Masticatory function according to body mass index. Part I: kinematic analysis using different food textures

Introduction: Chewing is a learned orofacial function, important in the nutrition process of most mammals. It has been described that it can vary according to the characteristics of the individuals and the characteristics of the food. The aim of this study was to compare the kinematic cha-racteristics of mastication in subjects with different body mass index (BMI), including foods of different hardness in the analysis. Material and Methods: A cross-sectional observational study was con- ducted. The mastication of 3.7 g of peanut (soft food) and 3.7 g of carrot (hard food) was compared among three study groups formed according to BMI: normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9) and obese (BMI ?30); each with 7 participants. The kinematics of the masticatory movement were assessed with a 3D Electromagnetic Articulograph, the characteristics analyzed were number of masticatory cycles, masticatory frequency, speed and area of the cycles. Results: No significant differences were noted among the study groups for the number of masticatory cycles, frequency or speed in the two foods studied. It was observed that when chewing carrot, the horizontal area of the masticatory cycles was significantly larger in the obese than in the overweight group. However, when chewing peanuts, this parameter did not present significant differences among the different groups. A comparison of the characteristics of mastication of the two foods revealed that the carrot chewing presented a significantly greater masticatory frequency and speed than the peanut chewing. Conclusion: This study demonstrated that food hardness influences the kinematic characteristics of mastication more than BMI, noting that hard foods are masticated faster and more frequently than soft foods and that masticatory frequency tends to increase with BMI.