Effectiveness of the transpalatal arch in controlling orthodontic anchorage in maxillary premolar extraction cases: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the effectiveness of the transpalatal arch (TPA) as an anchorage device in preventing maxillary molar mesialization during retraction of the anterior teeth after premolar extraction. MATERIALS AND METHODS: This systematic review intended to include patients indicated for upper premolar bilateral extraction and subsequent retraction of anterior teeth, considering the use of TPA as an anchorage tool in one of the treatment groups. The search was systematically performed, up to April 2015, in the following electronic databases: Medline, Embase, and all evidence-based medicine reviews via OVID, Cochrane Library, Scopus, PubMed, and Web of Science. Risk of bias assessment was performed using Cochrane's Risk of Bias Tool for randomized clinical trials (RCTs) and Methodological Index for Nonrandomized Studies (MINORS) for non-RCTs. RESULTS: Fourteen articles were finally included. Nine RCTs and five non-RCTs presented moderate to high risk of bias. Only one study investigated the use of TPA in comparison with no anchorage, failing to show significant differences regarding molar anchorage loss. A meta-analysis showed a significant increase in anchorage control when temporary anchorage devices were compared with TPA (mean difference [MD] 2.09 [95% confidence interval CI 1.80 to 2.38], seven trials), TPA + headgear (MD 1.71 [95% CI 0.81 to 2.6], four trials), and TPA + utility arch (MD 0.63 [95% CI 0.12 to 1.15], 3 trials). CONCLUSION: Based on mostly moderate risk of bias and with some certainty level, TPA alone should not be recommended to provide maximum anchorage during retraction of anterior teeth in extraction cases.