Abstract
Objectives.The objective of this retrospective clinical study was to assess the accuracy of a method of predicting post-movement root position during orthodontic treatment, using a 3D digital crown/root model (3DCRM), which was created with pre-movement records of both CBCT and dental-arch digital scans.Material & Methods.Pre-movement CBCT scans, post-movement CBCT scans, and dental-arch digital scans of five patients who had completed orthodontic treatments were used in this study with the approval of internal review board of Iwate Medical University. The 3DCRM was superimposed onto post-movement scanned dental-arch to identify the post-movement root position (test method). Post-movement CBCT (referenced as current method) served as the control used to identify the actual post-movement root position. The predicted root positions by the two methods were compared using color displacement mapping and 3D coordinate XYZ analysis.Results.Color displacement mapping showed that the average root displacement of five cases was -0.16 mm ±0.05 mm. 3D coordinate analysis revealed no significant differences between test and current methods in X and Y axis. However, the discrepancy in Z axis (especially in cases of intrusion) was greater than all other directions (mesial, distal, labial, palatal and extrusion direction) for all three tooth types examined (central incisor, lateral incisor and canine, p <0.05). A strong positive correlation between the degree of discrepancy and the distance of tooth movement was observed on the Z axis (r =0.71).Conclusions.The 3DCRM method showed promising potential to accurately predict root position during orthodontic treatments without the need for a second CBCT. However, root resorption, which affected the Z axis prediction, needs to be closely monitored using periapical radiographs to complement this method.Clinical Relevance.The 3DCRM method can be a useful tool to better evaluate root positioning during and after orthodontic treatment without the need to expose patients to an additional CBCT scan.