The medico-legal importance of establishing human identity by palatal rugoscopy: evaluation of the immutability and individuality of palatal rugae under the influence of ante mortem orthodontic treatment

Abstract

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."Introduction: The palatal rugae can be an alternative method of forensic identification. Through the years, several investigations focused on the effect of orthodontic treatment in the palatal rugae pattern. Objectives: Evaluate the concepts of immutability and individuality of the palatal rugae in a Portuguese adult population submitted to orthodontic treatment, for the purpose of medico-legal identification through Thomas and Kotze classification system. Additionally, we wanted to establish comparison of the palatal rugae of each subject, and between genders. Materials and Methods: Thirty three pairs of study dental casts, from thirty three patients submitted to orthodontic treatment in the Department of Orthodontics in College of Dentistry - University of Lisbon, were photographed and classified according to the classification system described by Thomas and Kotze. We proceeded to a statistical analysis running SPSS for Windows, version 20.0, using descriptive analysis and tests, with an inclusion level p <0.05. The tests applied were normality tests and T Student for paired samples. Results: The number and length of primary rugae remain identical when comparing the situation before and after orthodontic treatment. The number of secondary rugae decreases after orthodontic treatment. The variation of the angle of divergence was not statistically significant. The area of primary rugae presented statistically significant reduction after orthodontic treatment. There has no statistically significant differences between genders for total number number of rugae or average length of primary rugae (p <0.05). Discussion and Conclusion: The palatal rugae pattern does not remain stable after orthodontic treatment, and this refutes the supposed long term stability of the palatal rugae pattern. Therefore, it influences the ability to establish a positive medico-legal identification of a recent copse, if the person was submitted to ante mortem orthodontic treatment. The identification might still be possible if we possess a last ante mortem palatal record in these situations, to allow identification based on positive individual characteristics, through comparison with the post-mortem record. Considering gender, no statistically significant differences were found. This subject remains controversial and deserves further research.