Caries bacteria species

There is no clarity yet on a possible causative bacterial species for dentin caries. An increase in the proportion of Gram-positive bacteria has been noted. Especially lactobacilli have been isolated from the most advanced parts of dentin lesions (Edwardsson, 1987). 

The presence of S. mutans and other cariogenic bacteria contributes towards the formation of a biofilm known as dental plaque, and their metabolism of fermentable carbohydrates in the diet leads to the formation of acids [12]. Dental caries has been described as a complex imbalance in physiologic equilibrium between tooth mineral and biofilm [13]. Biofilms imply the involvement of microbiological species [14], but the key concept included within this definition is that the bacteria involved are native to the body, not a group of specific invasive bacteria causing infection [14]. 

Shu M, Wong L, Miller JH, Sissons CH Development of multi-species consortia biofilms of oral bacteria as an enamel and root caries model system. Arch Oral Biol 2000 -1. 27 -10. 

In the context of a chapter on plaque as a reservoir for active ingredients, plaque structure has an important influence on the penetration and clearance of such materials and also of various other species involved in the caries process. We have discussed in previous sections the thermodynamic approach to caries susceptibility adopted by Margolis et al. [1,4-5] that focuses on calculations of the DS of the plaque fluid with respect to dental enamel based on extensive chemical analyses of plaque samples. Dawes, Dibdin and their co-workers [12-19], on the other hand, have modelled essentially the kinetics of the saliva-plaque system to compute Stephan curves within plaque and at the enamel surface following sucrose exposure. Sucrose (and related highly water-soluble species such as glucose) strictly speaking are not retained in plaque, but are either rapidly cleared from the mouth by saliva or converted to other molecules by plaque bacteria. The H+ ions that determine pH are one product of such conversion processes and are retained to an extent. 

Current evidence supports the idea that the initiation of caries is associated with specific acidogenic streptococci, and periodontal disease with the toxic products of anaerobic proteolytic organisms such as Bacteroides species and spirochaetes. In theory therefore it should be possible to control these diseases by long-term selective inhibition of the pathogenic bacteria rather than by the elimination of all plaque organisms. 

In addition to its weak muscle-relaxant action (251), bisnordihydrotoxi-ferine (4c) has sedative properties, brought about by a marked depressant effect on the CNS (490). The alkaloid is antidiarrhoeic (476, 562). It exhibits some bacteriostatic activity against both gram-positive and gram-negative bacteria, more especially against Streptococcus species associated with dental caries. The related C-alkaloid H is also active (4e) (492,493). 

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