Effect of additional coating of bonding resin on the microtensile bond strength of self-etching adhesives to dentin / 대한치과보존학회지

This study investigated the hypothesis that the dentin bond strength of self-etching adhesive (SEA) might be improved by applying additional layer of bonding resin that might alleviate the pH difference between the SEA and the restorative composite resin. Two SEAs were used in this study; Experimental SEA (Exp, pH: 1.96) and Adper Prompt (AP, 3M ESPE, USA, pH: 1.0). In the control groups, they were applied with two sequential coats. In the experimental groups, after applying the first coat of assigned SEAs, the D/E bonding resin of All-Bond 2 (Bisco Inc., USA, pH: 6.9) was applied as the intermediate adhesive. Z-250 (3M ESPE, USA) composite resin was built-up in order to prepare hourglass-shaped specimens. The microtensile bond strength (MTBS) was measured and the effect of the intermediate layer on the bond strength was analyzed for each SEA using t-test. The fracture mode of each specimen was inspected using stereomicroscope and Field Emission Scanning Electron Microscope (FE-SEM). When D/E bonding resin was applied as the second coat, MTBS was significantly higher than that of the control groups. The incidence of the failure between the adhesive and the composite or between the adhesive and dentin decreased and that of the failure within the adhesive layer increased. According to the results, applying the bonding resin of neutral pH can increase the bond strength of SEAs by alleviating the difference in acidity between the SEA and restorative composite resin.

Effect of baking temperature of gold-porcelain blended layer on bond strength of porcelain fused to Ni-Cralloy / 实用口腔医学杂志

Objective:To compare the differences of bond strength usi ng gold intermediate layer between Ni-Cr alloy and opaque porcelain(OP) baked at different temperatures. Methods:36 standard samples of Ni-Cr al loy and 36 of gold were prepared. The samples were divided into 4 groups with 9 in each. In group 1,OP was smeared to the surface of the samples and then baked at 950 ℃. In group 2,3 and 4 blendgold neu(a gold past) was put on the surface of the samples, then baked at 820 ℃,890 ℃ and 960 ℃ respectively. The samples were proccessed for further tests.The bond strength was tested by shear bond te st, and the electron probe was used to observe interfacial bond state and diffus ion of interfacial elements. Results:The bond strength(MPa) in g roup 1,2,3 and 4 was 19.66? 1.83,22.34?2.73,21.33?2.75 and 28.02?5.71 res pectively(group 1 vs group 4 P