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Objectives: Our model has in recent years been a valuable tool to study a variety of properties of dental plaque. This study explored whether this biofilm model could also be used to de- and remineralize bovine enamel. Methods: Demin/remin was monitored by Quantitative Light Fluorescence (QLF) using a commercial instrument and image analysis software from Inspektor (Amsterdam, NL). Bovine enamel discs (6.5 x 1.5 mm) were used as biofilm substrate. The biofilm model comprising six species, is cultured in 24-well plates in 70% saliva and 30% medium. In this set of experiments variable carbohydrate (CHO) and Sörensen phosphate buffer (BU) concentrations were applied. Optimal demineralization conditions were assessed in a checkerboard design covering CHO concentrations between 0-5% and BU concentrations between 0-100% (0.66 M, pH 7.2) in the medium. Results: At a CHO concentration of 1% and with decreasing BU concentration, enamel discs showed a loss of fluorescence intensity (DF) between -10 and -25%. Raising the CHO concentration to >2.5% induced even stronger demineralization in the order of -40%, with the BU concentration having a marginal effect only. These observations were validated in a larger experiment (N=6) in which we aimed at obtaining consistent demineralization of approximately -30%. Using concentrations 1% CHO and 0% BU, demineralizations of -31.5% ± 3.1% were achieved. If our standard concentrations of 0.3% CHO and 100% BU were used with in vitro pre-demineralized enamel discs, the discs were increasingly remineralized, exhibiting after 64.5h a DF value of ~10%. Conclusions: The application range of our biofilm model has been widened. Now it is not only possible to study quantitatively the effect of the microbial composition of the biofilm on demin/remin, but also to assess experimentally the effect and mechanism of action of a great number of parameters that influence the mineral balance of enamel. |