The validity and reliability of mixed-dentition analysis methods: a systematic review.

BACKGROUND: The authors conducted a literature review to determine the validity and reliability of mixed-dentition analysis (MDA) methods used to predict permanent tooth size in the mixed dentition and to evaluate the effect of relevant variables. TYPES OF STUDIES REVIEWED: The authors searched eight online databases for studies of MDA. They selected 39 articles. Inclusion criteria included assessment of mesiodistal tooth width predictions of canines and premolars, use of study-model measurements with or without radiographs, reliability and validity of MDA values and a minimum sample size of 10. RESULTS: All MDA methods had positively correlated validity and high intrarater reliability. Mean differences were less than 2 millimeters with correlation coefficients that tended to be above 0.6. Correlation coefficients were less variable with multiple linear regression equations (MLREs) than with simple linear regression equations (SLREs) with the study-model method, but the opposite was true with the radiographic method. Polymorphisms based on ethnicity, sex, jaw or side of mouth did not meaningfully influence the validity of SLRE predictions, but some differences were apparent with the use of MLRE predictions. CLINICAL IMPLICATIONS: The results of this review call into question the clinical implications of the multiple variations of MDA that have been described in the literature.

Frictional resistance in self-ligating orthodontic brackets and conventionally ligated brackets. A systematic review.

OBJECTIVE: To compare the amount of expressed frictional resistance between orthodontic self-ligating brackets and conventionally ligated brackets in vitro as reported in the literature. METHODS: Several electronic databases (Medline, PubMed, Embase, Cochrane Library, and Web of Science) were searched without limits. In vitro studies that addressed friction of self-ligating brackets compared with conventionally ligated brackets were selected and reviewed. In addition, a search was performed by going through the reference lists of the selected articles to identify any paper that could have been missed by the electronic searches. RESULTS: A total of 70 papers from the electronic database searches and 3 papers from the secondary search were initially obtained. After applying the selection criteria, only 19 papers were included in this review. A wide range of methods were applied. CONCLUSIONS: Compared with conventional brackets, self-ligating brackets produce lower friction when coupled with small round archwires in the absence of tipping and/or torque in an ideally aligned arch. Sufficient evidence was not found to claim that with large rectangular wires, in the presence of tipping and/or torque and in arches with considerable malocclusion, self-ligating brackets produce lower friction compared with conventional brackets.