紫外線吸収並びに蛍光測定から見たEDTAによる硬組織脱灰過程の研究

Abstract

The decalcifying process of the dental and osseo hard tissues was investigated in EDTA solution by the methods of ultraviolet absorption spectrum and fluoro-metry together with the determination of dissolved saccharide, and the following conclusions were obtained :I. Ultraviolet absorption of EDTA solution1. The ultraviolet absorption spectrum of EDTA-Na salt solution considerably varies with the degree of dissociation of the solution.2. It has been already reported that the ultraviolet absorption of EDTA-Ca salt solution shifts to the shorter wave-lengths than that of EDTA-Na salt solution, but little attention has been paid to the findings that -Ca salt solution gives a higher absorption than -Na salt solution at longer wave lengths than 255 mμ.3. The absorption curves of the mixed solution containing EDTA-Na salt and -Ca salt at various proportions at pH 4.5 show an isosbestic point, which means that these solutions are the two-component system.4. Considerable variations are observed with the absorption of EDTA-Ca salt solution as pH varies, though it likely keeps an almost stable structure at pH 5-10.II. Decalcifying process in EDTA solution observed with ultraviolet absorption1. Decalcification of marbleThe change in absorption illustrates that EDTA-Na salt solution mainly changes into -Ca salt solution as the decalcification proceeds. In this case, a curve showing the change in absorption at 250 mμ under the decalcifying process well agrees with the result obtained from the determination of Ca by the titration method.2. Decalcification of dentin and boneDiffering from the above mentioned marble, dentin and bone give a steep increase of absorption at 270 mμ-300mμ at the beginning, this absorption then markedly decreases for a while and again gradually increases with a duration of the decalcification. It seem that such increase of absorption at the whole range of longer wave lengths than 270 mμ shows a simultaneous extraction of organic substances which gives absorption and also scattering at this range of wavelength.3. Decalcification of enamelThe steep increase of absorption observed with dentin and bone at the very beginning of the decalcification is not so obvious in this case, and the absorption shows an only gradual increase at the whole range.III. Fluoro-metry examined under the decalcification in EDTA solutionFluoro-substance is considerably extracted at the beginning of decalcification of dentin, but this fluoroescence becomes not observable for a while and then gradual dissolution of this substance seems to be proceeded again. This phenomenon is similar with the case of ultraviolet absorption.IV. Determination of saccharide in EDTA decalcifying solution of dentinThis solution gives some reactions of saccharide. The determination of saccharide by the “Anthron reaction” has shown that saccharide dissolves out considerably at the very beginning of decalcification, which followed by a decrease and again increase as observed with the of ore-mentioned ultraviolet absorption and fluoro-metry.