Reproducibility of Dental Bite Mark Overlay Analysis Using Digital 3D Models in Adult Participants

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.

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)