Confiabilidade dos sinais radiográficos preditivos de proximidade entre o terceiro molar inferior e canal da mandíbula em radiografia panorâmica: estudo comparativo com tomografia computadorizada de feixe cônico

Abstract

Purpose: To analyze the reliability of panoramic radiographic signs in predicting the proximity of the lower third molars to the mandibular canal using comparative images of cone beam computed tomography scans of the same patient. Patients and methods: An observational, cross-sectional and descriptive study was realized with panoramic radiographs and computed tomography of 150 patients, obtained from an image bank from a public university. The panoramic radiographs identified with at least one of the seven predictive signs of proximity to the mandibular canal proposed by Rood and Shehh: apex obscuration, apex deflection, apex narrowing, bifid apex, interruption of the mandibular canal radiopaque line, deviation of the mandibular canal and narrowing of the mandibular canal was compared to the respective tomography. All images were analyzed by three independent examiners previously calibrated using the Kappa test. Results: Kappa intra-rater values for panoramic radiographs ranged from 0.91 to 0.97 (near-perfect agreement). Intra-evaluative weighted Kappa values for tomography images ranged from 0.93 to 0.96 (near-perfect agreement). The binary logistic regression analysis showed that only the obscuration, deflection and narrowing of the root apexes besides the interruption of the mandibular canal radiopaque line in panoramic radiographs are able to predict the intimate contact of the roots of the third molar with mandibular canal (p <0,05). Conclusion: The obscuration, deflection and narrowing of the root apices as well as the interruption of the cortical canal of the mandible in panoramic radiographs are indicate the use of cone beam computed tomography for planning the third molar surgery.