Spathodea campanulata extract as an endodontic irrigant against Enterococcus faecalis: an in vitro and ex vivo study.

Abstract

Background: To evaluate the antibacterial activity of leaf extracts derived from Spathodea campanulata as an endodontic irrigant in both in vitro and ex vivo models against Enterococcus faecalis.

Materials and methods: Aqueous (AQESC), methanolic (MESC), ethanolic (EESC), acetonic (AESC), chloroformic (CESC), and hexanic (HESC) extracts derived from Spathodea campanulata were prepared. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. A well diffusion assay was employed to compare these extracts against Enterococcus faecalis ATCC 29,212. Human single-rooted teeth were collected, standardized, and inoculated to facilitate the development of a four-week biofilm. These teeth were subsequently divided into three experimental groups, each receiving positive pressure irrigation with 1 mL of one of the following solutions: phosphate-buffered saline (PBS), 2.5% sodium hypochlorite (NaOCl), and the extract from Spathodea campanulata exhibiting the most favorable MIC, MBC, and inhibition halo in prior tests. Biofilm samples were harvested from the root canals to quantify colony-forming units (CFU). Moreover, the extracts were analyzed for their total flavonoid, phenol, polyphenol, and tannin contents.

Results: AQESC lacked MIC and MBC values, whereas the other extracts demonstrated MIC and MBC values within the range of 12.5 to 50 µg/mL. AQESC, MESC, CESC, and HESC did not produce an inhibition halo at a concentration of 800 mg/mL. Conversely, EESC and AESC at this concentration exhibited bactericidal activity, with no statistically significant difference between them, when compared to 2.5% NaOCl. EESC at 800 mg/mL displayed the most superior antibacterial properties; consequently, this concentration was utilized in the ex vivo model. The analysis of CFU/mL revealed a significant reduction in the EESC group compared to 2.5% NaOCl (P < 0.0001). The extracts are abundant in flavonoids, phenols, polyphenols, and tannins, which may account for the observed results.

Conclusion: The extracts of Spathodea campanulata exhibit bacteriostatic and bactericidal properties at low concentrations, with the exception of AQESC. The inhibition halo against Enterococcus faecalis at 800 mg/mL of EESC and AESC is comparable to that produced by 2.5% NaOCl. Moreover, endodontic irrigation using 800 mg/mL of EESC significantly decreases the CFU of Enterococcus faecalis compared to 2.5% NaOCl.