~(-5)x~3y~2-3.439e~(-6)x~2y3-2.556e~(-7)xy~4+2.664e~(-6)y~5(r2=0.999 4)。结论在外界温度变化条件下,小鼠肝细胞18s rRNA降解与死亡时间关系符合三元五次方程分布,利用插值函数拟合的方法可在外界环境温度变化条件下进行死亡时间推断。     

中国“罪犯DNA数据库”STR基因座研究

选择合适的 STR基因座 ,建立中国“罪犯 DNA数据库”模式库。以 2 2 11名汉族、15 0名维吾尔族、10 4名回族群体为分析对象 ,提取罪犯血样 DNA,用复合 PCR和四色荧光技术检测了 D3S135 8、v WA、FGA、D8S1179、D2 1S11、D18S5 1、D5 S818、D13S317、D16 S5 39、TH0 1、TPOX、CSF1PO、D7S82 0等 13个 STR基因座及性别 Amelogenin基因座。在 13个 STR基因座中 ,除 TH0 1、TPOX基因座外 ,其余各基因座的个体鉴别能力 (DP)值均接近 0 .9,杂合度(H)均大于 0 .7,排除概率 (PE)大都在 0 .5以上 ,其中 FGA、D8S1179、D2 1S11和 D18S5 1基因座 DP≥ 0 .95 ,H≥ 0 .85 ,PE≥ 0 .6 5 ,表明它们在法医学上极有应用价值。TH0 1和 TPOX在多态性方面较差 (H分别为 0 .6 430和 0 .6 2 96 ,PE分别为0 .40 46和 0 .370 1) ,但也符合应用于法医学的要求。13个基因座的平均偶合率为 5× 10 - 1 5 ～ 1.2× l0 - 1 4 ,适合作为中国人群的遗传学标志 ,用于建立中国“罪犯 DNA数据库”     

手摇电话机输出电流致死一例

利用手摇电话机输出的电流电击致死案极为少见，现报告1例。毛某，男，24岁，农民，身体健壮，某夜3时许，被人用皮带将手摇电话机的输出线分别固定在左、右大腿部及左腰部、右胸部电击。电击时毛某大声叫喊，当固定在左胸部电击时，毛某即脸色发青，头下垂失去知觉，经抢救无效死亡。尸检死者双侧瞳孔等大等圆，睑结合膜见有出血点，鼻腔有淡红色液体外溢、皮肤烧灼痕多处分布于头下4cm、7cm处，向左后5cm处．大小均0.2×0．1cm，共3处。右胸乳头距腋前线7cm处，及腋中线处见0．4×0．4cm及0．2×0．2cm的皮肤烧灼痕7处。左骼前上嵴上3cm处…     

大剂量肌肉注射林可霉素致死一例

案例某女，20个月。某日因发烧、咳嗽到某个体诊所就诊。查体：T36．5℃，咽赤，心肺呼吸音粗糙。诊断：上感；咽喉炎。处置：洁霉素0．6×4，0.6／次，2／日，肌注；地塞米松5mg×4，5mg／次，2／日，肌注。8时30分肌注第一针林可霉素0．6g，未见好转于14时30分第二次肌注0．6g，一会儿患儿出现呼吸困难，喘促，口唇紫组，呼吸心跳停止。经抢救无效死亡。患儿体重9．75kg，发育营养良好；尸检见左臀外上方一个外痕，右臀外上方三个针痕；心脏内外膜及各瓣膜结构正常，卵圆孔已闭合，其他脏器淤血。镜检见气管、支气管和肺组织炎性细胞浸润…     

不同温度下兔玻璃体液K~+浓度与死亡时间的关系研究

目的探索在不同环境温度条件下,玻璃体液中钾离子浓度变化规律与死亡时间的关系。方法家兔处死后分别置于5℃、15℃、25℃和35℃温度下保存,在0~120h内每12h双眼交替微量提取玻璃体液80~100μL;应用罗氏DPPI生化分析仪检测玻璃体液中K~+的浓度;应用插值函数进行分析拟合,建立死亡时间推断方程。结果各温度组家兔玻璃体液中K~+浓度随死亡时间延长均呈上升趋势,对所得数据进行插值拟合,在5℃~35℃的温度变化区间内,K~+浓度变化与PMI关系的三元五次曲面方程:f(x,y)=-1.998e~(14)+1.345e~(12)x+5.902e~(13)y+0.005 585x~2-4.509e~(11)xy-3.876e~(12)y~2-0.000 286 8x~3+0.003 545x~2y+4.406e~(10)xy~2-1.746e~(10)y~3+2.669e~(-6)x~4-1.568e~(-5)x~3y-0.000 177 1x~2y~2-1.64e~9xy~3+6.669e~9y~4-8.672e~(-9)x~5+4.467e~(-8)x~4y+2.354e~(-7)x~3y~2+2.459e~(-6)x~2y~3+2.05e~7xy~4-1.214e~8y~5(R~2=0.995 6),其中温度为自变量x,K~+浓度值为自变量y,PMI为因变量f(x,y)。结论在5℃~35℃的环境温度区间内,家兔眼玻璃体液中K~+浓度变化与死亡时间关系符合三元五次方程分布,利用插值函数拟合的方法可将环境温度作为参数,实现在环境温度变化条件下进行死亡时间推断。     

原发性脑挫裂伤后无早期意识障碍1例

1　案例资料某男 ,2 6岁。身体健壮。 1998年 1月 2 4日 6时许 ,被人用不规则形木棒打伤头部 ,自行行走 2ｋｍ后倒地昏迷 ,送医院抢救无效 ,次日 2 1时死亡。尸检所见 :尸长 177ｃｍ。头额顶枕部有广泛皮下出血 (以右侧为甚 )伴表皮剥脱 ;头顶枕部 4条挫裂创 2 5ｃｍ× 0 2ｃｍ～ 3 5ｃｍ× 0 2ｃｍ)和右顶颞部挫裂创 ( 1ｃｍ×0 2ｃｍ)深达帽状腱膜 ,右顶枕部 1处 9ｃｍ× 0 7ｃｍ和后枕部 2处 ( 3ｃｍ× 0 5ｃｍ ,3ｃｍ× 0 3ｃｍ)的挫裂创深达骨质 ;双上肢有抵抗性损伤 ,头右顶部至后枕部颅骨有 18ｃｍ× 7ｃｍ的粉碎性骨折 ,右…     

对女性肋骨进行组织形态测量推断年龄

探讨人类密质骨的年龄变化规律 ,为法医学、人类学利用骨骼推断年龄提供新方法。收集 6 7例中国北方汉族女性右侧第六肋骨的中 1/3段 ,制作脱钙骨切片 ,在计算机图像分析仪上测量 9项组织形态学参数 ,并进行多元逐步回归分析 ,得到一个推断年龄的多元回归方程 :^Y =31 2 6 4+0 86 8X2 +2 86 6 93X4 +0 6 89X7-778 874X8-0 0 0 6X9,复相关系数和标准误分别是 0 92 3和 4 0 8。经 2 5例已知年龄的标本检验 ,预测年龄的误差在± 5岁以内的可达 84% ,误差在± 8岁以内的可达 10 0 %。结果表明 :应用肋骨的组织结构特征可准确推断死者年龄     

Inquiry into the Scientific Basis for Bitemark Profiling and Arbitrary Distortion Compensation

Abstract: Prediction of dental characteristics from a bitemark (bitemark profiling) and arbitrary photographic distortion compensation are two practices proposed in bitemark analysis. Recent research on the effect of inherent skin tension properties in bitemark analysis suggests that these practices are subject to review. A biting apparatus was used to create 66 bitemarks in human cadaver skin. The bitemarks were photographed, sized 1:1, and evaluated with Adobe Photoshop^®. Metric/angular measurements and hollow volume dental overlays were employed. Distortion produced was calculated and assessed. Results showed distortional ranges were nonuniform both between bites, as well as within each bite. Thus, enlarging/decreasing the photograph uniformly would not correct the distortion that resulted. With regard to bitemark profiling, 38% of the bites created patterns that could be misleading if profiled. Features were present/absent that were inconsistent with the biter’s dentition. Conclusions indicate bitemark profiling and arbitrary distortion compensation may be inadvisable.     

A study of multiple bitemarks inflicted in human skin by a single dentition using geometric morphometric analysis

Criticisms of the forensic discipline of bitemark analysis state that the range of distortion in the shape of bitemark impressions in skin has not been scientifically established. No systematic statistical studies exist that explore this problem. As a preliminary investigation of this issue, a single dentition was mounted in a mechanical apparatus and used to create 89 bitemarks in human cadaver skin, both parallel and perpendicular to tension lines. Impressions of the same dentition were also created in wax. 2D scanned images of the biting dentition were obtained. Locations of incisal edges of all 6 anterior teeth as well as the midpoint of the canine were captured as landmarks in all specimens. This set of landmark data was then studied using established geometric morphometric methods. All specimen shapes were compared using Procrustes superimposition methods, and by a variation of Procrustes superimposition which preserves scale information. Match criteria were established by examining the range of variation produced by repeated measurements of the dentition for each class of specimen. The bitemarks were also compared to a population of 411 digitally scanned dentitions, again using the match criteria. Results showed that bitemarks in wax had lower measurement error than scanned images of the dentition, and both were substantially lower than measurement error as recorded in skin. None of the 89 bitemarks matched the measured shape of the biting dentition or bitemarks in wax, within the repeated measurements error level, despite the fact that all bitemarks were produced by this dentition. Comparison of the bitemarks to the collection of 411 dentitions showed that the closest match to the bitemarks was not always the same dentition that produced the bitemarks. Examination of Procrustes plots of matched shapes showed non-overlapping distributions of measurements of bitemarks in skin, wax, and the dentition. All had statistically significant differences in mean shape. Principal component analysis (PCA) and canonical variates analysis (CVA) both showed clear segregation of the three types of data. The patterns of variance revealed by PCA showed several distinct patterns produced by skin distortion; alteration of relative arch width, and varying displacement of non-aligned teeth in the dentition. These initial results indicate that when multiple suspects possess similar dentitions, bitemark analysis should be approached with caution.     

Three‐Dimensional Comparative Analysis of Bitemarks*

Abstract: Historically, the inability to accurately represent bitemarks and other wound patterns has limited their evidentiary value. The development of the ABFO #2 scale by Krauss and Hyzer enabled forensic odontologists to correct for most photographic plane distortions. The technique presented here uses the ABFO #2 scale in conjunction with the evolving technologies of laser scanners and comparative software commonly used by the automobile industry for three‐dimensional (3D) analysis. The 3D software comparison was performed in which measurements were analyzed of the normal distance for each point on the teeth relative to the bitemarks. It created a color‐mapped display of the bitemark model, with the color indicating the deviation at each point. There was a correlation between the bitemark and the original teeth.     

Expert Interpretation of Bitemark Injuries—A Contemporary Qualitative Study

This study attempts to characterize the nature of disagreement among odontologists in determining the fundamental properties of suspected bitemark injuries. Fifteen odontologists were asked to freely comment on six images of supposed bitemarks. Qualitative analysis using a grounded theory approach revealed that practitioner agreement was at best fair, with wide‐ranging opinions on the origin, circumstance, and characteristics of the wound given for all six images. More experienced practitioners (>10 years) tended to agree with each other less than those who had 10 years or less experience in forensic odontology. The differences in opinions can be at least partly accounted for by the inconsistent nature of approaches used by different practitioners in assessing bitemark evidence. The results of this study indicate that more definitive guidelines as to the assessment of bitemarks as patterned injuries should be developed to ensure the highest possible level of practitioner agreement.     

Digital analysis of experimental human bitemarks: application of two new methods

Bitemark determination in forensic odontology is commonly performed by comparing the morphology of the dentition of the suspect with life-sized photographs of injury on the victim's skin using transparent overlays or computers. The purpose of this study is to investigate the suitability of two new different methods for identification of bitemarks by digital analysis. A sample of 50 volunteers was asked to make experimental bitemarks on the arms of each other. Stone study casts were prepared from upper and lower dental arches of each volunteer. The bitemarks and the study casts were photographed; the photos were entered into the computer and Adobe Photoshop software program was applied to analyze the results. Two methods (2D polyline and Painting) of identification were used. In the 2D polyline method, fixed points were chosen on the tips of the canines and a straight line was drawn between the two fixed points in the arch (intercanine line). Straight lines passing between the incisal edges of the incisors were drawn vertically on the intercanine line; the lines and angles created were calculated. In the painting method, identification was based on canine-to-canine distance, tooth width and the thickness, and rotational value of each tooth. The results showed that both methods were applicable. However, the 2D polyline method was more convenient to use and gave prompt computer-read results, whereas the painting method depended on the visual reading of the operator.     

The uniqueness of the human anterior dentition: a geometric morphometric analysis

The analysis of bitemarks has a significant bearing on forensic odontology and has attracted an increasingly sophisticated array of techniques in its evaluation. Two postulates underlie all bitemark analyses: firstly, that the characteristics of the anterior teeth involved in the bite are unique, and secondly, that this uniqueness is accurately recorded in the material bitten. Here, we investigate the question of the uniqueness of the anterior dentition. To do this, we use geometric morphometric techniques based on landmark and semilandmark data. The incisor and canine occlusal surfaces of 50 randomly selected orthodontic casts of young individuals (17-20 years) of both sexes form the material for this study. We analyzed the sizes of these teeth by means of landmark and semilandmark analysis to calculate Procrustes distances between tooth outlines. In order to analyze shape variation among individuals, we carried out principal components analyses on the partial warp scores. These are derived from Partial Procrustes coordinates aligned by means of thin-plate spline decomposition based on the bending energy matrix. The results indicate that there is no sexual dimorphism in the shape of the upper or lower arches. Plots of centroid size and first relative warps show less superposition among individuals than in shape analysis. This means that, when the size and shape are considered together, the difference between arches increases. Procrustes superimposition between the two individuals located most closely (0.0444) and the two most separated (0.1567) along the first axis of relative warp analyses show that individuals are not only differentiated by the relative position of their teeth but also by their arch shape. In conclusion, it appears that the incisal surfaces of the anterior dentition are in fact unique.     

Statistical Evidence for the Similarity of the Human Dentition

Abstract: Recent scrutiny of forensic science has focused on unreliability of expert witness testimony when based on statements of individuality. In bitemark analysis, assumptions regarding uniqueness of the dentition have been based on use of the product rule while ignoring correlation and nonuniformity of dental arrangement. To examine the effect of these factors, two separate sets of scanned dental models (n = 172 and n = 344) were measured and statistically tested to determine match rates. Results were compared to those of a prior study. Seven and 16 matches of the six anterior lower teeth were found in the respective data sets. Correlations and nonuniform distributions of tooth positions were observed. Simulation tests were performed to verify results. Results indicate that given experimental measurement parameters, statements of dental uniqueness with respect to bitemark analysis in an open population are unsupportable and that use of the product rule is inappropriate.     

Preliminary report on a new method of human age estimation from single adult teeth.

A total of 317 upper and lower third molars were randomly divided into working and control samples and used to estimate chronological age employing a method which combined multiple regression analysis of data from Gustafson's and Maples's scoring system, direct morphological measurements obtained with a Kontron image analysis system and logarithmic data transformation. The standard errors of estimate were 2.4-6.8 years in the working sample and 1.9-7.5 years when the derived formulae were tested on the control sample, respectively. Compared to previous studies, this method provides a smaller standard error of estimate from a single molar tooth. The method is presently being tested on other tooth categories, like premolars, canines and other types of molars.     

Patterns of Variation and Match Rates of the Anterior Biting Dentition: Characteristics of a Database of 3D‐Scanned Dentitions

An understanding of the variability of the anterior human dentition is essential in bitemark analysis. A collection of 1099 3D laser scans of paired maxillary and mandibular arches were studied using geometric morphometric methods. Analyses were performed without scale (shape only) and with scale (shape and size). Specimens differing by no more than experimentally obtained measurement error were counted as matches, or as indistinguishable. A total of 487 maxillary (396 size preserved), 131 mandibular (83 size preserved), and one paired dentition (two size preserved) matches were found. Principal component analysis and partial least squares revealed interpretable patterns of variation and covariation in dental shape, principally dominated by variation in dental arch width. The sensitivity of match rate to assumed degree of measurement error was also determined showing rapid increases in match rate as measurement error increased. In conclusion, the concept of dental uniqueness with regard to bitemark analysis should be approached with caution.     

New forensic approach to age determination in children based on tooth eruption

The present study proposes equations for age determination both in living and dead children, obtained with the help of stepwise ascending multiple linear regression. The equations should be applied, based on the number of erupted teeth and tooth germs, which were detected on radiographs, during clinical examination and in infant skeletal remains. The proposed equations proved to be efficient just like Demirjian's method used as a reference today, and permit age estimation till 20 years of age.