Dentine hypersensitivity: effect of interactions between metal salts, fluoride and chlorhexidine on the uptake by dentine.

A large number of compounds may be applied to the teeth for preventive or therapeutic purposes, most notably in dentine hypersensitivity. The uptake of any one compound by tooth substances may clearly be affected by another to produce synergistic, additive or antagonistic effects. This study determined whether uptake interactions occurred between fluoride, chlorhexidine, strontium, tin and zinc. All compounds, in particular tin, showed considerable affinity for dentine. Fluoride reduced the uptake of zinc but not tin, strontium or chlorhexidine. Chlorhexidine increased the uptake of zinc, but not tin, strontium or fluoride. Zinc and tin decreased fluoride uptake but strontium had no such effect. Finally, chlorhexidine uptake was increased by zinc and tin but not by fluoride or strontium. Based on the theories proposed for the reaction of these various compounds with calcified tissues, explanations for the interactions can be made. The results appear relevant to some reported clinical effects of combinations of these compounds and indicate that such interactions may have advantageous or disadvantageous consequences depending on the basis for treatment.