An in vitro microbial-based model for studying caries-preventive agents

Objective. The aim of the study was to develop an in vitro microbial-based caries model to test potentially caries-preventive agents. Material and methods. In this model, cariogenic Streptococcus mutans biofilms are grown on tooth samples within a reaction chamber hermetically surrounded by a bacteria-tight glove box allowing the manipulation of specimens during operation. The specimens were mounted in two rows on the inner and outer rims of a specimen turntable passing several inlet pipes transporting all necessary media. Using 64 lower incisors in 4 experiments, a 10 ppm NaF solution and an experimental potentially caries-preventive glycan solution were tested compared to a water control. The mean lesion depth was determined by confocal laser scanning microscopy. Results. The depths of the caries-like lesions showed no statistically significant difference irrespective of whether the specimens were mounted on the inner or outer rim of the specimen turntable. As expected, the NaF solution inhibited the development of caries-like lesions almost completely. The experimental glycan solution revealed a statistically significantly lower demineralization depth compared to the control and a significantly higher depth compared to the NaF group. The system could be operated over a period of more than 9 weeks without unintentional contamination and the manipulation of the tooth specimens could be accomplished. Conclusions. In conclusion, our in vitro system is suitable for testing potential caries-preventive agents in a reproducible way by using whole tooth samples and offers full access together with the possibility of manipulating the specimens during operation.