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Correlation of the masticatory biomechanics, adiposity and sleep disorders in patients with Down syndrome.


Down Syndrome (DS) is a genetic disorder characterized by an extra copy of chromosome 21 (Hsa21). The muscle hypotonia is one of the main phenotypical features of this syndrome which can be a deleterious condition for total or partial obstruction of the airways during sleep, causing Obstructive Apnea of Sleep (OSA).


This study assessed the masticatory biomechanics by means of electromyographic records of the masseter and temporal muscles at rest and in function, as well as the maximum bite force (MBF) and the maximum mouth opening (MMO). These findings were correlated with body fat distribution and risk of sleep disorders in patients with DS.


Twenty-four patients with DS were enrolled in this study to evaluate the electrical activities of the masseter and temporal muscles, bilaterally, at rest and in maximum voluntary clench (MVC). The MMO and MBF were also measured. The overcomes were compared with non-syndromic healthy individuals which were described in the literature. Furthermore, the body fat distribution (body mass index, BMI; neck and abdomen circumferences, NC and AC; and waist to hip ratio, WHR) and the subjective diagnosis for sleep disorders (Epworth Sleepiness Scale, STOP-BANG and Fletcher & Luckett questionnaires) were investigated.


The electromyographic records and the MBF, in function, showed lower values in our patients with SD than in non-syndromic healthy individuals. The MMO was slightly high in the DS group, probably, due to the relaxation and the stretch of the studied muscles. The body fat levels were high in BMI, NC, AC, and WHR in both the genders; however, the NC was only superior in men. The results showed that our patients were overweight or obese (obesity grade I), indicating risks for developing obesity-related diseases. The excessive daytime sleepiness, high risk of OSA, and impaired sleep quality were evidenced in women (42,8%, 42,8% and 14,3%) and men (35,3%, 64,7%, and 11,76%).


We concluded that the hypofunction of the temporalis and masseter muscles was found in our patients with DS, configuring a masticatory muscle hypotonia in these individuals. High MMO amplitude was also evidenced, probably, due to the extensibility of the studied muscles. The masticatory muscle hypotonia, associated with excess body fat, influenced the high risk of OSA, especially in men.


Down Syndrome, Muscles hypotonia; Adiposity; Sleep Wake Disorders.


Área Básica


Irene Moreira Serafim, Gabriela Pinto Mancilha, Lilian Chrystiane Giannasi, Gabriela Raine Carvalho Silva, Elaine Fillietaz-Bacigalupo, Sigmar Mello Rode, Miguel Angel Castillo Salgado, Mônica Fernandes Gomes