Comparative study of cephalometric measurements using 3 imaging modalities

Background

The authors conducted a study to compare 2-dimensional (2D) lateral cephalometric radiography (LCR), 2D cone-beam computer tomographic (CBCT)–generated cephalogram and 3-dimensional (3D) CBCT for assessing cephalometric measurements.

Methods

The authors took 2D LCR, 2D CBCT-generated cephalogram, and 3D CBCT images involving 60 participants. They obtained 11 angular and 11 linear measurements for all images. They used 1-way analysis of variance and the Fisher least significant difference test for statistical comparisons. The authors used Pearson correlation and Pearson χ² test to assess the relationship of these imaging modalities for vertical cephalometric analyses.

Results

Significant differences existed between the 2D cephalograms (LCR and CBCT-generated cephalogram) and the 3D CBCT in 2 angular measurements (maxillary first incisor-nasion (N) point A A] and mandibular first incisor-N point B (B) (P = .027 and P < .001, respectively) and 5 linear measurements (N mentonMe]/sella gonion Go], condylion Co]A, Co gnathion, Go-Me and anterior nasal spine-posterior nasal spine) (P < .004). These measurement values with significant differences were generally greater (approximately 5° for angular measurements and 10 millimeters for linear measurements) on the 3D CBCT scans than on the 2D cephalograms. No significant difference was found between the 2 2D cephalograms (P > .164). No significant difference was found among the 3 imaging modalities for the vertical cephalometric analyses (P > .466).

Conclusions

Significant differences existed between the 2D cephalograms (LCR and CBCT-generated cephalogram) and the 3D CBCT scans in 2 angular and 5 linear measurements. The 2 2D cephalograms were similar for cephalometric measurements. The 3 imaging modalities had no significant difference for the vertical cephalometric analyses. CBCT might not add value for every orthodontic situation.

Practical Implications

These results find the values of cephalometric measurements on 3D CBCT scans may be greater than on the conventional LCR for some parameters. The 2D CBCT-generated cephalogram could be an alternative to the conventional LCR for patients whose large-field-of-view CBCT images are already available.