Biological methods to test potential anticaries activity

Dental caries, the most prevalent infectious disease in humans, is an endogenous infection of the calcified tissues due to the accumulation of dental plaque on the tooth surface and is a result of its demineralisation by organic acids produced by those plaque bacteria that ferment dietary carbohydrates. The most important aetiological agents of enamel caries are Streptococcus mutans and Streptococcus sobrinus while additional aetiological agents are actinomyces and lactobacilli, the former contributing for root surface caries, while the latter are considered as secondary invaders. Caries is the only infectious disease for which daily prophylactic measures are required. Unfortunately, few individuals practice oral hygiene properly to ensure that sufficient plaque is removed to prevent the occurrence of this disease. Consequently, professional treatment is required to remove or restore teeth affected by caries in many individuals, and this places a great burden on health care budgets. Hence, in 2000, the cost of oral healthcare in the 28 member and accession states of the EU/EEA was approximately EUR 54 billion. The pathogenesis of dental caries is dependent upon the presence of fermentable sugars in the diet and the presence of cariogenic bacterial species. The disease can be considered to involve three main stages: 1) adhesion of bacteria to the tooth, 2) production of a glycocalyx resulting in the formation of a bacterial community embedded in the glycocalyx (i.e. a bioadhsive film) commonly known as dental plaque, 3) fermentation of sucrose within the biofilm mainly to lactic acid which demineralises the enamel making easier the production of the caries lesion. Several approaches are possible to caries prevention, such as the elimination of fermentable sugars from the diet, the elimination of the causative organisms, the prevention of bacterial adhesion, and the prevention of plaque formation. Chemicals able to achieve one or more of the above strategies have been shown to be present in a number of foods. The anti-caries potential of the various foods/beverages and constituents derived from these can be assessed in a number of in vitro assays employing organisms important in the aetiology of this disease. In a preliminary investigation the employed biological assays have to be simple, robust and high-throughput. The most important assays investigate the ability of each test food/substance to 1) prevent adhesion of the target organisms to hydroxyapaptite, 2) induce detachment from hydroxyapaptite, 3) prevent biofilm formation by the target organisms, 4) elicit an antibacterial effect against the target organisms, 5) prevent co-aggregation by the target organisms, 6) disrupt signal transduction in Streptococcus mutans, 7) disrupt pre-existing biofilms of the target organisms, 8) inhibit acid production by those target organisms associated with caries, 9) inhibit glucosyltransferase activity, 10) inhibit proton-traslocating F-ATPase activity. Some of the reported assay were applied to test the potential anticaries activity of coffee brew and isolated coffee melanoidins