Effectiveness of clear aligner therapy for orthodontic treatment: A systematic review

Orthod Craniofac Res. 2020 May;23(2):133-142. doi: 10.1111/ocr.12353. Epub 2019 Nov 13.


Objective: To analyse through a systematic review the effectiveness of clear aligners by assessing: (a) predictability of clear aligners and (b) treatment outcome comparison of clear aligner therapy with fixed appliance therapy.

Methods: An electronic search was made from January 2014 to April 2019 using MEDLINE, Embase, Web of Science and LILACS databases without any limitations on language. Three reviewers independently assessed the articles. Quality assessment of observational studies and randomized control trial was done by using the ROBINS tool and Cochrane risk of bias tool, respectively. GRADE instrument was used to assess certainty level for each identified outcome.

Results: Seven eligible articles (one randomized controlled trial and six retrospective cohort) were included in our systematic review. Most of the studies (six out of seven) had a moderate risk of bias and one had a high risk of bias.

Conclusions: 'Low to moderate level' of certainty in regard to specific clear aligner therapy tooth movements' efficiency was identified. Clear aligners may produce clinically acceptable outcomes that could be comparable to fixed appliance therapy for buccolingual inclination of upper and lower incisors in mild to moderate malocclusions. However, not all potential clinical scenarios have been assessed in the included studies. Most of the tooth movements may not be predictable enough to be accomplished with only one set of trays with clear aligners despite the recent advances in technology.

Keywords: clear aligner; predictability; systematic review; treatment outcome.

Publication types

  • Systematic Review

MeSH terms

  • Humans
  • Incisor
  • Malocclusion*
  • Orthodontic Appliances, Removable*
  • Randomized Controlled Trials as Topic
  • Retrospective Studies
  • Tooth Movement Techniques