[Fractionation of the salivary cellular elements by Percoll density gradient centrifugation and the distribution of oral malodour precursors].

Volatile sulphur compounds (VSC) are the cause of oral malodour. VSC are produced from thiol and disulphide contained in the salivary cellular elements. However, the distributions of thiol and disulphide have not yet been elucidated in the salivary cellular elements. Hence, Percoll density gradient was employed in this study to fractionate the cells, and the distributions of thiol and disulphide were also studied. The intact squamous cells distributed in upper layer fraction (density: less than or equal to 1.051 g/ml) separated by Percoll density gradient centrifugation, the cells were 40 to 50% of the salivary cellular elements. The degraded cells, which were out of shape or lost nucleus, distributed in middle (density: 1.051-1.076 g/ml) and lower layer fractions (density: greater than or equal to 1.076 g/ml). The density of cells was also found to increase in process of the cell degradation. The 24 hour incubation study of saliva showed that the intact cells decreased markedly, and the degraded cells increased in middle layer fraction. It was indicated that cell degradation was very slow in saliva. Disulphide and thiol of VSC precusors distributed with high concentration in lower layer fraction of high density. On the basis of the results high density cells might accumulate on the tongue dorsum for long time and be the major source of VSC precusors.