Rheology of fluoride gels

A number of fluoride gels containing a hydroxyalkyl cellulose thickening agent show non-Newtonian rheological behavior in the form of stress thinning (apparent viscosity decreasing with shear rate). Viscosities of 450 to 780 poise at low rates of shear down to 1.0 to 2.0 poise at high rates of shear were obtained. The effect of temperature on viscosity was comparatively small. One gel, containing a noncellulosic thickening agent showed a much more pronounced stress thinning (7,500 poise at low rates). Furthermore, at low rates of shear this material showed pronounced elastic behavior. This may well be clinically advantageous.