Dental caries is a biofilm-dependent oral disease, and fermentable dietary carbohydrates are the key environmental factors involved in its initiation and development. However, among the carbohydrates, sucrose is considered the most cariogenic, because, in addition to being fermented by oral bacteria, it is a substrate for the synthesis of extracellular (EPS) and intracellular (IPS) polysaccharides. Therefore, while the low pH environment triggers the shift of the resident plaque microflora to a more cariogenic one, EPS promote changes in the composition of the biofilms’ matrix. Furthermore, it has recently been shown that the biofilm formed in the presence of sucrose presents low concentrations of Ca, P_i, and F, which are critical ions involved in de- and remineralization of enamel and dentin in the oral environment. Thus, the aim of this review is to explore the broad role of sucrose in the cariogenicity of biofilms, and to present a new insight into its influence on the pathogenesis of dental caries.

The emphasis currently given to new technologies for enamel remineralization suggests that the changes in the understanding of the dental caries disease, which occurred in the last century, were either not yet adopted or were forgotten. Just like in the past, when the disease was "treated" by restoring cavities, there is presently a misunderstanding on the concept of incipient lesion remineralization. The aim of this paper was to review some concepts about caries, the natural phenomenon of enamel remineralization and the effect of fluoride (F) on it, and also to discuss the clinical relevance of remineralizing products recently launched in the marketplace aiming to "treat early caries lesions".

The composition of dental plaque formed in the presence of sucrose or glucose and fructose and its relation to cariogenicity was evaluated. Twelve adult volunteers took part in this crossover study done in three phases of 28 days each. For each phase, an acrylic resin appliance containing four human dental enamel blocks was constructed for the volunteers. Solutions containing 20% sucrose or 10% glucose + 10% fructose were dripped onto the enamel blocks 8 times a day, while in the control group no solution was used. Enamel surface and cross–sectional microhardness results showed that dental plaque formed in the presence of sucrose was more cariogenic than that formed in the presence of glucose + fructose (p<0.05). The concentration of alkali–soluble carbohydrates in dental plaque was higher in the sucrose group than in the control and glucose + fructose groups (p<0.05). Although concentrations of Ca, P and F were lower in plaque formed in the presence of sucrose than glucose + fructose and the control, significant differences (p<0.05) were only observed in relation to control. The electrophoretic profile of the matrix proteins of dental plaque showed distinct patterns when it was formed in the absence or presence of the different carbohydrates. Although the results suggest that the high cariogenicity of dental plaque formed in the presence of sucrose can be mainly explained by the high concentration of insoluble glucans of its matrix, the low inorganic concentration and its protein composition may have some contribution.

Since the currently available pH-cycling models do not differentiate the anti-caries potential of dentifrices with low fluoride (F) concentration, two models were developed and tested in the present. Bovine enamel blocks were subjected to the models and treated with F solutions containing from 70 to 280 mug F/mL in order to validate them in terms of dose-response effect. The models were also tested by evaluating the dentifrices Colgate Baby (500 mug F/g, as a low fluoride dentifrice), Tandy (1,100 mug F/g, as an active F-dentifrice) and Crest (1,100 mug F/g, as positive control). Enamel mineral loss or gain was assessed by surface and cross-sectional microhardness, and lesion depth was analyzed by polarized light microscopy. The pH-cycling models showed F dose-response effect either reducing enamel demineralization or enhancing remineralization. The low F dentifrice presented anti-caries potential, but it was not equivalent to the dentifrices containing 1,100 mug F/g. These data suggest that the models developed in this study were able to evaluate the anti-caries potential of low F dentifrice either on resistance to demineralization or on enhancement of remineralization.

In spite of decades of research on fluoride and the recognition of its role as the cornerstone of dental caries reduction in the last fifty years, questions still arise on its use at community, self-applied and professional application levels. Which method of fluoride delivery should be used? How and when should it be used? How can its benefits be maximized and still reduce the risks associated with its use? These are only some of the challenging questions facing us daily. The aim of this paper is to present scientific background to understand the importance of each method of fluoride use considering the current caries epidemiological scenario, and to discuss how individual or combined methods can be used based on the best evidence available.

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37 degrees C, 10% CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12% (concentration with recognized anti-plaque effect) and 0.05% NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05% NaF did not show antimicrobial effect but had similar effect to that of 0.12% CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.