Fourteen studies (n=335) were included in the review. The sample size ranged from 7 to 34. No details of the study designs were reported.
None of the included studies met more than half of the items on the validity checklist (validity scores ranged from 34 to 50%), and all had problems regarding sample selection, description and statistical approach.
Main transverse dental changes were as follows:
maxillary intermolar width, 6.74 mm (95% CI: 4.59, 8.89, p<0.05); maxillary intercanine width, 5.35 mm (95% CI: 4.31, 6.39, p<0.05); maxillary intermolar angle, 3.1 degrees (95% CI: -2.08, 8.27); maxillary interincisal apex width, 3.9 mm (95% CI: 3.3, 4.49, p<0.05); midline diastema, 2.98 mm (95% CI: 2.77, 3.2, p<0.05); mandibular intermolar width (buccal-buccal), 0.53 mm (95% CI: -0.07, 1.14).
Main vertical and anteroposterior dental changes were as follows:
maxillary molar cusp to palatal plane, 0.53 mm (95% CI: 0.24, 0.82); overjet, 1.29 mm (95% CI: 1.02, 1.56, p<0.05); maxillary incisor-sella nasion (SN) plane, -0.86 degrees (95% CI: -1.02, -0.7, p<0.05); interincisnal angle, 2.31 degrees (95% CI: -0.62, 5.25).
Main transverse skeletal changes.
The only statistically significant changes were nasal cavity width (intercondyle width) and left jugale-right jugale (interalveolar width) landmarks of 2.14 mm (95% CI: 1.56, 2.72) and 2.73 mm (95% CI: 1.84, 3.62), respectively.
Main vertical and anteroposterior skeletal changes.
The only statistically significant changes observed were changes in the mandibular plane of 1.65 degrees (95% CI: 1.4, 1.9) to the palatal plane and 1.97 (95% CI: 1.75, 2.19) degrees to the SN plane. The angulation of the palatal plane with respect to the SN plane was not significant (0.30 degrees; p>.05).