Masticatory Performance in Elderly by Evaluating the Swallowing Behavior.

There has been little masticatory performance investigation in the eldery by evaluating their swallowing behavior. This study was conducted to investigate whether a study of swallowing behavior can be used to determine the relationship between mastication and aging by evaluating the timing of the electromyographic (EMG) activity of jaw opening and closing muscles.Young and elderly dentates (ten subjects respectively) were asked to randomly chew pudding, raisins, and a mixture of both textures until swallowing. Surface EMGs of the bilateral posterior temporal, masseter, myohyoid, and anterior belly of digastric muscles were simultaneously recorded with mandibular movements using Mandibular Kinesiograph (Myo-Tronics). Time differences of burst onset (TDBO) among workingside jaw opening and closing muscles were observed throughout the mastication sequence. Time simultaneity of burst onset of jaw opening and closing muscles was revealed for each cycle and analyzed by cumulative frequency distribution.In raisin or mixed food chewing, TDBO in elderly subjects increased and were delayed significantly compared with the young dentate group. However, there was no difference between both groups during pudding chewing. The elderly subjects had a fewer swallowing cycles compared to the young subjects when chewing the foods that were difficult to crush or to form a bolus of raisin and mixture of pudding and raisins.It was suggested that masticatory deterioration by aging may be affected by bolus formation ability and oral sensitivities.