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Microtensile bond strengths for six 2-step and two 1-step self-etch adhesive systems to enamel and dentin

Abstract:

Purpose: To examine the microtensile bond strengths (μTBS) of six 1-step and one 2-step self-etch systems to dentin and ground enamel. Methods: Resin composite buildups were bonded to buccal and lingual ground enamel surfaces, and to occlusal dentin of third molars using the following 1-step adhesives: Xeno IV (XE), GBond (GB), Clearfil S3 Bond (CS3); Adper Prompt L-Pop (AD); Go (GO) and All Bond SE (1-step; ABSE), in comparison to the 2-steps (All Bond SE; (2-step ABSE) and Clearfil SE Bond (CSE). After storage in water (24 hour/37°C), the bonded specimens were sectioned into beams approximately 0.9 mm2. These beams were tested until failure at a crosshead speed of 0.5 mm/minute. Data were subjected to appropriate statistical analysis (α= 0.05). Results: The total number of specimens/premature debonding specimens (PDS) for each adhesive were, respectively, in enamel: XE (59/36), GB (63/33), CS3 (62/29), AD (47/19), GO (53/14), 1-step ABSE (61/29), 2-step ABSE (57/14) and CSE (58/13); and in dentin: XE (51/24), GB (50/7), CS3 (53/13), ADP (51/1), GO (43/8), 1-step ABSE (59/2), 1-step ABSE (56/0) and CSE (47/0). The fracture pattern was predominantly adhesive/mixture for all adhesives in dentin (51.5 to 99%) and in enamel (34.8 to 75.4%), however XE (61.2) and GB (52.5) had more than 50% PDS. For ground enamel, no significant difference was detected among materials in the same subgroup (with or without PDS). However, there was a significant difference for all adhesives when subgroups (with and without PDS, respectively) were tested against each other: XE (7.9/10.5 ≠ 19.7/5.5), GB (8.6/10.5 ≠ 17.2/7A), CS3 (8.8/10.3 ≠ 15.7/5.6), AD (13.0/12.0= 20.3/8.9), Go (18.2/13.8= 25.1/10.0), 1-step ABSE (15.9/11.4= 16.2/5.4), 2-step ABSE (8.4/9.1 ≠ 25.3/7.9) and CSE (17.6/16.3= 19.9/7.8). For dentin, no difference was found when subgroups for the same adhesive were tested against each other (with or without PDS). However, significantly higher resin-dentin bond strength was observed for adhesives in the following order: CSE (38.5/6.5= 38.5/6.5)≥ 2-step ABSE (41.4/16.3 + 42.4/19.3)= 1-step ABSE (43.9/17.7= 44.2/17.1)= AD (34.4/14.2= 35.2/13.3)≤ CS3 (31.9/19.4= 40.1/13.4) ≠ GB (14.3/6.3= 16.3/5.9)= Go (14.2/13.9=22.4/12.6) ≠ XE (7.1/5.4= 9.5/5.1), respectively for with PDS and without PDS. All materials showed similar performance on ground enamel. The performance of one-step self-etch systems to dentin appears to be material-dependent. Adper Prompt L-Pop, Clearfil S3 Bond and the 1-step All Bond SE had μTBS similar to Clearfil SE Bond and the 2-step All Bond SE, while Xeno IV and GBond had significantly lower μTBS values. Go had an intermediate performance. (Am J Dent 2013;26:44-50). CLINICAL SIGNIFICANCE: Laboratory evaluation of new materials provides clinicians with useful resources to learn about the performance of such adhesives and guide clinical selection. All materials appeared to function similarly on ground enamel, but presented significant differences when bonded to dentin. The 1-step Adper Prompt L-Pop, Clearfil S3 Bond and All Bond SE are similar to Clearfil SE Bond and the 2-step All Bond SE.