ABSTRACT
PURPOSE: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. MATERIAL AND METHOD: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37°C/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm². Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm.min-1). Data were analyzed using two-way ANOVA and Tukey's tests (p<0.05). RESULTS: The anticipated hypothesis was not confirmed (p<0.0001). The bond strengths (MPa) were not statistically different between the two adhesive systems when light-activated composite was used (OS+Z100 = 24.7±7.1ª; PB+Z100 = 23.8±5.7ª). However, with use of the chemically activated composite (B2B), PB (7.8±3.6b MPa) showed significantly lower dentin bond strengths than OS (32.2±7.6ª). CONCLUSION: The low pH of the adhesive system can affect the bond of chemically activated composite to dentin. On the other hand, under the present conditions, the low pH did not seem to affect the bond of light-activated composites to dentin significantly.
ABSTRACT
O objetivo deste trabalho foi simular in vitro, situações que ocorrem no dia-a-dia do paciente, em relação à absorção de saliva artificial e de um anti-séptico bucal, sobre os materiais restauradores estéticos. Para tanto, foram confeccionados 60 corpos-de-prova (CP) a partir de uma matriz de 5 mm de diâmetro x 3 mm de profundidade. Os CPs foram subdividos em 4 grupos: GI (controle) TPH Spectrum, GII TPH Spectrum, GIII P60 e GIV Esthet-X. Após a fotoativação, os CPs foram identificados e pesados em uma balança analítica de precisão. Em seguida, os CPs foram imersos em saliva artificial, por 7 dias a 37°C. Então, foi realizada nova pesagem, e os CPs dos grupos GII, GIII e GIV foram imersos em anti-séptico bucal e os CPs do grupo GI foram novamente imersos em saliva artificial, todos a 37°C. Foram realizadas mensurações periódicas, após 6, 12 e 36 horas. Resultados: GI (controle): 0,125g ± 0,003; GII:0,120g ± 0,001; GIII: 0,127g ± 0,004 e GIV: 0,120g ± 0,006. Os dados foram submetidos à análise estatística, empregando o teste ANOVA (p > ou = 0,5) e os resultados demonstraram não haver diferença estatística quanto ao peso inicial e final nos grupos estudados. Concluímos que nenhuma das resinas compostas testadas sofreu absorção pela saliva artificial ou anti-séptico bucal no período correspondente a 6 anos de uso diário