The aim of this study was to show the reaction varieties of human tooth enamel and dentin with a carbonated soft drink, Sprite. After one week exposing into the soft drink, the sliced tooth specimens were examined by macroscopic and microscopic and then carried out the micro X-ray diffraction analysis using a 100 gm diameter X-ray beam. The macroscopic and microscopic results showed the wide varieties from the one showing a very slight increase white-spot areas in the enamel to the another showing almost complete decay of the enamel. The crystallites in the examined enamel and dentin changed drastically as follows; the one enamel sample showed the decrease of crystal amount and some ionic substitutions, and the another dentin sample showed the increase in crystallinity and ionic substitutions. These results clearly showed that the original tooth enamel and dentin had their own crystallographic properties differing from each others. This study provided a crystallographic basic data which will be applied to a tayler-made individual preventive dentistry in near future.