Establishing the reliability of palatal rugae pattern in individual identification (following orthodontic treatment)

This study aims to determine the stability of palatal rugae before and after orthodontic treatment. 50 orthodontic cases were selected with pre- and posttreatment casts and 50 casts were randomly selected as variables. Landmarks on the palatal raphe and rugae were marked on the maxillary casts. Points were made on medial and lateral ends of first, second and third rugae. Each cast was photographed, measured and then trimmed leaving only the rugae area of the hard palate. In the pre and post-treatment group, changes in transverse measurements were significantly different for lateral points of first rugae and anteroposterior changes were significant for the distances between first and second rugae. All inter-point measurements of third rugae were stable in post-treatment casts. Thirty blinded examiners compared 50 trimmed preorthodontic casts to similarly prepared one hundred casts for possible matches based on pattern of rugae. The percentages of correct matches for examiners had a median of 90%. The matching of pre-operative and post-operative orthodontic casts demonstrated that although some changes do occur in the rugae during orthodontic treatment, the morphology of palatal rugae remains stable throughout life. Hence carefully assessed rugae pattern may have a definite role in forensic identification. Further, points associated with the third palatal ruage were the most immutable over a person's life and hence could be used as a reference to evaluate the changes in teeth positions during orthodontic treatment.