Application of a novel age estimation model based on permanent maxillary canine morphometric features in a Japanese population.
Authors
Affiliations (3)
Affiliations (3)
- Division of Oral and Maxillofacial Radiology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Dentistry and Health Sciences, Niigata University, 2-5274 Gakkocho-dori, Chuo- ku, Niigata, 951-8514, Japan.
- Department of Forensic Odontology, Faculty of Dental Medicine Universitas Airlangga, Surabaya, 60132, Indonesia.
- Division of Oral and Maxillofacial Radiology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Dentistry and Health Sciences, Niigata University, 2-5274 Gakkocho-dori, Chuo- ku, Niigata, 951-8514, Japan. [email protected].
Abstract
This study aims to clarify the growth curves of the long axis and apical foramen diameter of permanent maxillary canines (PMCs), and to create and evaluate a new nonlinear age estimation (NAGE) model by integrating their inverse functions within a machine learning framework. CT measurements of length (L), apical shortest width (SW) and longest width (LW) were obtained from 726 PMCs (aged 1 to 23 years). Growth curves were modeled using Gompertz function for L and Gamma-type function for SW and LW. Inverse functions were integrated into the NAGE model: [Formula: see text]. Parameters were optimized using Soft-L1 robust least squares (SciPy, NumFOCUS, USA). Validation applied to 14 independent longitudinal cases (75 PMCs, 3-15 years). Agreement between predicted age (PA) and chronological age (CA) was evaluated using root mean squared error (RMSE), coefficient of determination (R<sup>2</sup>), and Wilcoxon signed-rank test. The Gompertz and Gamma-type functions effectively captured PMC growth, with RMSE of 2.5 mm (L), 1.07 mm (SW), and 1.45 mm (LW). The NAGE achieved RMSE of 1.89 years (R<sup>2</sup> = 0.85) in the 1-23 years group, improving to 1.29 years (R<sup>2</sup> = 0.89) in the 1-16 years group. In longitudinal cases, the overall mean difference between PA and CA was 0.12 years (1.4 months) with an RMSE of 0.99 years (R<sup>2</sup> = 0.86) and individual errors ranging from 0.25 to 2.09 years. The proposed NAGE model showed promising performance for dental age estimation based on PMC length and apical foramen widths. Further studies in other teeth are needed.