Intraoral Transfer of Topically Applied Stannous Fluoride

Abstract

A series of experiments was conducted to show whether or not Sn++ and F- ions could be transferred intraorally to untreated control teeth, when part of the dentition in the same mouth is topically treated with Sn F2. In this study, a solution of Sn F2 was topically applied to one quadrant of rats'' teeth or to one-half of the dentition of human volunteers who wore partial dentures bearing squares of human enamel. Chemical analyses of the animal teeth or human enamel squares showed that an intraoral transfer of tin and fluoride ions to the "untreated control" side of the mouth was unavoidable, in a practical sense, even if great caution was employed to avoid any direct contamination. Some transfer of other topically applied agents has to be suspected. These results throw a serious doubt on the validity of clinical half-mouth studies as the error induced, i.e., a reduction of caries in the "control" teeth, will be greater, the greater the effectiveness of the applied anticaries agent at low concentrations.