Characterizing orthodontic tooth movement in real time using dental monitoring scans: A pilot study

This pilot study aimed to quantify the magnitude and type of tooth movement occurring in short time intervals within the regular monthly orthodontic visits for patients with fixed appliances and undergoing maxillary canine retraction. Additionally, this pilot study aimed to provide a descriptive evaluation for the accuracy and reliability of the Dental Monitoring (DM)-captured scans to those of an iTero digital scans in an extraction space closure model.

3D intraoral photographic scans (DM) for 12 patients with maxillary first premolar extractions in a single-centre academic institution.

Twelve patients treated with fixed appliances and undergoing space closure for maxillary premolar extraction(s) were included. Nickel-titanium (200 g) closing coil springs were used for canine retraction. At initiation of space closure (T1), iTero scans were acquired, and patients were instructed to take DM scans every 4-5 days until their next visit in 4-5 weeks (T2). At T2, a final iTero scan in addition to a DM scan was taken. The number of patients who did the scans regularly as instructed declined as time elapsed. Stereolithography (STL) files generated from the DM scans were superimposed with the STL files from the iTero scans using GOM Inspect software to determine the accuracy of the DM 3D models. To assess rate, type and direction of tooth movement, each of the 3D image STL files generated from the DM scans, taken every 4-5 days by each patient, was superimposed on the previously captured scan. The rate of tooth movement for the maxillary molars and canines was calculated in the 3 planes of space (X, Y, Z) at each time point, until the end of the experiment.

Preliminary results indicated that the maxillary canines appeared to be displaced the greatest amount in the first 4-5 days with initial distolateral movement. As time elapsed, the rate of tooth movement decreased, and the tooth started moving distolingually.

Dental monitoring software provides a high-tech platform to monitor tooth movement in a 'real-time' approach. Accuracy of the photographic scans in relationship to the intraoral scans appears promising. There seems to be some evidence that the greatest amount of movement occurs initially in the first few days after activation, dropping thereafter to become a slower constant rate of tooth movement.