Longitudinal evaluation of the effect of saliva contamination during the bonding protocol with a self-etch adhesive system

Aim: To evaluate the influence of saliva contamination on the short- and long-term bond strength of a self-etch adhesive system. Methods: One hundred and twelve non-carious human molars were randomly divided according to: substrate (enamel/dentin); presence of saliva [none (control- C), before primer (BP), after primer (AP) and after bonding agent (AB)]; treatment of the contamination [none (1), rinsing + drying (2), drying (3) and primer re-application (4)] and specimen storage (24 h or 6 months). A self-etch adhesive system was applied to the dental surfaces followed by incremental insertions of composite resin. After storage in water at 37oC, the specimens were perpendicularly cut into beams for microtensile bond strength testing. Data in MPa were compared by A NOVA followed by Tukey’s test (p< 0.05). Micrographs were obtained by low vacuum scanning electron microscopy. Results: Control groups (G1 and G8) presented higher bond strength than all other groups. The factors presence of saliva, treatments of the contaminant and specimen storage showed no statistically significant results for the two dental substrates. Contaminants could be detected by LV-SEM. Six-month storage did not affect bond strength. Conclusions: The presence of saliva during the application of the self-etch system was deleterious to the bond to enamel and dentin, irrespective of the operative step in which the contamination occurred.

Effect of saliva contamination on the bond strength of an etch-and-rinse adhesive system to dentin / Efeito da contaminação salivar na resistência de união de um adesivo etch-and-rinse em dentina

Purpose: The aim of this study was to investigate the effect of saliva contamination on bond strength of an etch-and-rinse system to dentin. Methods: Fifty bovine incisors were embedded in acrylic resin and divided into 5 groups: G1 (control) - application of the adhesive system (Adper Single Bond 2 - 3M-ESPE); G2 - saliva contamination after acid etching of dentin, rinsing and drying; G3 - saliva contamination after acid etching of dentin and drying; G4 - saliva contamination after adhesive application, rinsing and drying; G5 - saliva contamination after adhesive application and drying. Contamination was performed by using 4 µL of simulated human saliva for 20 s. The adhesive system was applied according to the manufacturer's instructions; a composite resin was built as an inverted cone and was tested after 24 h at a cross-head speed of 0.5 mm/min. Results: When saliva contamination occurred after the adhesive photo-polymerization, bond strength was significantly reduced. The adhesive strength (MPa) mean values were: G1 = 18.1(±4.7) a; G2 = 20.5(±5.7) a; G3 = 17.3(±3.4) a; G4 = 12.6(±4.0) b; G5 = 9.8(±2.1) b (means followed by distinct letters are statistically different, P < 0.05). Conclusion: Saliva contamination negatively influenced bond strength of an etch-and-rinse adhesive, especially after the final polymerization of the adhesive system; in this condition, treatments were not efficient to recover adhesion.

Objetivo: Investigar o efeito da contaminação salivar na resistência de união de um adesivo condicione-e-lave em dentina. Metodologia: Cinquenta incisivos bovinos foram divididos em 5 grupos: G1 = (controle) aplicação do sistema adesivo (Adper Single Bond 2 - 3M-ESPE); G2 = contaminação com saliva após condicionamento ácido da dentina + lavagem e secagem; G3 = contaminação após o condicionamento ácido da dentina + secagem; G4 = contaminação com saliva após a aplicação do adesivo + lavagem e secagem; G5 = contaminação com saliva após a aplicação do adesivo + secagem. A contaminação foi realizada com 4 µL de saliva humana estimulada por 20 s. O sistema adesivo foi usado de acordo com as instruções do fabricante. A resina composta foi aplicada na forma de cone invertido, com o teste de tração realizado após24 h a 0,5 mm/min de velocidade. Resultados: As médias de resistência de união (em MPa): G1 = 18,1(±4,7) a; G2 = 20,5(±5,7) a; G3 = 17,3(±3,4) a; G4 = 12,6(±4,0) b; G5 = 9,8(±2,1) b, demonstrando que a resistência de união foi reduzida significativamente quando a contaminação salivar ocorreu após a fotopolimerização do adesivo. Conclusão: A contaminação influenciou negativamente a resistência de união do adesivo somente após a sua polimerização; nesta condição os tratamentos realizados não foram eficientes para recuperar a adesão.