Compositional Changes after Heating of Enamel Crystals Demineralized by Soft Drink

• Published in: International Journal of Oral-Medical Sciences Vol. 22; no. 2; pp. 85 - 90
• Main Authors: Watanabe, Arata, Kono, Tetsuro, Ogawa, Takahiro, Togashi, Yuya, Sakae, Toshiro, Okada, Hiroyuki
• Format: Journal Article
• Language: English
• Published: Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo 16.03.2024
• Subjects: biological apatite; human tooth enamel; micro-FTIR; soft drink; thermal decomposition
• ISSN: 1347-9733; 2185-4254
• DOI: 10.5466/ijoms.22.85

To date, significant research has been conducted on biological apatite, the composition of which deviates considerably from that of hydroxyapatit（eCa（POl0 4）（6 OH）2）. Our previous studies have shown individual differences in the composition of biological apatite in human enamel and diversity in enamel. Furthermore, heating amplified the variability of the components. A study on soft drink demineralization has found that Sprite® has the highest enamel solubility among many soft drinks. Fourier transform infrared spectrophotometers are often used to analyze the composition of materials. This study comprehensively investigated the mechanism of Sprite® induced demineralization. Human enamel demineralized with Sprite® and heated was compared with that heated after resting in a container moistened with saline solution. The samples were then analyzed by micro-Fourier transform infrared spectroscopy（micro-FTIR）. The results showed that the peak values for carbonate were consistent with those of common biological apatite crystals. The peak values for phosphate were 471 to 594 cm-1 for the PO43ν-2 absorption band, 555 to 675 cm-1 for the PO43ν- 4 absorption band, 960 to 1,192 cm-1 for the PO43ν- 1 absorption band, and 1,003 to 1,227 cm-1 for the PO43ν- 3 absorption band. Additionally, the peak intensity of the carbonate peak decreased in all samples after demineralization, whereas the phosphate peak partially increased in intensity and shifted significantly to the left. Furthermore, decreased intensity of the carbonate peak was observed in all samples in the experimental group, suggesting that carbonate was leaking into the Sprite® soaking solution. Other papers have not found such significant changes in phosphate in caries or in demineralization reactions with other demineralizing solutions. The difference may be because Sprite® was used for demineralization. Future studies should compare the components of the Sprite® soaking solution before and after demineralization to clarify the kinds of chemical reactions that have occurred.