Efficacy of Cranberry Extract against established Endodontic Biofilm in an In vitro Tooth Model TischkeGail MB 2019 Efficacy of Cranberry Extract against established Endodontic Biofilm in an In-vitro Tooth Model INTRODUCTION: Cranberry (Vaccinium macrocarpon), a native North American fruit, has been reported to have anti-bacterial, anti-adhesion, anti-tumorigenic, anti-inflammatory and antiox-idant activity. Besides its broad-spectrum antimicrobial activity against microorganisms, cran-berry extract has also demonstrated inhibition against biofilms of Enterococcus faecalis. OBJECTIVES: The purpose of this investigation is to determine the efficacy of cranberry wash as an endodontic irrigant against established multispecies mixed culture endodontic biofilm in an in vitro tooth model. MATERIALS/METHODS: Seventy-two extracted human single canal teeth were collected and standardized to a length of 14 mm. Teeth were cultured in Schaedler broth with Fusobacterium nucleatum, E. faecalis, and Porphyromonas gingivalis for 21 days and then randomly assigned to 6 treatment groups [sterile saline; 5.25% sodium hypochlorite (NaOCl); 2% chlorhexidine (CHX); three cranberry extracts]. The teeth were instrumented and irrigated with 6 mL of the irrigants. Culture in the canals were sampled before and after instrumentation for viable bacte-ria. Viable bacteria in the dentinal tubules were also determined after instrumentation. Data was analyzed using Kruskal-Wallis chi squared test (P < 0.05). RESULTS: Bacterial growth was noted in all root canal samples prior to instrumentation. NaOCl and CHX significantly reduced bacterial viability. However, cranberry extracts did not demon-strate significant germ-kill efficacy compared to the non-treatment control (saline group). CONCLUSIONS: Although cranberry extract has been reported to reduce supra-gingival plaque biofilm adherence and formation, it did not demonstrate significant germ-kill effect as an effective endodontic irrigant against pre-established multi-species biofilm.