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A plaque growth chamber was developed for long-term growth of five separate plaques from the same plaque or saliva sample under identical conditions of temperature and gas phase. Reagent addition and growth conditions for each plaque could be independently controlled, and each was accessible for sequential sampling and electrode insertion. Plaques were cultured for over six weeks on pellicle-coated Lux (TM) 25-mm diameter cover-slips at 35 degrees C under 5% CO2 in N2, and supplied with a medium containing 0.25% mucin (BMM) at 3.6 mL/h, and with periodic 5% sucrose. Electron microscopy and flora analysis of microcosm plaques showed that they had close similarities to reported characteristics of natural dental plaques. Diverse motile bacteria were present. Sucrose-induced Stephan pH curves and urea-induced pH rises were also similar to those reported for natural plaques. Changes in plaque urease, calcium, phosphate concentrations, and the flora were followed over five weeks in a plaque supplied with BMM containing additional 2.5 mmol/L calcium and 7.5 mmol/L phosphate. Despite this high environmental calcium phosphate concentration, there was no continuing increase in calcium levels, although plaque phosphate doubled. Urease levels fluctuated. Changes in the cultivable flora were minor. A urea-containing calcium phosphate/mono-fluorophosphate pH 5 solution, applied for six min every two h for seven days, increased plaque calcium, phosphate, and fluoride to high levels. Thus, plaques grown over several weeks in the multi-station artificial mouth exhibited metabolic and pH behavior typical of natural plaques, could be analyzed during development, and the system allowed manipulation of environmental variables important in plaque pH control and calcification.

A mouthrinse formulated to fulfill physicochemical requirements for rapid remineralization of early carious lesions was investigated in vivo using intraoral appliances in adults. Human enamel slabs with artificially induced early lesions were embedded in the appliances. Complete rehardening of the inner 40–50 μm and twofold rehardening of the remaining body of the lesion occurred in 160-μm deep lesions with a 1-min mouthrinse on each of 14 consecutive days. Saliva alone rehardened the inner 20 μm only. At least the inner half of lesions 65 μm deep rehardened completely and the remaining body of the lesion rehardened fourfold over 14 days. Monofluorophosphate toothpastes, tested similarly remineralized to the same extent as saliva alone and increased the surface layer hardness. The remineralizing solution shows potential value as a daily mouthrinse for the prevention or reversal of early carious lesions.

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