Cytotoxicity Test of One-Step Self-Etching Bonding Agents by Standardized Dentin Barrier Test Using Polyurethane Discs

Cytotoxicity and Genotoxicity of Epoxy Resin-Based Root Canal Sealers before and after Setting Procedures

Epoxy resin-based sealers are commonly used for successful endodontic treatment. This study aimed to evaluate the cytotoxicity and genotoxicity of epoxy resin-based sealers under unset and set conditions. Three epoxy resin-based sealers were used: Adseal, AH Plus, and Dia-Proseal. To test cytotoxicity, an agar overlay test and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay were performed using unset and set sealers on L929 mouse fibroblasts. The genotoxicity test of the comet assay was performed using the same cell line. Extract dilutions in the culture media were used as test materials for the MTT and comet assays. The comet tail produced by the damaged DNA was calculated by image analyses. Statistical analyses were performed using one-way analysis of variance and Tukey’s post hoc test. Unset sealers did not show defined decolorized areas. Hardened specimens of resin-based sealers showed circular discolored zones in the agar overlay test. Dia-Proseal was the least cytotoxic after hardening. These results were confirmed in the MTT assay. Cell viability was significantly higher in cells treated with hardened sealers in both groups than that in cells treated with freshly mixed sealers in the MTT assay. Unset AH Plus^® and Dia-Proseal™ significantly increased cell viability with decreasing dilution. Adseal™ was the least cytotoxic. Freshly mixed Adseal™ was more genotoxic when freshly mixed than when set. Unset epoxy resin-based sealers were generally more cytotoxic and genotoxic than set materials. Cytotoxicity does not always match the genotoxicity results; therefore, various test tools are required to test toxicity. It is necessary to properly evaluate the toxic effects to establish a biocompatibility test that mimics clinical conditions.

Porous zirconia ceramic as an alternative to dentin for in vitro dentin barriers cytotoxicity test

OBJECTIVES

This study assessed the potential of porous zirconia ceramic as an alternative to dentin via an in vitro dentin barrier cytotoxicity test.

METHODS

The permeability of dentin and porous zirconia ceramic was measured using a hydraulic-conductance system, and their permeability was divided into two groups: high and low. Using an in vitro dentin barrier test, the cytotoxicity of dental materials by dentin and porous zirconia ceramic was compared within the same permeability group. The L-929 cell viability was assessed by MTT assay.

RESULTS

The mean (SD) permeability of the high and low group for dentin was 0.334 (0.0873) and 0.147 (0.0377) μl min^-1 cm^-2 cm H₂O^-1 and for zirconia porous ceramic was 0.336 (0.0609) and 0.146 (0.0340) μl min^-1 cm^-2 cm H₂O^-1. The cell viability of experimental groups which are the low permeability group was higher than that of the high permeability group for both dentin and porous zirconia ceramic as a barrier except for Maxcem Elite^™ by porous zirconia ceramic. There was no significant difference between dentin and porous zirconia ceramic in cell viability, within either the high or low permeability group for all materials. The SD for cell viability of the porous zirconia ceramic was less than that of the dentin, across all materials within each permeability group, except for Maxcem Elite^™ in the high permeability group.

CONCLUSIONS

Porous zirconia ceramic, having similar permeability to dentin at the same thickness, can be used as an alternative to dentin for in vitro dentin barrier cytotoxicity tests.

CLINICAL RELEVANCE

In vitro dentin barrier cytotoxicity tests when a standardized porous zirconia ceramic was used as a barrier could be useful for assessing the potential toxicity of new dental materials applied to dentin before applying in clinical and may resolve the issue of procuring human teeth when testing proceeds.

Effect on vascular permeability of a self-etching adhesive system containing an antimicrobial quaternary ammonium polymer QAMP into subcutaneous tissue of rats

OBJECTIVE

This study investigated the effect of a self-etching adhesive system containing an antimicrobial quaternary ammonium methacrylate polymer (QAMP) on the vascular permeability using Evans blue and laser-Doppler flowmetric methods.

DESIGN

Forty rats were anesthetized and divided into groups: saline solution; Clearfil™ Protect Bond; Clearfil™ SE Bond; Clearfil™ SE Bond containing QAMP. Injections of Evans blue were administrated intravenously and the substances were injected intradermally. Immediately before injection and after 3 and 6h, was evaluated the blood flow. The animals were killed 3 and 6h after injection. The dorsal skin was dissected and experimental sites were obtained. The vascular permeability was evaluated by dye extravasation area, the dye was extracted and absorbance measured.

RESULTS

Concerning the Evans blue method, Clearfil™ SE Bond containing QAMP showed an extravasation area statistically similar to Clearfil™ SE Bond and lower than Clearfil™ Protect Bond. No statistical difference was verified among experimental groups for the amount of dye extracted. Clearfil™ SE Bond containing QAMP provided better laser-Doppler flowmetric parameters than Clearfil™ Protect Bond immediately and 3h after injection.

CONCLUSION

The QAMP had lower effect on the exudative phase of the inflammatory process.