Disruption of endodontic biofilms using plasma polymer encapsulated D-amino acids.

Objectives: Enterococcus faecalis (Ef) is a predominant species present in the root canal system of failed endodontically treated teeth. Among several virulence factors, Ef has the ability to form biofilms. We have shown that a mixture of D-amino acids (DAAs) disrupt established and developing Ef biofilms. Our objectives are to investigate the effectiveness of individual DAAs on Ef biofilms and to use encapsulation technologies to provide a sustained release of DAAs that can be used to improve the success of root canal therapy.
Methods: A micro-titre tray biofilm assay was used to compare the effect of individual DAAs on Ef biofilms. A mixture and individual DAAs of D-methionine, D-tyrosine, D-leucine and D-tryptophan were encapsulated with a plasma polymer (1-7 octadeine) for 10, 20 and 40 minutes to allow for variations in shell thickness of the particles. Polymer encapsulated DAAs (PEPDAAs) were analysed with SEM. Diffusion of DAAs from the PEPDAAs was measured over 7 days.
Results: Using SEM, the shell thicknesses of the PEPDAAs ranged between 30-60nm - indicating a substantial coating of plasma polymer and the thickness of polymer coating increased with plasma coating time. HPLC results showed a sustained diffusion of DAAs from the PEPDAAs over 7 hours. Biofilm disruption of individual DAAs varied between 24, 72 and 144 hour biofilms.
Conclusions: Polymer encapsulation is a promising technology to maintain a sustained release of DAAs and may greatly improve the success rates of endodontic treatment.