Grosso Alicia R
Department of Physical Therapy, Clarkson University, Potsdam, New York, USA.
J Forensic Sci. 2022 Jan;67(1):102-111. doi: 10.1111/1556-4029.14897. Epub 2021 Sep 29.
Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to estimate teeth-per-inch (TPI) of a saw used in postmortem dismemberment cases. However, error rates for TPI estimation are still under development and knowledge of how bone tissue affects TH measurements remains unclear. The purpose of this research was to investigate the effects of tissue variability through the use of different taxa on the accuracy and precision of TH measurements in the bone to estimate TPI of the blade. A total of 1766 TH measurements were analyzed from human, pig, and deer long bones cut by two 7 TPI saw blades of different tooth type. Fifty distance-between-teeth measurements before and after sawing were collected directly from each blade for comparison to bone-measured TH to assess potential effects of tooth wear on TH variability. ANOVA and F tests were used to compare mean TH and variance, respectively, by saw-species (i.e., crosscut-deer, rip-deer) and species groups (i.e., all deer, all pig), with significance determined at the p < 0.05 level. TH measurements were converted to usable TPI ranges, which would typically be presented in a forensic report. It is concluded that significant differences in TH (mm) do not necessarily reflect significant differences in associated TPI ranges of suspect blades. Forensic reports should report mean TPI ± 1.5-2.5 TPI while providing a sample size indicating number of TH measured rather than just number of cuts or cut surfaces examined.
法医研究表明，齿距（TH）是锯切骨骼的一项重要测量指标，因为它可用于估计死后分尸案件中所用锯子的每英寸齿数（TPI）。然而，TPI估计的误差率仍在研究中，而且骨组织如何影响TH测量的相关知识仍不清楚。本研究的目的是通过使用不同的分类群来研究组织变异性对骨骼中TH测量的准确性和精密度的影响，以估计锯片的TPI。对由两种不同齿型的7 TPI锯片切割的人类、猪和鹿的长骨进行了总共1766次TH测量。在锯切前后直接从每个锯片收集50次齿间距离测量值，与骨骼测量的TH进行比较，以评估牙齿磨损对TH变异性的潜在影响。分别使用方差分析和F检验，按锯的种类（即横切锯-鹿骨、纵切锯-鹿骨）和物种组（即所有鹿骨、所有猪骨）比较平均TH和方差，显著性水平确定为p < 0.05。TH测量值被转换为可用的TPI范围，这通常会在法医报告中呈现。得出的结论是，TH（毫米）的显著差异不一定反映嫌疑锯片相关TPI范围的显著差异。法医报告应报告平均TPI ± 1.5 - 2.5 TPI，同时提供样本量，表明测量的TH数量，而不仅仅是检查的切口或切割面数量。
