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Background: Dental caries has been strongly associated with mutans streptococci, particularly Streptococcus mutans and S. sobrinus. Many studies have linked these organisms to the carious process and counts of mutans streptococci have been used to monitor caries risk. The high levels of caries generally found in Iceland have enabled several studies to be performed on the variation within strains of S. mutans. Methods: This paper reports some studies showing phenotypic differences between strains of S. mutans that were related to whether the strain was isolated from an individual with active caries or from a caries-free subject. Results: Strains from individuals with active caries generally adhered better to apatite, were more vigorous in decalcifying apatite and had bacteriocin-like activity that was likely to help the strain compete successfully with other strains, for example in the dental plaque biofilm. Conclusions: Phenotypic differences exist between strains of S. mutans depending on the caries activity of the individual from whom the strain was isolated. [ABSTRACT FROM AUTHOR]

Objective. Carious tissue fluoresces with a wavelength different from sound tissue when stimulated by light with a wavelength of 655 nm. This difference is thought to have a bacterial origin rather than indicating demineralization. This study aimed to measure fluorescence emitted by normal cultivable caries-associated bacterial flora and typical porphyrin-producing bacteria with DIAGNOdent, and to verify earlier findings that demineralization of the dental hard tissue does not affect DIAGNOdent readings. Material and methods. Bacterial samples were collected from five occlusal caries lesions in three subjects. From these, mixed anaerobic flora, Lactobacilli and mutans Streptococci were cultured in up to three different kinds of culture medium. Colonies of Lactobacilli and mutans Streptococci were also measured after transferring them to glass slides. Laboratory teaching strains of Prevotella spp., Porphyromonas gingivalis and Actinomyces odontolyticus were cultured anaerobically and fluorescence measured directly after an appropriate incubation period. Sound enamel surfaces of 15 extracted premolars were demineralized and changes in fluorescence measured. Results. DIAGNOdent readings > 20 were only obtained from young colonies of Prevotella and from colonies of mutans Streptococci cultured on mitis–salivarius–bacitracin agar. Higher measurements were obtained as the bacterial colonies aged. Lower measurements were obtained after transferring colonies to glass slides. Demineralization of enamel did not affect the DIAGNOdent measurements. Conclusions. The change in fluorescence measured with DIAGNOdent has a bacterial origin rather than occurring as a result of demineralization. The measurements are presumably dependent on bacterial metabolites rather than bacteria themselves, and probably record synergistic effects during the carious process rather than the quantity or species of bacteria involved. [ABSTRACT FROM AUTHOR]

Non-carious destruction of teeth has been observed in archaeological material from various parts of the world and clearly pre-dates the first appearance of dental caries. Whilst the dental profession, at least in affluent parts of the world, was engaged in diagnosing, treating and later preventing dental caries these other causes of tooth destruction were largely ignored. Tooth wear may be an indication of underlying reflux disease or bulimia. Collaboration between medical and dental practitioners is important in treating such cases.