The Effect of Anatomic Clearance Between Tongue and Soft Palate on Retronasal Olfactory Function

Abstract

Research shows that odorants travel to the olfactory receptors by two routes. Oral conditions, mouth movements, mastication, and swallowing are known to influence the perception of retronasal stimuli. The dimension of the anatomical clearance between the soft palate and tongue might affect the retronasal olfaction because retronasal olfaction is only possible when the soft palate-tongue barrier is opened. Therefore, in this present study, our aim is to evaluate the effect of the anatomical clearance between tongue and soft palate on retronasal olfactory function. After rating the mallampati score for the classification of the clearance between tongue and soft palate, the "Sniffin' Sticks" test for orthonasal olfaction and retronasal olfactory testing were performed. The study was carried out on 276 subjects, and the mean age of the participants was 27 years ranging from 19 to 53 years. The participants were divided into two groups: Group 1 included participants with mallampati Class 1 and 2 scores; Group 2 included participants with mallampati Class 3 and 4 scores. This study clearly shows that the dimensional differences in the anatomical clearance between the soft palate and tongue had no effects on retronasal olfaction.