Bonding Durability of Single-Step Adhesives to Previously Acid-Etched Dentin

Abstract

This study investigated the effect of phosphoric acid etching on the dentin bond strength of five single-step self-etch adhesive systems; Absolute, Clearfil tri-S Bond, Fluoro Bond Shake One, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied on the prepared dentin surfaces with and without prior phosphoric acid etching and light irradiated. Resin composite was condensed into a mold (ø4x2 mm), light irradiated and stored in water at 37 degrees C. Four groups (n=10) were made per adhesive system: with and without prior acid etching and with and without thermal cycling between 5 degrees C and 55 degrees C for 10,000 cycles. The specimens were tested in a shear mode at a crosshead speed of 1.0 mm/minute. Two-way ANOVA, Student t-test and Tukey HSD test at a level of 0.05 were done. For specimens without prior acid etching, the mean bond strengths to bovine dentin ranged from 12.8 to 17.1 MPa and ranged from 6.7 to 13.3 MPa for specimens with prior acid etching after 24 hours storage in water. When the specimens were subjected to thermal cycling, the mean bond strengths ranged from 10.7 to 24.8 MPa for the specimens without prior acid etching and 4.6 to 13.9 MPa for the specimens with prior acid etching. The changes in dentin bond strength were different among the adhesive systems tested. Failure modes were commonly adhesive failure associated with mixed failure for specimens with prior acid etching. For specimens without prior acid etching, failures in composite and dentin were increased. From the results of this in vitro study, prior acid etching might be not acceptable for increasing the dentin bond strengths of single-step self-etch adhesive systems.

Resin–dentine interfacial morphology following CPP–ACP treatment

“…Prior phosphoric acid etching resulted in greater hybrid layer thickness for a 1-step self-etching primer adhesive (0.5 mm compared with 3-5 mm), but significantly lower dentine bond strengths. 26 In correlation with the above findings, phosphoric acid etching also resulted in greater hybrid layer thickness in our study, but this was not reflected in mSBS, which was significantly lower on deep dentine for CSE and on superficial dentine for GB. This further adds strength to the theory that hybrid layer thickness does not correlate with bond strength.…”

Comparative study of adhesive systems applied to different regions of dental substrate

“…In all the groups adhesive failure predominated, in agreement with other studies like Ikeda et al [28]. The exclusively adhesive failures allowed real bond strength between the material and dental structure, since the conventional tests with bond strength values higher than 20 MPa indicated cohesive failure in dentin, as they were unable to measure high values [19].…”

Effect of Phosphoric Acid Pre-etching on Fatigue Limits of Self-etching Adhesives

“…Phosphoric acid conditioning of dentin, followed by air-drying of the treated surface, has been shown 43 to result in collapsed collagen fibrils that inhibit resin monomer penetration into the entire depth of the decalcified dentin. Adhesives that contain hydrophilic HEMA and water, such as the SU singlestep self-etching adhesive and the OX two-step selfetching adhesive, may help to re-expand collapsed collagen fibrils and enhance the penetration of adhesive monomers into demineralized dentin.…”