Orofacial myofunctional reeducation assisted by a prefabricated reeducation appliance: a systematic review of the literature

Introduction: Several cross-sectional studies have shown the association of a dysfunctional orofacial environment with a greater prevalence of malocclusions. Orofacial myofunctional reeducation (OFMR) is the rehabilitation of the muscles, functions and resting postures of the orofacial complex. It is used in the therapeutic management of orofacial dysfunction in patients of all ages and with a wide range of disorders and comorbidities. RMOF mainly uses isotonic and isometric exercises targeting the oral and oropharyngeal structures, combined with specific exercises for ventilation, swallowing and mastication. It may involve the use of prefabricated reeducation appliances (PRAs), which may also be prescribed to modify the shape and relationship of the dental arches.

Objectives: The primary objective of this systematic review of the literature was to describe and evaluate the efficacy of prefabricated reeducation appliance-assisted OFMR in orthodontics, occlusodontics and dental sleep medicine. Its secondary objective was to assess whether the use of currently available PRAs is associated with adverse effects.

Materials and methods: The systematic literature review was undertaken using five electronic databases: Medline (via PubMed), Web of Science, Cochrane Library, Embase, and Google Scholar, to identify studies evaluating the efficacy of PRA-assisted OFMR in the treatment of orofacial dysfunctions and parafunctions, temporo-mandibular dysfunction (TMD) or obstructive sleep apnea (OSA) in children, adolescents and adults, published until 20 March 2023. The primary outcome of interest was the therapeutic efficacy of PRA-assisted OFMR. In patients with obstructive sleep apnoea (OSA), efficacy was assessed primarily by a decrease in the apnoea/hypopnoea index (AHI) of at least five episodes per hour from baseline, improvement in subjective sleep quality, sleep quality measured by nocturnal polysomnography and subjectively measured quality of life. In patients with orofacial dysfunctions, parafunctions or TMD, efficacy was assessed mainly by electromyography (EMG), history and clinical examination. Secondary outcomes were dentoalveolar or skeletal improvements, and possible adverse effects of the PRAs used, including adverse effects on occlusion.

Results: Only fourteen studies met all inclusion criteria: two randomised controlled trials, one non-randomised controlled trial, five prospective case-control studies, two retrospective case-control studies, two prospective case series and two retrospective case series. The two randomised controlled trials were assessed as "low risk of bias" according to the Cochrane Back Review Group's 12 risk of bias criteria. The methodological quality of the remaining 12 included studies was assessed using the ROBINS-I tool, according to the recommendations of the Cochrane Handbook. One was judged to have a measured risk of bias, eight a significant risk of bias and three a critical risk of bias. Based on the available evidence, PRA-assisted OFMR results in a statistically significant (p=0.0425) reduction in AHI in children with mild to moderate obstructive sleep apnea. In children with obstructive sleep apnoea undergoing adenoid and/or tonsil surgery, postoperative OFMR combined with a flexible PRA leads to a greater reduction in AHI compared to a control group and an improvement in SaO2 at 6 months and 12 months after surgery (p<0.01). It also contributes to greater improvement in sleep disturbance, physical fitness, daytime lethargy in the treated group than in the control group 6 months and 12 months after surgery (p<0.05). PRA-assisted OFMR provides correction of atypical swallowing and improvement in orofacial muscle balance. GRPs are generally less effective than activators for the treatment of Class II Division 1 malocclusions and appear to cause more adverse effects, mainly vestibuloversion of the mandibular incisors. The use of PRA-assisted OFMR for the management of TMD is not validated by current evidence.

Conclusions: Published data, albeit of uneven methodological quality, appear to show the superiority of OFMR combined with the use of a PRA, compared with the implementation of OFMR without PRA. Prospective studies with large sample sizes would be useful to better evaluate the new therapeutic possibilities brought by the combination of OFMR with a PRA. Continued attention should be paid to the monitoring of possible adverse effects of PRA-assisted OFMR on the dental arches, especially the vestibuloversion of the mandibular incisors. It might be useful to reflect on the relevance of the arguments put forward by manufacturers about the particularities of their devices and their supposed effects. PRA-assisted OFMR appears to be a necessary paradigm shift , which it seems useful to bring to our patients.

Protocol registration: This protocol was registered on March 02, 2023 in the International Prospective Register of Systematic Review (PROSPERO) and received the CRD number: CRD42023400421.