Abstract
In the previous report, it was pointed out that the Okamoto's original histochemical method for tin was not applicable to enamel owing to its strong acidity.
Therefore, the purpose of this experiment was to improve the original procedure in order to establish the reliable histochemical method for tin in dental enamel.
The first experiment was concerned with the spectroscopic observation on the tin-gallein complex. The tin-gallein ethanol solution showed a strong absorption at 500mμ, while no distinct absorption was found in the range of visible light with the gallein ethanol solution alone. Thus, the differentiation between both was very easy.
On the contrary, the original acidic galleinethanol solution itself had a strong absorption at 460 mμ, which resembled that of the gallein-tin complex at 480 mμ. The contrast between these two colors was too weak to distinguish each other. The advantage of the gallein-ethanol solution was thus clearly demonstrated.
In the application of the staining, freshly extracted teeth were first treated with stanuous fluoride. After stained by the gallein ethanol solution, thin ground sections were made of them and observed under the microscope. The characteristic findings on ground sections were that the artificially decalcified lesions such as disussed in the previous report were never found at any potion. The red spots representing gallein-tin complex were clearly distinguishable from the other portions of enamel structure.
The procedure for the improved histochemical method was: stain the tooth or tooth section in 0.1% gallein ethanol solution at 37°C (optional) for 5 days or more.
From the results mentioned-above, the improved gallein method will serve for the histochemical observation of tin in or on enamel to elucidate the mode of action of stannous fluoride in preventing dental caries.
