Development of a simulated tongue substrate for in vitro soft “oral” tribology study

Abstract

The tribological principle of the relative movement amongst food particles as well as between food particles and oral surface is considered as an important physical mechanism governing food oral processing and sensory perception. Various in vitro techniques which mimic oral lubrication have been reported in literature, but most of such approaches were not representative of oral features, in particular the substrate. Therefore, it is necessary to reveal the topographic characteristics of human tongue and the morphological features of fungiform and filiform papillae. With this background, this work applied imaging technique to investigate distributions of the fungiform and filiform papillae among young Chinese subjects. The distribution and average size of the two types of papillae were analyzed. A significant negative correlation was observed between the density of filiform papillae and average tongue roughness (r = −0.47, p < 0.01). A substrate simulating topographic features as well as mechanical strength of human tongue was fabricated using a moulding technique. The reliability of the substrate was verified by lubrication testing over a wide range of sliding speed and surface load, using water and syrup solutions as model systems. Results show that the current substrate provides a feasible application to soft tribometers for in vitro oral tribology study.