ABSTRACT Purpose proper chewing and swallowing functions have great importance in general health, since it potentially affects food’s digestion and the subject’s nutritional status. The aim was to assess the validity and reliability of the self-applied Quality of Masticatory Function Questionnaire (QMFQ) in a convenience (non-referred) sample of Brazilian adolescents divided into three groups: control (n=57), dental caries (n=51) and malocclusion (n=54). Methods caries and malocclusion were evaluated using DMF-S index (number of decayed, missing and filled primary and permanent surfaces) and Index of Orthodontic Treatment Need, respectively. The QMFQ comprises 26 items regarding frequency and intensity of chewing problems with five domains: Food-Mastication, Habits, Meat, Fruits and Vegetables. Data were submitted to descriptive statistics, Kolmogorov-Smirnov and Chi-square tests. Psychometric evaluation included measures of reliability (internal consistency - Cronbach's alpha and matrix of correlation) and discriminant validity (Kruskal-Wallis/Dunn post-test). Results the instrument showed satisfactory internal consistency, with significant positive correlations between the domains scores except between Habits and Vegetables. Total scale Cronbach's alpha coefficient was 0.87 and the coefficient did not increase significantly with the removal of each domain. Significant differences were found between controls and caries group in Food-Mastication, Meat and Fruits scores. Caries group also showed higher median values in Food-Mastication and Fruits than the malocclusion group. Conclusion the Quality of Masticatory Function Questionnaire showed acceptable properties regarding internal consistency, reliability, and discriminant validity in evaluating the impact of caries on the perception of the masticatory function quality of Brazilian adolescents.

RESUMO: Objetivo: traduzir o instrumento em língua francesa "Questionnaire D'Alimentation" para o português brasileiro e realizar a adaptação transcultural em adolescentes brasileiros. Métodos: a tradução foi realizada com base em protocolo que consistiu na tradução para o português brasileiro (por um professor formado em Letras e uma Cirurgiã Dentista fluentes em francês), tradução reversa para o francês (realizada por dois professores de francês), revisão por Comitê de especialistas (duas tradutoras, uma nativa e uma juramentada, e duas professoras universitárias, sendo uma Cirurgiã Dentista e uma Fonoaudióloga) e equivalência cultural (pré-teste). A versão utilizada no pré- teste consistiu de 26 questões com cinco respostas possíveis (5-Likert), distribuídas em cinco domínios (Alimentação- mastigação, Hábitos, Carnes, Frutas e Legumes). O pré-teste e teste-reteste foram realizados com uma amostra de 20 adolescentes (10 meninos/10 meninas) de escolas públicas de Piracicaba (Brasil). Nesta fase, a alternativa "não entendi" foi incluída a cada questão, a fim de identificar aquelas não compreendidas. A confiabilidade teste-reteste foi avaliada para cada domínio utilizando os coeficientes de correlação intra-classe (CCI). Resultados: no pré-teste, foi observada uma excelente compreensão do instrumento; no teste-reteste, os CCIs variaram entre 0,45-0,81 (moderada a excelente concordância). Conclusão: a versão em Português do Questionnaire D'Alimentationmostrou ser de fácil compreensão por parte dos adolescentes brasileiros e útil na avaliação da função mastigatória e dos distúrbios de alimentação e deglutição que podem alterar a ingestão de alimentos.

ABSTRACT: Purpose: to translate the French language instrument "Questionnaire D'Alimentation" to Brazilian Portuguese and culturally adapt it for adolescents. Methods: the translation was based on a protocol that consisted of translation to Brazilian Portuguese (by a professor with a Literary Arts degree and a Doctor of Dental Surgery, both fluent in French and Brazilian Portuguese); back-translation into French; revision by a Committee of specialists (two translators, one native and one sworn translator, and two university professors, one being a Doctor of Dental Surgery and a Speech Therapist) and cultural equivalence (pre-test). The version used in the pre-test consisted of 26 questions with five possible responses (5-Likert), distributed in five domains (Food-Mastication, Habits, Meats, Fruits and Vegetables). The pre-test and test-retest was performed with a sample of 20 adolescents (10 boys/10 girls) from public schools of Piracicaba (Brazil). At this stage, the alternative "I did not understand" was added to each question in order to identify those that were not understood. Test-retest reliability was assessed for each domain using intra-class correlation coefficients (ICCs). Results: in the pre-test, an excellent comprehension of the instrument was observed; in test-retest, ICCs ranged from 0.45 to 0.81 (moderate to excellent agreement). Conclusion: the Portuguese version of the Questionnaire D'Alimentationhas shown to be easy to understand by Brazilian adolescents and useful in the evaluation of the masticatory function and feeding or swallowing disorders that may affect food intake.