Avaliação da resistência ao cisalhamento do compósito Right-On em diferentes condições de esmalte

Abstract

OBJETIVO: avaliar a resistência ao cisalhamento da união de braquetes metálicos colados com o compósito Right-On, em diferentes condições de superfície. MATERIAL E MÉTODOS: foram utilizados 45 incisivos inferiores permanentes bovinos divididos em três grupos (n = 15). No grupo 1 (controle), as colagens foram realizadas com Transbond XT seguindo as recomendações do fabricante, ou seja condicionamento com ácido fosfórico a 37%, lavagem, secagem, aplicação de XT primer e colagem propriamente dita. Nos outros dois grupos, os braquetes foram colados com Right-On, sendo que no grupo 2 seguiu-se as instruções do fabricante, ou seja condicionamento com ácido fosfórico a 37%, aplicação do líquido ativador do compósito na superfície condicionada e na base do braquete e posterior inserção do compósito na base do braquete e posicionamento. No grupo 3 a superfície dentária foi condicionada com o ácido-primer Transbond Plus Self-Etching Primer e líquido ativador do compósito foi aplicado apenas na base do braquete. Após a colagem, realizou-se o ensaio de cisalhamento de toda amostra à velocidade de 0,5mm por minuto em máquina Instron de ensaios mecânicos. RESULTADOS E CONCLUSÕES: os resultados (MPa) mostraram não haver diferenças estatísticas entre os grupos 1 e 2 (p > 0,05), entretanto estes grupos foram estatisticamente superiores ao grupo 3 (p < 0,05). Os resultados do IRA evidenciaram maior número de fraturas na interface braquete/compósito.

Influence of dental erosion on the shear bond strength of orthodontic brackets: an in vitro study

“…Groups 3 and 4, using Orthoprimer/Orthobond adhesive system obtained, respectively, 12.76 MPa and 13.01 MPa. This average was also higher than previous researches 3 . These great extent are explained by variations of 3.5 MPa to 27.8 MPa found 5 , and due to different methodology used in the SBS test studies, such as: the position of the knife-edge rod in the bracket 24 , storage time after bonding 25,26 , bracket base area 2 , adhesive polymerization time, and the crosshead speed of the test 5 .…”

“…Significant differences were found in this study between SBS of the adhesive systems of healthy groups 1 and 3, as previously reported by Pithon et al 3 (2008), and between eroded groups 2 and 4. However, in spite of these statistical differences found, both adhesive systems obtained SBS compatible to clinical use, higher than the average strength -6 MPa to 8 MPa, recommended by literature 2,3 . The prevalence of the ARI score 2, over 50% adhesive on enamel, was found in this study, mainly for groups 3 and 4, with lower SBS values, nevertheless no statistical differences were found between the tested groups, in accordance with other studies 21,24,27 .…”

“…The adhesive infiltrates monomer links to the enamel surface by resin tag formation, creating a bonded system. To avoid premature debonding, minimum clinical adhesive strength of [6][7][8] MPa is required, as advised by previous studies 2,3 . Thus, during the clinical bonding procedure, different factors could affect the bonding strength between bracket and enamel, such as different methods of etching 4 , adhesive polymerization time 5 , contamination 6 , adhesive systems [7][8][9] , and bracket base configuration 10 .…”

In vitro analysis of shear bond strength and adhesive remnant index comparing light curing and self-curing composites

“…On the other hand, our results confront studies which reported the majority of disruptions in the interface composite/ bracket. 4,15,16,19,24 After shear bond strength test and during the ARI evaluation enamel fractures were observed in four specimens distributed among the four groups. This relative frequency of fractures among groups, supported by the study by Liu et al, 10 may be associated with high strength supported by the samples.…”

“…tubes (Tigre) with 25 mm of diameter / 25 mm of height, filled with special plaster stone (Durone -Dentsply). 16 In the moment of the teeth insertion, the buccal surfaces were positioned perpendicular to the ground, using as an aid a juxtaposed square to the bonding surface and the excesses were removed with a spatula LeCron (Duflex). The specimens were stored again at 0.9 % saline solution.…”