Masticatory laterality--evaluation and influence of food texture.

The purpose of this study is the objective and quantitative evaluation of masticatory laterality and its daily variability. Various foods with different textures were used to investigate whether food texture influenced masticatory laterality. Ten healthy subjects and seven foods were used. Recordings of chewing movements were repeated three times at intervals of 1 week. Masticatory laterality was assessed with an Asymmetry Index [AI: (number of right side strokes - number of left side strokes)/number of total strokes]. Medians and ranges of the three recordings were calculated. The observed AI ranges in the three trials were limited with the exception of two subjects. Among the other subjects, averages of the absolute values of the medians were from 32.5 to 73.4%. Statistically significant differences between the hardest food and softer foods were observed in absolute value of AI medians. Masticatory laterality could be evaluated by an AI. Eight of 10 subjects showed limited ranges of AI in three recordings. It should be noted that a few people actually chew on either side but might chew on one side only on a particular day. Hard food evoked more masticatory laterality, and seemed more appropriate for laterality examinations.