Adesão à dentina úmida e seca: resistência de união à microtração e infiltração marginal
Bonding to wet and dry dentin: microtensile bond strength and marginal leakage
Spazzin, A.O.; Carlini Júnior, B.; Moraes, R.R.; Mesquita, M.F.
Rev. odontol. UNESP, vol.37, n1, p.91-96, 2008
Resumo
Este estudo avaliou o efeito da adesão à dentina úmida ou seca na resistência de união e selamento de restaurações de resina composta. Quarenta molares foram obtidos: em metade dos dentes foi exposta uma superfície plana em dentina para adesão e posterior teste de microtração; a outra metade recebeu preparos cavitários nas faces vestibular e lingual, com margens em dentina/ cemento, para o teste de infiltração marginal. Nos substratos preparados, após aplicação de ácido fosfórico a 37% por 15 segundos e lavagem por 15 segundos, a umidade da dentina foi removida com algodão (dentina úmida) ou utilizando jato de ar por 15 segundos (dentina seca). Em seguida, aplicou-se agente de união com solvente acetona e as restaurações foram realizadas. Os corpos de prova para avaliação da resistência de união foram seccionados em fatias, sendo realizada constrição da interface de união no formato de ampulhetas, que foram fixadas em máquina de ensaios com a interface de união paralela ao plano horizontal e submetidas à microtração. Os dados foram analisados pelo teste-t de Student (5%). As cavidades restauradas foram submetidas à ciclagem térmica e imersas em solução de azul de metileno a 2%, por 4 horas. A penetração do corante foi avaliada sob aumento (10x), com escores padronizados de profundidade de penetração do corante. Os dados foram submetidos ao teste de Mann-Whitney (5%). A resistência de união (MPa) à dentina úmida (17,3 ± 11) foi significativamente maior (p = 0,001) que à dentina seca (9,1 ± 5,7), enquanto o selamento marginal foi semelhante para as duas técnicas (p = 0,343).
Palavras-chave
Adesivos dentinários, dentina, infiltração dentária, resistência à tração
Abstract
This study evaluated the effect of adhesion to wet or dry dentin on the bond strength and sealing of resin composite restorations. Forty molars were obtained: in half of the teeth, a flat surface in dentin was exposed to adhesion and further microtensile testing; in the other half, cavity preparations were made in the buccal and lingual faces, with margins placed in dentin/cementum, for the marginal leakage test. On the prepared substrates, following the application of 37% phosphoric acid for 15 seconds and washing for 15 seconds, the removal of dentin moisture was made with a cotton pellet (wet dentin) or with a air stream for 15 seconds (dry dentin). A bonding system with acetone solvent was then applied and the restorations were made. Samples for bond strength evaluation were sectioned in slices and the bonding interface trimmed to hour-glass specimens, which were attached to a testing machine with the interface parallel to the horizontal axis and submitted to microtensile testing. Data were analyzed by Student’s t-test (5%). The restored cavities were submitted to thermalcycling and immersed in 2% methylene blue solution, for 4 hours. Dye penetration was evaluated under magnification (10x), using standard scores regarding the depth of penetration. Data were submitted to Mann-Whitey’s test (5%). The bond strength to wet dentin (17.3 ± 11) was significantly higher (p = 0.001) than to dry dentin (9.1 ± 5.7), whereas the marginal sealing was similar for the both techniques (p = 0.343).
Keywords
Dentin-bonding agents, dentin, dental leakage, tensile strength
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