Conflict of interest: non-existent stimulation of supporting structures, such as bones and teeth and for favoring that the harmonious craniofacial growth occurs³ .The chewing pattern can be influenced by several factors, such as occlusal interferences, dental and/ or periodontal problems, tooth loss, muscle and/or temporomandibular joints problems².It is known that in a unilateral mastication, the chewing muscles are mainly characterized by increased muscle strength on the working side, in other words, where chewing is occurring. The muscles of the balancing side, opposite side to the working side, is generally more elongated and with NTRODUCTIONChewing is considered by many authors as one of the most important and most studied functions of the stomatognathic system¹,². When performed in a alternating bilateral way, there is synchrony of masticatory muscles, which in turn are crucial for the ABSTRACT Purpose: to investigate the relationship of the masticatory preference side in the electrical activity of masseter and temporalis muscles. Methods: the sample was composed by 115 children aged between 7 and 12 years. The acquisition of the electrical activity of the masticatory muscles was recorded during 5 seconds of isometric contraction in maximal intercuspal position. The children were divided into four groups according to masticatory preference observed: Chewing Preferential Right, Left, Bilateral Alternating, and Bilateral Simultaneous. The electromyographicdata were analyzed using the SPSS 17.0 software, and for determination of statistical difference between the electrical activity of the right and left masseter and temporalis muscles was performed by Paired Student t-test (p <0.05). Results: from the total of 115 children, 76 (63.4%) had a preferred side during mastication, whereas 44 (36.7%) children had masticatory right and 32 (26.7%) preferred chewing left. Of the individuals without a preferred side, it was found 25.8% (n = 31) alternating with bilateral chewing and 10.8% (n = 13) with simultaneous bilateral chewing. After comparing the electrical activity of the masseter and temporal, right and left, according to the group chewing, it was found that the average electrical activity of the muscles on the left side showed no statistically significant differences when compared with the average of its peers right side. Conclusion: for the study sample, there was no relationship between the habitual chewing side and electrical activity of the muscles masseter and temporal.

Conflict of interest: non-existent temporomandibular joint (TMJ) 1 . The morphology of TMJ in newborn presents with flattening of the articular cavity, without the presence of articular eminence for the function of suction is feasible. Subsequently, they begin to perform more elaborated and coordinated mandibular movements, generating the development of the articular eminence that allows the realization of biomechanics, promoting mandibular movements of mouth opening, lateral and protrusion 2 . In this, the condylar movements are not only determined by the articular eminence, disc and the ligaments of the TMJ, as well as for occlusal and neuromuscular 3 factors. The static and dynamic relations between anatomical structures of the TMJ, occlusal areas and their functional relation participate in the normal and pathological process of temporomandibular system functions 4 .