Influence of a new push-out test method on the bond strength of three resin-based sealers.

AIM: Compare the displacement resistance of AH Plus, Ad Seal and Real Seal on dentine discs (DDs) treated with 10% citric acid, 17% EDTA or 2.5% NaOCl, through a new push-out test method. METHODOLOGY: From the middle third of the roots of 15 maxillary central incisors, three dentine discs 1 ± 0.1 mm thick were obtained. On the axial surface of each dentine disc, three 1.2-mm-wide holes were drilled. In the third dentine disc from the same root, each hole was treated with one of three irrigating solutions for 30 s, rinsed with distilled water and dried. Each hole of the same dentine disc was filled with sealer, and the discs were maintained at 37 °C for 7 days. The dentine discs were fixed on a testing machine to test the shear strength. Data were compared using the univariate anova test with a 5% significance level. The Tukey test was used for multiple comparisons. RESULTS: The irrigating solutions did not affect the adhesion of the sealers (P > 0.05). There was no significant difference between the Ad Seal and AHPlus (P > 0.05); however, Real Seal had a significantly lower shear bond strength (P < 0.05). CONCLUSION: The use of different irrigating solutions did not affect resistance to the displacement of resin sealers. Real Seal sealer was less resistant than Ad Seal and AHPlus.

A multiparametric assay to compare the cytotoxicity of endodontic sealers with primary human osteoblasts.

AIM: To compare the cytotoxicity of four endodontic sealers (Sealapex, Pulp Canal Sealer EWT, Real Seal and MTA Fillapex) either 1 or 7 days after mixing, when assessed through a multiparametric analysis employing human primary cells closely related to periapical tissues. METHODOLOGY: Extracts of each sealer were prepared following 24-h exposure to culture media, at either 24 h or 7 days after mixing. Primary human osteoblasts were exposed to extracts for 24 h, at 37 °C with 5% CO(2) , and cell viability was evaluated by a multiparametric assay assessing sequentially, on the same cells, mitochondrial activity (XTT), membrane integrity (neutral red test) and total cell density (crystal violet dye exclusion test). Results from each test and experimental time were compared by 2-way analysis of variance (anova). RESULTS: All endodontic sealers had strong cytotoxicity 24 h after mixing, according to all parameters evaluated. At a longer setting period (7 days), viability for Sealapex was significantly increased (P < 0.05) and Pulp Canal Sealer achieved levels of cytocompatibility similar to the control group. The anova indicated a general correlation between the cytotoxicity of the materials and the time after mixing, with some level of dependence on the cell viability assay employed. CONCLUSIONS: All materials had high cytotoxic levels for human primary cells, mostly on a time-dependent basis, as shown by three different cell viability tests.