Bond Strength Evaluation of Two Adhesive Systems in Fiberglass Posts Cementation

Objective: To compare the bond strength of three-step and self-etch adhesive systems with and without prior acid etching on bonding of fiberglass posts in root canals. Material and Methods: Experiments were conducted on roots of five upper molars without curvature and sectioned in a cervical-apical direction. With the aid of a highspeed turbine and diamond tips, cylindrical cavities 7 mm in depth and 1.4 mm in diameter were made in the dentine. The roots of the same tooth were used, where the retainers were cemented, thus generating three groups: Group A: Adper Scotchbond Multipurpose Plus (SBMP) + Rely X ARC; Group B: Single Bond Universal (SBU-1) + Rely X ARC, with acid etching prior to adhesive insertion; Group C: Single Bond Universal (SBU-2) + Rely X ARC. The samples were stored in a bacteriological incubator at 37ºC with 100% humidity for 48h and were subsequently cross-sectioned to obtain 3 dentine discs 1mm in thickness. Forty-five specimens were subjected to the push-out test. Results: Through the analysis of variance and Tukey's test, it was found that SBMP showed, with statistical significance (p<0.05), highest bond strength when compared with the SBU-1 and SBU-2 systems. The observed difference in the discs was located in the cervical portion. Conclusion: The three-step adhesive system had higher bond strength with the substrate than the self-etching adhesive only in the disc in the cervical portion; further, statistically, the prior application of phosphoric acid in SBU-1 did not affect its bond strength significantly.

Avaliação da resistência flexural de próteses parciais fixas confeccionadas em In Ceram Zircônia / Flexural strength evaluation of fixed partial denturesmade in In Ceram Zirconia

Avaliar a resistência flexural do In Ceram Zircônia em 20 corpos de prova, simulando uma prótese parcial fixa.Metodologia: foram utilizados 20 corpos de prova em forma de barra com as seguintes dimensões: 20mm de comprimento, 1,2mm de espessura e 4mm de largura e divididas em dois grupos: Grupo A - com distância do span de 12mm; e, Grupo B - com distância do span de 18mm, simulando respectivamente um e dois pônticos. As barras foram submetidas ao teste de carregamento de 3 pontos, análise fractográfica e microscópica eletrônica de varredura.Resultados: ANOVA, fator único não encontrou diferença estatística significante nos resultados da resistência flexural entre os grupos A e B, mas o resultado das tensões e a força de ruptura demonstraram o oposto.Conclusão: o aumento da distância entre os apoios não diminuiu a resistência flexural do material. Existe uma maior concentração de tensões quando se aumenta a distância entre os apoios, podendo representar uma tendência a ruptura para próteses com maior extensão...

This study evaluated the flexural strength of In Ceram Zirconia in 20 specimens, simulating a fixed partial denture.Methodology: a total of 20 specimens in the form of bar with the following dimensions: 20mm long, 1.2 mm thick and 4mm wide and divided into two groups: Group A with span distance of 12mm and Group B with span distance of 18mm, simulating one and two pontics respectively. Samples were submitted in loading test with three points, fractographic analysis and scanning electron microscopy.Results: ANOVA, single factor did not found significant statistically difference in the results of flexural strength between groups A and B, but the result of stress and rupture strength showed the opposite.Conclusion: increasing the distance between the supports did not reduce the flexural strength of the material. There is a higher stress concentration when the distance between the supports increases, this represent a tendency to break for prostheses with greater length...