Dilution Of Saliva And Caries, Experimental Model With Biofilms.

Objectives: Saliva has been described as a powerful modulator of the caries process, but it is not clear whether a minimum quantitative threshold is required to exert a protective effect.

Objective: To evaluate the effect of saliva dilutions on Streptococcus mutans (S. mutans) in vitro, considering demineralization and microbiological characteristics of the biofilm.
Methods: A caries model with S. mutans biofilms was used on enamel and root dentin slabs. Biofilms were exposed to treatments comprising a dilution of saliva in a soy trypticase culture medium: (1) 5% Saliva + 10% Sucrose, (2) 10% Saliva + 10% Sucrose, (3) 25% Saliva + 10% Sucrose, (4) 50% Saliva + 10% Sucrose, (5) 75% Saliva + 10% Sucrose, (6) 100% Saliva + 10% Sucrose. A positive → 0% Saliva + 10% Sucrose and a negative control → 0% Saliva + 0.9% NaCl were included. Each slab was exposed to 10% sucrose for five minutes, three times per day, four days for dentine and five days for enamel. Acidogenicity, demineralization, biomass, viable microorganisms and polysaccharides were analyzed. The experiment was carried out in triplicate in two phases (n=6).
Results: In enamel and dentin, there was a tendency to decrease acidogenicity and demineralization as the volume of saliva increased, in each dilution. In enamel, treatment 6 with 100% saliva had a potent inhibitory effect on pH drop. Treatment with only 5% saliva (Group 1) was highly effective in reducing demineralization. In both tissues a significant reduction of the biomass, viable microorganisms of S. mutans and polysaccharides was observed when saliva was present in high concentrations.
Conclusions: High concentrations of saliva can almost completely inhibit dental demineralization and some properties of cariogenic biofilms.