Forensic age estimation using new models of mathematical regression formula constructed with molar indexes: dental age assessment

Introduction
In forensic science, age estimation for identification purposes of living and deceased individuals, is of great importance. It is crucial for humanitarian reasons in both civil and criminal cases. Objectives: The aim of this study was to contribute to the process of forensic age estimation using dental age assessment with mineralization stages of Demirjian method, and maturity indexes of permanent mandibular second (I2M) and third molars (I3M).

Material and methods
Two samples were used from a Portuguese population; for I2M, 591 orthopantomo­graphy’s aged between 7 and 15 years and for I3M, 350 orthopantomography’s aged between 12 and 23 years. Age estimation was obtained using linear regression models, each model was estimated with all observations and without observations, in which I2M or I3M = 0.

Results
The results of ICC for intra- and inter-observer validation varied between 0.608 and 0.999 for both indexes. Pearson correlation coefficient between each index and chronological age showed that all indexes were significantly negatively correlated with chronological age. The standard error of estimate and the mean absolute error were continually low without patients with null index.

Conclusions
Application of I2M is reproducible in a Portuguese population for medical-legal application in a population aged 7 to 15 years, when the corresponding index is positive. Third molar must be used only if its index is positive. The inclusion of Demirjian staging in both models significantly increases accuracy.