Abstract
Consumption of various kinds of soft drinks containing fruit juices has increaced remarkably in the past ten years in Japan. Most fruit juices contain large amounts of organic acids, and some experimental studies of the influence of these acids on human teeth have been reported. However, there have been few studies regarding soft drinks.
In this thesis the author examines the effects on human tooth enamel of some organic acids normally found in soft drinks, and discusses some countermeasures. Part I describes the methods employed: Part II compares the decalcifying effects of various kinds of soft drinks: Part III compares the effects of three organic acids-citric acid, tartaric acid, and malic acid-on human enamel powder: Part IV describes the effects of orange-flavored soft drink on human enamel powder: Part V describes the decalcifying effects of orange-flavored soft drink on human enamel powder that has been treated with fluoride compounds: and Part VI describes the decalcifying effects of orangeflavored soft drink on the enamel of deciduous teeth.
The author's findings are as follows:
1) Soaking the enamel of permanent teeth in various soft drinks and in citric acid showed that lemon drink caused the strongest decalcification, followed by orange, apple, grape and pineapple drinks, in that order. The decalcification caused by these drinks was stronger than that caused by citric acid solutions in which the pH was adjusted to the same value as the acid contained in each of the drinks.
2) Citric acid caused the strongest decalcification of enamel powder, followed by tartaric acid and malic acid.
3) The decalcification of enamel powder of both permanent and deciduous teeth caused by orange drink was stronger than that caused by citric acid. There was some slight indication that citric acid decalcified deciduous teeth more than permanent teeth, but there was no significant statistical evidence to support this. Soft drinks caused more decalcification of deciduous enamel powder than of permanent enamel powder.
4) Acid-proofing enamel powder of both permanent and deciduous teeth with a 2 % sodium fluoride solution and with Brudevold's II solution appeared to be more effective against the decalcification caused by soft drinks than against that caused by citric acid. Brudevold's II solution was more effective than 2 % sodium fluoride solution.
5) When deciduous teeth were soaked in soft drinks, the teeth treated with fluoride compounds were less affected than untreated teeth. In addition, Brudevold's II solution was decidedly more effective than 2 % sodium fluoride solution.
