Novel Sustained Release Gel to combat endodontic biofilm

Objectives: While Calcium Hydroxide (CH) is the most used intracanal medicament in endodontic treatments, its activity against the most commonly recovered bacterium from failed treatments, Enterococcus faecalis, was shown to be insufficient. Despite several attempts to provide alternatives, CH remains as the dominant intracanal medicament. In this study, we use Sustained Release Gels (SRGs), that have high resiliency in water and release either Chlorhexidine (CHX) or Cetylperidinium chloride (CPC) in a sustained manner. Our aim is to determine the biological effects of different SRGs on E. faecalis’ biofilm as potential intracanal medicaments.
Methods: First we tested the biological sustained release effects of three different SRGs in an agar diffusion assay against E. faecalis by measuring the zone of inhibition (ZOI) around the SRGs. After this, we studied the effects of the SRGs on static biofilm formation in vitro measuring its metabolic activity at different time points using the tetrazolium salt assay (MTT). The SRGs used in this study had either a relatively fast release rate in vitro (CPC-4, and CHX-DIA-13) or a relatively slow release rate (CPC-13).
Results: CPC-13 produced a significant ZOI for six days in the agar diffusion assay, whereas CPC-4 and CHX-DIA-13 inhibited bacterial growth for only four days. In the MTT experiment, CPC-4 inhibited metabolic activity of E. faecalis’ biofilm for no less than ten days, while CHX-DIA-13 was effective for only three days and CPC-13 for two days.
Conclusions: SRGs are capable of continuously delivering antimicrobials to their immediate environment and inhibiting E. faecalis’ biofilm formation for a time span similar to the usual time between endodontic appointments, hence their appeal as potential alternative to existing intracanal medicaments.