Cone beam computed tomography-based models versus multislice spiral computed tomography-based models for assessing condylar morphology

Objective: To quantitatively compare condylar morphology using cone beam computed tomography (CBCT) and multislice spiral computed tomography (MSCT) virtual three-dimensional surface models.

Study design: The sample consisted of secondary data analyses of CBCT and MSCT scans obtained for clinical purposes from 74 patients treated with condylar resection and prosthetic joint replacement. Three-dimensional surface models of 146 condyles were constructed from each scan modality. Across-subject models were approximated and voxel-based registration was performed between homologous CBCT and MSCT images, making it possible to create average CBCT- and MSCT-based condylar models. SPHARM-PDM software provided matching points on each corresponding model. ShapeAnalysisMANCOVA software assessed statistically significant differences between observers and imaging modalities. One-sample t-tests evaluated the null hypothesis that the mean differences between each CBCT- and MSCT-based model were not clinically significant (<.5 mm). Tests were conducted at a significance level of P < .05.

Results: ShapeAnalysisMANCOVA showed no statistically significant difference between the average CBCT- and MSCT-based models (P > .68). During pairwise comparison, the mean difference observed was .406 mm (SD, .173). One sample t-test showed that mean differences between each set of paired CBCT- and MSCT-based models were not clinically significant (P = .411).

Conclusion: Three-dimensional surface models constructed from CBCT images are comparable to those derived from MSCT scans and may be considered reliable tools for assessing condylar morphology.