Evidence-Based Methodology for Bite Mark Analysis

An evidence-based methodology for the analysis and comparison of human bite marks in skin with teeth

Douglas R. Shassir¹ BDS, MFML

Honorary Clinical Senior Lecturer at the University of Glasgow, Glasgow G12 8QQ, UK

OPEN ACCESS

PUBLISHED: 31 January 2025

CITATION: Shassir, D. R. 2025. An evidence-based methodology for the analysis and comparison of human bite marks in skin with teeth. Medical Research Archives, 10(1): 123.

COPYRIGHT: © 2025 European Society of Medicine. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

DOI: https://doi.org/10.18103/mra.v13i1.6158

ISSN 2375-1924

Abstract

The limited scientific evidence in the analysis and comparison of human bite marks in skin with teeth demonstrates that distortion and cognitive bias are significant factors. The manuscript examines the extensive scientific evidence in the forensic sciences that utilise the visual comparison of crime scene evidence with reference material and how this may be applied to bite mark analysis and comparison. Specifically, the manuscript considers how the effects of distortion and bias may be limited by applying techniques used in comparative forensic science. A feature based analysis and comparison methodology is described and proposed that relies on an evidence-based rationale for the management of distortion and bias. The concept of the forensic significance of a bite mark determining whether or not the mark may be reliably compared with teeth is noted. The limitations of bite mark analysis and comparison are indicated. KEYWORDS: Bite marks, human skin, forensic analysis, comparison, distortion, bias

Introduction

Bite marks are a common in medico-legal evidence, particularly in forensic odontology. In the interests of science and justice, the controversy around bite mark analysis and comparison needs to be resolved. Due to the nature of skin and the action of biting, human bite marks in skin are distorted, partial representations of the biter’s anterior dentition. The interpretation of ambiguous dental features in a bite mark involves subjective judgement that is susceptible to cognitive bias. The unquantified degree of distortion in bite marks in skin and the unquenchable influence of bias in the analysing odontologist necessitate a new methodology.

Unique Features of Human Dentition

The manuscript examines the unique features of human dentition that may exhibit significant distortion and bias. The results indicated that statements of dental uniqueness related to bite marks in an open population were unsystematic and confirmed that the use of the product rule was inappropriate.

Forensic Significance of Bite Marks in Skin

Experimental research of bite marks in human skin, by its nature, difficult to conduct and consequently, studies have mainly used artificial media or animal skin. The dentition that produced test bites in skin was recognised with a high degree of reliability by examiners; however, bite marks in non-vital skin, which is more ambiguous, did not demonstrate the same level of reliability. This inconsistency raises concerns regarding the scientific basis of bite mark analysis.

Cognitive Bias in Bite Mark Analysis

Research on expert performance and decision making has been conducted in many branches of forensic science. Studies demonstrated that contextual information undermined the reliability of fingerprint experts making identification. A meta-analysis of the two studies implied that the fingerprint experts’ judgements involved significant bias.

Rationale for Bite Mark Analysis and Comparison Methodology

The nature of skin and the action of biting create a potentially unique, three-dimensional episode of contact that prevents the accurate and complete recording of the features of the anterior dentition in skin. Consequently, research indicated that statements of dental uniqueness related to bite marks were unsupportable in an open population.

Feature Based Analysis and Comparison Methodology

The human dentition demonstrates anatomical features that are classified as class characteristics and individual characteristics that may be evident in a bite mark. The representations of the class and individual characteristics of the anterior dentition form the basis of identifying the mark as a human bite mark and potentially identifying the culprit.

Interpretation of Bite Mark, Preparation of Predictor of Causal Dentition – Predictive Stage

The human dentition characteristics are associated with the interproximal embrasures as a representation of the spacing between adjacent teeth. The absence of an individual element may be false; a non-unique space may indicate either an absent tooth or a deficiency in the incisal/cuspal level.

Examination of Suspect Biter’s Dental Casts

The examination of the dental casts commences after the attested completion of the unbiased predictor of the causal dentition. On receipt of the dental casts the analysing odontologist confirms that the casts conform to the accredited standards of dental tone and surface integrity.

Confirmation Bias in the Analysing Methodology

The scientific evidence demonstrates that interpretation of the crime scene evidence is influenced by factors that cause a bias in the analysis and comparison techniques. Consequently, there are no scientific methods that can determine the forensic significance of a human bite mark.

Conflict of Interest:

None declared.

Finding statement