A Comparison Between Manual and Computerized Bite-Mark Analysis

Background: Bite marks are observed primarily in sexual assault cases, where the suspect might bite the victim or the victim might bite the suspect in self defence. Bite mark analysis is based on the assumption that human dentition is unique, but relating a particular bite mark to a specific dentition is near impossible. Thus a need for formatting a standardised analysis technique where in the subjective variations between the examiners are minimal, is essential. Aim and Objective: To compare the subjective variability between the examiners in manual and computerised bite mark analysis. Materials and Methods Used: A total of ten subjects without any prominent malocclusion were selected and asked to bite on a bite registration wax. Impressions from the bite registration wax were made using elastomeric impression material. Dental cast were made from the alginate impressions taken from the subjects. The procedure was blinded and the three examiners were individually asked to analyse and compare the cast overlays to the elastomer impression of the bitemark using both manual and computerised overlay analysis. Result: The kappa coefficient for the computerized analysis was found to be 0.5901 showing moderate agreement and the manual analysis was found be 0.1764 showing only slight agreement between the examiners. Landis and Koch's magnitude guidelines for the kappa values were used to determine the level of agreement. There was 76.6% positive matching with computerized analysis and 53.3% with manual analysis. Inference: The subjective variation between the examiners in computerised analysis was minimal in comparison to the manual analysis suggesting that the computer assisted overlay was more reliable when matched by multiple examiners. Clinical Significance: Bite mark analysis plays an important role in the criminal justice system. The onus lies on the forensic odontologist to minimize errors in the analysis due to its significant contribution to the final verdict.