OBJECTIVETo compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing.

METHODSA nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing.

RESULTSP60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen.

CONCLUSIONThe nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.

Acrylic Resins ; Composite Resins ; Dental Materials ; Dental Polishing ; Materials Testing ; Polyurethanes ; Surface Properties

Objective To investigate the relationship between the optimal cutoff point of serum homocyste-ine(Hcy)and premature delivery in pregnant women ,and to analyze the influence of Hcy levels on the outcome of preterm infants. Methods Totally 114 cases of pregnant women were chosen as observation group and 103 cases of normal as control group. Hcy,D-D and hypersensitive C reactive protein were detected;analysis of the ROC curve was conducted by using the SPSS 13 software and the risk factors for preterm delivery were analyzed using logistic multivariate regression analysis. Results (1)The levels of Hcy,HS-CRP and D-D in preterm pregnant women were higher than those in control group and the difference was statistically significant (P < 0.05). (2) Logistic regression analysis showed that the relative risk coefficient(OR)of Hcy was 9.736,and the regression equation of premature birth probability was obtained.(3)ROC curve to evaluate the predictive value of Hcy in risk factors of preterm birth was 0.931;when Hcy was 13.8μmol/L,the Youden index was 0.784.(4)Elevated levels of Hcy in preterm women led to a marked increase in the likelihood of SGA. Conclusion When predicting risk factors for preterm birth,the best predictive cutoff value for Hcy is 13.8μmol/L,which is one of the independent risk factors for preterm birth.