2019 年 28 巻 2 号 p. 129-138
To elucidate the crystallo-chemical reaction between the enamel and carbonated soft drink, a micro-X-ray diffraction analysis (micro-XRD) was conducted using the human tooth sections soaked in the drink (Sprite®) for 1 and 7 days. In this study, 4 typically and heavily dissolved teeth were selected from 20 teeth, and the divergence of the crystallographic properties of the enamel was analyzed.
All of the untreated human tooth enamels exhibited only the apatitic XRD patterns. We confirmed that the carbonated soft drink changed the macro- and microscopic morphological features of individual tooth enamel. The following 4 results were obtained from our study: i) the unit cell dimensions and crystallinity of the untreated enamel apatite varied between the layers and the individual teeth; ii) after the soaking experiment, the crystallographic properties of the enamels changed remarkably and displayed non-uniformity; iii) no relationship was discerned between the enamel’s crystallographic properties and the sensitivity of the carious attack; and iv) the intermediate reaction product of soaking was uncovered; however, it was not identified at this time. The presence or absence of occurrence and variations in the amount of intermediate product reflected the complex chemical and crystallo-chemical reactions between the decalcification solution and the human tooth enamel crystallites.
We clearly established that the untreated human tooth enamels differed in their crystallographic properties and did not react in the same manner, which resulted in varied apatitic structures after soaking. These results necessitate reconsideration of the generally accepted caries protection methods that are applied as common standards for all individuals and tooth enamels.
