Comparison of Curvature Severity Between Sagittal and Coronal Planes of Mesial Canals in Permanent Mandibular First Molars Using Schneider's and Weine's Methods and Multiple Complexity-Risk Criteria: A Cone-Beam Computed Tomography Cross-Sectional Study.

BACKGROUND

There is a strong association between root canal curvatures and iatrogenic complications during root canal treatment.

INTRODUCTION

This study compared the curvature of mesiobuccal (MB) and mesiolingual (ML) canals in mandibular first molars between sagittal and coronal planes using cone-beam computed tomography.

METHODS

Two hundred mesial roots (400) canals from a Brazilian subpopulation were analysed. Curvature angles were measured in sagittal and coronal planes using Schneider's and Weine's methods, while curvature radii were calculated geometrically. The prevalence of S-shaped canals was also recorded. Curvature severity was classified according to the American Association of Endodontists Case Difficulty Assessment form, EndoApp, and modified versions incorporating curvature and radius. The influence of the angle measurement method and radius on case complexity was evaluated. Statistical analyses were performed using t-tests and chi-squared tests, with significance set at p ≤ 0.05.

RESULTS

Sagittal planes showed significantly greater angles and smaller radii than coronal planes. Weine's method yielded consistently higher angles and smaller radii than Schneider's. Severe single curvatures (≥ 30°) were more frequent in sagittal planes, whereas S-shaped canals were more prevalent in coronal planes. MB was more often classified as higher difficulty than ML canals. Incorporating radius into the classification systems generally shifted cases towards greater severity.

CONCLUSIONS

Sagittal planes revealed more severe single curvatures, whereas coronal planes showed a higher prevalence of S-shaped canals. Weine's method resulted in greater curvature severity than Schneider's. Inclusion of radius increased case severity grading. These findings highlight the importance of considering both measurement method and projection plane in endodontic treatment planning and research.