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Purpose: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system., Materials and Methods: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray) and Hybrid bond (Sun-Medical), a self-etching primer, Clearfil SE Bond (Kuraray), and an etch-and-rinse system, Admira Bond (Voco), were selected. Thirty human molars were used. The root of each tooth was removed and the crown was sectioned into halves. The convex enamel surfaces were reduced by polishing on silicone paper to prepare a flat surface. The bonding systems were applied on this surface. Prior to adhesive curing, a hollow cylinder (2.0 mm height/0.75 mm internal diameter) was placed on the treated surfaces. A resin composite was then inserted into the tube and cured. After water storage for 24 h, the tube was removed and shear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The results were analyzed with ANOVA and the Tukey.-Kramer test at a 59 degrees confidence level. The enamel of five additional teeth was ground, and the etching component of each adhesive was applied and removed with absolute ethanol instead of being light cured. These teeth and selected fractured surfaces were examined by SEM., Results: Adhesion to ground enamel of the Futurabond DC (25 +/- 3.5 MPa) and Clearfil SE Bond (23 +/- 2.9 MPa) self-etching systems was not significantly different from the etch-and-rinse system Admira Bond (27 +/- 2.3 MPa). The two self-etching adhesives Clearfil S Tri bond and Hybrid Bond demonstrated significantly lower bond strengths (14 +/- 1.4 MPa; 11 +/- 1.9 MPa) with no significant differences between them (p < 0.05)., Conclusion: Bond strengths to ground enamel of self-etching adhesive systems are dependent on the type of adhesive system. Some of the new adhesive systems showed bond strength values comparable to that of etch-and-rinse systems. There was no correlation between bond strength and morphological changes in enamel.

Objectives: To evaluate the effect of increasing the dentin conditioning time with self-etching primers of different aggressiveness (pH) on the microtensile bond strength (muTBS) of three resin cements., Materials and Methods: Pre-cured composite blocks were cemented with M-Bond, Bistite II DC, or Panavia F to flat occlusal dentin surfaces of human third molars, which were conditioned with M-Bond or Bistite II-primer for 30, 60 or 180 s or with Panavia-primer for 60 or 180 s. Each dentin-composite block assembly (four in each group) was longitudinally sectioned to obtain 1x1 mm microbars and tested for the muTBS. The morphology of the conditioned dentin surface and the hybrid layer was examined with SEM., Results: Extending the primer conditioning time for Bistite II DC from 30 to 60 s significantly increased the muTBS (p<0.001) but did not further increase from 60 s to 180 s. For M-Bond there was only a significant increase from 30 to 180 s (p<0.05). For Panavia F the primer-conditioning time had no influence on the muTBS. SEM observations of conditioned dentin showed that the Bistite II DC and M-Bond self-etching primers with the lowest pH completely dissolved the dentin smear layer and plugs and formed well-defined hybrid layers. This was not found for Panavia F., Significance: Dentin bond strength of resin cements using more aggressive self-etching primers is improved by increasing the conditioning time. To enable resin infiltration of highly filled resin cements, sufficient smear layer dissolution is necessary.

Objectives: To investigate the Microtensile bond strength (microTBS) and failure mode of resin cements bonded to composite and ceramic CAD/CAM blocks following various surface treatments., Methods: Paradigm composite blocks and Cerec Vitablocs received three surface treatments following the control treatment of surface grinding with 600 SiC grit. (1) Application of adhesive resin (Adh), (2) etching with hydrofluoric acid and silanization (HF+S) or (3) combination of the previous two treatments (HF+S+Adh). Three resin cements (Tetric Flow, Nexus 2, RelyX ARC) were applied to these surfaces and built-up in layers. After 24 h water storage at 37 degrees C, the non-trimming version of microTBS test was used to produce 1 mm(2) microbars. The Microbars were subjected to a tensile load using a modified testing device. The broken specimens were examined with a stereomicroscope and SEM to determine the failure mode., Results: All control and adhesive treated groups of the ceramic substrate showed premature debonding during cutting. The overall mean microTBS for the three resin cements bonded to ceramic following HF+S and HF+S+Adh surface treatment, was 27 and 29.2 MPa and for the resin cements bonded to composite substrate was 42.3 and 54.2 MPa, respectively. The mode of failure was 98% adhesive with composite as a substrate and 68% mixed failures with ceramic as a substrate., Clinical Significance: CAD/CAM restorations fabricated from processed composite blocks may have advantage over the ceramic blocks with regard to the higher bond strength with resin cements.

Purpose: To examine and compare the effect of increasing the priming time and the adhesive resin pre-curing time on shear bond strength of new dentin bonding systems (DBS)., Materials and Methods: Two multi-step/total etch DBS, Scotchbond Multi-Purpose Plus (SBMP+) and OptiBond FL (OB FL), and one one-bottle/total etch DBS, Single Bond (SB), were used. One hundred flat dentin specimens were prepared from extracted human molars. Approximately 1 mm of dental structure was ground to expose superficial dentin. The specimens were randomly assigned to the three DBS, and minimum of five specimens were used for each test condition. For each multi-step DBS, 40 specimens were divided into four groups with priming times of 10, 20, 30, and 40 seconds. Each group was further subdivided into two subgroups with adhesive resin pre-curing times of 20 and 40 seconds. The SB specimens were divided into four subgroups with a waiting time of 10, 20, 30, and 40 seconds before drying and curing of its one-bottle adhesive. Shear bond strength tests were performed using a universal testing machine (Instron) at a crosshead speed of 0.5 mm/minute. Results were analyzed using ANOVA and Duncan's multiple range tests., Results: For the multi-step DBS, increasing the priming time up to 30 or 40 seconds caused a significant increase in the mean shear bond strength values (P < 0.0001). Lengthening the adhesive resin pre-curing time did not cause any significant increase (P = 0.05) in the mean shear bond strength values except with 30-second and 40-second priming times. For SB, increasing the one-bottle adhesive waiting time before drying and curing to 30 seconds resulted in a statistically significant increase (P < 0.002) in the mean shear bond strength.

The aim of this investigation was to compare the shear bond strengths of three dentine adhesives tested using an Instron Universal Testing machine at a crosshead speed of 0.5 mm/min. Sixty human molar teeth were used and divided into 3 equal groups where the occlusal surfaces were ground and adhesives were applied overlaid by composite material. Samples were fixed to the Universal Testing machine. Results were recorded in kg/cm2 and converted into MPa units then tabulated and statistically analyzed. Duncan's multiple range statistic test at p < 0.05 showed no statistically significant difference between the shear bond strength values of Scotchbond 2 and Amalgambond; whereas the shear bond strength values of Scotchbond 2 and Amalgambond were significantly higher than those of Gluma. Scanning electron microscopic examinations at X10 and X2500 magnifications showed a dominant adhesive pattern of failure in the samples treated with Gluma, and a mixture of cohesive and adhesive-cohesive patterns of failures in the samples treated with Scotchbond 2 and cohesive patterns of failures in the samples treated with Scotchbond 2 and Amalgambond.