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Photodynamic killing of Enterococcus faecalis in dentinal tubules using mTHPC incorporated in liposomes and invasomes
Anna Ossmann1, Stefan Kranz, Guellmar Andre
1Department of Conservative Dentistry and Periodontology, Jena University Hospital, Friedrich-Schiller-University, An der alten Post 4, Jena, 07743, Germany.
Objectives:
The present in vitro study investigates the antimicrobial photodynamic efficiency of the photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC) incorporated in liposomes (LIP) and highly flexible invasomes (INV) on the endodontopathogenic species Enterococcus faecalis in infected dental root canals.
Materials And Methods:
A total of 48 root canals were prepared mechanically to file size ISO 50 and inoculated with E. faecalis for 48 h. In the test groups, the infected root canals were subjected to aPDT with either mTHPC linked to LIP or INV. The controls were either incubated with 1 % chlorohexidine gel (CHX, positive control) or root canals were irrigated with normal saline (NaCl, negative control). After treatment all canals were mechanically enlarged (ISO 50-110), and the debris of each filing process was subjected to bacterial culture analysis.
Results:
Both mTHPC formulations showed a significant antimicrobial effect. A bacterial reduction by up to 3.6 log-steps was ascertained for INV directly at the root canal wall. aPDT using INV (ISO 60) was more effective than CHX, which caused a decrease in only 1.2 log-steps. It was found that both liposomal mTHPC formulations were capable to suppress E. faecalis inside the dentinal tubules up to 300 μm.
Conclusions:
The results show that mTHPC linked to LIP and INV is capable of efficiently reducing E. faecalis in dental root canals.
Clinical Relevance:
As evidenced, E. faecalis is resistant to several conventional antibacterial treatment measures. In this context, photodynamic treatment with mTHPC delivered by INV is superior to temporary dressing with 1 % CHX gel applied for 24 h.
Insights
Antimicrobial photodynamic therapy using 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC) in invasomes (INV) effectively reduced Enterococcus faecalis in root canals. This treatment outperformed chlorohexidine, offering a superior approach for endodontic infections.
Area of Science:
- Endodontology
- Microbiology
- Photochemistry
Background:
- Enterococcus faecalis is a prevalent pathogen in persistent endodontic infections.
- Conventional antimicrobial treatments often face challenges with bacterial resistance and deep penetration.
- Novel delivery systems are needed to enhance the efficacy of antimicrobial agents in root canals.
Purpose of the Study:
- To evaluate the antimicrobial photodynamic therapy (aPDT) efficiency of 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC) delivered via liposomes (LIP) and invasomes (INV).
- To assess the effectiveness of mTHPC-loaded LIP and INV against Enterococcus faecalis within infected dental root canals.
- To compare the efficacy of mTHPC-based aPDT with chlorohexidine (CHX) and saline controls.
Main Methods:
- In vitro study involving 48 mechanically prepared root canals infected with E. faecalis.
- Application of aPDT using mTHPC-LIP or mTHPC-INV on infected canals.
- Control groups received 1% CHX gel or normal saline (NaCl). Bacterial analysis was performed on canal debris after mechanical enlargement.
Main Results:
- Both mTHPC formulations demonstrated significant antimicrobial activity against E. faecalis.
- Invasome-delivered mTHPC achieved up to a 3.6 log-step bacterial reduction at the root canal wall.
- mTHPC formulations suppressed E. faecalis within dentinal tubules up to 300 μm, outperforming CHX.
Conclusions:
- mTHPC incorporated in LIP and INV is highly effective in reducing E. faecalis in dental root canals.
- Photodynamic therapy with mTHPC delivered by invasomes shows superior efficacy compared to 24-hour 1% CHX treatment.
- This approach offers a promising alternative for managing resistant endodontic infections.
