Anatomical Features in Impacted Canine Orthodontic Treatment Using CBCT

Objectives: The purpose of this study is to analyze cone-beam computed tomography (CBCT) images pre- and post-orthodontic treatment of impacted canines and describe the skeletal and dental features around it.
Methods: CBCT’s before and after orthodontic treatment of thirty-five patients with impacted maxillary canines were analyzed using the Avizo software. Up to twenty-seven landmarks were selected for each CBCT obtained from the Graduate Orthodontic Clinic patient pool in Edmonton, Alberta and Minnesota. Intraclass correlation coefficient (ICC) was used to examine the reliability and measurement error in locating landmarks. Linear and angular measurements were then calculated using the coordinates. All of the data from the impacted canine side was pooled and changes between the two time points (time two minus time one) were investigated for statistical significance (p<0.05) using Paired T-Test and ANOVA.
Results: ICC values of above 0.976 in all axis report excellent reliability. The largest measurement error was in the z-axis for 1.23±2.13mm for the alveolar bone level of the right impacted canine. The greatest meaningful change, -1.48±1.81mm, was in the apex to pulpal horn length of the lateral incisor on the impacted side. This change is both clinically and statistically significant. ANOVA shows that a significant change in the apex to pulpal horn distance of the lateral incisor is associated with significant changes in linear and angular measurements that reflect changes in the position, angulation and bone level of the impacted canine.
Conclusions: As the impacted canine was brought into alignment, the root length of the adjacent lateral incisor on average shows a clinically and statistically significant decrease. Changes after treatment in the position, angulation and bone level of the impacted canine affects the change in root length of the corresponding lateral incisor.