Evaluation of push-out bond strength of four luting agents and SEM observation of the dentine/fibreglass bond interface.

AIM: To assess the dentine/fibreglass-bonded interface by scanning electron microscopy and the push-out bond strength of four luting cements. METHODOLOGY: Forty root-filled human canines, with similar root lengths, were restored with fibreglass posts and randomly divided into four groups according to the cements employed (CG Gold Label I, RelyX ARC, BisCem and RelyX U100). After standardized post-space preparation, the root dentine was pre-treated for dual-polymerizing resin cements and untreated for the other cements. The mixed luting cement paste was inserted into root canals with a spiral filler and applied to the post-surface that was seated into the root canal. After 7 days, the teeth were sectioned perpendicular to their long axis into 1-mm-thick sections and submitted to a push-out test (1 mm min(-1)). Statistical analyses were carried out by two-way anova and Tukey's tests (P < 0.05). RESULTS: The bond strength was significantly affected by the type of cement (P < 0.001) and by the longitudinal region of the root canal (P < 0.031). All cements exhibited gaps at the dentine/cement interface. CONCLUSIONS: The self-adhesive materials and the glass ionomer cements had the highest push-out bond strength values when compared with the dual-curing resin cement.

A comparison of bond strengths of complete crowns using two types of cements and three cleaning agents.

This study evaluated the influence of three cleaning agents on the bond strength of complete crowns cemented with zinc phosphate and polycarboxylate cements. For the polycarboxylate cement group, three cleaning agents were used: Tergentol; Tergentol + polyacrylic acid; Tergentol + citric acid. Zinc phosphate cement was used as a control group with Tergentol. There were no statistically significant differences of mean retentive force for either cement regardless of the test conditions. The marginal fit after cementation was also evaluated and the results of zinc polycarboxylate were lower than zinc phosphate cement and were statistically significant.

[Negative carving: clinical applications]. / Escultura negativa: aplicação clinica.

The objective of the negative carving technique is to develop properly the occlusal principles during fabrication of occlusal surfaces of temporary crowns or metalhi restorations.

Evaluation of fracture resistance of endodontically treated maxillary premolars, restored with ceromer or heat-pressed ceramic inlays and fixed with dual-resin cements.

The aim of this study was to evaluate the fracture resistance of endodontically maxillary premolars restored with mesio-occlusal-distal (MOD) inlays made with ceramic (IPS-Empress 2) and ceromer (Targis) and luted with three different dual-cured resin cements (Enforce, Variolink II, Panavia F). Sixty maxillary premolars were randomly distributed into six groups, according to their mesio-distal and facio-lingual dimensions. The teeth were endodontically treated and MOD cavities prepared. After the restorations were cemented, the samples were thermocycled and submitted to an axial compressive load by the action of a rounded end steel cylinder contacting the incline planes of occlusal surfaces of the teeth. The mode of fracture was analysed with a microscope. The best results were found with the combinations (cement/restorative material) Enforce/Targis (107.57 kgf) and Enforce/Empress (90.21 kgf) followed by Variolink II/Targis (86.44 kgf)-Variolink II/Empress (84.07 kgf) and Panavia F/Targis (82.43 kgf)-Panavia F/Empress (76.73 kgf). Analysis of variance (P < 0.05) showed a significant difference between Enforce and Panavia cements regardless of the restorative material. Considering the same luting agent there was no statistically significant difference between the restorative materials. Fracture of lingual cusps occurred in 55 of the 60 teeth and most of them were of the cohesive type.

[Traction resistance of cast metal posts with and without retention, cemented with zinc phosphate cement in smooth and rough canals]. / Avaliação da resistência à remoção por tração de núcleos metálicos fundidos com e sem retenção, fixados com cimento de fosfato de zinco em condutos lisos e com retenções.

The purpose of this research was to test the traction resistance of cast posts and cores with and without roughness cemented with zinc phosphate cement in cuspids roots, with smooth and roughness canals walls. From the results of the tests and statistical analysis there was significant difference between roughness posts cemented in root canals with roughness walls and smooth posts cemented in smooth root canals. It was also analyzed, the retention of cast crows cemented on roughness posts and canals and it was concluded that posts are responsible for crows retention, when the cores were done at the correct way.