title: DNA double-strand breaks caused by new and contemporary endodontic sealers.
abstract: OBJECTIVE
  To investigate the cytotoxicity and genotoxicity of a new silicate-based BioRoot RCS®sealer in comparison with contemporary sealers.
  
  
  METHODS
  A periodontal ligament cell line using lentiviral gene transfer of human telomerase reverse transcriptase (hTERT) was used and exposed to subtoxic concentrations of 24-h eluates from two epoxy resin-based (AH Plus Jet®and Acroseal®), four various methacrylate-based endodontic sealers (EndoREZ®, RealSeal®, RealSeal SE®and Hybrid Root SEAL®) and three silicate-based sealers (BioRoot RCS®, iRootSP®and MTA Fillapex®). The XTT-based cell viability assay was used for cytotoxicity screening of materials. The γ-H2AX assay was used for genotoxicity screening. In the γ-H2AX immunofluorescence assay, PDL-hTERT cells were exposed to eluates of the substances for 6 h and DNA double-strand breaks (DSB) were detected microscopically. Induced foci represented DSBs, which can induce ATM-dependent phosphorylation of the histone H2AX. The statistical significance of the differences between the experimental groups was compared using the Student's t-test (P < 0.05).
  
  
  RESULTS
  The cytotoxicity of the 24-h eluates could be ranked in the following order: Hybrid Root SEAL®>RealSeal®>Acroseal®>RealSeal SE®≥ AH Plus Jet®> EndoREZ®>MTA Fillapex®> iRoot SP®>BioRoot RCS®. In negative controls (cells which received medium only) 4.08 ± 0.53 DSB foci (mean ± SEM) whilst in positive controls 10.76 ± 4.05 DSB foci/cell were found. BioRoot RCS®and RealSeal SE®exhibited significant differences in foci formation at 1/3 EC50 compared with their 1/10 EC50 concentration (P < 0.05). Both concentrations (1/10 and 1/3 of EC50) of AH Plus Jet®, Acroseal®, RealSeal®and MTA Fillapex®sealers were not significantly different when compared with the medium control (P < 0.05).
  
  
  CONCLUSIONS
  New BioRoot RCS®was not toxic whilst Hybrid Root SEAL®demonstrated more toxicity and DNA double-strand breaks when compared with other resin- and silicate-based root canal sealers.
authors.affiliation: Department of Endodontics, Selcuk University, Konya, Turkey.
authors.forename: A U
authors.initials: AU
authors.lastname: Eldeniz
authors.affiliation: Department of Operative/Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians-University of Munich, Munich, Germany.|Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University of Munich, Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Shehata
authors.affiliation: Department of Operative/Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians-University of Munich, Munich, Germany.|Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University of Munich, Munich, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Högg
authors.affiliation: Department of Operative/Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians-University of Munich, Munich, Germany.|Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University of Munich, Munich, Germany.
authors.forename: F X
authors.initials: FX
authors.lastname: Reichl
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003188:Composite Resins / Q000633:toxicity; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004853:Epoxy Resins / Q000633:toxicity; D006801:Humans; D009152:Mutagenicity Tests; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects; D010895:Pit and Fissure Sealants / Q000633:toxicity*; D012387:Root Canal Filling Materials / Q000633:toxicity*
chemical_list: C477053:Acroseal; D003188:Composite Resins; C481259:EndoRez; D004853:Epoxy Resins; D010895:Pit and Fissure Sealants; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer
keywords: DNA double-strand breaks; PDL-hTERT cells; cytotoxicity; eluates; sealers