Have you Read these Recent Systematic Reviews in Orthodontics?

February 11, 2011

Effectiveness of orthodontic treatment with functional appliances on mandibular growth in the short term. Am J Orthod Dentofacial Orthop. 2011 Jan;139(1):24-36.Marsico E, Gatto E, Burrascano M, Matarese G, Cordasco G.

INTRODUCTION: The aim of this study was to analyze the current literature for the best evidence (randomized clinical trials) about the efficacy of functional appliances on mandibular growth in the short term.
METHODS: A survey of articles published up to September 2009 was performed by using the following electronic databases: PubMed, Embase, Ovid Medline, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, and Google Scholar. The reference lists of the retrieved articles were hand-searched for possible missing articles. No language restriction was applied during the identification of the published studies. A methodologic scoring process was developed to identify which randomized clinical trials were stronger methodologically. The selection process and the quality assessment were undertaken independently and in duplicate by 2 authors. A meta-analysis was attempted by using random-effects models. Clinical and statistical heterogeneity was examined, and a sensitivity analysis was performed.
RESULTS: Electronic searches identified the following items: 146 articles were retrieved from PubMed, 45 from Cochrane Central Register of Controlled Trials, 29 from Ovid, 42 from LILACS, 628 from Web of Science, and 1000 from Google Scholar. Thirty-two articles fulfilled the specific inclusion criteria and were identified as potentially appropriate randomized clinical trials to be included in this meta-analysis. Only 4 articles, based on data from 338 patients (168 treated vs 170 controls) with Class II malocclusion in the mixed dentition, were selected for the final analysis. The quality analysis of these studies showed that the statistical methods were at the medium-high level. The outcome measurements chosen to evaluate the efficacy of the various functional appliances were Co-Pg, Pg/Olp + Co/Olp, and Co-Gn and the values were annualized and standardized to a uniform scale with the standardized mean differences (SMD). The results of the meta-analysis from the random-effects model showed a statistically significant difference of 1.79 mm in annual mandibular growth of the treatment group compared with the control group (SMD = 0.61, 95% CI, 0.30 to -0.93; chi-square test, 5.34; 3 df; P = 0.15; I(2) = 43.9%; test for overall effect, Z = 3.83 and P = 0.0001). The sensitivity analysis showed a substantially similar outcome of 1.91 mm (SMD = 0.65, 95% CI, 0.25 to 1.25; chi-square test, 4.96; 2 df; P = 0.08; I(2) = 59.7%; test for overall effect, Z = 3.19 and P = 0.001).
CONCLUSIONS: The analysis of the effect of treatment with functional appliances vs an untreated control group showed that skeletal changes were statistically significant, but unlikely to be clinically significant.

Efficacy of short-term chincup therapy for mandibular growth retardation in Class III malocclusion. Angle Orthod. 2011 Jan;81(1):162-68. Liu ZP, Li CJ, Hu HK, Chen JW, Li F, Zou SJ.

OBJECTIVE: To assess the efficacy of chincup therapy for mandibular growth retardation in early orthopedic treatment of Class III malocclusion.
MATERIALS AND METHODS: An electronic search for articles reporting randomized clinical trials, controlled clinical trials, and cohort studies testing the efficacy of chincup appliance for Class III malocclusion published up to the present was done through four databases: Cochrane Central Register of Controlled Trials (CENTRAL; to March 2010), MEDLINE (1950-March 2010), EMBASE (1980-March 2010), and CBM (1978-March 2010). Study quality assessment and data extraction were done by two reviewers independently. Meta-analysis was done with the assistance of Revman 5.01.
RESULTS: The search resulted in 50 articles. After selection following the established criteria, four cohort studies qualified for the final review analysis. The results showed that chincup therapy decreased SNB angle and increased ANB angle; the total pooled weighted mean difference values (95% confidence interval) were −1.18 (−1.69, −0.67; P < .00001) and 1.90 (0.60, 3.21; P = .004), respectively. Two studies showed a increase in Gonial angle (P < .05) but no significant change in the mandibular length (Cd-Gn; P = .059 and .39, respectively). One study indicated that chincup therapy exerted no effect on mandibular growth retardation, and mandibular growth continued after the treatment in a downward direction.
CONCLUSION: There are insufficient data in these studies to make clear recommendations regarding the efficacy of chincup therapy in the retardation of mandibular growth.

Systematic review of self-ligating brackets.Am J Orthod Dentofacial Orthop. 2010 Jun;137(6):726.e1-726.e18; discussion 726-7. Chen SS, Greenlee GM, Kim JE, Smith CL, Huang GJ.
INTRODUCTION: Self-ligating brackets have been gaining popularity over the past several decades. Various advantages for these systems have been claimed. The purposes of this systematic review were to identify and review the orthodontic literature with regard to the efficiency, effectiveness, and stability of treatment with self-ligating brackets compared with conventional brackets.
METHODS: An electronic search in 4 data bases was performed from 1966 to 2009, with supplemental hand searching of the references of retrieved articles. Quality assessment of the included articles was performed. Data were extracted by using custom forms, and weighted mean differences were calculated.
RESULTS: Sixteen studies met the inclusion criteria, including 2 randomized controlled trials with low risk of bias, 10 cohort studies with moderate risk of bias, and 4 cross-sectional studies with moderate to high risk of bias. Self-ligation appears to have a significant advantage with regard to chair time, based on several cross-sectional studies. Analyses also showed a small, but statistically significant, difference in mandibular incisor proclination (1.5 degrees less in self-ligating systems). No other differences in treatment time and occlusal characteristics after treatment were found between the 2 systems. No studies on long-term stability of treatment were identified.
CONCLUSIONS: Despite claims about the advantages of self-ligating brackets, evidence is generally lacking. Shortened chair time and slightly less incisor proclination appear to be the only significant advantages of self-ligating systems over conventional systems that are supported by the current evidence.

In-vitro orthodontic bond strength testing: a systematic review and meta-analysis. Am J Orthod Dentofacial Orthop. 2010 May;137(5):615-622.e3.  Finnema KJ, Ozcan M, Post WJ, Ren Y, Dijkstra PU.

INTRODUCTION: The aims of this study were to systematically review the available literature regarding in-vitro orthodontic shear bond strength testing and to analyze the influence of test conditions on bond strength.
METHODS: Our data sources were Embase and Medline. Relevant studies were selected based on predefined criteria. Study test conditions that might influence in-vitro bond strength were independently assessed by 2 observers. Studies reporting a minimum number of test conditions were included for meta-analysis by using a multilevel model with 3 levels, with author as the highest level, study as the second level, and specimens in the study as the lowest level. The primary outcome measure was bond strength.
RESULTS: We identified 121 relevant studies, of which 24 were included in the meta-analysis. Methodologic drawbacks of the excluded studies were generally related to inadequate reporting of test conditions and specimen storage. The meta-analysis demonstrated that 3 experimental conditions significantly affect in-vitro bond strength testing. Although water storage decreased bond strength on average by 10.7 MPa, each second of photopolymerization time and each millimeter per minute of greater crosshead speed increased bond strength by 0.077 and 1.3 MPa, respectively.
CONCLUSIONS: Many studies on in-vitro orthodontic bond strength fail to report test conditions that could significantly affect their outcomes.


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