Application of 3D models of palatal rugae to personal identification: hints at identification from 3D-3D superimposition techniques.

Palatal rugae are known in literature as individualizing anatomical structures with a strong potential for personal identification. However, a 3D assessment of their uniqueness has not yet been performed. The present study aims at verifying the uniqueness of 3D models of the palate. Twenty-six subjects were recruited among the orthodontic patients of a private dental office; from every patient, at least two dental casts were taken in different time periods, for a total of 62 casts. Dental casts were digitized by a 3D laser scanner (iSeries, Dental Wings©, Montreal, Canada). The palatal area was identified, and a series of 250 superimpositions was then performed automatically through VAM©software in order to reach the minimum point-to point distance between two models. In 36 matches the models belonged to the same individual, whereas in 214 mismatches they came from different subjects. The RMS (root mean square) of point-to-point distances was then calculated by 3D software. Possible statistically significant differences were assessed through Mann-Whitney test (p < 0.05). Results showed a statistically significant difference in RMS mean point-to-point distance between matches (mean 0.26 mm; SD 0.12) and mismatches (mean 1.30; SD 0.44) (p < 0.0001).All matches reached an RMS value below 0.50 mm. This study first provided an assessment of uniqueness of palatal rugae, based on their anatomical 3D conformations, with consequent applications to personal identification.