Abstract
Introduction There is evidence that patients with posterior crossbite (PXB) have neuromuscular changes in the masticatory muscles. However, up to the present time, the relationship among these changes on the electromyographic activity of the masticatory muscles is still unclear. Objective To systematic review the available literature on the electromyographic activity of masticatory muscles in adults with PXB. Methods Between August 22 and September 9, 2020, we searched the following seven electronic databases: PubMed, EMBASE, Web of Science, Cochrane Library, SciELO, LILACS, and Scopus. No restrictions were applied regarding the language and year of publication. This systematic review was registered in the Prospective Register of Systematic Reviews (PROSPERO - CRD42020205057) database and conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. After data selection and extraction, the methodological quality of the selected studies was conducted independently by two reviewers, using two different evaluation tools. Results 6957 records were initially located after the search process. In the end, eight papers were selected. Most studies were classified as having average to low methodological quality and moderate to high risk of bias. Based on the available evidence, adult patients with PXB have electromyographic activity changes in the masticatory muscles when compared with individuals without PXB. Moreover, adult patients with unilateral posterior crossbite (UPXB) have asymmetrical electromyographic activity when the crossbite side is compared with the noncrossbite side. Conclusion Despite the lack of studies with high methodological quality, electromyographic evaluation of masticatory muscles should be considered in the diagnosis and in the orthodontic treatment plan of patients with PXB. Prospective studies with a higher sample size and follow-up time, conducted using a rigorous scientific methodology, are necessary to reach a more reliable conclusion.
Highlights
Posterior crossbite (PXB) is defined as an inverted crosssectional relationship between upper and lower teeth, when the vestibular cusps of premolars and upper molars occlude the occlusal fossae of the lower antagonist teeth [1]. e prevalence of PXB is from 8 to 22% in orthodontic patients in the mixed dentition stage and from 5 to 15% in the general population [2]
Ere is evidence suggesting that patients with PXB present changes in the neuromuscular activity of masticatory muscles [4–6]. is condition is associated with a functional mandibular lateral displacement caused by occlusal interferences, especially in patients with UPXB [4, 7]. is displacement changes the position of condyles in the glenoid cavity and can corroborate the development of facial asymmetries and temporomandibular disorders (TMD) in adult patients [8]
E quasiexperimental clinical trial presented problems in the description of the following domains: little information about the cause and effects evaluated, absence of control group, insufficient follow-up time, results measured in an unreliable manner, and inappropriate statistical analysis
Summary
Posterior crossbite (PXB) is defined as an inverted crosssectional relationship between upper and lower teeth, when the vestibular cusps of premolars and upper molars occlude the occlusal fossae of the lower antagonist teeth [1]. e prevalence of PXB is from 8 to 22% in orthodontic patients in the mixed dentition stage and from 5 to 15% in the general population [2]. Ere is evidence suggesting that patients with PXB present changes in the neuromuscular activity of masticatory muscles [4–6]. E relation between muscular activity and skeletal morphology can influence the diagnosis of many pathologies [7]. In this sense, an accurate orthodontic diagnosis can be performed in patients with PXB through a morphological and functional evaluation [6, 9, 10]. CBCT and 3D cephalometry can be used for the analysis of the soft tissue facial profile measurements and for the study of skeletal discrepancy with respect to ideal values [9, 10]. E functional evaluation of patients with changes in masticatory muscle activity, on the other hand, can be performed by surface electromyography (sEMG) [6]. With sEMG, it is possible to identify the intensity, frequency, and onset of muscle contraction between the right and left sides [5, 6, 13]. is information is important for determining muscle power, the specificity level of recruitment of motor units, and the degree of muscle balance and coordination between sides
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