Effect of Air-drying Time of Single-application Self-etch Adhesives on Dentin Bond Strength

Abstract

This study examined the effect of air-drying time of adhesives on the dentin bond strength of several single-application self-etch adhesive systems. The adhesive/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), Clearfil Tri-S Bond/Clearfil AP-X (CT), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Gradia Direct (GB) and One-Up Bond F Plus/Palfique Estelite (OF). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. Adhesives were applied according to each manufacturer's instructions followed by air-drying time for 0 (without air-drying), 5 and 10 seconds. After light irradiation of the adhesives, the resin composites were condensed into a mold (phi4x2 mm) and polymerized. Ten samples per test group were stored in 37 degrees C distilled water for 24 hours; they were then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD tests (alpha = 0.05) were done. FE-SEM observations of the resin/dentin interface were also conducted. Dentin bond strength varied with the different air drying times and ranged from 5.8 +/- 2.4 to 13.9 +/- 2.8 MPa for AP, 4.9 +/- 1.5 to 17.1 +/- 2.3 MPa for CT, 7.9 +/- 2.8 to 13.8 +/- 2.4 MPa for FB, 3.7 +/- 1.4 to 13.4 +/- 1.2 MPa for GB and 4.6 +/- 2.1 to 13.7 +/- 2.6 MPa for OF. With longer air drying of adhesives, no significant changes in bond strengths were found for the systems used except for OF. Significantly lower bond strengths were obtained for the 10-second air-drying group for OF. From FE-SEM observations, gaps between the cured adhesive and resin composites were observed for the specimens without the air drying of adhesives except for OF. The data suggests that, with four of the single-application self-etch adhesive systems, air drying is essential to obtain adequate dentin bond strengths, but increased drying time does not significantly influence bond strength. For the other system studied, the bond strength of the non-air dried group was not significantly different from the five second drying time, but prolonged drying was very detrimental to bond strength. For all five of the systems studied, a five-second air-drying time appeared to be appropriate.

Two-year clinical evaluation of one-step self-etch systems in non-carious cervical lesions

“…10,11,20,21) Water is essential in one-step self-etching systems to ionize acidic monomer enough to dissolve the smear layer and demineralize dentin.…”

Effect of Placement Agitation and Drying Time on Dentin Shear Bond Strength: An In Vivo Study

“…The significantly better bond strength with five-second air drying time in the agitation group could be related to better solvent evaporation and dispersion of water. 13 Better bonding with active agitation could be attributed to better removal of the smear layer, dispersal of fluid content and better diffusion of dentin primer into the collagen-rich partially-demineralized zone, which helps in achieving the micromechanical and chemical interaction with the underlying dentin. 10 Active agitation of self-etching bonding agents may improve bonding by enhancing the interaction of acid monomers with tooth structure and dispersing etching byproducts into the hybrid layer.…”

“…14 While Bonilla and others 15 reported maximum bond strength with a dry time of one second with both the self-etch and total-etch systems, Chiba and others 13 reported maximum bond strength with a dry time of five seconds with the self-etch systems. Furthermore, Miyazaki and others 10 found that drying time varied for two total-etch systems tested.…”

“…7 Primed tooth surfaces are usually air dried to evaporate solvents and disperse water, because the remaining liquid primer on the adhesive surface may act as an inhibitor of polymerization of the bonding agent. 13 Excess water competes for space with HEMA molecules within the collagen network, resulting in lower HEMA density inside the collagen mesh, thus lowering bond strength.…”

Effect of Operator-specific Handling on Tooth-composite Interface and Microleakage Formation

“…1,4,[39][40][41][42] In addition to the material-specific parameters and equipment used, the variability in handling by the clinical operators plays an important role. 1,6,[43][44][45][46][47][48] Etch-and-rinse adhesives are considered to be partially technique-sensitive. 1 To overcome these challenges, simplified and user-friendly self-etch adhesives have been developed.…”