Analysis of Mandibular Landmarks and Planes in 2D and 3D

Objectives: To compare and evaluate the correlation of a novel 3D mandibular analysis method versus conventional 2D cephalometric measurements.
Methods:
The total sample size of this retrospective study was 30 Cone Bean CT scans of 15 male and 15 female orthodontic patients, with the mean age 10.6 ± 1.4 years. 3D mandibular landmarks and planes were digitized using Mimics V.18 software (Materialise, Leuven, Belgium) and they were compared with the 2D counterparts. i.e., mandibular plane angle, gonial angle, mandibular length.
Results: When comparing the variables between male and female subjects, there was a statistically significant difference between male and female subjects in age, but there was no statistically significant difference between male and female subjects in any of the 2D and 3D measures. When correlating between 2D and 3D images, we found statistically significant positive correlation between 2D and 3D mandibular length measures (r=0.5, p= 0.002) and statistically significant negative correlation between 2D and 3D gonial angle measures. However, there was no statistically significant correlation between 2D and 3D mandibular plane measures.
Conclusions: These results demonstrate statistically significant positive correlation between 2D and 3D mandibular length measures. The use of 3D measurements in the orthodontic field is promising for growth analysis and treatment planning. Different 3D landmarks and larger sample size may yield more significant correlations with conventional 2D measurements.