Relationship of the Pulp-to-Enamel Volume Ratio of Impacted Mandibular Third Molars with Chronological Age in an Iranian Population

Objectives: This study aimed to examine the relationship of pulp-to-enamel volume ratio of third molars on cone-beam computed tomography (CBCT) images with chronological age, in order to create a regression equation that can be used to estimate age in both males and females. Materials and Methods: A total of 122 impacted mandibular third molars of patients over the age of 18 years, who were referred to the dental clinic of Tehran University of Medical Sciences were analyzed in this cross-sectional study. CBCT images in DICOM format were imported into 3D Slicer software for calculation of pulp and enamel volumes. Data were analyzed by multiple linear regression (backward method) and Pearson's correlation coefficient (alpha=0.1 in regressions, and 0.05 in correlations). Results: There was a significant inverse correlation between the pulp-to-enamel volume ratio and chronological age in both males (-0.55, P<0.001) and females (-0.517, P<0.001), as determined by the Pearson’s correlation coefficient. The mean absolute error (MAE) was lower in females (4.67 years) than in males (8.02 years) when using the pulp-to-enamel volume ratio as the sole independent variable. The regression formula that utilized the pulp-to-enamel volume ratio as a sole independent variable was able to estimate age in both sexes. Conclusion: The results showed a statistically significant correlation between age and pulp-to-enamel volume ratio of impacted mandibular third molars, and this ratio may be applied as a useful index for age estimation.