Ultrasonographic Evaluation of The Effects of Orthodontic or Functional Orthopaedic Treatment on Masseter Muscles: A Systematic Review and Meta-Analysis.

Romeo Patini,Massimo Cordaro,Paola Cozza,Patrizia Gallenzi,Roberta Lione

doi:10.3390/medicina55060256

Abstract

Objectives: This review investigated the effects of orthodontic or functional orthopedic therapy on masseter muscle thickness through the use of ultrasonography (US) in growing subjects when compared with untreated subjects. Materials and Methods: This review systematically assessed studies that investigated growing subjects undergoing orthopedic therapy for the correction of malocclusion of vertical, sagittal and transversal plane. Electronic databases (CENTRAL, MEDLINE-PubMed, Scopus and Web of Science) were searched up to February 2019, including available RCTs and CCTs, without language restrictions. The primary outcome was the effect of orthopedic or functional treatment on masseter muscle thickness. The risk of bias of included studies was assessed through the Newcastle-Ottawa quality assessment scale with the aim of defining their methodological quality. A random-effects meta-analysis analyzing mean differences with 95% confidence intervals was used for quantitative analysis. Results: The search retrieved 749 titles, but the studies selection resulted in a final sample of 5 CCTs. The studies retrieved data from 233 children (age range: 5–22 years) and were conducted at university dental clinics. Children were treated for Class II malocclusion, increased vertical dimension or lateral cross-bite variably with rapid or slow maxillary expansion, twin block, bite block, mandibular activators, quad helix, alone or in combination. Risk of bias was assessed as medium for three studies, low for one and high for another. The meta-analysis determined that at the end of orthopedic or functional treatment masseter muscle thickness, measured through the use of US, is significantly reduced (MD −0.79 mm; 95% CI −1.28 to −0.31). The reduction in muscle thickness, therefore, could be considered an indicator for the evaluation of the success of therapy with orthodontic appliances. Conclusions: Although the meta-analysis revealed that US could be considered a less invasive and effective method to evaluate the masseter muscle thickness, single-blinded RCTs, are required to confirm US reliability in this field of application. This review was registered on PROSPERO with the following registration number: CRD42018068402.

Highlights

Maxillofacial morphology is significantly affected by masticatory muscle function
The elimination of duplicate results led to 428 titles of which 416 were removed analyzing their title and abstract
Even though Midori Castelo et al [9] reported data regarding two patient groups, two phases and three treatment periods, they found no evidence of masseter muscle thickness changes in all comparisons made

Summary

Introduction

Medicina 2019, 55, 256 pattern of growth; facial form of individuals with less thick muscles, on the contrary, showed an association with mesocephalic patients who have a higher rate of variation in facial morphology since the muscles do not influence craniofacial growth pattern in such a determinant way [1,2]. It has been [3,4,5] reported that the presence of an agent that undermines the balance of the neuromuscular system might lead to severe malocclusions. Few studies [3,5] have been carried out about the muscular changes during orthopedic or functional treatment in growing subjects

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