Possible Contributions of Lingual Papillae to Intraoral Texture Sensation

Objectives: This study aimed to test the hypothesis that lingual papillae play a crucial role in intraoral texture sensation, much like fingerprints for the hands. We investigated possible associations between morphometric characteristics of the lingual papillae, haptic texture, and other mechanical sensations on the tongue mucosa.
Methods: Twenty-four healthy adults, with no clinical oral abnormalities, participated in this study. To evaluate the morphometric characteristics of the lingual papillae, dorsal surface roughness of the anterior tongue was measured. This was accomplished by X-ray micro-computerized tomography image analysis of silicone replicas of the participants’ anterior tongue dorsum. The threshold of graininess detection was set as the lowest concentration of aqueous suspension containing microcrystalline cellulose which particles were recognizable. Additionally, the two-point discrimination and tactile detection thresholds were evaluated to determine thresholds of mechanical sensation.
Results: The thresholds of graininess detection, two-point discrimination, and tactile detection, had ranges of 0.1-3.2 wt%, 1.2-3.6 mm, and 2.52-6.30 gf/mm², respectively. No significant correlations were found between any two sensory thresholds. The two-point discrimination and tactile detection thresholds did not correlate significantly with any morphometric parameters of surface roughness. However, the graininess detection threshold was significantly correlated with several morphometric parameters; it correlated positively with Rsk (skewness) and negatively with both Rq (root mean square deviation) and Ra (arithmetical mean deviation).
Conclusions: Morphometric characteristics of the lingual papillae correlated significantly with intraoral sensitivity for graininess. It is possible that intraoral texture sensation is mediated by the deformation and vibration of the oral mucosa. These movements are generated as the tongue scans the surface of objects, such as foodstuffs, in the mouth. Abovementioned findings suggest that more rough lingual papillae might enhance intraoral texture sensation through their deformation and/or vibrations.