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Teste de microtração em esmalte de um sistema adesivo universal pela técnica etch-and-rinse e etch-and-dry
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Objetivo: Recorrendo ao teste de microtração, avaliar e comparar as forças adesivas em esmalte cortado de um sistema adesivo universal (Scotchbond Universal Adhesive, 3M ESPE, St. Paul, MN, USA) usado segundo as instruções do fabricante, nos modos etch-and-rinse e etch-and-dry. A hipótese nula testada é a de que não existem diferenças estatisticamente significativas nas forças de adesão ao esmalte cortado entre as duas estratégias de adesão propostas pelo fabricante para o mesmo adesivo universal. Materiais e Métodos: Foi usada uma amostra de oito terceiros molares humanos. Cortaram-se as superfícies coronárias no sentido mesio-distal, de forma a obter dois segmentos de coroa por dente. Os dentes foram aleatoriamente distribuídos por um dos grupos de teste, de acordo com a estratégia de adesão: SBU aplicado como self-etch de um passo (SBU SE); SBU aplicado como etch-and-rinse de dois passos (SBU TE). Nos segmentos de coroa do grupo SBU TE foi realizado condicionamento com ácido ortofosfórico a 32% (Scotchbond Universal Etchant, 3M ESPE, St Paul, MN), durante 15 segundos. Foram aplicados incrementos de compósito sobre as superfícies dentárias preparadas, até perfazer uma altura de aproximadamente 6 mm. Após 24h numa estufa de incubação a 37º, os dentes foram seccionados de forma a obter palitos com uma área de aproximadamente 1 mm2. Os palitos foram submetidos a uma força de tração, a uma velocidade de 1 mm/minuto. A análise estatística foi realizada com o teste t para amostras independentes. Resultados: As forças médias de resistência à microtração (em MPa) e desvios padrão em cada grupo foram: SBU TE = 22,8 (12,3); SBU SE = 14,3 (6,7). Verificaram-se diferenças estatisticamente significativas entre os grupos (p = 0,000). Conclusões: A hipótese nula foi rejeitada. O condicionamento ácido da superfície do esmalte cortado aumentou significativamente as forças de adesão produzidas pelo sistema adesivo Scotchbond Universal Adhesive.
Objective: To evaluate microtensile bond strength (μTBS) to bur cut enamel of a new universal adhesive (SBU Scotchbond Universal Adhesive, 3M ESPE, St Paul, MN) used according to the manufacturers’ instructions, in the etch-and-rinse and etch-and-dry modes. The null hypothesis tested was that there were no differences in enamel microtensile bond strengths (μTBS) among these two different adhesion strategies. Materials and Methods: Eight human third molars were sectioned to obtain two enamel fragments. The enamel surfaces were roughened with a diamond bur in a standardized procedure. Teeth were randomly assigned to two groups, according to the adhesive strategy: SBU applied as one-step self-etch adhesive (SBU SE); SBU applied as two-step etch-and-rinse adhesive (SBU TE). The etched specimens were previously conditioned with 32% phosphoric acid (Scotchbond Universal Etchant, 3M ESPE, St Paul, MN), for 15 seconds. Composite resin blocks (ENAMEL plus HRi, Micerium S.p.A. Avegno GE Italy) of approximately 6 mm were then incrementally built up over the prepared tooth substrate. After 24h of water storage (37º), the bonded specimens were sectioned into beams with a cross sectional area of 1 mm2 and tested under tension (1 mm/min). The data were analyzed with an independent-sample t test, when the assumption of normality was valid. Results: The μTBS (MPa) and standard deviations were: SBU TE = 22,8 (12,3); SBU SE = 14,3 (6,7). These values were statistically significantly different. Conclusions: The null hypothesis was rejected. Preliminary etching of enamel significantly increased bond strength for the universal adhesive Scotchbond Universal Adhesive
Objective: To evaluate microtensile bond strength (μTBS) to bur cut enamel of a new universal adhesive (SBU Scotchbond Universal Adhesive, 3M ESPE, St Paul, MN) used according to the manufacturers’ instructions, in the etch-and-rinse and etch-and-dry modes. The null hypothesis tested was that there were no differences in enamel microtensile bond strengths (μTBS) among these two different adhesion strategies. Materials and Methods: Eight human third molars were sectioned to obtain two enamel fragments. The enamel surfaces were roughened with a diamond bur in a standardized procedure. Teeth were randomly assigned to two groups, according to the adhesive strategy: SBU applied as one-step self-etch adhesive (SBU SE); SBU applied as two-step etch-and-rinse adhesive (SBU TE). The etched specimens were previously conditioned with 32% phosphoric acid (Scotchbond Universal Etchant, 3M ESPE, St Paul, MN), for 15 seconds. Composite resin blocks (ENAMEL plus HRi, Micerium S.p.A. Avegno GE Italy) of approximately 6 mm were then incrementally built up over the prepared tooth substrate. After 24h of water storage (37º), the bonded specimens were sectioned into beams with a cross sectional area of 1 mm2 and tested under tension (1 mm/min). The data were analyzed with an independent-sample t test, when the assumption of normality was valid. Results: The μTBS (MPa) and standard deviations were: SBU TE = 22,8 (12,3); SBU SE = 14,3 (6,7). These values were statistically significantly different. Conclusions: The null hypothesis was rejected. Preliminary etching of enamel significantly increased bond strength for the universal adhesive Scotchbond Universal Adhesive
Descrição
Tese de mestrado, Medicina dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2014
Palavras-chave
Materiais dentários - esmalte - adesivos Teses de mestrado - 2014