Modeling Oral Multispecies Biofilm Recovery After Antibacterial Treatment

TL;DR

This study investigates the recovery dynamics of multispecies oral biofilms after antibacterial treatment, combining experimental observations with a mathematical model that highlights quorum sensing and growth factors as key recovery mechanisms.

Contribution

The paper introduces a comprehensive mathematical model of biofilm recovery that incorporates multiple bacterial phenotypes, quorum sensing, and growth factors, validated by experimental data.

Findings

NaOCl is the most effective antibacterial agent.

Biofilm recovery occurs within weeks, returning to pre-treatment levels.

Biofilm source has minimal impact on recovery dynamics.

Abstract

Recovery of multispecies oral biofilms is investigated following treatment by chlorhexidine gluconate (CHX), iodine-potassium iodide (IPI) and Sodium hypochlorite (NaOCl) both experimentally and theoretically. Experimentally, biofilms taken from two donors were exposed to the three antibacterial solutions (irrigants) for 10 minutes, respectively. We observe that (a) live bacterial cell ratios decline for a week after the exposure and the trend reverses beyond a week; after fifteen weeks, live bacterial cell ratios in biofilms fully return to their pretreatment levels; (b) NaOCl is shown as the strongest antibacterial agent for the oral biofilms; (c) multispecies oral biofilms from different donors showed no difference in their susceptibility to all the bacterial solutions. Guided by the experiment, a mathematical model for biofilm dynamics is developed, accounting for multiple bacterial phenotypes, quorum sensing, and growth factor proteins, to describe the nonlinear time evolutionary behavior of the biofilms. The model captures time evolutionary dynamics of biofilms before and after antibacterial treatment very well. It reveals the crucial role played by quorum sensing molecules and growth factors in biofilm recovery and verifies that the source of biofilms has a minimal to their recovery. The model is also applied to describe the state of biofilms of various ages treated by CHX, IPI and NaOCl, taken from different donors. Good agreement with experimental data predicted by the model is obtained as well, confirming its applicability to modeling biofilm dynamics in general.