Estimation of the Velocity of the Salivary Film at Some Different Locations in the Mouth

Abstract

Previously, we studied the clearance rates of KCl from agarose gels positioned at different locations in the mouth, and showed that the rates were much slower than when clearance was into a well-stirred solution. We designed the present in vitro study to test the effect on KCl clearance of the velocity of a 0.1-mm-thick film of water flowing over an agarose gel of the same diameter and composition as those used in vivo. The thickness of the salivary film overlying dental plaque has been estimated to be about 0.1 mm, and we assumed that when clearance rates in vitro matched those found in vivo, velocities of the fluid film (in vitro) and the salivary film (in vivo) must be equal. On this basis, it was calculated in the present experiments that when salivary flow was unstimulated, the velocity of the salivary film at the level of the teeth varied between about 0.8 mm/min (upper-anterior buccal region) and 8.0 mm/min (lower-anterior lingual region). When salivary flow was stimulated, this was estimated to increase the velocity of the salivary film from 2 to 40 times, depending on the location in the mouth. It is postulated that the slow movement of the salivary film when flow is unstimulated allows for accumulation of diffusants from dental plaque, which reduces the concentration gradient for diffusion from plaque and prolongs the clearance time of such metabolic products as acid.

Up-regulation of competence- but not stress-responsive proteins accompanies an altered metabolic phenotype in Streptococcus mutans biofilms

“…1). Medium at pH 7?0 was pumped into the bottom of the reactor and passed out at the top at a standard flow rate of 1?75 mm min 21 over the glass surfaces to mimic the flow rate of saliva over oral tissues (Dawes et al, 1989). A number of these flow reactors maintained at 37 uC were used in any one experiment to obtain sufficient biofilm-grown cells for 2-dimensional electrophoretic (2-DGE) analyses.…”

Adhesion of Streptococcus sanguinis to Dental Implant and Restorative Materials in vitro

“…The dispenser and flow chamber were connected by tubes to a peristaltic pump (Spetec GmbH, Erding, Germany) with an integrated speed controller. Flow rate of the suspension was 0.8 ml/min, which corresponded roughly to physiological conditions of low shear in the oral cavity 11) . The system was placed on a shaker adjusted at 260 impulses/min to maintain the homogeneity of the bacterial suspension at room temperature for one hour (Fig.…”

Supragingival Calculus: Formation and Control

“…As Collins and Dawes (1987) have suggested, saliva is present in the mouth not as a bulk volume but as a mobile film of 0.1 mm average thickness. For unstimulated salivary flow, the velocity of the film over tooth surfaces is estimated to vary between 0.8 and 8 mm/min, depending on different oral regions and status of saliva; for stimulated salivary flow, the velocity is from 1.3 to about 350 mm/min (Dawes et al, 1989). The lowest film velocity of 0.8 to 1.3 mm/min occurs on the facial surfaces of the upper incisors, while the highest salivary film velocities are observed on the lingual surfaces of teeth (Dawes et al, 1989).…”