Objective. To assess the accuracy of cone-beam computed tomography (CBCT) in periimplant fenestration and dehiscence detection, and to determine the effects of 2 voxel sizes and scan modes. Study Design. One hundred titanium implants were placed in bovine ribs in which periimplant fenestration and dehiscence were simulated. CBCT images were acquired with the use of 3 protocols of the i-CAT NG unit: A) 0.2 mm voxel size half-scan (180 degrees); B) 0.2 mm voxel size full-scan (360 degrees); and C) 0.12 mm voxel size full scan (360 degrees). Receiver operating characteristic curves and diagnostic values were obtained. The Az values were compared with the use of analysis of variance. Results. The Az value for dehiscence in protocol A was significantly lower than those of B or C (P < .01). They did not statistically differ for fenestration (P > .05). Conclusions. Protocol B yielded the highest values. The voxel sizes did not affect fenestration and dehiscence detection, and for dehiscence full-scan performed better than half-scan. (Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:121-127)1151121127