Rees, Loyn, Hunter, Sadaghiani, Gilmour nally and embedded in a low exotherm epoxy resin ersult (Stycast 1266, Emerson & Cuming, Westerlo, Bel- The results for the initial pH values are given gium). The outer surface of the enamel samples in Table 2. The pH of the flavoured waters tested were lightly ground with first 600-grit and then ranged from 2.64-3.24 compared to a value of 3.68 1200-grit abrasive discs (Kemet International Ltd., for orange juice. Parkwood Trading Estate, Maidstone, Kent) to pro- The results for the neutralisable acidity values duce a flat surface. Three baseline readings using are given in Table 2. These values ranged from a profilometer (Planer Products Ltd., Sunbury on 4.16 mls for Volvic Touch of Fruit Still Orange and Thames, UK) were recorded for each enamel sam- Peach to 16.30 mls for Boots sparkling cloudy ple. Only samples with a stylus deflection of less lemonade spring water. The positive control or- than an average ± 0.30 μm deflection were used ange juice had the highest neutralisable acidity in the study. The diamond stylus had a tip radius value of 19.68 mls. of 20 μm with a head velocity of 10 mm/min. The The amount of enamel lost following immer- force of the stylus varied linearly with deflection sion in the various drinks tested is shown in Table at a rate of 8 mg/μm up to a maximum of 1 g at 2. The amount of enamel removed, ranged from 100 μm. 1.18 to 6.86 μm. In comparison, the orange juice After baseline profiles were determined in du- positive control produced a mean surface loss of plicate, enamel samples were taped to expose a 2 3.34 μm. Two drinks produced significantly lower mm width of enamel (approximate enamel area of levels of enamel erosion; Volvic orange and peach 10 mm2). Five enamel specimens were exposed to and the elderflower drink. The values for the 250 mls of each drink and stirred in a thermostati- Volvic orange and peach were significantly lower cally controlled water bath at 37°C for one hour. than Volvic lemon and lime (P<.01), cranberry Following exposure, the enamel specimens were (P<.001), Boots lemonade (P<.05), Boots orange rinsed in water, dried and the tapes removed. Sur- juice (P<.001) and Waitrose grapefruit (P<.005). face enamel loss was measured on the profilom- The values for the elderflower drink were sig- eter in triplicate, with the amount of enamel loss nificantly lower than the Volvic lemon and lime recorded in micrometers. Averages were calcu- (P<.001), cranberry (P<.001), Boots lemonade lated from triplicate measurements. (P<.001) and Boots orange juice (P<.001). Five enamel specimens were also immersed in Tropicana™ brand orange juice for one hour as a dIscuIon positive control and in distilled water as a negative The pH values for all the flavoured waters control. tested fell within a narrow band of 2.64-3.24 and Statistical analysis of the results for pH, neu- all were slightly more acidic than the control or- tralisable acidity and enamel erosion was carried ange juice. Although the values were numerically out using analysis of variance followed by Tukey’s similar it must be remembered that pH is a loga- test. The threshold for statistical significance was rithmic scale, so that small changes in pH values equate to larger changes in the hydrogen ion con- centration. Previous studies have shown that the pH values of both still and carbonated bottled wa- set at P<.05. Table 2. Initial pH value, neutralisable acidity and enamel erosion values (SD in parentheses). Drink Volvic Touch of Fruit still lemon and lime Boots Shapers still cranberry juice spring water Boots Shapers sparkling cloudy lemonade spring water Boots Shapers still Floridian orange juice spring water Volvic Touch of Fruit still orange and peach Waitrose grapefruit spring water drink Bottlegreen presselight elderflower Tropicana natural orange juice January 2007 - Vol.1 European Journal of Dentistry pH 2.64 (0.05) 3.14 (0.05) 2.78 (0.04) 3.24 (0.05) 2.82 (0.07) 2.74 (0.05) 3.04 (0.05) 3.68 (0.04) 7 Neutralisable acidity (mls) 7.20 (0.18) 11.02 (0.07) 16.30 (0.09) 11.6 (0.22) 4.16 (0.10) 14.04 (0.16) 13.62 (0.27) 19.68 (0.31) Enamel erosion (microns) 5.00 (1.16) 6.86 (1.20) 6.29 (0.35) 5.34 (2.46) 2.01 (0.54) 4.43 (0.96) 1.18 (0.14) 3.24 (0.62)