The effects of stannous and stannic ions on the formation and acidogenicity of dental plaque in vivo

Abstract

The present study was concerned with the effect of stannous and stannic ions on the formation and acidogenicity of dental plaque in vivo. Five dental students participated in the study on inhibition of plaque formation. They rinsed for four days with 0.2% aqueous solution of either Sn²⁺ or Sn⁴⁺ and in addition 15% w/v sucrose to enhance plaque formation. The Pl.I. was recorded after each series. Another test panel participated in the study on inhibition of acid production. The pH of the plaque was measured in situ. The stannous ion showed marked inhibiting activity on plaque formation whereas the stannic ion showed only a slight effect. The stannous ion also showed an effect in reducing the acidogenicity of dental plaque whereas the stannic ion showed no such effect. These findings support the concept that the stannous ion reduces the metabolic activity of plaque by oxidation of thiol groups by affinity for these groups. This is not the case with stannic ions. It seems conceivable that the reduced metabolic activity in plaque is the main factor which causes plaque inhibition. The slight plaque inhibiting effect of the stannic ions may be caused by inhibition of adsorption as such as this ion has no direct effect on the metabolism of the plaque.