Portuguese legal age thresholds of 12 and 14 years old

Objective: Better understanding of dental age assessment may help in cases of age estimation in Forensic Clinics. The first aim was to provide essential information on method reliability for upcoming studies using dental age assessment by second molar index (I2M), and third molar index (I3M) for age estimation on legal ages of 12 - 14 years. The second aim was to document forensic method outcomes of the Demirjian method which has already been used in forensic clinic. Material and methods: Two samples were used for this purpose: for I2M, 633 orthopantomographs (270 females / 363 males), the age range from 7 to 17 years and for I3M, 471 orthopantomographs (253 females / 218 males), the age range from 10 to 23 years, from the database population of Lisbon North University Hospital Center, approved by the Ethic Committee. Results: The I3M cut-off point (1.133) for 12- year- olds obtained better results than the cut-off point stated by the I2M (0.135). Besides, I2M cut-off point (0.001) for 14- year- olds showed better results when compared with the cut-off point (0.705) established by the I3M. Both methods are reliable for the legal age thresholds of 12 and 14 years. However, using I2M and I3M allows us to vary the cut-off value to privilege sensitivities or specificity, depending on which is more appropriate to the intended application. Conclusions: The accuracy (88.94%) of I3M obtained better results for the 12- year- old cut-off point (1.133) and the accuracy (90.21%) of the I2M performed better for the 14- year- old cut-off point (0.001).