Objective : To evaluate the effect of different surface treatments on the bonding strength between highly translucent zirconia and veneering porcelain and to provide a research basis for improving the zirconium porcelain bond strength between zirconium and ceramic material. Methods : Thirty cylindrical zirconia blocks with 10-mm diameter and 10-mm height were prepared and divided into four groups (n=7), labeled as control group (C), sandblasting group (S), bonding group (B), and sandblasting and bonding group (SB). The surface morphology of zirconia before and after sandblasting was observed in the remaining two specimens. Group C was veneered (2 mm in height and 5 mm in diameter) with porcelain powder by layering after grinding. Group S was sandblasted after grinding. Group B was veneered with a thin layer of porcelain powder as bond coating. Group SB was sandblasted and veneered with a thin layer of porcelain powder. After sintering, the shear specimens were embedded, and a shear bond strength test was conducted. Statistical analysis was conducted to analyze the data. Fracture surface analysis was also performed to determine the failure modes by stereomicroscopy. Results : The bonding strength of group C was 21.86 ± 3.18 MPa. For group S, it was 22.12 ± 3.06 MPa. For group B, it was 19.19 ± 1.46 MPa. Finally, for group SB, it was 27.76 ± 1.95 MPa. There was no significant difference in shear strength between group C, group S and group B. There was a significant difference in shear strength between each group and group SB (P < 0.05). Under a stereomicroscope, the observed fracture modes of each group were mainly mixed failure. Conclusion Sandblasting cannot significantly increase the bonding strength between zirconia and veneering porcelain. Veneering with a thin layer of porcelain powder as the bond coating has no obvious effect on the bonding strength. Sandblasting and veneering with a thin layer of porcelain powder as a bond coating can significantly improve the bonding strength between zirconia and veneering porcelain.

OBJECTIVE To establish a method for simultan eous determination of 5 kinds of pentacyclic triterpenoids as 3-O- acetyl-pomolic acid in Chaenomeles speciosa ，and to analyze the difference in the contents of C. speciosa from different producing areas by different processing technologies . METHODS HPLC method was adopted . The determination was performed on COSMOSIL 5 C18-MS-Ⅱ column with mobile phase consisted of acetonitrile -0.005 mol/L ammonium dihydrogen phosphate solution （pH value adjusted to 6.5 with phosphoric acid ）（70∶30，V/V）at the flow rate of 1.0 mL/min. The column temperature was set at 30 ℃. The detection wavelength was set at 210 nm，and sample size was 20 μL. The contents of the other four pentacyclic triterpenoids were calculated according to quantitative analysis of multi -components by single -marker（QAMS）using oleanolic acid as internal reference . The results were compared with those determined by external standard method . The total content of oleanolic acid and ursolic acid ，the total content of 5 components in C. speciosa from different producing areas and different processing technologies were compared . RESULTS The linear range of 3-O-acetyl-pomolic acid ，betulinic acid ，oleanolic acid ，ursolic acid and 3-O-acetyl ursolic acid were 4.06-81.2，2.12-42.4，9.62-192.3，7.77-155.4，4.21-84.1 μg/mL，respectively（R2＞0.999）. RSDs of precision ，reproducibility and stability （24 h）tests were all lower than 3%. The average recoveries were 98.29%-101.38% （RSDs＜3%，n＝6）. The mass fraction of 3-O-acetyl-pomolic acid ，betulinic acid ，ursolic acid and 3-O-acetyl ursolic acid measured by QAMS w ere 0.023%-0.060%，0.044%-0.528%，0.101%-0.368%，0.067%-0.221%，respectively；the deviations from the results measured by external standard method were all within 8%. The total content of oleanolic acid and ursolic acid， the total content of 5 components in C. speciosa processed by fresh -cut technology from the same producing area were higher than those in C. speciosa processed by traditional technology ，and the total content of 5 components in C. speciosa from Chongqing Qianjiang were significantly higher than those from other producing areas （P＜0.05）. CONCLUSIONS QAMS method is established for the simultaneous determination of 3-O-acetyl-pomolic acid ，betulinic acid ，oleanolic acid ，ursolic acid and 3-O-acetyl ursolic acid in C. speciosa. Established method is simple ，rapid and accurate . The total content of 5 components in C. speciosa produced in Chongqing Qianjiang is higher ，and the total content of C. speciosa processed by fresh -cut technology from the same origin is higher than C. speciosa processed by traditional technology .