Is the chlorophyll derivative Zn(II)e6Me a good photosensitizer to be used in root canal disinfection?

Publication date: Available online 21 April 2018
Source:Photodiagnosis and Photodynamic Therapy
Author(s): P. Diogo, M. Mota, C. Fernandes, D. Sequeira, P. Palma, F. Caramelo, M.G.P.M.S. Neves, M.A.F. Faustino, T. Gonçalves, J.M. Santos
BackgroundThe aim of this study was to assess antimicrobial efficacy and cytotoxic outcomes of a chlorophyll based photosensitizer (PS) Zn(II)chlorin e6 methyl ester (Zn(II)e6Me), when applied to human dentin discs and root blocks infected with 48 h biofilms. The results were compared with the ones obtained with FotoSan® (commercial Toluidine Blue O formulation) and 3% sodium hypochlorite (NaOCl).MethodologyDentin and root blocks were infected with mixed biofilms of Enterococcus faecalis and Candida albicans; exposed for 15 min to 0.1 mg/mL of Zn(II)e6Me or Fotosan^® and then irradiated with red light (627 nm, 75 mW, 3150 J/cm²) for 90 s or treated with NaOCl. Biofilm removal was calculated with safranin red assay and biofilm cells viability with XTT® assay. The PSs cytotoxicity was evaluated over human apical papilla primary cell line (hAPCs) with AlamarBlue® assay and cell morphology assessed with widefield fluorescence microscopy.ResultsAt dentin discs, the chlorophyll derivative performed better in biofilm removal (59.1%) than FotoSan® agent (57.5%), however, with lower efficacy than NaOCl (68.1%) (P = 0.0185). Conversely, at the root block, the chlorophyll Zn(II)e6Me (79.7%) present better antimicrobial efficacy than NaOCl (75.5%) and the disinfection pattern was more consistent at inner and outer samples for the former. No dark or photoinduced cytotoxic outcomes were detected for Zn(II)e6Me over human cells at 24 and 48 h when compared with other PSs (FotoSan^®, Rose Bengal and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin - TMPyP).ConclusionsThe chlorophyll derivative Zn(II)e6Me showed adequate antimicrobial efficacy, performing better in mixed biofilm removal than FotoSan^® in both experimental conditions. No cytotoxic effects over human apical papilla cells were identified for this chlorophyll derivative, subsequently it deserves further evaluation to assess its potential use in endodontic therapy.



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