Efficacy of clear aligner wear protocols in orthodontic tooth movement—a systematic review

Summary Background and objectives Different expedited aligner wear protocols are currently in practice. This review was undertaken to systematically appraise the available evidence on the comparative efficacy of orthodontic tooth movement (OTM) across the different wear protocols. Search methods Two assessors conducted comprehensive searches of electronic databases, including MEDLINE (via PubMed), Scopus, Embase, Web of Science, Google Scholar, Directory of Open Access Journals, Cochrane Library, OpenGrey, and Clinical Trial Registry, till 18 February 2024. Titles and abstracts were independently screened. Selection criteria Prospective or retrospective studies comparing expedited wear protocols with the conventional 14-day protocol were included. Data collection and analysis A pre-piloted data extraction form was used. Risk of bias (RoB) assessment employed the Cochrane RoB 2.0 tool for randomized-controlled trials (RCTs) and the Newcastle–Ottawa scale for non-RCTs. The quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation Pro tool. Results Six studies, including 3 RCTs and 3 non-RCTs, were selected from 9076 records. Four studies (two RCTs and two retrospective cohort) found no statistically significant difference (P > 0.05) in the OTM efficacy between expedited and conventional protocols. Two studies (one RCT and one prospective cohort) found greater efficacy (P < 0.05) with the 14-day protocol, with the RCT reporting greater efficacy for certain movements, such as maxillary posterior intrusion, maxillary posterior distal tipping and buccal torquing, and mandibular posterior intrusion and extrusion. One RCT reported statistically insignificant difference (P > 0.05) in pain perception between the 10-day and 14-day protocols. Two studies demonstrated low RoB, two moderate, and two high RoB. The evidence level was very-low for OTM efficacy and high for pain perception. Meta-analysis was precluded due to significant heterogeneity among the studies. Conclusions Within the limitations of the study, the 7-day, 10-day, and 14-day protocols did not show any significant difference in OTM efficacy, except for certain movements that exhibited superior outcomes with the 14-day wear. Hence, a ‘hybrid aligner-wear protocol’, based on clinical judgement, might serve a better alternative in complex situations. Registration PROSPERO CRD42021288179