Properties and modification of soft drinks in relation to their erosive potential in vitro

The objective was three-fold; (1) to test the erosive potential (EP) of various soft drinks, (2) to determine properties related to the soft drinks that were important for EP, and (3) to test possibilities of reducing the EP of soft drinks by modification.

Sixteen soft drinks from the Icelandic market including three modified soft drinks were used. The pH, calcium, phosphorus, and titratable acid (TA) to pH 5.5, 7.0, and 10.0 were determined in each drink. From these results the buffer capacity (beta) at pH 4.5, 6.3, and 8.5, degree of saturation with respect to hydroxyapatite (DS(HAP)), and critical pH (DS(HAP)=1) were calculated. One orange juice was modified by addition of various concentrations of calcium and phosphate. EP was determined as weight loss from tooth pieces after immersion into the soft drinks for 24 and 72 h as well as calcium increase in the soft drink upon immersion.

EP of the drinks varied from 0-10% weight loss and 0-31 mmol calcium increase. The pH in carbonated and sport drinks was lower than in fruit juices, whereas TA and beta was considerably higher in fruit juices. Significant correlations were obtained between EP and TA, beta, pH, and DS(HAP) (r(s)=0.69-0.90). Addition of calcium and phosphate to the experimental drinks considerably decreased their EP.

We conclude that several properties related to soft drinks have an impact on their EP upon long exposure time to teeth and that moderate modification could be a helpful measure to reduce the EP of soft drinks.