Anterior temporalis and masseter muscles electromyographic evaluation in cerebral palsied

Objectives: Evaluate the electromyographic activity of right and left anterior temporalis and masseter muscles in physiological mandible resting position in individuals with cerebral palsy (CP) on a dental chair, before and after postural stabilization. Methods: A group of 28 non-institutionalized quadriplegic spastic cerebral-palsied individuals of both genders with age ranging from 7 to 13 years old (mean age ± SD = 9.8 ± 4.7) were evaluated at the dental clinics of Individuals with Special Needs Discipline of the Cruzeiro do Sul University, São Paulo, Brazil. The electromyographic signals (EMG) of electric activity were obtained using a 8-channel module (EMG System do Brasil Ltda®, São José dos Campos, SP, Brazil) from the studied muscles in two stages (S1 and S2), stored and analyzed as root-mean-square (RMS) with values expressed in microvolts (µV). The electrodes were placed parallel to the muscle fibers with a center-to-center distance of 30 mm. The individuals were firstly positioned on the dental chair in their usual seating position (USP) with no assisted stabilization or head control (S1). After one week the same individuals were evaluated and positioned according to the neurodevelopmental treatment method (NDT) (S2). The nonparametric Wilcoxon t-test, with significance level of 95%, was used to compare the EMG activity of the muscles on the two stages. Results: The right and left anterior temporalis muscles showed a statistically significant reduction in electromyographic activity (p<0.001 and p<0.001) after postural stabilization (S2), and the same pattern was observed for the right and left masseter muscles (p<0.001 and p<0.001) (S2). Conclusions: The spastic muscle tonus was clinically observed regarding the postural stabilization (S2) decreasing thus the electromyographic activity of the anterior temporalis and masseter muscles due to the inhibition of their pathological postural reflexes facilitating the dental treatment of individuals with cerebral palsy.