Influences of Habitual Mouth-breathing on Taste Sensation

Objectives: Habitual mouth-breathing is reported to cause various disorders of orofacial growth and function, such as narrow face, dry mouth, malocclusion, periodontal diseases, and sleep disruption. It is also regarded as a risk factor of taste disorder. However, the relationship between habitual mouth-breathing and taste disorders has not been investigated sufficiently. This study aimed to examine the influence of habitual mouth-breathing on taste sensitivity and oral condition.
Methods: Twelve volunteers (6 men and 6 women) aged 21-31 years (average: 27 years) participated in the study. Based on their responses to a questionnaire regarding habitual breathing type, subjects were assigned to the mouth breather (MB) or control (C) group (n=6 for each group). Recognition thresholds for five basic tastes were measured using the filter paper disk method. Eight concentration steps of sucrose, NaCl, citric acid, quinine hydrochloride and monosodium glutamate were used for sweet, salty, sour, bitter and umami stimuli, respectively. The stimulation points were the tip, lateral border, and root of the tongue. The salivary flow, salivary viscosity (spinnability), and oral moisture were also measured as factors related to taste sensitivity.
Results: At certain stimulation points, the recognition thresholds for sweet, sour, salty, and umami tastes were significantly higher in the MB group (p<0.05, Mann-Whitney U-test). However, no significant difference was found in the thresholds for bitterness, salivary flow, salivary spinnability, and oral moisture.
Conclusions: This study suggests that habitual mouth-breathing deteriorates taste function.