Removable expansion plate improves transversal dental dimensions of maxilla, Study says

The authors, A-S Van de Velde and associates from the Department of Oral Health Sciences-Orthodontics, KU Leuven & Dentistry, University Hospitals Leuven, Leuven, Belgium conducted a prospective cohort study wherein they investigated the short term effects of interceptive orthodontic treatment with a removable expansion plate, evaluating the changes in occlusion in all its dimensions: transversal, sagittal and vertical.

A total of 226 patients treated with a removable expansion plate (slow maxillary expansion, SME) by orthodontic residents were included. The patients had a mean age of 8.5 years at the start of the treatment.

The mean treatment time was 6.9 months. Transversal measurements (intercanine and intermolar width) and occlusal characteristics (molar occlusion, overjet, overbite and functional shift) were collected before (T0) and after active treatment (T1).

Statistical analysis was performed using the Wilcoxon signed rank test, Sign test and McNemar test for assessing changes between T0 and T1. Linear models were used to assess the associations between patient factors and the amount of expansion.

The results shown were as follows-

a. A significant increase in transversal width at different occlusal landmarks was found.

b. Correction of unilateral, bilateral and frontal crossbites was successful in 99.0%, 95.2% and 93.6% of the cases respectively.

c. Changes in sagittal molar occlusion were significant: 64.9% (right side) and 62.6% (left side) remained stable, 28.4% (right) and 29.3% (left) improved and 6.7% (right) and 8.1% (left) deteriorated.

d. Overbite changes were found to be statistically significant, though clinically irrelevant.

e. Overjet changes were non-significant.

Therefore, the authors concluded that "a removable expansion plate is successful in improving the transversal dental dimensions of the maxilla. Statistically significant sagittal effects on molar occlusion were found. Long-term follow-up is needed to evaluate the long-term stability of this treatment."