Effects of increased hardness on jaw movement and muscle activity during chewing of visco-elastic model foods

• DOI: 10.1007/s00221-001-0916-5
• Publication Date: 2002-10-06T13:44:04Z
• Authors: Peyron M.; Lassauzay C.; Woda A.
• Keywords: Adult; Male; 570; electromyography; jaw movements; mastication; Physical Exertion; model food; Temporal Muscle; Models, Biological; Bite Force; Feedback; 03 medical and health sciences; 0302 clinical medicine; food texture; Humans; [SDV.MHEP] Life Sciences [q-bio]/Human health and pathology; Electromyography; Masseter Muscle; Proprioception; Elasticity; Jaw; Masticatory Muscles; Mastication; Female; Stress, Mechanical; [SDV.MHEP]Life Sciences [q-bio]/Human health and pathology; Muscle Contraction

When food is chewed, sensory feedback adapts the motor program to the characteristics of the food. However, the relationship between the physical properties of different foods and the motor response is poorly understood. In this study, we developed edible and well-controlled model foods in order to describe some of the stimulus-response functions of the food-mastication loop. Four gelatine-based visco-elastic model foods identical in shape and size but differing in hardness were prepared. They displayed reproducible sensory and physical characteristics and were distributed on a wide hardness scale. Electromyographic activity of masseter and temporalis muscles and jaw movements in the frontal plane were simultaneously recorded during mastication in 15 young men with intact dentition and good oral status. Almost all EMG and jaw movement parameters were clearly affected by increasing hardness of model foods. However, it is possible to summarise the results by reducing the number of parameters to three: the number of chewing cycles, EMG activity of any one of the two temporal or the two masseter muscles and the amplitude of the opening mandibular movements. Indeed, these were the best transcriptors of the hardness range of the model foods used in this study. As inferred from these parameter recordings, the food hardness modifications were strongest during the first five strokes, began as early as the first stroke and lasted for the whole sequence.