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

This study investigated the effect of chlorhexidine (CHX) on demineralization, cell viability and matrix composition in EPS-rich (EPS⁺) and poor (EPS^-) oral biofilms.

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.

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.

While CHX effectively reduced bacterial counts, its antimicrobial effect may not be enough to reduce the enamel demineralization caused by mature EPS-rich biofilms.