In this paper we analyzed examination results of the Beijing Community Dentistry Professional Post Assessment and related factors, also discussed the measures for improving the quality of the post assessment. In 325 examinees 244 passed with a pass rate of 75.1%. There significant differences among examinees, educational background and academic training were most influential

OBJECTIVE To investigate the disinfection efficacy of dental high-speed hand-pieces contaminated by HBV with the method of pressure steam sterilizer.METHODS Taking 50 oral clinical patients randomly,and three group-samples which included saliva,hand-pieces contaminated by clinical operation and disinfected by pressure steam sterilizing were collected,then the samples were detected HBsAg and HBV DNA,respectively.RESULTS There were 95% of the saliva samples being HBsAg positive,the positive rate of the high-speed hand-pieces contaminated by clinical operation was lower than the saliva samples,and the positive rate of the hand-piece disinfected by pressure steam sterilizing was the lowest.HBV DNA was undetectable in the sample before or after disinfected hand-pieces used in patients′ saliva which HBsAg s/co value higher than 5.0.CONCLUSIONS Pressure steam sterilizing is effective to reduce the contaminated HBV on hand-pieces,but the biology test should be taken to demonstrate whether the complete sterilizing is achieved.

OBJECTIVE To investigate the factors influencing the effects of disinfection of HBV on dental hand piece. METHODS After polluted with HBV positive serum,the dental hand piece was disinfected with sterilizer at the condition of 134℃ for 5 minutes according different treatment procedures.The samples were then taken and detected HBsAg by the automatic enzyme immune analyzer using the third generation EIA agent.The efficacy of disinfection of HBV was presented by the reaction of HBsAg detection. RESULTS If the dental hand piece was sterilized directly not cleansed using clean water after pollution and dried in room temperature,there were 96.87% of the samples being HBsAg positive,and the polluted but dried hand piece,even cleansed there were 87.5% of positive result, even if prolonged the time of sterilization and the frequencies of vacuumization,the HBsAg positive rate of the sample was still up to 56.25%.But if the hand piece was irrigated and cleansed immediately after pollution and sterilized,all samples were HBsAg negative. CONCLUSIONS Whether or not cleansed immediately is the most important factor influencing the efficacy of hand piece sterilization after pollution.

Objective This study aims to investigate bond strength between zirconia and resin cement through sur-face treatments with Er:YAG laser,Nd:YAG laser,and Si-Zr coating.Methods Seventy-five round pre-sintered zirco-nia discs with a diameter of 18 mm and a thickness of 1.5 mm were prepared by a powder compactor.Fifty discs were randomly divided into five groups of 10 discs each and were subjected to five surface treatments:no treatment(control group),sandblasting with alumina particles(sandblasting group),Er:YAG laser treatment(Er:YAG laser group),Nd:YAG laser treatment(Nd:YAG laser group),and Si-Zr coating treatment(Si-Zr coating group).The discs were then bonded to composite resin columns with resin cement.The shear bond strength of each group was tested with a universal tester.Roughness tester,scanning electron mi-croscope(SEM),and energy dispersive spectroscopy were used to analyze surface performance.Results The bond strength of the Si-Zr coating group was higher than that of the remaining groups(P<0.05).The difference in bond strength between the sandblasting group and the Er:YAG laser group was not statistically significant(P>0.05),but both of them had higher bond strength than the Nd:YAG laser group(P<0.05).The Si-Zr coating group had the highest sur-face roughness(P<0.05).The surface roughness of the sandblasting,Er:YAG laser,and Nd:YAG laser groups was high-er than that of the control group(P<0.05),but the difference among the three groups was not statistically significant(P>0.05).SEM observations showed irregular scratches on the surface of the sandblasting group and large pits with holes on the surface of the Er:YAG and Nd:YAG laser groups.In the Er:YAG laser group,the crystal structure was replaced by a smooth surface with a large amount of microcracks due to partial melting.Complex porous structures that comprised"is-land-like"structures and mass pores among the grains were observed on the surface of the Si-Zr coating.Only Zr,O,and Y were detected on the surfaces of the control,Er:YAG laser,and Nd:YAG laser groups.Al was found on the surface of the sandblasted group,and a higher proportion of Si was detected on the surface of the Si-Zr coating group.Conclusion Er:YAG laser and Nd:YAG laser treatment on the zirconia ceramic surface could increase roughness and improve the bond strength to resin cement.Si-Zr coating treatment is an effective alternative for increasing the roughness and bond strength of zirconia surface and is superior to sandblasting and laser treatments.

Objective To evaluate the effect of SiO2-ZrO2 slurry coating on surface performance of zirconia ceramic.Methods Seventy pre-sintered zirconia discs were randomly divided into seven groups with 10 discs per group.Sample discs in each group received one of the following seven different surface treatments, namely, sintered(group AS), sand blasting after sintered(group SB), coated with slurry of mole ratio of SiO2 to ZrO2 2: 1(group 2SiO2-1ZrO2), coated with slurry of mole ratio of SiO2 to ZrO2 1: 1(group 1SiO2-1ZrO2), coated with slurry of mole ratio of SiO2 to ZrO2 1 : 2(group 1SiO2-2ZrO2), coated with slurry of mole ratio of SiO2 to ZrO2 1 : 3(group 1SiO2-3ZrO2), coated with slurry of mole ratio of SiO2 to ZrO2 1:4(group 1 SiO2-4ZrO2).Profilometer, X-ray diffractometer(XRD), energy dispersive spectrometer, scanning electron microscopy(SEM) were used to analyze surface performance.Results The surface roughness of the discs in group AS was lower than those in the other groups[(0.33 ± 0.03) μm] (P＜0.05), there was no statistically significant difference(P＞0.05) among group 2SiO2-1ZrO2[(3.85±0.38) μm], group 1SiO2-1ZrO2[(3.78±0.56) μm] and group 1SiO2-2ZrO2[(4.06 ± 0.48) μtm], and no difference(P＞0.05) was observed between group 1SiO2-3ZrO2 [(1.02±0.09) μm] and group 1SiO2-4ZrO2[(1.53±0.23) μm] either.However, surface roughness in all coating groups was higher than those in group SB[(0.86 ± 0.05) μm] (P＜0.05).According to the XRD pattern, group AS and all coating groups consisted of 100％ tetragonal airconia and monoclinic zirconia was detected at surface of group SB.Contents of surface silicon of coating groups increased significantly,however, no silicon was detected at sample surface of group AS and group SB.SEM showed that zirconia grains of coating exposed since part of silicon was etched by hydrofluoric acid, a three-dimensional network of intergrain nano-spaces was created.Conclusions SiO2-ZrO2 slurry coating could make surface of zirconia rough and increase Si content without creating monoclinic zirconia.

Objective: To investigate the effects of zirconia micro coating on the proliferation and differentiation of osteoblasts on the surface of zirconia ceramic, and to provide a strategy for zirconia implant surface treatment. Methods: Forty tablets of zirconia ceramic, with the diameter of 15 mm and the thickness of 1.5 mm, were prepared. Then, twenty tablets polished by water sandpaper were taken as the control group, and 20 pieces of the zirconia coating after sintering micron were taken as the experimental group. The micromorphology of the surface of the two groups were observed by scanning electron microscope. The cell morphology after inoculation with MC3T3-E1 of osteoblasts on the surface of the material was investigated for 1, 3, and 5 days by scanning electron microscope. The cell proliferation was detected at 1 and 3 days by methyl thiazolyl tetrazolium. The cell differentiation ability was detected at 3 and 7 days by real-time quantitative PCR. Statistical analysis was conducted by independent sample t test. Results: After coating with zirconia micron particles, pores with the diameter of 1-20 μm could be observed on the surface of the test group of tiles through high temperature sintering. The growth of osteoblasts on the surface of the ceramic chip in the test group and control group exhibited the similar cell morphology. As they were cultured for 1 day, the experimental group exhibited a similar quality of cells as those in the test group (P>0.05). After 3 days' incubation, comparing with the cell quality of the test group (1.067 ± 0.077) (P<0.05), the quality of osteoblasts on the surface of zirconia ceramics coating increased to 1.763±0.165, and the expression of mRNA in alkaline phosphatase (ALP), osteopotin (OPN) and osteocalcin (OCN) also increased with the amount of 1.63±0.28, 1.99±0.41 and 1.60±0.30, respectively, compared with the test group (1.00± 0.00) (P<0.05). Seven days later, the expression of mRNA in Runt-related transcription factor-2 (RNUX2) (1.33±0.19), special AT-rich sequence binding protein-2 (SATB2) (1.64 ± 0.36), as well as alkaline phosphatase (ALP) (1.78±0.40), OPN (2.25±0.36), and OCN (1.88±0.21), showed a remarkably increase compared with the test group (1.00±0.00) (P<0.05). Conclusions Zirconia micro coating on the surface of zirconia ceramics promoted the proliferation and differentiation of osteoblasts adhered.