Objective: To validate two-dimensional (2D) digital intraoral and three-dimensional (3D) cone beam CT (CBCT) images in assessment of periodontal bone craters and furcation involvements. Methods: Forty-one periodontal bone defects of human skulls were evaluated using intraoral digital radiography and CBCT. Digital radiographs were made with a size #2 CCD sensor and a 60 kV DC X-ray unit, with a 0.28 mAs exposure setting. For CBCT, jaw bone images were obtained at 120 kV and 23.87 mAs. Periodontal bone craters and furcation involvements on both imaging modalities were assessed and compared with the gold standard, the direct skull observation. Results: Detection of both craters and furcation involvements was improved significantly by using 3D CBCT images (p = 0.374 and p = 1.000 respectively) than by 2D intraoral CCD images (p = 0.001 and p = 0.006 respectively), when compared with the gold standard. 2D images had a failure rate of 31% and 42% for detection of craters and furcation involvements. In contrast there was 100% detection with 3D CBCT. For crater assessment, 2D images overestimated in 62% of sites and underestimated in 13% of sites. CBCT showed 88% accurate classifications, and 12% overestimations. For furcation involvements, only 25% were correctly classified from the 2D digital images. CBCT images allowed correct classification 100% of the time. Distinctions between the vestibular and oral bony defects were only marked on CBCT images. Conclusion: CBCT demonstrated more potential in the morphological description of periodontal bone craters and furcation involvements than 2D intraoral images. The latter mostly overestimated the defects or showed insufficient information of the bone defects. These findings may be useful for further studies on periodontal diagnosis using CBCT. Schlagwörter: cone beam CT, crater, furcation involvement, intraoral radiography, jaw bone, periodontium