Cysteamine Enhances Biofilm Eradication Efficacy of Calcium Hydroxide

Calcium hydroxide (Ca[OH]2) is a widely used interappointment dressing, but its antibacterial property is compromised by dentin. Hence, the addition of chlorhexidine (CHX) with Ca(OH)2 has been proposed. However, the antimicrobial efficacy of this mixture compared with Ca(OH)2 alone is currently still debatable. Cysteamine is a mucolytic agent used to reduce the viscosity of mucus through the disruption of proteins, which are also important components of the extracellular matrix of biofilms. The aims of this study were to determine the efficacy of cysteamine alone and in combination with Ca(OH)2 to eradicate Enterococcus faecalis biofilm compared with CHX with Ca(OH)2, and to determine if this effect is affected by dentin.

The biofilm eradication efficacies of Ca(OH)2 alone and with cysteamine were determined using 7-day E. faecalis biofilm cultured on dentin discs and compared with Ca(OH)2 with 2% CHX. The effects of dentin on the efficacies of Ca(OH)2 alone and with either cysteamine or CHX were examined.

Cysteamine alone completely abolished E. faecalis biofilm at 200 mg/mL. The combination of Ca(OH)2 with either cysteamine at 10 mg/mL or 2% CHX completely obliterated E. faecalis biofilm. Cysteamine with Ca(OH)2 completely eradicated E. faecalis biofilm despite preincubation with dentin, whereas CHX with Ca(OH)2 was less effective.

Cysteamine effectively eliminated E. faecalis biofilm and showed synergistic effects in combination with Ca(OH)2, which were unaffected by dentin. Hence, our findings support the use of cysteamine as a potential adjunct to Ca(OH)2 as an interappointment dressing.