Clinical effectiveness of clear aligner treatment compared to fixed appliance treatment: an overview of systematic reviews

Objective To evaluate the available evidence regarding clinical effectiveness of clear aligner treatment (CAT). Materials and methods A comprehensive literature search was conducted for systematic reviews investigating effectiveness of CAT published up to July 15, 2021. This was accomplished using different electronic databases. No language restriction was applied. Screening, quality assessment, and data extraction were performed by two authors independently. Information was categorized and narratively synthesized for the key findings from moderate and high-quality reviews. Results A total of 361 potentially eligible reviews were identified. After excluding the non-relevant/low-quality reviews, 18 systematic reviews were included. CAT was found to be effective for mild to moderate malocclusions, and was associated with inferior outcomes when treating severe cases or with achieving specific tooth movements. There were conflicting results regarding treatment duration; however, CAT may be associated with shorter treatment in mild to moderate cases. Relapse was greater with CAT, while periodontal health was better. The risk of root resorption tended to be lower with CAT. Regarding pain, the results were unclear, although CAT was found to be more comfortable and associated with a reduced impact on eating and chewing. Conclusions The level of evidence regarding CAT is moderate; hence, further high-quality randomized clinical trials are required. Evidence supports use of aligners as an alternate to fixed appliances in patients with mild-to-moderate malocclusion but not in severe cases. Advancement in technology could enhance the accuracy of CAT in delivering planned outcomes. Registration PROSPERO registration number: CRD42021246855.

Automated summary

The study evaluated the clinical effectiveness of clear aligner treatment (CAT). The findings showed that CAT is effective for mild to moderate malocclusions but less effective for severe cases or specific tooth movements. There were conflicting results regarding treatment duration, but CAT may lead to shorter treatment in mild to moderate cases. CAT had a higher risk of relapse but better periodontal health. The risk of root resorption tended to be lower with CAT.