The pH and titratable acidity of a range of diluting drinks and their potential effect on dental erosion

To investigate, in vitro, the potential dental effects of diluting juices by measuring their acidity levels and to examine the effect dilution has on the potential erosive properties of the drinks.

Four commonly available diluting drinks were assessed for both pH and titratable acidity at a variety of dilutions, reflecting the range of concentrations over which such drinks may be consumed. Predetermined dilutions of citric acid and hydrochloric acid, with similar pH values to those of the drinks, were used as positive control acidic solutions. The pH measurements throughout the study were made using a pH electrode connected to an Orion EA940 IonAnalyser.

All four drinks demonstrated a high degree of resistance to a rise in pH, indicating high intrinsic buffering capacity. The measured pH changed very little with increasing dilution ratio when compared to the citric and hydrochloric acid controls, even when considered extremely dilute. In contrast, the titratable acidity of each of the drinks reduced proportionally with increasing dilution, thereby reducing considerably its erosive potential.

While dilution had very little effect on the measured pH values, the titratable acidity reduced as the drink became more dilute. Since there appears to be a direct relationship between dilution and titratable acidity, the erosive potential of diluting juices may be reduced substantially by the addition of water. It remains unlikely, however, that the drinks would ever be consumed at a 'safe' level of dilution due to diminished taste and colour.