Objectives: The purpose of this study was to investigate the effect of self-etching primer application duration on resin penetration into dentin and dentin bond strength. Methods: Two self-etching primer systems, Mac Bond II (Tokuyama Dental) and Clearfil Mega Bond (Kuraray Medical) were employed. The facial surface of bovine mandibular incisors were ground wet on 600-grid SiC paper. The self-etching primer was applied on dentin surface for 5, 20 sec and 10 min. Adhesive was applied and resin composite was cured. After 24 h storage in water, specimens were sectioned through the bonded interface, then polished with diamond pastes down to 1.0 mm particle size. Raman spectra were successively recorded along a line perpendicular to the dentin/resin interface in steps of 0.2 mm using a micro-Raman spectroscopic system (System 2000, Renishaw). The relative amounts of the hydroxyapatite (960cm^-1, P-O), adhesive (640cm^-1, aromatic ring), and alkyl group (1450cm^-1, C-H) in the bonding interface were calculated. Also, micro-tensile bond strength test was conducted with the sample size of 8. One-way ANOVA followed by Duncan's multiple comparison was done (p=0.05). Results: From the Raman spectroscopy, the width of demineralization increased with the longer duration of primer application. The penetration of the adhesive resin into the demineralized dentin for the 10 min group was less than for the other groups. Micro-tensile bond strength obtained with 10 min group (25.4-27.2 MPa) was significantly lower than the other duration groups (37.2-45.9 MPa). Conclusions: From the results of this study, the dentin bond strength was lower with the longest duration of self-etching primer application which may be related to insufficient adhesive penetration into etched dentin. Supported by Nihon University Individual Research Grant for 2002, #02-111.

Back to the Dental Materials: II - Adhesion-Other Program
Back to the 32nd Annual Meeting and Exhibition of the AADR (March 12-15, 2003)

Top Level Search