Abstract Previous 3D superimposition studies of digital scans of the human palate,
using geometric and surface morphology comparisons, have shown its usefulness in assisting
in the identification process, including its ability to distinguish identical twins.
This study aimed to evaluate the discriminative potential when only simple geometric
analysis is used. Its aim is not only to determine if geometric comparison alone is
sufficient not only to assist in identification but if it supports the hypothesis
of assisting in sex discrimination when no other comparative data is available. The
palates of 64 monozygotic (M.Z.T.) and 39 dizygotic (D.Z.T.) twins were digitized
three times using a scanner. Digital smoothing was used to remove the rugae, and palatal
height, depth, and width were measured. The study confirmed that the smoothing function
had little effect on the discriminatory function since the Mean Absolute Distance
(MAD) between M.Z.T. (0.430?±?0.018?mm versus 0.425?±?0.022?mm p = 0.061) or D.Z.T.
(0.621?±?0.058?mm versus 0.586?±?0.053?mm, p = 0.284) scans show little change. By
combining the height, depth, and width into a discriminative function, the sex correctly
correlated 83.9% of the time, identity by 91.2% sensitivity, and twining by 68.5%.
The difference in the 3D palatal model between twin siblings is primarily due to palate
geometrics. Since geometric comparison requires far less computation time, geometric
comparison alone can be used as an adjunct metric for limiting the possible matches
in a dental 3D database in determining both sex and identity, especially if no other
evidence is available.
