Age estimation in Indians from pulp/tooth area ratio of mandibular canines

Abstract 

In India, age estimation of living individuals is gaining importance, particularly in cases of child labour, ascertaining majority status and to assess disputed age in criminals. Previous studies on adult age prediction in Indians have focused on histological parameters, which are invasive in nature and not feasible in the living. Methods for age estimation in living adults make use of radiographs to indirectly measure the rate of secondary dentine deposition and studies have focused on ratios of linear measurements rather than absolute dimensions per se. Recently, the ratio of the pulp/tooth area of canines was suggested by a group in Italy who developed regression formulas for age estimation [10]. The present study has assessed the usefulness of one of the formulas on an Indian sample and also examined the use of an India-specific equation in age prediction. Intraoral periapical digital radiographs of mandibular canines were obtained from 143 individuals (aged 20–70 years) using the paralleling technique; pulp and tooth areas were measured using a commercially available computer software programme and the pulp/tooth area ratio was computed. Age was calculated using the Italian formula which revealed a mean absolute error (MAE) of 11.01 years in Indians, an error recognisably greater than the 4.38 years reported in the Italian sample. The divergence may be explained on account of population differences that exist between Italians and Indians as well as variation in the pattern of secondary dentine deposition in Indians. The Indian formula derived (age=64.413−(195.265×PTR), where PTR is the pulp/tooth area ratio) was applied on a control group of 35 radiographs. The Italian formula was also applied on the control sample to ascertain if the Indian formula markedly improved age prediction. No apparent difference was observed between the two (MAE was 10.76 and 11.58 years, respectively, using the Indian and Italian formula) however, the Indian formula had a tendency to produce more ‘stable’ age estimates. This could be on account of low correlation (r=−0.34) between secondary dentine deposition and age in Indians and the consequent large pulp/tooth area ratio in some cases; such cases would invariably result in very low age estimates using the Italian formula, unlike the Indian formula which had factored in the low correlation.

Keywords: Age assessment, Secondary dentine deposition, Radiographic evaluation, Population variation, Regression analysis, Forensic anthropology population data