Effect of Hyposalivation on Bread Mastication in Healthy Individuals

Solid foods mix with saliva during mastication to form a bolus. The water content of the food bolus and lubrication in the oral cavity are critical factors that determine the dynamics of the masticatory muscles. Among other factors, fat is believed to affect masticatory behaviour by lubricating foods.

The effects of artificially induced hyposalivation on masticatory behaviour and bolus properties were investigated using bread with varying water content and spreads to evaluate how these properties affect masticatory behaviour with hyposalivation.

Twenty healthy volunteers were instructed to eat bread with and without spreads. Before and after atropine administration, electromyographic activity was recorded in the masseter, suprahyoid and infrahyoid muscles. Masticatory movements and bolus properties were compared between breads, oral cavity conditions and spreads.

Hyposalivation directly affected mastication behaviour only for dry bread, with masticatory duration and cycle time, and suprahyoid muscle activity increasing. These effects were primarily observed during the middle and late stages of mastication, particularly in the absence of spreads. The effect of spreads was significant only on dry bread with hyposalivation, decreasing masticatory cycle time and masseter and suprahyoid activity at the middle-to-late stage. Hyposalivation decreased the water content and increased the hardness of the bolus in dry bread, both with and without spreads.

Bolus formation and transport during the mastication of dry bread are interrupted by hyposalivation. The addition of spreads can compensate for the affected masticatory movements without significant changes in bolus properties.