To evaluate the effect of three surface treatments and two resin cements on microtensile bond strength of zirconia to dentin. Sixty human molars were embedded in acrylic resin and sectioned 3 mm below the occlusal plane. Teeth specimens and sixty zirconia specimens were randomized into 3 groups according to the following surface treatments (n=20): no treatment (control), sandblasting and silane application (SB+SI), sandblasting then silica coating and silane application (SB+SC+SI). In each group, half of the ceramic-tooth assemblies were cemented with PanaviaTM F (Kurary Dental), the rest with RelyX Unicem (3M ESPE). All specimens were cut into microtensile sticks that were loaded in tension until failure. Data were analyzed using two-way ANOVA and Tukey’s HSD test (α=0.05). The SB+SC+SC group presented higher values than SB+SI and the control group (P<0.05). Bond strength in PanaviaTM F groups were significantly higher than those in RelyX Unicem regardless of the surface treatment (P<0.05). Data indicated that both surface treatment and resin cement have significant effects on bond strength of zirconia to dentin.

Abstract. To evaluate the color changes of tetracycline stained teeth after restored with IPS-EMPRESS Ⅱ ceramics. Simulated tetracycline stained teeth were divided according to staining degree into four groups: mild, moderate, severe, and very severe groups; each group had ten specimens which were repaired with IPS-EMPRESS Ⅱ ceramics veneers, bonded with Vitique Esthetic Cementation System. The ShadeEye-NCC color system was used to analyze the change in L, a and b. ΔE were calculated to compare color difference among the four groups.Before and after bonding, the values of L, a, b were significantly different (P <0.05). Mild tetracycline stained teeth bonded using resin adhesive without opaque bonding have a better effect than moderate and severe tetracycline stained teeth bonded with opaque resin adhesive; while, it is best to use other restorations to repair very severe tetracycline stained teeth. The IPS-EMPRESS Ⅱ ceramics can effectively improve the color of discolored tooth, however , the final color of the veneered teeth is easily influenced by the color of the abutment teeth. Aluting agent with color masking ability can do some improvements in the final color. An appropriate bonding agent should be chosen to perfect the final results of the veneered tooth.

The aim of this study was to observe the absorption enhancing effect of sodium dodecyl sulfate on metformin hydrochloride in colon of rat. Using in vivo intestinal loop model in rat while the ileum was took as blank group and colon as the experiment groups with different concentration of sodium dodecyl sulfate (1%, 2%, 4%). The colon/ileum ratio of the absorption rate constant of metformin hydrochloride was evaluated through calculating the residual dose of circulating solution in presupposition time points. Intergroup absorption rate constant and the rising percent of the absorption rate constant were different significantly (P<0.05). The absorption rate constant of colon were -0.22±0.03, -0.37±0.06, -0.89±0.09, -0.86±0.05μg•h-1•cm-1 (n=6) and the rising percent of the constant absorption value were 68.66 ± 8.28%, 304.88 ± 28.76%, 293.75 ± 33.19% (n=6), respectively. The result showed that the absorption of metformin hydrochloride was increased with the concentration of sodium dodecyl sulfate. However, the absorption rate constant reached maxium when the concentration of sodium dodecyl sulfate was 2%, this may be because the circulating metformin hydrochloride solution could be more viscous which affect the absorption of metformin hydrochloride when sodium dodecyl sulfate was raised. In conclusion, the absorption of metformin hydrochloride can be promoted by sodium dodecyl sulfate in the colon of rat and this can provide biophamaceutics data for novel pharmaceutical preparation.

To evaluate the effect of various liner thickness on the color of Y-TZP based all-ceramic restorations. Forty disc specimens (10 mm diameter, 0.5 mm thick) were fabricated from IPS e.max ZirCAD core material. The specimens were randomly divided into four groups (n=10) according to layering with different ZL1 IPS e.max ZirLiner thicknesses as: 0.1 mm, 0.2 mm, 0.3 mm and one group had received no treatment as the control group. And 0.6 mm veneering porcelain was fired on the IPS e.max ZirCAD core material by traditional layering technique. Using a spectrophotometer to measure Color parameters L, a and b of the specimens after veneered. ΔE were calculated to compare color difference among the four groups. Intergroup differences of ΔE in different thicknesses were statistically significant at P<0.05. The ΔE between groups with different thickness were 2.03±0.07, 2.88±0.07, 3.54±0.07, 0.86±0.06, 1.47±0.06 and 0.67±0.06 respectively.Usually researchers apply ΔE=1.5 as the threshold for distinguishing two different colors by the human eye. Color difference ΔE between different groups with and without liner application was more than 1.5, which was in the perceptible range, but ΔE of liner application with the thickness of 0.1 mm, 0.2 mm and 0.3 mm were undistinguishable by human eye (ΔE<1.5). Thus liner application of the all ceramic system could significantly affected the final color of the all ceramic restorations and it ameliorated esthetics of Y-TZP all-ceramic restorations to good purpose. However, Changes in the thickness (0.1 mm-0.3 mm) of liner application have no significant effect on the final shade of Y-TZP based all-ceramic restorations.

No abstract