Aim was to systematically search the literature and assess the available evidence regarding the clinical effectiveness of the Invisalign® system. Electronic database searches of published and unpublished literature were performed. The reference lists of all eligible articles were examined for additional studies. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three RCTs, 8 prospective, and 11 retrospective studies were included. In general, the level of evidence was moderate and the risk of bias ranged from low to high, given the low risk of bias in included RCTs and the moderate (n = 13) or high (n = 6) risk of the other studies. The lack of standardized protocols and the high amount of clinical and methodological heterogeneity across the studies precluded a valid interpretation of the actual results through pooled estimates. However, there was substantial consistency among studies that the Invisalign® system is a viable alternative to conventional orthodontic therapy in the correction of mild to moderate malocclusions in non-growing patients that do not require extraction. Moreover, Invisalign® aligners can predictably level, tip, and derotate teeth (except for cuspids and premolars). On the other hand, limited efficacy was identified in arch expansion through bodily tooth movement, extraction space closure, corrections of occlusal contacts, and larger antero-posterior and vertical discrepancies. Although this review included a considerable number of studies, no clear clinical recommendations can be made, based on solid scientific evidence, apart from non-extraction treatment of mild to moderate malocclusions in non-growing patients. Results should be interpreted with caution due to the high heterogeneity.

Summary: Background: Social media are one of the most common and easily accessible ways of gaining information about orthodontic treatment. Objective: The main objective of this study was to systematically search the literature and determine the various aspects of the interrelationship between social media and orthodontics from the patient’s perspective. Search methods: Electronic database searches of published and unpublished literature were performed. The reference lists of all eligible articles were hand-searched for additional studies. Selection criteria: Randomized clinical trials (RCTs), prospective, retrospective, and cross-sectional studies were included. Data collection and analysis: Study selection, data extraction, and risk of bias assessment were performed individually and in duplicate by the first two authors. Results: One RCT, three retrospective, and four cross-sectional studies were deemed as eligible for inclusion in this review. The studies included patient’s statements in social media or results from questionnaires given to patients. The social media reported were with order of frequency: Twitter, YouTube, Facebook, Google+, Pinterest, and Instagram. The feelings the patients expressed seemed to be more positive than negative: enthusiasm, self-esteem and pleasure, excitement about the aesthetic result, excitement after braces removal but also antipathy, annoyances, reduced self-esteem, and impatience for removing mechanisms. In addition, one study referred to bullying through Twitter. Limitations: The high amount of heterogeneity precluded a valid interpretation of the results through pooled estimates. Conclusions and implications: This systematic review demonstrated that information about orthodontics, how the patient feels, and other psychosocial facets are spread through social media. It is intuitive that research relating to the effects and impact of orthodontic interventions should account not only for the physical impacts of treatment but also to encompass patient-centered outcomes. Registration: The protocol of this study was not registered in publicly assessable database. Conflicts of interest: None to declare.