Antibacterial effect of coffee: Calcium concentration in a culture containing teeth/biofilm exposed to Coffea Canephora aqueous extract

Abstract

This study determined the changes of calcium concentration in a medium containing teeth/biofilm exposed to Coffea canephora extract (CCE). Enamel fragments were randomly fixed into two 24-well polystyrene plates containing BHI. Pooled human saliva was added to form biofilm on fragments. Specimens were divided into treatment groups (G, n = 8 per group) and treated with 50 μl daily for 1 min per week, as follows: G1, 20% CCE; G2, Milli-Q water (negative control); G3, antibiotic (positive control). Six fragments represented the blank control (G4). The calcium content was observed at baseline, 4 and 7 days of treatment by atomic-absorption spectrophotometry. Cross-sectional hardness of enamel was a demineralization indicator. Calcium increased in the medium after 4 and 7 days of treatment in G1 (3·80 ± 1·3 mg l-1 and 4·93 ± 2·1 mg l-1, respectively) and G3 (4th day = 5·7 ± 1·8 mg l-1; 7th day = 6·7 ± 3·5 mg l-1) (P > 0·05). Calcium from G2 decreased after 7 days, which was different from G3 (P < 0·05). The lower calcium content, at the end of the experiment, was represented by G4, 2·16 ± 0·2 mg l-1. The increase in calcium after treatment with CCE is probably due to its antibacterial effect, which caused the bacterial lysis and consequent release of calcium in the medium. © 2014 The Society for Applied Microbiology.