The effect of bracket slot size on the effectiveness of orthodontic treatment: A systematic review

To assess, by means of a systematic review, the scientific evidence of the influence of 0.018-inch or 0.022-inch bracket slots on treatment time, efficiency of space closure, efficiency of alignment, quality of orthodontic finishing, level of discomfort, and level of root resorption. The PubMed, Bireme, Medline, Scopus, Web of Science, Open Grey, and Google Scholar databases were searched, with no date and language restrictions, for randomized clinical trials and controlled clinical trials, using controlled terms related to bracket slots. After the selection and removal of duplicate articles, the risk of bias was assessed, and the data from the included studies were extracted by two independent researchers. The search yielded 2640 studies. After applying the eligibility criteria, eight articles were fully read and four studies were selected for the qualitative systematic review. No randomized clinical trials assessed the duration of treatment in patients treated with 0.018-inch and 0.022-inch bracket slots. Due to heterogeneity of the data available, a meta-analysis could not be conducted. While most studies indicated a shorter duration of treatment in patients with 0.018-inch bracket slots, no available data confirmed the higher efficiency of one system over the other. The biases in the studies did not allow for a reliable conclusion; therefore, new studies with a better methodologic design are needed.