Bite Mark Analysis, Forensic Dentistry
Conditions
Brief summary
This study aims to evaluate the reproducibility and repeatability of a standardized digital overlay protocol used in forensic odontology for bite mark analysis. Bite mark analysis methods have been increasingly questioned due to concerns about their scientific reliability. This study focuses on the methodological evaluation of an overlay generation protocol independently of biological trace interpretation. Thirty adult participants requiring routine dental care involving intraoral scanning will be included. A digital impression of the maxillary dentition will be obtained using a standard intraoral scanner, which is a non-invasive and routine clinical procedure. Digital dental models will be anonymized and processed using dedicated software to generate overlays. Four operators with different levels of expertise will independently perform the overlay procedure at two separate time points. The study will assess intra-operator repeatability and inter-operator reproducibility using quantitative 2D and 3D metrics. The objective is to determine the variability of the protocol and to contribute to the standardization and reliability of overlay-based analyses in forensic dentistry.
Detailed description
This is a prospective methodological study designed to evaluate the reproducibility and repeatability of a standardized digital overlay protocol used in forensic odontology. Background: Bite mark analysis has been increasingly challenged due to concerns regarding its scientific validity and reliability. In this context, there is a need to assess the methodological robustness of tools used in this field, particularly digital overlay techniques used for comparison purposes. Objectives: The primary objective is to assess intra-operator repeatability and inter-operator reproducibility of a standardized overlay generation protocol. Secondary objectives include evaluating the influence of operator expertise and testing quantitative metrics for overlay comparison. Methods: Thirty adult participants undergoing routine dental care involving intraoral scanning will be recruited. Participation involves a single, non-invasive intraoral scan of the maxillary dentition, performed using a standard optical scanner. Digital dental models will be anonymized and exported in STL and PLY formats. A standardized overlay protocol will then be applied using CloudCompare and complementary image processing software. Four operators with different levels of expertise will independently generate overlays from each model at two separate time points (T1 and T2), spaced by several days, in order to assess repeatability and reproducibility. Outcome Measures: Quantitative analysis will be performed using 2D and 3D metrics, including distances between point clouds, root mean square deviation (RMS), and surface overlap measurements. Data Management: Only anonymized digital models and limited demographic data (age and sex) will be collected. Data will be stored on secure systems with restricted access and will not be transferred outside the European Union. Ethics: The study involves minimal risk, as intraoral scanning is a routine, non-invasive procedure. No biological samples are collected, and no additional interventions are performed beyond standard care. Significance: This study aims to provide objective data on the variability of overlay generation methods and to contribute to the standardization and scientific reliability of forensic dental analyses.
Interventions
OTHER3D Digital Model Overlay Analysis
Standardized overlay protocol applied to digital dental models (STL/PLY files). Each model is analysed twice by each of four operators at two separate time points (T1 and T2) to assess intra- and inter-operator reproducibility.
Sponsors
Nantes University Hospital
Study design
Observational model
CASE_ONLY
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Age ≥18 years * Patients requiring dental care including intraoral optical scan * Able to understand the study and provide informed consent * Sufficient dentition allowing usable maxillary scan
Exclusion criteria
* Age \<18 years * Individuals under legal protection (guardianship or curatorship) * Oral conditions preventing intraoral scanning * Refusal to participate * Completely edentulous patients * Partially edentulous patients (\>8 missing maxillary teeth)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Intra-operator Reproducibility of Overlay Concordance Measurements | Baseline and Day 7 (±2 days) | Agreement between repeated overlay analyses performed by the same operator on the same digital maxillary model across two measurement sessions |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Inter-operator Reproducibility of Overlay Concordance Measurements | Baseline and Day 7 (±2 days) | Agreement between overlay analyses performed by different operators on the same digital maxillary model, assessed using quantitative concordance indicators generated from the standardized overlay protocol. |
| Distance Between Point Clouds in 3D Overlay Analysis | Baseline and Day 7 (±2 days) | Three-dimensional distance between point clouds generated during overlay comparison of digital maxillary models, assessed using dedicated 3D analysis software. Higher values indicate greater discrepancy between overlays. |
| Surface Overlap in Digital Overlay Analysis | Baseline and Day 7 (±2 days) | Surface overlap measured during comparison of digital maxillary overlays using standardized image processing and 3D analysis methods. Higher values indicate greater overlap between overlays. |
| Influence of Operator Expertise on Overlay Reproducibility | Baseline and Day 7 (±2 days) | Comparison of overlay reproducibility metrics according to operator expertise level across repeated analyses of the same digital maxillary models. |
Countries
France
Contacts
CONTACTLise Malfroy-Camine, MD, PhD
CONTACTAlexandra Poinas, PhD
Outcome results
None listed