Objective: To evaluate the effect of surface conditioning on the Shear Bond Strength (SBS) of two self-etch adhesives to enamel and dentin. Methods: Ninety-six freshly extracted bovine mandibular incisor crowns were mounted in chemically-polymerized methacrylate with the facial surfaces exposed; grounded flat to simulate cut enamel and finished to 600-grit SiC sandpaper. Self-etch adhesive systems, FL-Bond II and BeautiBond (Shofu) were used to bond to enamel. After SBS was tested, the surfaces were grinded and finished for bonding to dentin. Study variables included: Surface conditioning (Etched/Non-etched) and testing time (15 minutes/24 hours) (N=12) per group. The etched groups were conditioned with 37.5 % phosphoric acid prior to application of the adhesive, which was then applied and polymerized according to manufacturer's instructions. The specimens were placed in a bonding jig (Ultradent), filled with resin composite Z100 (3M-ESPE) and polymerized for 20 seconds. SBS was recorded at 15 minutes and 24 hours of storage at 37°C/100% humidity using an Ultratester testing machine (Ultradent) at a speed of 1 mm/min. The results were expressed in MPa and analyzed using a Student t-test. Results: At 24 hours, FL-Bond II reported statistically significant differences between etched and non-etched groups for both enamel (P=0.019) and dentin (P=0.001). BeautiBond bonded to dentin showed statistically significant differences between etched and non-etched groups at both 15 minutes (P=0.004) and 24 h (P=0.005).
| FL-Bond II | BeautiBond | ||
| Enamel | Dentin | Enamel | Dentin |
Non-etched, 15 min | 26.8 (4.7) | 33.3 (4.0) | 19.8 (4.7) | 25.7 (5.5) |
Etched, 15 min | 27.9 (3.7) | 33.1 (4.6) | 23.0 (3.8) | 18.2 (6.0) |
Non-etched, 24h | 28.3 (6.3) | 37.7 (3.2) | 26.4 (6.8) | 27.8 (8.0) |
Etched, 24h | 33.3 (2.7) | 28.0 (8.5) | 28.4 (3.4) | 18.3 (6.7) |
Conclusion: Selective etching of enamel may help improve SBS of both self-etch adhesives. However, this is not the case for dentin.