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clavijo_vgr_dr_arafo.pdf: 969958 bytes, checksum: 57064b07ad94167d21ebb9ba66873da2 (MD5) === Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) === Neste estudo avaliou-se a resistência ao cisalhamento por extrusão de pinos de fibra de vidro, reembasados ou não com compósito, cimentados com dois tipos de cimentos resinosos em dentina intra-radicular, avaliando os segmentos cervical, médio e apical. Selecionaram-se 40 incisivos bovinos com dimensões semelhantes, removendo a porção coronária, padronizando o comprimento das raízes em 14 mm. Após, incluiu-se as raízes em resina acrílica, realizando tratamento endodôntico e, então o preparo dos espaços para os pinos, dividindo- as, em seguida, aleatoriamente em quatro grupos com dez amostras cada. Os elementos do grupo 1 receberam retentores de fibra de vidro cimentados com cimento resinoso RelyX ARC, grupo 2 retentores de fibra de vidro cimentados com cimento resinoso RelyX U100, grupo 3 retentores de fibra de vidro reembasados com resina composta e cimentados com cimento resinoso RelyX ARC e grupo 4 retentores de fibra de vidro reembasados com resina composta e cimentados com cimento resinoso RelyX U100. Ao término dos procedimentos de cimentação, realizou-se a secção dos segmentos radiculares, submetendo, então, os corpos-de-prova ao teste push-out em máquina de ensaios universal, através de ponta ativa cilíndrica com 1 mm de diâmetro, à velocidade de 0,5 mm/min, até extrusão do retentor. Obteve-se os seguintes valores médios de resistência de união, em MPa: grupo 1, terços cervical = 6,22 ± 2,64(a), médio = 4,25 ± 2,01(a) e apical = 4,45± 2,81(a); grupo 2, terços cervical = 5,04 ± 2,34(a), médio = 3,06 ± 2,12(a) e apical = 3,26 ± 2,38(a). grupo 3, terços cervical = 11,85 ± 1,67(b), médio = 11,83 ± 3,84(b) e apical = 10,39 ± 2,44(b). grupo 4, terços cervical = 12,05 ± 1,14(b), médio = 11,98 ± 3,23(b) e apical = 10,96 ± 2,14(b). Submeteram-se os valores à análise de variância e ao teste de Tukey com nível de significância de 5% indicadas... === This study evaluated the bond strength of fiber posts, relined or not with composite resin, luted with resinous cement to radicular dentin, evaluating cervical, median and apical root segments. Fourty bovine incisors, with similar dimensions, were selected and cut 16 mm from the apical limit. The roots were embedded in acrylic resin and the radicular canals were root treated and post space prepared with a depth of 9 mm. Samples were randomly assigned to two groups of ten roots each. Group 1 received glass fiber posts luted with dual-cure resin cement RelyX ARC in association with a bonding system. In Group 2 the same type of posts were relined with composite for further cementation with resin cement RelyX U100. In Group 3, glass fiber post were relined with composite and cemented with resin cement RelyX ARC and in Group 4 glass fiber posts were relined ith composite and cemented with resin cement RelyX U100. After cementation procedures roots were sectioned transversally and three sections, from cervical, medium and apical thirds were obtained. Push-out test was performed in a universal testing machine with a 1 mm diameter steel rod at cross-head speed of 0,5 mm/min until post extrusion. Collected data was statistically analyzed by two- way ANOVA and Tukey HSD test (p<0,05). The measured retention strengths for cervical, medium and apical thirds were: Group 1, cervical thirds = 6,22 ± 2,64(a), medium = 4,25 ± 2,01(a) e apical = 4,45± 2,81(a); group 2, cervical thirds = 5,04 ± 2,34(a), medium = 3,06 ± 2,12(a) and apical = 3,26 ± 2,38(a). Group 3, cervical thirds = 11,85 ± 1,67(b), medium = 11,83 ± 3,84(b) and apical = 10,39 ± 2,44(b). Group 4, cervical thirds = 12,05 ± 1,14(b), medium = 11,98 ± 3,23(b) and apical = 10,96 ± 2,14(b). Glass fiber composite relined posts presented statistically higher retention values in cervical, medium and apical thirds when compared... (Complete abstract click electronic access below)
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