Franco A, Willems G, Souza Phc, Coucke W, Thevissen P
Department of Oral Health Sciences - Forensic Dentistry, KU Leuven & Dentistry, University Hospitals Leuven, Belgium; Department of Dentistry - Stomatology, School of Life Sciences, Pontifícia Universidade Católica do Paraná, Brazil.
Department of Oral Health Sciences - Forensic Dentistry, KU Leuven & Dentistry, University Hospitals Leuven, Belgium.
J Forensic Leg Med. 2017 Feb;46:58-65. doi: 10.1016/j.jflm.2017.01.005. Epub 2017 Jan 21.
The uniqueness of the human dentition (UHD) is an important concept in the comparative process in bitemark analysis. During this analysis, the incisal edges of the suspects' teeth are matched with the bitemarks collected from the victim's body or crime scenes. Despite playing an essential part to exclude suspects, the UHD contained in the involved incisal tooth edges remains an assumption on bitemark level. The present study was aimed, first, to investigate three-dimensionally (3D) the UHD within different quantities of dental material from the incisal edges; second, to test these outcomes in a bidimensional (2D) simulation. Four-hundred forty-five dental casts were collected to compose 4 study groups: I - randomly-selected subjects, II - orthodontically treated subjects, III - twins and IV - orthodontically treated twins. Additionally, 20 dental casts were included to create threshold groups on subjects from whom the dental impressions were taken at 2 different moments (Group V). All the dental casts were digitalized with an automated motion device (XCAD 3D (XCADCAM Technology, São Paulo, SP, Brazil). The digital cast files (DCF) were integrated in Geomagic Studio (3D Systems, Rock Hill, SC, USA) software package (GS) for cropping, automated superimposition and pair-wise comparisons. All the DCF were cropped remaining 3 mm (part 1), 2 mm (part 2) and 1 mm (part 3) from the incisal edges of the anterior teeth. For a 2D validation, slices of 1 mm, not including incisal edges (part 4), were also cropped. These procedures were repeated in Group V, creating specific thresholds for each of the study parts. The 4 study groups were compared with its respective threshold using ANOVA test with statistical significance of 5%. Groups I, II and III did not differ from the corresponding threshold (Group V) in all study parts (p > 0.05). Scientific evidence to support the UHD was not observed in the current study. Bitemark analysis should not be disregarded but considered carefully when the suspects present similar dental alignment and morphology, such as in orthodontically treated subjects and twins, respectively.
人类牙列独特性（UHD）是咬痕分析比较过程中的一个重要概念。在该分析过程中，将嫌疑人牙齿的切缘与从受害者身体或犯罪现场采集的咬痕进行比对。尽管在排除嫌疑人方面起着至关重要的作用，但所涉切牙边缘中包含的UHD在咬痕层面仍只是一种假设。本研究的目的，首先是从切缘对不同数量的牙齿材料进行三维（3D）研究UHD；其次，在二维（2D）模拟中测试这些结果。收集了445个牙模以组成4个研究组：I组 - 随机选择的受试者，II组 - 接受过正畸治疗的受试者，III组 - 双胞胎，IV组 - 接受过正畸治疗的双胞胎。此外，纳入20个牙模以创建阈值组，这些牙模取自2个不同时间的受试者（V组）。所有牙模均使用自动运动设备（XCAD 3D（XCADCAM Technology，圣保罗，巴西圣保罗州））进行数字化处理。将数字牙模文件（DCF）集成到Geomagic Studio（3D Systems，美国南卡罗来纳州罗克希尔）软件包（GS）中，用于裁剪、自动叠加和两两比较。所有DCF均从前牙切缘保留3毫米（第1部分）、2毫米（第2部分）和1毫米（第3部分）进行裁剪。为了进行二维验证，还裁剪了不包括切缘的1毫米切片（第4部分）。在V组中重复这些程序，为每个研究部分创建特定阈值。使用方差分析（ANOVA）检验将4个研究组与其各自的阈值进行比较，显著性水平为5%。I组、II组和III组在所有研究部分与相应阈值（V组）均无差异（p > 0.05）。在本研究中未观察到支持UHD的科学证据。当嫌疑人呈现相似的牙齿排列和形态时，如分别为接受过正畸治疗的受试者和双胞胎，咬痕分析不应被忽视，而应仔细考虑。
