The effect of cinnamon and ginger essential oils against Enterococcus faecalis biofilm: An in vitro feasibility study

Abstract

Aim: Enterococcus faecalis has gained attention in the endodontic literature as it is frequently isolated from root canals in cases of failed treatments. Current medicaments are unlikely to predictably achieve a bacteria-free root canal system, which can lead to these failures. Phytotherapeutic substances are attractive medicaments as they are generally safe and well tolerated. This study evaluated the antimicrobial potential of two phytotherapeutic agents, cinnamon and ginger oils, against in vitro preformed biofilms of an oral strain of E. faecalis. Methods: A biofilm of E. faecalis was grown in 96-well plate under anaerobic conditions to simulate root canal conditions during reinfection. The biofilms were treated with 1% cinnamon oil in brain–heart infusion (BHI) media or saline, which were compared to the widely used medicament, calcium hydroxide, under the same conditions. A 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-([phenylamino] carbonyl)-2H-tetrazolium hydroxide assay was employed for measuring cell viability. All tests were performed with a minimum of five technical replicates and in biological triplicate. A single biological trial was also conducted using 1% ginger oil following the same protocol. Data were analyzed using Kruskal–Wallis and Student's t-tests. Results: Cinnamon oil demonstrated antimicrobial activity in the eradication of E. faecalis biofilm. A statistically significant difference was detected between 1% cinnamon oil and 0.1% calcium hydroxide (P < 0.05). Ginger oil also displayed a reduction of the biofilm. Both oils showed a significant difference between BHI and saline conditions (P < 0.05), in which the biofilm reduction was maximized in saline. Conclusion: Cinnamon oil may provide a potential adjunctive therapy in treating endodontic infections associated with E. faecalis.