Method: It applied a prospective cohort study with 20 adult morbidly obese patients from a bariatric surgery reference centre covered by the Brazilian Public Health System, in the city of Recife, state of Pernambuco, northeast of Brazil. The following data were obtained during the first half of 2011, through clinical evaluation with a protocol on the Orofacial Myofuncional area called MBGR. The primary study was approved by protocol 259/09. It was considered a 95% of confidence interval and the chi-squared test of association.
Result: A sample of 20 volunteers, 17 females and three males, aged between 23 and 58 years, divided into two equal groups regarding the operative phase (interval between assessments 60 days). 60% of patients who underwent surgery had changed chewing, with a significant difference between groups. In patients undergoing preoperative chewing is presented in most investigated, with increased speed, noise, unusual muscle contractions, crushing inefficient, unsystematic and lock lips with a preferred chewing side, while everyone in the postoperative phase showed a decreased rate of chewing, there being systematic in most lip closure, lack of side preference chewing and pain when chewing as a difference (p <0.05).
Conclusion: According to the results were significant differences between the oral masticatory function for the group of obese adults, compared before and after bariatric surgery, and one should consider the sample size.