Objective: To synthesize currently existing data and investigate the prevalence of tooth transposition as well as its relation to gender, dental arch, and quadrant occurrence. Materials and Methods: Several electronic databases were searched in order to identify the potentially relevant studies. Initially, 591 papers were retrieved. After applying specific inclusion and exclusion criteria, nine studies were eligible for inclusion in this evaluation. Meta-analysis was performed by determining the event rate and the 95% confidence intervals estimated by the random effect model. Results: Analysis of the data of the primary studies revealed that tooth transposition has a mean prevalence of 0.33%. This prevalence seems to be the same between the two genders. However, tooth transposition appears more frequently in the maxilla than in the mandible and more unilaterally than bilaterally. Conclusion: Tooth transposition is a rare phenomenon that affects various populations, including across genders, in a similar manner. Some maxillary predisposition exists, and its unilateral occurrence is higher than that of bilateral. (Angle Orthod. 2010;80:275-285.)

BackgroundChin cup is regarded as the oldest orthodontic appliance for the management of Class III malocclusion. To assess its clinical effectiveness in pre-pubertal patients, a meta-analysis on specific cephalometric values is attempted.MethodsDetailed electronic and hand searches with no restrictions were performed up to July 2014. Only randomized controlled trials (RCTs) and cohort studies, i.e. prospective controlled trials (pCCTs) and (retrospective) observational studies (OS), were included. Analyses were performed by calculating the standard difference in means and the corresponding 95% confidence intervals, using the random effects model. Data heterogeneity and risk of bias assessment of the included studies were also performed. Study selection, data extraction and risk of bias assessment were performed twice. The level of significance was set at P ≤ 0.05 for all tests, except for heterogeneity (P ≤ 0.1).ResultsSeven treated groups from five studies (no RCTs, four pCCTs, one OS) were eligible for inclusion, assessing only the short-term occipital pull chin cup effects. In total, 120 treated patients (mean age: 8.5 to 11 years) compared with 64 untreated individuals (mean age: 7.3 to 9.89 years) were assessed by means of 13 cephalometric variables. The overall quality of these studies was low to medium. In comparison to untreated individuals, the SNB and gonial angles decreased significantly following chin cup use, whereas ANB, Wits appraisal, SN-ML, N-Me and overjet increased. For the rest of the variables, no statistically significant differences were detected.ConclusionsAlthough the occipital chin cup affects significantly a number of skeletal and dentoalveolar cephalometric variables, indicating an overall positive effect for the treatment of Class III malocclusion, data heterogeneity and between-studies variance impose precaution in the interpretation of the results.Electronic supplementary materialThe online version of this article (doi:10.1186/s40510-014-0062-9) contains supplementary material, which is available to authorized users.

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Rapid Palatal Expansion (RPE) is a traditional orthodontic/orthopedic procedure for the skeletal widening of the maxilla according to which the two maxillary bones tear apart and the gap between them is filled in with hemorrhagic tissue which is gradually replaced by new bone formation. Indications for RPE are severe absolute or relative skeletal discrepancies with the maxilla being narrower than normal. This procedure seems to be accompanied by concomitant skeletal changes.A prospective control clinical trial was designed in an effort to verify these alterations. A treated sample and a control sample consisted of 23 individuals each. The age of the examined patients was 14-16 years. The patients of the treated sample underwent RPE whereas in the control sample they received no treatment at all. Measurements were made before treatment (To), after RPE and 3 months retention with the appliance still in place (T1) and at the end of the orthodontic treatment (T2). Equivalent measurements were made in the control group as well. The variables measured were the lips length, the width of the base of the nose and the Soft Tissue Lower Anterior Face Height (SLAFH).According to the results of this study, no statistically significant alteration found in the length of the lips due to the RPE procedure. On the contrary, the base of the nose presented statistically significant increase. The SALFH also increased with statistical significance due to RPE. These concomitant changes of the lower part of the face need to be taken into account and to be integrated in a patients' treatment plan according to his facial type (dolichofacial or brachyfacial).Further investigation with bigger sample sizes and more long term results can give more insight into this subject.