Fatigue resistance of the bond of a glass-infiltrated alumina ceramic to human dentin

Purpose: To evaluate the fatigue resistance of the bond between dentin and glass-infiltrated alumina ceramic, using different luting protocols. Materials and Methods: The null hypothesis is that the fatigue resistance varies with the luting strategy. Forty blocks of In-Ceram Alumina were prepared, and one surface of each block was abraded with 110-μm aluminum oxide particles. Then, the blocks were luted to flat dentin surfaces of 40 human third molars, using 4 different luting strategies (luting system [LS]/ceramic surface conditioning [CSC]) (n=10): (G1) [LS] RelyX-Unicem/[CSC] airborne abrasion with 110-μm Al2O3 particles; (G2) [LS] One-Step + Duo-Link (bis-GMA-based resin)/[CSC] etching with 4% hydrofluoric acid + silane agent; (G3) [LS] ED-Primer + Panavia F (MDP-based resin)/[CSC] Al2O 3; (G4) [LS] Scotchbond1+RelyX-ARC (bis-GMA-based resin)/[CSC] chairside tribochemical silica coating (air abrasion with 30-μm SiO x particles + silane). After 24 h of water storage at 37°C, the specimens were subjected to 106 fatigue cycles in shear with a sinusoidal load (0 to 21 N, 8 Hz frequency, 37°C water). A fatigue survivor score was given, considering the number of the fatigue cycles until fracture. The failure modes of failed specimens were observed in a SEM. Results: G3 (score = 5.9, 1 failure) and G4 (score = 6, no failures) were statistically similar (p = 0.33) and had significantly higher fatigue resistance than G1 (score = 3.9, 5 failures) and G2 (score = 3.7, 6 failures) (p < 0.03). SEM analysis of fractured specimens of G1 and G2 showed that almost all the failures were between ceramic and cement. Conclusion: The MDP-based resin cement + sandblasting with Al2O3 particles (G3) and bis-GMA-based resin cement + tribochemical silica coating (G4), both using the respective dentin bonding systems, were the best luting protocols for the alumina ceramic. The null hypothesis was confirmed.

Direitos e garantias fundamentais no direito societário

Pós-graduação em Direito - FCHS

Volumetric microleakage assessment of glass-ionomer-resin composite hybrid materials

Objective: This study was intended to quantify the marginal leakage of three glass-ionomer-resin composite hybrid materials and compare it with the leakage exhibited by a glass-ionomer cement and a bonded resin composite system. Method and materials: Standardized Class V cavities were prepared on root surfaces of 105 extracted human teeth, randomly assigned to five groups of 21 each, and restored with either Ketac-Fil Aplicap, Z100/Scotchbond Multi-Purpose Plus, Vitremer, Photac-Fil Aplicap, or Dyract. The teeth were thermally stressed for 500 cycles and stained with methylene blue. The microleakage was quantified spectrophotometrically, and the data were statistically analyzed with Friedman's test. Results: There were no significant differences in microleakage among the five groups. Restorations of all tested materials showed some marginal leakage in Class V cavities. Conclusion: The microleakage performance of glass-ionomer-resin composite hybrid materials was similar to those of a conventional glass-ionomer and a bonded resin composite system.

As convenções da OIT no ordenamento jurídico brasileiro à luz do tripartismo

Pós-graduação em Direito - FCHS

O discurso do ódio: a cultura do medo e a influência midiática sobre a (in)efetividade dos direitos fundamentais

Pós-graduação em Direito - FCHS