• antioxidants;
  • apple;
  • biofilms;
  • dental caries;
  • polyphenols;
  • Streptococcus mutans



To assess the anticaries activity of an antioxidant-rich apple concentrate (ARAC) in an experimental biofilm caries model on enamel.

Methods and Results

A validated caries model with Streptococcus mutans UA159 biofilms was used. Biofilms were formed on enamel slabs during 5 days. To mimic cariogenic challenges, triplicate slabs were exposed three times per day for 5 min to 10% sucrose followed by five additional minutes of exposure to serial dilutions of ARAC in 0·9% NaCl. A triplicate slab exposed to 10% sucrose followed by 0·9% NaCl served as caries-positive control. Acidogenicity was estimated by medium pH twice per day. After the experimental phase, biofilms were recovered to determine biomass, viable bacteria and intra- and extracellular polysaccharides. Slabs were used to estimate demineralization by the percentage of surface microhardness loss (%SHL). Differences among treatments were analysed by anova and Bonferroni test (P < 0·05). Streptococcus mutans biofilms were exposed to ARAC after a cariogenic challenge with sucrose-induced lower enamel demineralization than the positive control. The highest dilution of ARAC at 1 : 100 000 (v/v) showed the most marked reduction in demineralization of about 57%. Although no differences were observed in the number of bacterial cells, the intracellular polysaccharides or in the biomass (P > 0·05), the highest dilution of the apple concentrate induced significantly lower extracellular polysaccharide formation by the biofilm.


An apple concentrate in low concentrations appears to have a potential anticaries activity on enamel. Data suggest a metabolic rather than an antimicrobial mechanism, but further research is needed.

Significance and Impact of the Study

Phenolic compounds contained in apple concentrates seem to have anticaries properties that may be effective even in the presence of sucrose and in very low doses. Nutritional interventions that do not require rescinding from sucrose might be derived from these findings.