Objective : To determine the accuracy of volumetric measurement of a simulated alveolar bone defect using cone-beam computed tomography (CBCT) scans. Design : Laboratory-based observational study. Setting : University dental teaching hospital. Methods : Scans of a dried skull with an artificially created maxillary bone defect. Main Outcome Measures : The skull was scanned using an i-CAT CBCT scanner (Imaging Sciences International, Hatfield, PA) at 0.2 mm resolution. The superior and inferior aspects of the void were identified, and the volume was calculated by three-dimensional (3D) computational analysis of the CBCT scan using an algorithm created with MATLAB software (The Mathworks Inc., R2009a, Natick, MA). The skull was then scanned using micro computed tomography (micro-CT) at 0.0934 mm resolution, and the volume of the defect was determined using the Studio Max 2.2 program (Volume Graphics, 2012, Heidelberg, Germany). The process was repeated two additional times, and the volumes were compared using a two-sample t test (P < .05). To determine the interobserver reproducibility of the identification of the superior and inferior aspects of the defect, the slices chosen to represent these extremities were selected by four separate observers and the data assessed using an F-test (P < .05). Results : The interobserver reproducibility of the identification of the superior and inferior boundaries of the defect was good (P = .18). The volumes computed from the i-CAT CBCT images were 4.11% lower than those computed from the micro-CT images; however, the difference was not statistically significant (P = .71). Conclusions : 3D volumetric measurement of simulated alveolar bone defects using i-CAT CBCT scans is similar to the volumes determined using micro-CT.