Nancy Kudsi Carvalho

Push-out bond strength of MTA HP, a new high-plasticity calcium silicate-based cement

This study was designed to investigate the resistance to dislodgment provided by MTA HP, a new high-plasticity calcium silicate-based cement. Biodentine and White MTA Angelus were used as reference materials for comparison. Three discs 1 ± 0.1 mm thick were obtained from the middle third of the roots of 5 maxillary canines. Three 0.8-mm-wide holes were drilled on the axial surface of each root disc. Standardized irrigation was performed. Then the holes were dried with paper points and filled with one of the three tested cements. The filled dental slices were immersed in a phosphate-buffered saline (PBS) solution (pH 7.2) for 7 days before the push-out assessment. The Kruskal-Wallis test was applied to assess the effect of each endodontic cement on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. All specimens had measurable push-out values and no premature failure occurred. There were significant differences among the materials (p <0.05). The Biodentine specimens had the highest push-out bond strength values (p < 0.05). MTA HP had significantly higher bond strength than White MTA (p < 0.05). MTA HP showed better push-out bond strength than its predecessor, White MTA; however, Biodentine had higher dislodgment resistance than both MTA formulations.

Push-out Bond Strength of Fast-setting Mineral Trioxide Aggregate and Pozzolan-based Cements: ENDOCEM MTA and ENDOCEM Zr

Introduction: The present study investigated the root canal dentin bond strength of 2 newly developed fast‐setting mineral trioxide aggregate (MTA) and pozzolan‐based cements: ENDOCEM MTA (Maruchi, Wonju, Korea) and ENDOCEM Zr (Maruchi). White MTA (Angelus, Londrina, Brazil) was used as the reference material for comparison. Methods: Root slices (1 mm ± 0.1 mm) were obtained from the middle third of 15 maxillary incisors previously selected. Three canal‐like holes (0.8 diameter) were drilled perpendicularly on the axial surface of each root slice. A standardized irrigation protocol was applied for all samples, and after drying, each hole was filled with 1 of 3 test repair materials. Finally, slices were stored in contact with phosphate‐buffered saline solution (pH = 7.2) for 7 days at 37°C before the push‐out assay. Data were nonparametrically evaluated at &agr; = 5%. Results: The Friedman test was unable to confirm a significant dissimilarity in push‐out ranks among the tested cements (P = .220). Conclusions: The new fast‐setting MTA and pozzolan‐based cements ENDOCEM MTA and ENDOCEM Zr present suitable bond strength performance, which is comparable with white MTA. HIGHLIGHTSNewly developed fast‐setting mineral trioxide aggregate (MTA) and pozzolan‐based cements ENDOCEM MTA and ENDOCEM Zr present similar push‐out values to white MTA.The use of zirconium oxide as the radiopacifying agent rather than bismuth oxide in ENDOCEM Zr has no influence in push‐out results.ENDOCEM MTA and ENDOCEM Zr present suitable bond strength performance.

Cytotoxicity Profile of Endodontic Sealers Provided by 3D Cell Culture Experimental Model

The aim of the present study was to evaluate the cytotoxic effects of five endodontic sealers (AH Plus, Endomethasone N, EndoSequence BC, MTA Fillapex and Pulp Canal Sealer EWT) using a three-dimensional (3D) cell culture model. A conventional bi-dimensional (2D) cell culture model was used as reference technique for comparison. Balb/c 3T3 fibroblasts were cultured in conventional bi-dimensional cell culture and in rat-tail collagen type I three-dimensional cell culture models. Then, both cell cultures were incubated with elutes of freshly mixed endodontic sealers for 24 h. Cell viability was measured by the methyl-thiazol-diphenyltetrazolium assay (MTT). Data were statistically analyzed using ANOVA and the Tukey test at a significance level of p<0.05. All tested sealers exhibited cytotoxic effects; however, cytotoxic effect was culture model- and sealer-dependent. Sealers showed higher cytotoxicity in 2D than in 3D cell culture model (p<0.05). In both conditions, EndoSequence BC showed the lowest cytotoxicity (p<0.05). MTA Fillapex was much more cytotoxic than the other tested endodontic sealers (p<0.05), with the exception of AH Plus in the 2D cell culture model (p>0.05). Endomethasone N and Pulp Canal Sealer EWT showed lower cytotoxic effects than AH Plus in 2D cell culture model (p<0.05); however no statistical differences was observed among these sealers in 3D cell culture model. It may be concluded that cytotoxicity was higher in 2D cell culture compared to 3D cell culture. EndoSequence BC sealer exhibited the highest cytocompatibility and MTA Fillapex the lowest cytocompatibility.

Influência do pó de MTA manipulado com água destilada ou solução salina tamponada com fosfato no desempenho push-out

Objective: to investigated the bond strength of MTA powder handled with distilled water (DW) or phosphate buffered saline (PBS). Material and Methods: two horizontal cross-section were prepared in the root of fifteen incisors, followed by drilling of two canal-like holes on its axial surface. Holes were filled with MTA with DW or PBS. Load was applied until MTA displacement. Mann-Whitney and Friedman tests were selected to establish the influence of independent variables on push-out strength. Results: MTA handled with DW and PBS showed similar values (p>0.05). Conclusion: DW or PBS do not interfere in push-out bond strength of MTA.Objective: to investigated the bond strength of MTA powder handled with distilled water (DW) or phosphate buffered saline (PBS). Material and Methods: two horizontal cross-section were prepared in the root of fifteen incisors, followed by drilling of two canal-like holes on its axial surface. Holes were filled with MTA with DW or PBS. Load was applied until MTA displacement. Mann-Whitney and Friedman tests were selected to establish the influence of independent variables on push-out strength. Results: MTA handled with DW and PBS showed similar values (p>0.05). Conclusion: DW or PBS do not interfere in push-out bond strength of MTA.

Bond Strength of Experimental Root Canal Sealers Based on MTA and Butyl Ethylene Glycol Disalicylate

This study investigated the bond strength of two experimental root canal sealers based on MTA and butyl ethylene glycol disalicylate: MTAe and MTAe-HA. The reference materials used for comparison were AH Plus and MTA Fillapex. Twenty human upper incisors were selected and one 1 mm slice was obtained from the cervical third of each root. On the coronal surface of each slice, four 0.9 mm wide holes were drilled through the dentine. Standardized irrigation was performed and holes were filled with one of the four tested sealers: AH Plus, MTA Fillapex, MTAe, and MTAe-HA. The filled slices were stored in a PBS solution (pH 7.2) for 7 days at 37 °C. A push-out assessment was performed with a 0.7 mm plunger tip. Load was applied at a crosshead speed of 0.5 mm/min until sealer displacement. The results were expressed in MPa. The Kruskal-Wallis test was applied to assess the effect of each sealer on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. Significant differences among medians values obtained by materials were observed (p<0.001). AH Plus displayed the highest value of bond strength (p<0.001). In contrast, MTA Fillapex presented the lowest bond strength among all tested sealers (p<0.001). Experimental sealers showed intermediary bond strength values, with no statistical differences between them (p>0.05). In conclusion, experimental root canal sealers presented suitable bond strength outcomes when compared to MTA Fillapex.

A comparative evaluation of efficacy of a reciprocating system for gutta-percha removal with or without a solvent

Objective: to evaluate the efficacy of Reciproc System, with or without solvent for endodontic filling removal from oval shaped root canals. The time required for gutta-percha removal and the instrument fracture were also evaluated. Material and Methods: forty straight single-rooted premolars were prepared up to a size 30 and filled with gutta-percha and sealer, then randomly assigned to two retreatment groups (n = 20), treated with Reciproc System with or without chloroform (RS+C and RS). For all roots, procedural errors, time of retreatment and apically extruded material were recorded. After retreatment, roots were split longitudinally and then photographed. All images were evaluated with Image Tool software to calculate the percentage of residual material. Kolmogorov Smirnov and t tests were used to determine significant differences at P < .05. Results: no treatment completely removed the root filling material from the root canals. Analysis of the total area did not reveal statistical differences between the two groups (P >.05). Both groups also showed similar results in all tested thirds, with no statistical differences (P >.05). RS without solvent was faster in filling material removal than RS+C (P <.05). For both groups, none of the instruments showed intracanal fracture or visible signs of plastic deformation. Conclusion: taken together, our results demonstrated that Reciproc System used without solvent required less time to remove the same amount of root filling material than Reciproc System with solvent. However, regardless of solvent use, the same cleaning quality was obtained.