Twelve studies (n=163 reported in 11 studies; one study did not report numbers of participants) were included in the review. The types of study designs were not reported.
The quality scores ranged from 1 to 7 points. One study scored 7 points, one scored 6 points, one scored 5 points, one scored 4 points and seven scored 2 to 3 points, and one scored 1 point.
Immediate changes.
Dental changes (8 studies): all of the studies reported a greater immediate expansion at the molar level after SARME, which progressively reduced to the cuspid level. Reported mean expansions were from 7.1 to 8.7 mm in the first molars (5 studies), 5.5 and 7.1 mm in the second molars (2 studies), 4.9 to 5.2 mm in the canines (2 studies), and 7.8 and 8.1 mm in the first biscuspids (2 studies).
Skeletal changes (5 studies): all of the studies reported immediate significant transverse expansion after SARME. In addition, one found neither vertical nor sagittal changes, while another study reported a significant change in palatal plane inclination (1.5 degrees) and a sagittal decrease in the SNB (not defined) angle of 1.78 degrees.
Volumetric and area changes (1 study): the study reported a total increased nasal volume of 4.7 cm3 immediately after SARME, which increased the nasal dimensions and resulted in an improvement in nasal patency.
Changes after expansion retention.
Dental and skeletal changes (1 study): the study reported relapses in dental and skeletal changes during the retention phase immediately after expansion, but the reported changes were considered clinically insignificant.
Changes after orthodontic treatment.
Dental changes (4 studies) all 4 studies reported increased molar expansion with progressive concomitant anterior reduction up to the cuspids with SARME at the end or orthodontic treatment. The mean maxillary molar expansion ranged from 3.8 to 7.2 mm (3 studies) and the mean canine expansion was 4.1 and 4.2 mm (2 studies).
Long-term changes.
Dental changes (6 studies): 4 studies reported greater molar expansion compared with cuspid expansion from at least 1 year after orthodontic post-expansion treatment; mean molar expansions varied from 5.6 to 7.3 mm (4 studies). Two studies reported minor mean maxillary molar expansion relapses of 0.88 and 2.6 mm.
Skeletal changes (1 study): the study reported a minor mean relapse at the maxillary posterior alveolar level of 0.3 mm.