Impact of apical foramen diameter on periapical lesion volume and sphericity: a retrospective cone-beam computed...

This study aims to evaluate the anatomical characteristics of periapical lesions in untreated teeth by correlating lesion diameter, volume, surface area, and sphericity with the root canal diameter measured 1 mm short of the apical foramen. Additionally, the study compared lesion classifications according to the cone-beam computed tomographic periapical index (CBCTPAI) and the cone-beam computed tomographic periapical volume index (CBCTPAVI) across different anatomical regions.

A total of 500 CBCT scans were assessed to identify periapical radiolucencies in teeth without previous endodontic treatment. Lesions were classified using CBCTPAI based on maximum diameter and CBCTPAVI based on volume. The apical canal diameter was measured 1 mm from the apex in buccolingual and mesiodistal directions. Lesion volume and surface area were segmented semi-automatically, and sphericity was calculated. Statistical analyses were performed using the Kruskal-Wallis and Spearman's correlation tests (α = 0.05).

Smaller apical diameters were associated with periapical lesions of smaller diameter and higher sphericity, particularly in mandibular anterior teeth. CBCTPAI scores of 4 were more prevalent in the anterior and posterior maxillary regions and posterior mandibular region. CBCTPAVI score 6 predominated across all regions. Lesions causing cortical bone expansion exhibited significantly larger apical diameters (p = 0.028). No significant differences in root canal diameter were observed across sphericity categories. Overall, the anatomical region influenced the correlation between root canal diameter and lesion characteristics.

Periapical lesions varied in size, volume, and morphology according to anatomical region and apical canal diameter. The findings highlight the relevance of CBCT-based volumetric and morphometric assessments to support individualized diagnosis and treatment planning. However, the clinical applicability of lesion volume and sphericity measurements warrants further investigation.

Accurate CBCT assessment of periapical lesion dimensions and morphology, combined with measurement of apical canal diameter, can improve treatment planning and prognostic evaluation in endodontics, particularly in cases requiring surgical intervention.