Abstract： Objective To compare the use of cone beam computed tomography (CBCT) and conventional approach (clinical probing and periapical radiograph) in assessing furcation involvement (FI) of maxillary molars and making treatment decisions.Methods Thirty-two subjects were selected from the pool of patients at the Department of Periodontology,Tianjin Stomatology Hospital & Hospital of Stomatology,NanKai University from January 2015 to December 2016.All the patients have a diagnosis of generalized chronic periodontitis.Ninety-five maxillary molar with FI from the radiography database were analysed.Two doctors used conventional approach and CBCT images to assess FI and make treatment decision respectively.If the clinical and radiographic findings did not clearly indicate a distinct periodontal therapy,two treatment options were considered.Results There was statistical difference of the FI diagnosis between traditional group and CBCT group assessment of the 95 molars (P=0.000).Thirty-five maxillary molars (36.8％,17 patients) got two treatment recommendations by conventional approach but 7 (7.4％,5 patients) by CBCT-based approach.When with the less invasive treatment recommendation,there was statistical difference between conventional approach and CBCT-based approach (P=0.001).An agreement was observed in 63.2％ (60/95) of the teeth,while in another 29.5％ (28/95) the CBCT-based treatment decision was more invasive than the conventional approach.When with the more invasive treatment recommendation,there was also statistical difference between two approaches (P=0.045).An agreement was observed in 86.3％ (82/95) of the teeth,while in another 3.2％ (3/95) the CBCT-based treatment decision was more invasive than the conventional approach.Conclusions CBCT images of maxillary molars may provide detailed information of FI and a reliable basis for treatment decision.