# Three-dimensional morphological evaluation of anatomical models for 101 primary maxillary central incisors

## TL;DR

This study reconstructs and analyzes the 3D anatomy of primary maxillary central incisors in children from Beijing, revealing new canal variations and creating an average model for educational use.

## Contribution

The study introduces a detailed 3D anatomical model of primary maxillary central incisors and identifies novel canal variations previously unreported.

## Key findings

- Most PMCIs have a single root, with Type I canals being the most common (61.4%).
- An average main-type model was constructed, reflecting typical PMCIs characteristics.
- No significant differences in anatomy were found between left/right or male/female PMCIs.

## Abstract

Research on primary maxillary central incisors (PMCIs) remains limited, and their morphological variations have rarely been documented. This study aimed to reconstruct anatomy of PMCIs in children from Beijing (China) and to analyse their commonalities and variations.

Employing a threshold-based semi-automated region segmentation method, anatomical models of 101 PMCIs were reconstructed from existing cone-beam computed tomography (CBCT) images. Models were classified according to the Vertucci classification. For each variant type, representative morphological parameters of the hard tissue, pulp chamber, and canals were measured. The type with the highest prevalence was selected as the main type and its average model was constructed, representing the most common characteristics of PMCIs.

All PMCIs had a single root, whereas novel canal variations were identified. The most common canal type was Type I (61.4%), followed by Type V (20.8%) and Type III (17.8%). Anatomical parameters of main-type PMCIs were as follows: hard-tissue length = 15.76 ± 0.89 mm; pulp chamber and canal length = 12.94 ± 1.15 mm; and apical labial curvature angle was 22.57°. Statistical analysis indicated no differences between left and right, and no sex-related differences (p > 0.05). Statistically significant differences between the main-type and other variants were noted for several pulp-chamber and canal measurements (p < 0.05), but not for hard-tissue measurements (p > 0.05). An average main-type model was constructed; its inner and outer profiles conformed to the general characteristics of main-type PMCIs.

PMCI canal variations were more complex than previously recognised, with uniform hard-tissue anatomy. Furthermore, an average main-type model was constructed, as a potentially valuable tool for dental education.