ObjectiveThis study aimed to assess the accuracy of cone beam computed tomography (CBCT) in detecting furcation involvement (FI) in maxillary molars.MethodsThirty-one maxillary molars of 15 patients with generalized chronic periodontitis considered for furcation surgery were assessed. Clinical examination and CBCT were performed, and the FI degree was evaluated. Clinical and CBCT-based FI assessments were compared with intrasurgical data.ResultsThe agreement between clinical and intrasurgical assessments was weak in all sites, with a kappa of less than 0.4; the complete, overestimated, and underestimated agreement percentages were 42.0%, 24.7%, and 33.3%, respectively. The agreement between the CBCT and intrasurgical assessments was strong, with a kappa of 0.831; the complete, overestimated, and underestimated agreement percentages were 88.2%, 3.2%, and 8.6%, respectively. The agreement between both assessments was the highest in the buccal furcation entrance (κ=0.896), followed by that in the distopalatal (κ=0.822) and mesiopalatal (κ=0.767) furcation entrances.ConclusionCBCT images demonstrated high accuracy in assessing the horizontal bone loss of FI in maxillary molars.