Estudo de resistência à tração de três sistemas adesivos associados a resina composta em superfícies dentinárias

Este trabalho teve como objetivo comparar a resistência à tração de três sistemas adesivos associados a resina composta aderidos à superfície dentinária. Quarenta e cinco superfícies de dentina foram obtidas a partir de molares humanos extraídos, sobre elas foi preparado "smear layer" e foram divididas em 3 grupos: G1) adesivo autocondicionante + resina micro-híbrida; G2) adesivo de componente único + ácido e resina micro-híbrida e G3) adesivo convencional (ácido + "primer" + bond) + resina micro-híbrida, aplicados de acordo com as instruções dos fabricantes. Os corpos-de-prova foram preparados para teste de tração, imersos em água destilada por 24 horas a 37ºC. Findo este tempo, o teste de tração foi realizado em máquina de ensaio Inströn com velocidade constante de 0,5 mm/min. Os resultados foram expressos em MPa e submetidos a análise de variância (p < 0,05). Os autores concluíram que: o tipo de sistema adesivo influenciou na resistência à tração das resinas compostas testadas; o sistema adesivo de componente único apresentou os melhores resultados de resistência adesiva.The aim of this in vitro study was to compare the tensile bond strength of 3 different bonding systems, associated to composite resins, bonded to dentinal surfaces. Forty-four dentinal surfaces were obtained from recently extracted human molars. A standardized smear layer was obtained and the surfaces were divided in 3 groups: G1) self etch + microhybrid composite; G2) single-component adhesive + phosphoric acid + microhybrid composite and G3) conventional system (acid + primer + bond) + microhybrid composite. Specimens made of composite resin were constructed in the shape of an inverted truncated cone with 3 mm of diameter. Tensile bond strength test was performed at the speed of 0.5 mm/min, and the results were expressed in MPa. The analysis of variance ANOVA (p < 0.05) determined that the type of bonding system used influenced tensile bond strength. Tukeys test, however, showed that the results of the comparison between G2 and G3 were the only statistically significant ones, with G2 showing greater values of tensile bond strength

Effect of Different Abutments and Connections in Deformation Crestal Bone

STATEMENT OF PROBLEM The use of Morse taper connections is increasing, but little is known about the biomechanical use of abutments and their use in fixed prostheses. PURPOSE This study evaluated the transmission of load on the bone implant-supported dentures, varying the type of prosthetic connection and abutment. MATERIAL AND METHODS Using 4 polyurethane models, 3 implants were inserted into each block, establishing the following groups: (a) external hexagon and Micro-Unit abutments; (b) external hexagon and UCLA abutment; (c) Morse taper and Micro-Unit abutments; and (d) Morse taper and UCLA abutments. The prosthetic structures were cast, and in a universal testing machine, load was applied midway between the implants, with cantilever intervals of 5, 10, 15, 20, and 25 mm. Data were analyzed by Mann-Whitney, Friedman, and Kruskal-Wallis tests (P < 0.05). RESULTS Regarding the prosthetic connection, there was no difference in the use of hexagonal or Morse taper, but the use of Micro-Unit abutment showed lower deformation values than UCLA for the 2 connections. CONCLUSIONS The use of intermediate abutments affects the distribution of masticatory loads: the greater the length of the cantilever, the greater the surface deformation of the bone around the distal implant