Do malocclusion and orthodontic treatment impact oral health? A systematic review and meta-analysis

Introduction: Currently, there is limited evidence on the effects of malocclusion on oral health and whether the correction of malocclusion results in an improvement in oral health. In this review, we examined the evidence from randomized controlled trials and prospective cohort studies to provide information on any association between malocclusion and oral health and the effects of orthodontic treatment. Methods: We conducted this review in 2 parts: (1) we looked at the impact of malocclusion on oral health, and (2) we reviewed the evidence on the effect of orthodontic treatment on oral health. We searched for randomized controlled trials and prospective cohort studies. The searches were completed for articles published between January 1, 1990 and October 8, 2018 and covered Medline via Ovid, Embase, and the Cochrane Database of Systematic Reviews. References of included articles and previous systematic reviews were hand-searched. No language restrictions were applied. Two members of the study team assessed the quality of the studies using the Appraisal Tool for Cross-Sectional Studies to appraise the quality of studies in part 1. The assessment was performed at the study level. Two authors assessed each study independently, with a third author consulted when a disagreement occurred. For studies in part 2, we used the Newcastle-Ottawa scale to assess the risk of bias. When studies were included in a Cochrane review, we incorporated the risk of bias assessment. We developed data extraction forms for each area of oral health under investigation (trauma, quality of life, caries, and periodontal disease). Each author piloted the form, and we held discussions to inform any necessary refinements. We extracted data from studies into 2 3 2 tables, which provided a binary analysis of malocclusion vs the outcome of interest. If these data were not available from the published paper, then studies were not included in the meta-analysis. The authors were contacted when possible to request data in this format. Results: For part 1 of the study, we identified 87 studies. The overall quality was low. We could not include any of the data into an analysis because of a large variation in the nature of the studies, data collected, and outcome measures that were selected. For part 2 of the study, we found 7 studies; however, there were similar deficiencies in the data as in part 1, and thus, we could not reach any strong conclusions. Conclusions: Overall, there is an absence of published evidence regarding the effects of malocclusion on oral health and the impact of orthodontic treatment on oral health.