Potential of Bouea macrophylla kernel extract as an intracanal medicament against mixed-species bacterial-fungal biofilm. An in vitro and ex vivo study

Abstract

Objective: To investigate the antimicrobial activity of B. macrophylla kernel extract against mixed-species biofilms of E. faecalis, S. gordonii and C. albicans in vitro. To evaluate the efficacy of the extract as an intracanal medicament compared with Ca(OH)₂ and chlorhexidine in ex vivo tooth model.

Methods: The antibiofilm effect of B. macrophylla kernel extract was determined by AlamarBlue™ assay and the effect on biofilms was visualized by LIVE/DEAD® BacLight™ viability test. Mixed-species biofilms were incubated into the tooth model (N = 42) for 21 days. The teeth were randomly divided into 4 medicament groups for 7 days: (i) normal saline, (ii) calcium hydroxide (Ca(OH)₂), (iii) chlorhexidine gel, (iv) B. macrophylla kernel extract. Dentine samples were collected, qPCR with PMA was used to quantify the viability and species composition of each sample. SEM was used to visualize the effect of medicament on biofilm structure.

Results: The MBIC was 6.25 mg/mL and the MBEC was 50 mg/mL. The integrity of microbial cells was progressively compromised as concentration increased, resulting in greater cell death. Ex vivo tooth model revealed that biofilm treated with 50 mg/mL of the B. macrophylla extract demonstrated a significantly higher proportions of dead cells than in Ca(OH)₂, chlorhexidine and normal saline groups (p < 0.01). Disruption of biofilm structure and enlargement of dentinal tubules was observed in B. macrophylla group on SEM.

Conclusion: The extract of B. macrophylla kernel exhibited significant antibiofilm effect against the mixed-species biofilms of E. faecalis, S. gordonii and C. albicans.

Keywords: Bouea macrophylla; Mixed-species bacterial-fungal biofilm; Root canal medicament.