Between-Individual Characteristics of Dental-Plaque-Microcosm Microbiota, Sucrose-Induced pH and Enamel Lesions

Individual variations in oral microbiota may contribute to differences in caries risk. Objectives: To investigate the variation in plaque microbiota and pH response to high sugar exposures and their relation to enamel lesion formation. Methods: In a Multiplaque Artificial Mouth, dental plaque-microcosms were cultured on resin-embedded enamel blocks for 14 days from the saliva of three donors (A, B and C). Plaques were continuously supplied with artificial saliva and pulsed with 10% sucrose 5 times daily over 12h with a 12h rest period. Plaque pH was monitored. 40 microbial species in saliva and plaques were measured by Checkerboard DNA-DNA Hybridization analysis. Lesion formation in enamel was analysed using backscattered-scanning electron microscopy. Results: Donor B and C had more acidic plaques than donor A with mean pH sucrose (SE) of 4.0 (0.03), 4.0 (0.02) and 4.7 (0.01) respectively and 12 h post-sucrose pH (SE) of 5.4 (0.14), 5.3 (0.16) and 6.4 (0.10) respectively (p<0.01). The formers had a higher proportion of the cariogenic streptococci, S. mitis, S. oralis, S. parasaguinis, S. anginosus (but not the `mutans streptococci') and Lactobacillus fermentum (p<0.01), and more severe demineralized enamel. Nevertheless, lesion depths were comparable, range 80 - 120µm. Conclusion: Between-person variation in the plaque microbiota is likely to contribute to differences in plaque pH responses to sucrose and enamel lesion properties