New predictive regression models for estimating the size of unerupted canines and premolars in the Egyptian population.

BACKGROUND: Mixed dentition space analysis assesses the discrepancy between the available and required space within the dental arches during the mixed dentition stage, thereby facilitating the diagnosis and treatment planning of developing malocclusions. So, this study aimed to develop Egyptian population-specific regression equations for predicting the combined mesiodistal widths of permanent canines and premolars (Σ345) and to compare their predictive accuracy with that of the Tanaka and Johnston method. METHODS AND MATERIALS: A retrospective cross-sectional study was conducted on 450 dental casts obtained from Egyptian adolescents aged 13-17 years (230 females and 220 males). The mesiodistal crown widths of the maxillary and mandibular permanent incisors, canines, and premolars were measured using a calibrated digital caliper. Multiple linear regression analysis was performed to develop new prediction equations. The predicted widths obtained using the newly developed equations and the Tanaka and Johnston method were compared with the actual tooth measurements. RESULTS: The mesiodistal widths of the maxillary and mandibular central and lateral incisors demonstrated the strongest correlations with the combined widths of permanent canines and premolars and were therefore used to generate the prediction equations. The newly developed Egyptian equations demonstrated good predictive performance, with coefficients of determination of R² = 0.672 for the maxillary arch and R² = 0.602 for the mandibular arch. Furthermore, they showed smaller mean prediction errors (0.00 ± 1.03 mm and 0.00 ± 1.34 mm for the maxillary and mandibular arches, respectively) than the Tanaka and Johnston equations (- 1.02 ± 1.22 mm and - 1.30 ± 1.45 mm, respectively). CONCLUSION: The newly developed Egyptian-specific regression equations provided more accurate estimates of the mesiodistal widths of unerupted permanent canines and premolars than the Tanaka and Johnston method and may serve as reliable tools for mixed dentition space analysis in Egyptian adolescents.