Bond Strength of Adhesive/Composite Combinations to Dentin Involving Total- and Self-etch Adhesives

To compare the bonding potential to human dentin of adhesive/composite combinations including five 2-step and two 3-step total-etch (TE) bonding systems, two systems with self-conditioning (SC) primers, and one SC all-in-one adhesive by use of the microtensile bond test. Hybrid resin composites were bonded to the occlusal dentin of 50 extracted human molars. After water storage (37°C, 24 h), 3 1-mm-thick slabs were cut from the middle of the teeth perpendicular to their long axis. Microtensile bond strength was determined and debonded surfaces were examined under the SEM for mode of failure. Statistics: GLM multivariate procedure for repeated measurements, Student-Newman-Keuls test (SPSS version 10.0; p = 0.05). Mean bond strengths of the simplified (2-step) TE systems (OptiBond Solo, Gluma One Bond, Solobond M, Prime&Bond NT, One Coat Bond; 19.9 MPa to 39.9 MPa) were not significantly lower than that of the traditional 3-step TE systems (EBS Multi: 26.0 MPa; OptiBond FL: 32.7 MPa), and not related to phosphoric acid concentration. Dentin treatment with SC primers (Clearfil Liner Bond 2: 22.0 MPa; Clearfil Liner Bond 2V: 22.4 MPa) was as effective as etching with phosphoric acid. The SC all-in-one adhesive (Etch″ 3.0: 10.1 MPa) produced significantly lower bond strength than all other systems evaluated. The use of adhesive/composite combinations including simplified bonding systems does not necessarily result in reduced bond strength to dentin. SC primers offer a promising alternative to phosphoric acid etching as far as bonding to dentin is concerned. In contrast, the SC all-in-one adhesive evaluated needs to be improved.