UCSF

The objective of this study was to utilize digital models and cone beam computed tomography (CBCT) radiographs to quantify the skeletal and dentoalveolar maxillary expansion in Phase I orthodontic treatment using clear aligner therapy. Fifty-four patients (22 female and 32 male) had measurements taken on both the pre-treatment intraoral scan and post-treatment intraoral scan from the mesiolingual cusps of the maxillary first permanent molars and the cusp tips of the maxillary primary canines to compare the amount of expansion of the dentition. This was compared with the planned amount of expansion seen in the ClinCheck setup. Twenty-nine patients (14 female and 15 male) had measurements taken on both the pre-treatment and post-treatment CBCT radiographs. The measurements included the upper first molar cusp width, upper first molar cementoenamel junction width, upper primary canine cusp width, upper primary canine cementoenamel junction width, the intermolar angle, and the intercanine angle. Samples were scanned with an iTero Element or iTero Element 2 intraoral scanner, and the CBCT radiographs were taken with an iCAT FLX (16x13cm field of view, 0.3mm voxel size, 623.9mGy/cm2 exposure). The scans were measured using OrthoCAD version 5.9.0.36 and ClinCheck Pro 5. The CBCTs were measuring using Anatomage Invivo6. 2.4mm of posterior expansion was observed between the molars and 4.01mm of anterior expansion was observed between the primary canines. A comparison with the ClinCheck showed a percent yield of posterior expansion to be 51.15% and a percent yield of anterior expansion to be 64.73%. The CBCT analysis displayed posterior expansion of 1.89mm between the molars, 1.87mm between the molar CEJs, an angle change of -1.16 degrees (buccal tipping) between the molars, anterior expansion of 3.64mm between the primary canines, 1.78mm between the canine CEJs, and an angle change of 24.73 degrees (facial tipping) between the canines. Thus, we demonstrated the impact of clear aligners in terms of maxillary expansion using models and CBCTs.