IADR Abstract Archives
Extracellular Polysaccharides Rich Matrix Reduces Chlorhexidine Effect on Enamel Demineralization
Objectives: A biofilm matrix rich in extracellular polysaccharides (EPS) may interfere with chlorhexidine antimicrobial and anticaries effect. Therefore, we investigated the effect of a 0.12% chlorhexidine (CHX) solution on cell viability and enamel demineralization in two in situ formed biofilms: one EPS-rich (E+) and other not (E-).
Methods: A double-blind, randomized, split mouth and crossover study was conducted where six volunteers used a palatal appliance having four bovine enamel blocks in two phases of 14 days. Three blocks were exposed 8x/day to a 20% sucrose solution (E+), and the other three to a 10.5% glucose + 10.5% fructose solution (E-). From day 7 to day 14, besides the carbohydrate exposures, volunteers also rinsed 2x/day either with a 0.9% NaCl (Negative control - NC) or a 0.12% CHX solution, depending on the phase they were. Four groups were evaluated: E-NC; E+NC; E-CHX, and E+CHX. Two enamel blocks and the biofilm formed on them (one of each condition: E+ or E-) were collected on the 7th (before treatment) and 14th day (after treatment). Biofilms were resuspended in 0.9% NaCl, plated on blood-agar, incubated at 37oC, 10% CO2 and CFU was counted. EPS was extracted and analyzed with phenol-sulfuric method. Enamel surface and cross-sectional hardness were determined, and surface hardness loss (SHL) and lesion area (△△S) were calculated. Three-way ANOVA was performed (α=5%).
Results: After treatment, %SHL values were similar between E+NC (68.9±29.0) and E+CHX (75.7±13.3) (p>0.05), however E-NC (77.3±28.3) had higher %SHL than E-CHX (46.1±21.9) (p<0.05). S values followed the same pattern. CFU counts (x106/mg wet biofilm) were similar between E-CHX (2.9± 5.1) and E+CHX (2.0±2.4) (p>0.05). EPS values (µg/mg wet biofilm) were similar between E-NC (1.1±0.6) and E-CHX (1.4±1.1) (p>0.05) but were higher in E+NC (20.5±7.9) than E+CHX (11.2±9.7).
Conclusions: An EPS-rich matrix may reduce chlorhexidine effect on dental demineralization without modifying its antimicrobial activity.
Methods: A double-blind, randomized, split mouth and crossover study was conducted where six volunteers used a palatal appliance having four bovine enamel blocks in two phases of 14 days. Three blocks were exposed 8x/day to a 20% sucrose solution (E+), and the other three to a 10.5% glucose + 10.5% fructose solution (E-). From day 7 to day 14, besides the carbohydrate exposures, volunteers also rinsed 2x/day either with a 0.9% NaCl (Negative control - NC) or a 0.12% CHX solution, depending on the phase they were. Four groups were evaluated: E-NC; E+NC; E-CHX, and E+CHX. Two enamel blocks and the biofilm formed on them (one of each condition: E+ or E-) were collected on the 7th (before treatment) and 14th day (after treatment). Biofilms were resuspended in 0.9% NaCl, plated on blood-agar, incubated at 37oC, 10% CO2 and CFU was counted. EPS was extracted and analyzed with phenol-sulfuric method. Enamel surface and cross-sectional hardness were determined, and surface hardness loss (SHL) and lesion area (△△S) were calculated. Three-way ANOVA was performed (α=5%).
Results: After treatment, %SHL values were similar between E+NC (68.9±29.0) and E+CHX (75.7±13.3) (p>0.05), however E-NC (77.3±28.3) had higher %SHL than E-CHX (46.1±21.9) (p<0.05). S values followed the same pattern. CFU counts (x106/mg wet biofilm) were similar between E-CHX (2.9± 5.1) and E+CHX (2.0±2.4) (p>0.05). EPS values (µg/mg wet biofilm) were similar between E-NC (1.1±0.6) and E-CHX (1.4±1.1) (p>0.05) but were higher in E+NC (20.5±7.9) than E+CHX (11.2±9.7).
Conclusions: An EPS-rich matrix may reduce chlorhexidine effect on dental demineralization without modifying its antimicrobial activity.