Journal of Dentistry
Fernanda T. Sadek, Annalisa Mazzoni, Lorenzo Breschi, Franklin R. Tay, Roberto R. Braga
Volume 38, Issue 4, April 2010, Pages 276-283 Objectives
:To evaluate the efficacy of simplified dehydration protocols, in the absence of tubular occlusion, on bond strength and interfacial nanoleakage of a hydrophobic experimental adhesive blend to acid-etched, ethanol-dehydrated dentine immediately and after 6 months.
Methods:Molars were randomly assigned to 6 treatment groups (n = 5). Under pulpal pressure simulation, dentine crowns were acid-etched with 35% H3PO4 and rinsed with water. Adper Scotchbond Multi-Purpose was used for the control group. The remaining groups had their dentine surface dehydrated with ethanol solutions: group 1 = 50%, 70%, 80%, 95% and 3 × 100%, 30 s for each application; group 2 the same ethanol sequence with 15 s for each solution; groups 3, 4 and 5 used 100% ethanol only, applied in seven, three or one 30 s step, respectively. After dehydration, a primer (50% BisGMA + TEGDMA, 50% ethanol) was used, followed by the neat comonomer adhesive application. Resin composite build-ups were then prepared using an incremental technique. Specimens were stored for 24 h, sectioned into beams and stressed to failure after 24 h or after 6 months of artificial ageing. Interfacial silver leakage evaluation was performed for both storage periods (n = 5 per subgroup).
Results:Group 1 showed higher bond strengths at 24 h or after 6 months of ageing (45.6 ± 5.9a/43.1 ± 3.2a MPa) and lower silver impregnation. Bond strength results were statistically similar to control group (41.2 ± 3.3ab/38.3 ± 4.0ab MPa), group 2 (40.0 ± 3.1ab/38.6 ± 3.2ab MPa), and group 3 at 24 h (35.5 ± 4.3ab MPa). Groups 4 (34.6 ± 5.7bc/25.9 ± 4.1c MPa) and 5 (24.7 ± 4.9c/18.2 ± 4.2c MPa) resulted in lower bond strengths, extensive interfacial nanoleakage and more prominent reductions (up to 25%) in bond strengths after 6 months of ageing.
Conclusions:Simplified dehydration protocols using one or three 100% ethanol applications should be avoided for the ethanol-wet bonding technique in the absence of tubular occlusion, as they showed decreased bond strength, more severe nanoleakage and reduced bond stability over time.Full Abstract