Effectiveness of clear orthodontic aligners in correcting malocclusion- systematic review

  • Maryam Baneshi

Student thesis: Unknown


Introduction: The clear aligner was created as an alternative solution to the fixed appliance, particularly for individuals concerned with appearance, as it is less visible and also provides many further benefits. The purpose of this research was to assess the effectiveness of clear aligners in treating various types of malocclusions when compared to fixed orthodontic appliances. Moreover, this research further seeks to discover if the effectiveness of clear aligners is comparable to that of fixed appliances in treating different types of malocclusions. Methods and Quality: The following databases were searched: EMBASE (Ovid), Medline (Ovid), the Cochrane Library, Latin America and the Caribbean Literature on Health Sciences (Lilacs), Web of Science and EBMR review until 2022. We did not impose any language or date constraints on our searches and only randomised controlled studies (RCTs) were considered for this review. Evaluation of the potential for bias in randomised controlled trials (RCTs) was carried out with the use of the revised Cochrane Risk of Bias instrument (ROB tool 2) for clinical trials of treatments. Available data was meta-synthesised using Review Manager 5.4. The primary outcome was the treatment accuracy of clear aligners versus fixed appliances, and included orthodontic tooth movement in terms of anteroposterior discrepancy, transverse discrepancy, vertical discrepancy and overjet. The secondary outcomes included the effectiveness of treatment, such as duration of treatment, periodontal health, root resorption and patient satisfaction in relation to the quality of life. Result: Thirteen RCT studies were selected from a total of 466 records and involved 647 participants. All 13 studies included a comparison of the effectiveness of clear aligners versus fixed appliances. Two of the studies were assessed to be at high risk of bias, whilst ten of the studies were assessed to be at unclear risk of bias, and only one study was found to be at low risk of bias. Based on the primary outcome, there was no significant difference in the ABO objective grading scores between the fixed appliances and clear aligner treatments. Meta- analysis was only possible for secondary outcomes. We found that the plaque index (MD= - 0.76, 95% CI: -1.14 to - 0.38, P=.00001), gingival index (MD= -0.61, 95% CI: -0.78 to - 0.44, P=.00001) and bleeding index (MD= -0.71, 95% CI: -0.92 to - 0.49, P=.00001) were significantly lower in clear aligners when compared to the fixed appliances. Clear aligners also appeared to have a better outcome with regard to chair time, pain and duration of treatment Conclusion: Both clear aligners and fixed appliances worked well in treating various types of malocclusions. There was no significant difference in the ABO Objective Grading System scores between the clear aligner and fixed appliance groups. Clear aligners showed advantages in periodontal health, the frequency of appointments, duration of treatment and pain. However, significant altered speech production was also observed. Root resorption was not statistically different between the clear aligner and fixed appliance groups.
Date of Award31 Dec 2023
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorAhmed El-Angbawi (Supervisor), Badri Thiruvenkatachari (Supervisor) & Lucy O'Malley (Supervisor)

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