The effect of tissue inhibitors on the antibacterial activity of chitosan nanoparticles and photodynamic therapy.
BACKGROUND
Newer antibacterial alternatives such as chitosan nanoparticles (CSnps) and photodynamic therapy (PDT) have been investigated to achieve effective root canal disinfection. The current study aims to assess the effect of various tissue inhibitors such as dentin, dentin matrix, pulp tissue, bacterial lipopolysaccharides (LPSs), and bovine serum albumin (BSA) on the antibacterial activity of CSnps and PDT.


METHODS
The antibacterial effect of CSnps and PDT using photosensitizers, rose bengal (RB), and methylene blue (MB) were tested on planktonic Enterococcus faecalis American Type Culture Collection 29212 with or without pretreatment using different tissue inhibitors for an hour. Bacterial survival was assessed after 1, 8, and 24 hours of incubation with CSnps and after PDT using RB and MB.


RESULTS
Pulp and BSA inhibited the antibacterial effect of CSnps significantly (P < .05). The antibacterial effect of CSnps was not affected by dentin, dentin matrix, or LPSs. The antibacterial activity of PDT using MB and RB was inhibited in a decreasing order by dentin matrix, BSA, pulp, dentin, and LPSs (P < .05). The effect of tissue inhibitors was higher in the case of PDT with RB. Depending on the antibacterial mechanism of CSnps and PDT, different inhibitory patterns were observed with different tissue inhibitors.


CONCLUSIONS
The tissue inhibitors existing within the root canal affected the antibacterial activity of CSnps and PDT at varying degrees. Further research is required to enhance their antimicrobial efficacy in an endodontic environment.
Discipline of Endodontics, University of Toronto, Toronto, Ontario, Canada.
Annie
A
Shrestha
Anil
A
Kishen
D000818:Animals; D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001672:Biocompatible Materials / Q000494:pharmacology*; D002417:Cattle; D048271:Chitosan / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003782:Dental Pulp / Q000502:physiology; D003804:Dentin / Q000502:physiology; D013293:Enterococcus faecalis / Q000187:drug effects*; D004926:Escherichia coli; D016326:Extracellular Matrix Proteins / Q000494:pharmacology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D053758:Nanoparticles; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D012395:Rose Bengal / Q000494:pharmacology; D012709:Serum Albumin / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
D000900:Anti-Bacterial Agents; D001672:Biocompatible Materials; D016326:Extracellular Matrix Proteins; D008070:Lipopolysaccharides; D017319:Photosensitizing Agents; D012709:Serum Albumin; D012395:Rose Bengal; D048271:Chitosan; D008751:Methylene Blue