DNA double-strand breaks caused by new and contemporary endodontic sealers

AimTo investigate the cytotoxicity and genotoxicity of a new silicate-based BioRoot RCS (R) sealer in comparison with contemporary sealers. MethodologyA 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((R)) and Acroseal((R))), four various methacrylate-based endodontic sealers (EndoREZ((R)), RealSeal((R)), RealSeal SE (R) and Hybrid Root SEAL((R))) and three silicate-based sealers (BioRoot RCS (R), iRootSP((R)) and MTA Fillapex((R))). The XTT-based cell viability assay was used for cytotoxicity screening of materials. The -H2AX assay was used for genotoxicity screening. In the -H2AX immunofluorescence assay, PDL-hTERT cells were exposed to eluates of the substances for 6h 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). ResultsThe cytotoxicity of the 24-h eluates could be ranked in the following order: Hybrid Root SEAL((R))>RealSeal((R))>Acroseal((R))>RealSeal SE (R) AH Plus Jet((R))> EndoREZ((R))>MTA Fillapex((R))> iRoot SP (R)>BioRoot RCS (R). In negative controls (cells which received medium only) 4.080.53 DSB foci (mean +/- SEM) whilst in positive controls 10.76 +/- 4.05DSB foci/cell were found. BioRoot RCS (R) and RealSeal SE (R) 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((R)), Acroseal((R)), RealSeal((R)) and MTA Fillapex((R)) sealers were not significantly different when compared with the medium control (P<0.05). ConclusionsNew BioRoot RCS (R) was not toxic whilst Hybrid Root SEAL((R)) demonstrated more toxicity and DNA double-strand breaks when compared with other resin- and silicate-based root canal sealers.