Second Order Differentiation Analysis of Micro FTIR Method Revealed the Variable Erosion Characteristics of Carbonated Soft Drink for the Individual Human Teeth Enamel

To clarify the chemical processes of dental caries in detail, and to clarify whether or not the caries processes are common through the whole part of various teeth, the micro-FTIR spectroscopic analysis was carried out using the human teeth sections soaking into a carbonated soft drink (Sprite (R) ) for 1 and 7 days. After the twenty human teeth examined, the teeth were grouped into two; the lightly dissolved one and extremely heavily dissolved one on the basis of the macroscopical and microscopical features after the soaking experiment. In this study, one lightly dissolved sample (A) and one heavily dissolved sample (B) were picked up and described. The micro-FTIR spectroscopy showed the drastic changes in the P-O absorption bands of the outer layer enamel of both samples, while those of the inner layer enamel remained almost unalterably. This result indicated that the erosive processes mainly attacked the phosphate ion environments in the biological apatite crystal structure of tooth enamel. The second order differential curves of the micro-FTIR patterns firstly reported here showed the small but significant P-O band peak shifts among the all analyzing points except for 7 days of Sample B, suggesting the individual physicochemical characteristic of tooth enamel apatite. This study presented only two extreme cases, but clearly showed the variety of human tooth enamel characteristics among the individuals and parts of the tooth enamel. It was suggested that generally accepted caries protection methods might not be a common standard for every people and every teeth enamels.