RESUMO
Abstract Introduction Clinical assessment in orofacial motricity is required for the speech therapist to diagnose and treat disorders involving the stomatognathic system. Validated tools can help establish a prognosis and outline intervention methods connected to human development. Objective The goal of the present study was to examine the domains of the oromyofunctional assessment of nursing infants and preschoolers according to sex and age group, as well as the application of the MMBGR Protocol - Nursing Infants and Preschool Children. Methods A quantitative technique was used to conduct an analytical and cross-sectional investigation. The present study included a total of 214 healthy breastfeeding infants and preschoolers of both sexes. The Mann-Whitney test was used to compare the medians. The Spearman correlation of each test domain was determined. R Core Team 2021 (R Foundation, Vienna, Austria) was used, and the significance threshold was set at 5%. Results In intraoral and extraoral examinations, there was a difference between sexes for tongue scores in nursing infants(d =-0.428; p = 0.045), worse in males. When the orofacial functions were considered in nursing infants, there were differences between the sexes for the liquid/solid/semisolid deglutition scores (d = 0.479; p = 0.031), with females performing worse. There were sex differences in solid/semisolid deglutition (d = -0.335; p = 0.043), and speech in preschoolers (d = - 0.478; p = 0.034), including the production of phones/phonemes (d = - 0.599; p = 0.007), which were always worse in males. Conclusion The research revealed sex disparities and related the domains of oromyofunctional assessment, according to scores, of the domains of myofunctional assessment, as recorded in a standardized oromyofunctional assessment protocol by age group.