Effects of Neo-Tetrazolium Chloride on the Phosphorescence of Teeth

¹ Western Reserve University School of Dentistry, Cleveland, Ohio

Phosphorescence is induced in teeth with an intensity and duration that permits them to be photographed by the light of their afterglow in a totally darkened room.

Exposing the surfaces of dental hard tissues to an 0.5 per cent aqueous solution of neo-tetrazolium chloride for a period of 1 hour results in a selected quenching effect on the phosphorescence previously exhibited in specific regions of certain teeth. In the main, pulp, cementum, and carious enamel are more prone to exhibit this quenching effect, whereas dentin is more resistant. The phenomenon probably represents a direct capture of electronic energy by the tetrazolium from some substance in the tooth that initially absorbed the ultraviolet radiation. This technique may be proved useful in analyzing changes in the chemical composition or physical state of the surfaces of hard tissues. Exploring the fluorescence and phosphorescence of uncooled and supercooled amino acid-neo-tetrazolium mixtures revealed that there is a specific quenching that occurs in L-tryptophane-neo-tetrazolium combinations; this is suggested as a possible mechanism for the neo-tetrazolium quenching in selected areas of dental structure. The failure of neo-tetrazolium to alter the intense white phosphorescence in L-proline is suggested as a possible reason why the dentin portion of the tooth tends to be more resistant to the quenching effect of the neo-tetrazolium solution.