Mandibular canal-related parameters interpreted in panoramic images and CBCT of mandibular third molars as risk factors to predict sensory disturbances of the inferior alveolar nerve

The aim of this study was to determine whether cone beam computed tomography (CBCT) before mandibular third molar removal can improve the risk assessment for neurosensory disturbances of the inferior alveolar nerve (IAN) compared to panoramic radiography (PAN). One hundred and six mandibular third molars examined by PAN and CBCT were removed. A temporary sensory disturbance of the IAN was present in 20 cases; a permanent disturbance was found in one case. Three blinded observers assessed radiographic risk factors in PAN and CBCT images. Positive (PPV) and negative (NPV) predictive values and positive (LR+) and negative (LR-) likelihood ratios were calculated for all parameters for all observers. Inter-observer reproducibility was expressed as both the percentage accordance and the kappa-statistic. Generally, the PPV and LR + were the same for PAN and CBCT, and there was good inter-observer reproducibility. The highest PPV and LR + for PAN were found when part of the roots were positioned inferior to the lower white border line of the canal, and for CBCT when the canal was positioned between the roots of the tooth. In conclusion, parameters assessed in PAN and CBCT are not reliable risk factors for neurosensory disturbances of the IAN, and CBCT appears not to improve the risk assessment.