Root canal morphometric indices of anterior teeth and their association with chronological age: a retrospective CBCT study in an Iranian population

Abstract Background This study examined the associations between root canal morphometric indices of anterior teeth and chronological age and evaluated their apparent model fit for age association analysis in an Iranian population using cone-beam computed tomography (CBCT). Methods In this retrospective cross-sectional study, 1,200 intact anterior teeth from 100 patients were analyzed using CBCT images. Although each patient contributed 12 anterior teeth, regression analyses were performed separately for each tooth type. Participants were evenly distributed across five predefined age strata (15–24, 25–34, 35–44, 45–54, and ≥ 55 years), while age was treated as a continuous variable in all analyses. Measurements included length ratio (LR), buccolingual and mesiodistal width ratios (WR), and canal shape ratio (CSR), obtained using OnDemand3D™ software. Multiple linear regression was used to assess age associations and construct exploratory age‑estimation models, while logistic regression was used for exploratory sex‑prediction analyses. Results The sample comprised 69% females and 31% males, with a mean age of 39.65 ± 14.58 years. Several morphometric indices showed tooth‑ and level‑specific associations with age. Buccolingual WR at the cementoenamel junction (CEJ) demonstrated the most frequent association. CSR showed significant negative associations with age in maxillary and mandibular central incisors and mandibular lateral incisors. LR showed only limited association with age. Sex demonstrated limited and inconsistent relationships. The maxillary right central incisor showed the strongest apparent model fit (R² = 0.465), with buccolingual WR at the CEJ as the most influential morphometric index across models. Conclusion Root canal morphometric indices exhibit tooth-specific associations with chronological age in this population. Central incisors and mandibular lateral incisors demonstrated the most consistent age-related associations, and buccolingual WR at the CEJ showed the most frequent association with age. Tooth‑specific variability in model fit suggests that morphometric behavior, rather than methodological factors, drives the strength of age‑related associations. These findings represent exploratory age‑estimation patterns.