Extracellular polysaccharide-rich biofilm reduces chlorhexidine effect on enamel demineralization: An in situ study.

OBJECTIVES: This study investigated the effect of chlorhexidine (CHX) on demineralization, cell viability and matrix composition in EPS-rich (EPS(+)) and poor (EPS(-)) oral biofilms. DESIGN: A split-mouth and crossover in situ study was conducted with six participants over two phases of 14 days each. During a lead-in step, biofilms were formed under either sucrose exposure (EPS(+)) or glucose + fructose exposure (EPS(-)). In the experimental step, participants rinsed with either 0.9 % NaCl (negative control) or 0.12 % CHX for seven days. RESULTS: Data showed that EPS(+) biofilms exhibited higher enamel surface hardness loss (%SHL), lesion area (∆S) and concentrations of soluble and insoluble EPS, compared to EPS(-) biofilms. After treatments, CHX significantly reduced the counts of colony-forming units (CFU) in both EPS(-) and EPS(+) biofilms. However, CHX only reduced ∆S within the EPS(-) group. There was no significant difference in demineralization change (%∆S) among treatments. Additionally, CHX decreased soluble and insoluble EPS concentrations in the EPS(+) group. CONCLUSION: While CHX effectively reduced bacterial counts, its antimicrobial effect may not be enough to reduce the enamel demineralization caused by mature EPS-rich biofilms.