Objectives: Assess the accuracy of 2D cephalograms reconstructed from 3D CBCT by comparing labial alveolar bone thickness over the most forward maxillary incisor (MFMI) in 2 dimensions vs 3 dimensions. Materials and Methods: Sixty cone-beam computed tomography (CBCT) images were coded, and 2-dimensional (2D) cephalograms were constructed using ray sum technique by using the entire volumetric data in the On demand 3DAPP software (version1.0.10.7s10;cybermed, korea). The 2D CBCT reconstructed images were analyzed using audax ceph 2d analysis software. The 2D and 3D MFMI crowns were located using (FH)-A-point line as the vertical reference line and alveolar bone labial to 3 points on the MFMI roots, using Frankfort horizontal FH line as a horizontal reference line, were measured. The 2D and 3D measurements were compared using paired t tests. A 5% significance level was used for all tests. Results: labial alveolar bone thickness over the 3 root points of MFMI and the MFMI distance to (FH)-A-point line were significantly greater in 2 dimensions than in 3 dimensions. Conclusions: Labial alveolar bone thickness over MFMI roots can be overestimated when evaluated using 2D reconstructed cephalograms compared with 3D evaluation. Alveolar bone measurements over maxillary incisors were interfered by ANS in two dimensions.