OBJECTIVE The narrowing of the mandible during opening and protrusion movements is defined as median mandibular flexure (MMF). MMF is caused by the attachment of mandibular muscles; therefore, it can be assumed that a greater amount of maximum occlusal force (MOF) may cause more flexion and could affect the survival of dental and implant restorations. The purpose of this study was to evaluate any relationship between MOF and MMF in a sample of adults. METHODS In vivo - comparative study. METHODS In this descriptive, cross-sectional, nondirectional study, a sample of 90 volunteers were recruited (45 men and 45 women). MOF was measured by applying the strain gauge receptor to the first molar region, and MMF was measured by calculating the variation in the intermolar distance by a digital caliper with an accuracy of 0.01 mm using an impression and resulted in the stone cast during the maximum opening and closed-jaw positions. The body mass index (BMI) also was calculated. METHODS Data were analyzed using the SPSS software (version 23) inferential and descriptive statistics, linear regression, and Pearson correlation coefficient. P < 0.05 was considered statistically significant. RESULTS There was no statistically significant relationship between MOF and MMF (P = 0.78), but there was a significant association between MOF and BMI (P < 0.001, r = 0.475) and gender. CONCLUSIONS Although MOF and MMF are both important and effective factors in the success of prosthetic restorations, one cannot be expected by the other and both should be considered in the treatment plan separately.