A comparison of methods for assessing root canal curvature using periapical radiographs: an intrarater/interrater...

This study aimed to evaluate the level of agreement among four different methods used to measure root canal curvature in first and second molars, based on periapical (PA) radiographs from patients.

This study investigated intra and interrater reliability and agreement, involving 150 root canals from the first and second molars of 103 patients. Radiographs were obtained from two dental imaging centers through convenience sampling, and each radiograph was assigned two unique identifiers to ensure blinding in measurements. An oral and maxillofacial radiologist and three dental students, who received training from the oral and maxillofacial radiologist, independently measured the curvature angles of all the canals using four different measurement techniques. In the initial round, each observer completed 600 measurements. After a ten-day period, the students repeated their measurements independently to evaluate consistency. The collected data were analyzed using SPSS version 26 and MedCalc version 23.2.7.

The average curvature angles measured by the Schneider, Hankins & ElDeeb, Weine, and Luiten methods were approximately 21.70° (± 12.62°), 21.81° (± 13.77°), 27.51° (± 18.07°), and 30.63° (± 18.95°), respectively, with each method showing different standard deviations. The Luiten method demonstrated the highest overall interrater agreement at 0.969, followed by Weine at 0.949, Hankins & ElDeeb at 0.935, and Schneider at 0.921. In terms of intrarater reliability, Weine (0.967) and Luiten (0.966) showed greater consistency than Schneider (0.939) and Hankins & ElDeeb (0.938). Pairwise comparisons revealed the strongest interrater agreement between Schneider and Weine (0.909), and between Weine and Luiten (0.963), whereas the weakest was between Schneider and Hankins & ElDeeb (0.575). Good agreement was also noted between Schneider and Luiten (0.876), and between Weine and Hankins & ElDeeb (0.721).

All four measurement techniques demonstrated excellent agreement levels, indicating their reliability in evaluating root canal curvature. However, given the highest interrater agreement observed with the Luiten method, it may be considered the most consistent choice for clinical practice, especially in situations requiring precise and reproducible measurements. Clinicians are advised to consider adopting the Luiten method or selecting a technique that best aligns with their specific clinical context to enhance treatment planning accuracy and outcomes.