GrE showed reduced molar angulation increases at T1 and reduced molar angulation decreases at T2 when compared with Gr6. At T2, the net increase of the upper intercanine distance in GrE was still significant compared with Gr6, indicating a more stable expansion in the anterior area.

No abstract

ClinicalTrials.gov Identifier NCT02798822.

The aim of this study was to review recent randomized clinical trials (RCTs) dealing with the effectiveness of various modalities of orthopaedic/orthodontic expansion of maxillary arches with crossbite and the associated 6 month post retention stability. The study selection criteria included RCTs involving subjects with maxillary deficiency with crossbite, with no limits of age. The authors searched the following electronic databases from 1999 to January 2011: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, LILACS, and WEB of SCIENCE. The search strategy resulted in 12 articles meeting the inclusion criteria. Most of the studies did not meet major methodological requirements; some studies were not relevant because of small sample size, possible bias and unaccounted for confounding variables, lack of blinding in measurements, and deficient statistical methods. Treatment outcomes were different depending on the appliance used, tooth tissue-borne/tooth-borne expanders, bonded semi-rapid maxillary expansion (SRME), or rapid maxillary expansion (RME); in any case, methodological flaws prevent any sound conclusion. Stable results have been measured at the 6 month follow-up after removal of the retention plate in the treated groups in the maxillary intermolar and intercanine distances. Long-term stability results should be assessed. The Consolidated Standards of Reporting Trials (CONSORT) Statement could be helpful in improving the reporting of RCTs.

BackgroundThe purpose of this controlled study was to investigate indirect effects on mandibular arch dimensions, 1 year after rapid palatal expansion (RPE) therapy.MethodsThirty-three patients in mixed dentition (mean age 8.8 years) showing unilateral posterior crossbite and maxillary deficiency were treated with a RPE (Haas type) cemented on the first permanent molars. Treatment protocol consisted of two turns per day until slight overcorrection of the molar transverse relationship occurred. The Haas expander was kept on the teeth as a passive retainer for an average of 6 months. Study models were taken prior (T1) and 15 months on average (T2) after expansion. A control group of 15 untreated subjects with maxillary deficiency (mean age 8.3 years) was also recorded with a 12-month interval. Stone casts were digitized with a 3D scanner (3Shape, DK).ResultsIn the treated group, both mandibular intermolar distance (+1.9 mm) and mandibular molar angulation (+9°) increased. Mandibular incisor angulation showed an increase of 1.9°. There was little effect on intercanine distance and canine angulation. Controls showed a reduction in transverse arch dimension and a decrease in molar and canine angulation values.ConclusionsRPE protocol has indirect widening effects on the mandibular incisors and first molars.