The effect of pH on the erosive potential of Iranian and imported soft drinks using atomic absorption spectrophotometry

An increase in pH can affect the erosive potential of soft drinks, but the possible role of calcium salts and phosphate has not been fully recognized. The aim of the present investigation was to evaluate the effect of pH on the erosive potential of soft drinks on permanent tooth enamel. This experimental in vitro study was performed on 8 beverages and 240 intact premolars extracted for orthodontic purposes. Two Iranian soft drinks (Cola and Orange Zamzam) and 2 imported ones (Pepsi and Mirinda) constituted the case group and 4 solutions with the same pH served as the control group. The teeth were divided into 3 groups (A, B and C) and further subdivided into 8 subgroups and immersed in 20 ml of one of the 8 beverages for 15 minutes (A), 45 minutes (B) and 12 hours (C). The amount of Ca++ released in each soft drink or solution was estimated by AA-spectrophotometry at the end of each exposure time. A statistically significant difference was found in the extent of erosion between the case and control groups which increased with exposure time (P<0.001). The pattern of Ca++ concentration changes were similar in both study groups (p=0.3915), but the case group revealed a higher erosive potential than the control group (P<0.001). The percentage of titratable acids seems to have a greater effect on the erosive potential of beverages when compared to pH. Measuring pH alone could not accurately estimate the erosive potential of different soft drinks.