The correlation of gagging threshold with intra-oral tactile and psychometric profiles in healthy subjects: A pilot study

Excessive gag reflex could be problematic for adequate dental care. Although various factors may increase the susceptibility to gagging, its contributing factors have not been fully determined. This study aimed to determine whether gag reflex was associated with tactile sensitivity and psychological characteristics. Fifteen volunteers of healthy males and females each were recruited for this study. After completing a questionnaire describing the self-perceived gag reflex activity, a disposable saliva ejector was inserted along the palate into the mouth until gagging was evoked. The ratio of the insertion depth to the palatal length was used as an index for the gagging threshold. The two-point discrimination (TPD) and Semmes-Weinstein monofilament (SWM) tests were performed to assess the tactile sensitivity of the palatal regions (hard palate, anterior and posterior soft palate). The Symptom Checklist-90-Revised was used to investigate the relationship between the gagging threshold and the psychological status. Our findings showed that the gagging threshold had a significant positive correlation with the TPD and SWM thresholds on the hard palate. The psychological profiles of psychoticism and hostility score were also significantly correlated with the gagging threshold. However, there were no significant differences in the tactile and gagging thresholds, as well as the psychological profiles, between males and females. Our results suggested that the tactile sensitivity of the anterior palate is a determining factor for the gagging threshold and implied that the initial response of the oral entry site to stimulation may lead to the development of gag reflex.