Temperature Effect on Soft Acidic Drink Enamel Erosion in vitro

Objectives: To measure erosion of human enamel subjected to a soft acid drink challenge at different temperatures by contact profilometry.

Methods: Ten drinks were investigated; two orange juices (predominantly citric acid based) and eight dilutable soft acidic drinks, of which three were predominantly citric acid based and five were predominantly based on mixed hydroxy organic fruit acids. The erosive potential of all drinks on enamel were investigated at temperatures of 4, 20, 37, 60 and 80°C. In addition, each drink was heated to 100°C prior to being cooled to 60°C before the enamel samples were investigated. For each beverage, at the specified temperature, five polished enamel samples were investigated. Samples were baselined using contact profilometry transversing in the x-axis to ensure a mean deflection of the z-axis of less than 0.3 microns. Treatment areas were masked to expose a 2mm window of enamel for treatment. Samples were fully immersed and agitated in drink at constantly regulated temperature for a total of 90 minutes and measured by profilometry at 30, 60 and 90 minutes. Samples were immersed in fresh drink after each measurement. Two way Analysis of Variance statistics were applied to the data.

Results: Depth of enamel erosion increased for all drinks as temperature rose to 60°C. Predominantly citric based drinks exhibited a significant (p<0.05) reduction in erosion investigated at 80°C and above compared with the mixed fruit acid drinks.

Conclusion: Citric drinks (juices and dilutable drinks) exhibit changes in erosive potential between 60 and 80°C. The reduction in erosion is stable on cooling to 60°C. This reduction in erosion is not evident in the mixed fruit acid drinks. Further investigation is warranted to develop and market citric drinks with less erosive potential.