3D CBCT Anatomical Patterns of Patients With Malocclusion Class I

Objectives: The purpose of this study was to locate the landmarks both in traditionally-used 2D lateral cephalogram images and newly suggested landmarks in 3D CBCT images to determine possible relationships between them and determine if they could be used to classify patients of malocclusion class I.
Methods: CBCT images from 30 patients with malocclusion class I were selected from the University of Alberta Graduate Orthodontic Program database. The images were then reconstructed using the AVIZO® software platform to visualize and locate landmarks. There were a total of forty-two landmarks chosen for analysis, which included pre-existing landmarks used in 2D imaging as well as new landmarks suggested for 3D analysis. To determine the reliability and measurement error of each landmark, ten images were analyzed three times to calculate the intraclass correlation coefficient (ICC). Descriptive statistics were also assessed using SPSS statistical package to determine any skeletal and dental relationships.
Results: ICC values were above 0.910 for all landmarks in all axes, with the highest measurement error of 3.32mm +/- 2.37 SD in the Y axis for Gonion (Left). Linear and angular measurements were calculated with the coordinates of each landmark. Descriptive statistics show that the linear and angular measurements used in 2D images did not correlate well with measurements in CBCT. The lowest standard deviation obtained was 0.04 for S-GoL/N-Me with a mean of 0.70mm. The highest standard deviation was 17.46 for FH-MPL with a mean of 41.53mm.
Conclusions: The traditional landmarks used for 2D analysis of malocclusion showed good reliability when transferred to 3D images; however, they did not show specific skeletal or dental patterns for analyzing and classifying 3D images as malocclusion class I. Thus, an alternative method needs to be considered when trying to classify 3D CBCT images for malocclusion class I.