The pH of fruit juices and carbonated drinks are known to be low and have, therefore, been implicated in the increasing incidence of erosion. The ability of a drink to resist pH changes brought about by salivary buffering may play an important part in the erosion process. The aims of this study were to measure the initial pH of several widely available soft drinks and determine their buffering capacities. As part of a larger study, the following groups of drinks were tested: pure fruit juices, non-fruit-based carbonated drinks, fruit-based carbonated drinks, flavoured spring waters, and plain carbonated mineral waters as positive controls with still water as the negative control. The measurement of pH was carried out using a pH electrode connected to an Orion EA940 Ionanalyser. One hundred millilitres of each drink was then titrated with 1 M sodium hydroxide, added in 0.5 mL increments, until the pH reached 10. Each titration was repeated three times. The average initial pH was lowest for the non-fruit-based drinks (2.81+/-0.274) and highest for plain mineral water (7.4+/-0.1002). The buffering capacities can be ordered as follows: fruit juices>fruit-based carbonated drinks and flavoured mineral waters>non-fruit-based carbonated drinks>sparkling mineral waters>still mineral water. It is concluded that fruit juices and fruit-based carbonated beverages, with their increased buffering capacities, may induce a prolonged drop in oral pH.

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The aims of this study were firstly to investigate the fluoride-releasing characteristics of five commercial glass ionomer materials: Ketac Fil, Chemfil Superior, Fuji II LC, Aquacem and Vitrebond. The second aim was to assess the fluoride uptake and subsequent release from the same range of materials. In both tests, ten discs, 6 mm in diameter with a thickness of 1.5 mm, were made for each material. The initial fluoride release was assessed over a 60-day period for all materials. Each disc was immersed in 2 ml of de-ionised water within a plastic vial. The solutions were changed daily up to day 15, and thereafter every 3 and 4 days until the end of the test. All of the materials released measurable amounts of fluoride throughout the test period, with a considerable range on day 1 (15.3–155.2 ppm F). The concentration of fluoride released on the 2nd day fell sharply for all materials (range 6.3–44.3 ppm F). By day 60 all materials continued to release fluoride, albeit to a lesser extent (range 0.9–3.99 ppm F). With regard to the uptake and release of fluoride, a similar protocol was employed, although all samples were immersed in 1 litre of de-ionised water for 60 days to allow the majority of the fluoride to leach out from the materials. The ten pellets for each material were divided into two groups, five samples as control and five samples as test. Each day over a 20-day period all test samples were exposed to a 1000-ppm F solution for 2 min. Fluoride uptake/release was assessed from the 2 ml of de-ionised water in which the samples had been immersed for 24 h. The control samples continued to release small concentrations of fluoride throughout the test. The test samples, exposed to the 1000-ppm F solution, consistently released more ionic fluoride than the controls at all time points from day 1 to day 20, indicating that fluoride had been taken up and subsequently released. The values ranged at day 1 from 3.29 ( ± 0.14) for Aquacem to 7.63 ( ± 0.13) for Ketac Fil at day 1, rising to values between 869 ( ± 1.88) for Aquacem to 10.34 ( ± 1.61) for Vitrebond at day 20. This study indicates that all five glass ionomer cements take up as well as release fluoride and that the amount of fluoride released may be of profound clinical significance.

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).