Exploring the degrees of distortion in simulated human bite marks

Neha Dama,Andrew Forgie,Gavin Revie,Scheila Mânica

doi:10.1007/s00414-019-02163-5

Neha Dama, Andrew Forgie + Show 2 more

Open Access

https://doi.org/10.1007/s00414-019-02163-5

Copy DOI

Abstract

The properties of the skin and the posture of the body during photographic recording are factors that cause distortion in the bite mark injury. This study aimed to explore the degree of distortion between a ‘touch mark’ (method 1) and a ‘bite mark’ (method 2) on the left upper arm at three different positions (arm relaxed; arm flexed in two different positions). A pair of dental casts with biting edges coated in ink was used to create a mark in 30 subjects (6 ♂, 24 ♀) aged 20–50 years old. Photographs were taken using a Nikon DX digital camera (D5000). The mesiodistal widths and angle of rotations of both upper right central incisor and lower right central incisor and the inter-canine distances were analysed and compared with the true measurements using Adobe Photoshop CC 2017. Statistical analysis was carried out using SPSS Statistics 22 applying a 2 (mark type) × 3 (position) repeated measures ANOVA. For all measures studied, there was a statistically significant difference between mark types and positions. In the case of bite marks, a great degree of distortion was detected, and this increased further when changing the position of the arm. The findings demonstrated that skin properties and posture influence distortion. This could lead to inaccurate measurements and misleading pattern interpretation of bite mark injuries.

Highlights

Bite mark analysis is the process where the patterned injury and the circumstances surrounding it are taken into consideration
This study aimed to explore the degree of skin distortion between a ‘touch mark’ and a simulated ‘bite mark’ on the middle third area of the left upper arm at three different positions
A previous study investigated the size variation in bite marks produced by a single dentition, and the findings indicated that change in arch width is the predominant effect of distortion in skin [14]

Summary

Introduction

Bite mark analysis is the process where the patterned injury and the circumstances surrounding it are taken into consideration. Even though bite mark evidence is accepted in courts, its fundamental validity and scientific basis are frequently challenged. This has resulted in increased scrutiny in courts to ensure its reliability [2]. In the 1970s, research about human tooth shape variability has occurred in superficial attempts and ‘uniqueness’ became confirmed in court room statements by dentists [4] Another reasons for uncertainty about ‘the value and scientific validity of comparing and identifying bite marks’ are the unsatisfactory nature of skin as a substrate for registration of tooth impressions (primary distortion) and the posture of the body (secondary distortion) [5,6,7]. Postural distortion occurs when the bite mark is photographed in a position different to the position the bite was initially created in [6]

Objectives

Methods

Conclusion