En-masse maxillary anterior retraction to close the extraction space with fixed orthodontic appliances: A systematic review

Objective: To evaluate the evidence on the treatment results and patients’ reported outcomes of the en-masse maxillary anterior retraction technique. Material and methods: Web of Science™, MEDLINE (via PubMed®), and Scopus electronic databases and reference lists of relevant studies were comprehensively searched on September 24, 2024 with no time frame limitation but, with the language limited to English. Randomized clinical trials investigating en-masse retraction in orthodontic patients who needed maxillary first premolars extraction were selected using keywords to search the titles and abstracts before a detailed reading of each full text in the next steps. Primary outcomes included rate, duration, or amount of anterior retraction and anchorage loss while secondary outcomes included positional changes in the anterior and molar teeth, root resorption of the anterior teeth, and patients’ experiences. The Cochrane Collaboration's risk of bias tool was used for risk of bias and quality assessment of the included studies. Results: There were 257 articles deemed potentially suitable for the review. Removing duplicates, careful reading the titles and abstracts, and applying the inclusion/exclusion criteria left 22 articles were included. The risk of bias assessment showed 3, 7, and 12 studies of “high”, “some concerns” or “low” risk of bias respectively. En-masse retraction produced similar incisor retraction and anchorage loss in about half the time needed by the two-step mechanics. Corticotomy, micro-osteoperforation, and low level laser therapy showed positive results for accelerating en-masse retraction. while piezocision and platelet rich plasma did not. Root resorption of the incisors could increase when using mini-screws, especially infra-zygomatic mini-screws. Conclusions: There is need for future RCT on the different outcomes done according to standardized methodologies. Corticotomy, micro-osteoperforation, and low-level laser showed positive results in accelerating en-masse retraction, but the clinical significance remains unclear. Rate of tooth movement was similar in piezocision, platelet-rich plasma, and the control groups. Mini-screws, especially infra-zygomatic mini-screws, increase the chance of root resorption, but the force system arrangement is crucial.