Age estimation by measuring open apices in teeth: a new formula for two samples of South African black and white children.

In this cross-sectional study, the accuracy of Cameriere's European formula was tested and a new specific model was developed for two samples of black and white South African children with known age and sex. For these purposes, 970 children of black South African ethnicity (girls 491, boys 479) and 974 with European ethnicity, living in South Africa (girls 493, boys 481), were retrospectively analyzed. The application of the European formula showed that there is a trend in the error estimates: the ages of the younger children are overestimated and those of the older children are underestimated, in both white and black children. A new model, based on the relationship between the apical width and the tooth length (maturity index) of the seven permanent mandibular teeth, was therefore constructed. The new developed equation for the South African population was able to explain 76% of total variance in white girls and 80% in white boys' subgroup. On the other side, the model explained 76% of total variance in black girls and 78% in the black boys' subgroup. The mean absolute error of the residuals (residuals = predicted age minus observed age) ranged from 0.718 to 0.769 years, with the interquartile range (IQRres) ranging from 1.19 to 1.31 years. Differently from the Cameriere's European formula, the plot did not tend to underestimate the chronological age significantly as the age increases. Cameriere's maturity index is reproducible in both samples of South African black and white children, for forensic purposes, and the Bayesian calibration approach is useful for a more accurate and precise estimation.