Objective:To evaluate the effect of TiN coating on retentive force of conus telescopic crowns after repeated insertion/separation tests. Methods: Fourteen pairs of standard metal specimens fabricated by precision Computer Numerical Control (CNC) Lathe were randomly divided into experimental group and control group, seven pairs in each group. The external surfaces of inner crowns and internal surfaces of outer crowns of experimental group were coated with a 2.0 μm titanium nitride (TiN) by multi-arc ion plating method. The group without titanium nitride coating was served as control. The retentive forces of two group telescopic crowns was investigated by repeated insertion/separation tests. Statistical analysis of group t-test was performed by SPSS 13.0 software package. Results: The results demonstrated that the initial retentive force of titanium nitride group in our study were lower than that of uncoated titanium nitride group. The retentive forces of two groups gradually decreased depending on the number of insertion/separation cycles and the rate of retention attenuation was found to be statistically significant. It was also shown that the retentive force of titanium nitride coating group began to decrease after 3 000 cycles and declined slowly not only before 3 000 cycles but also after 7 000 cycles. Conclusion: Titanium nitride coating deposited on external surface of inner crowns and internal surface of outer crowns can significantly decrease retention attenuation rate of conus telescopic crowns and maintain persistent retentive force.

Objective To evaluate the relationship between fragile fracture sites in hospitalized geriatric and nutritional status.Methods On the basis of whether the fracture,293 cases were divided into fracture group(n =140)and normal control group(n =153),51 males(36.4%)and 89 females(63.6%)in 140 fracture patients. Results The age was (74.04 ±8.58)years in the fracture group,that in the normal control group was (74.77 ± 8.14)years,there was statistically significant difference between the two groups(t =-0.743,P >0.05).The femoral neck fracture was 51 cases(36.4%)and intertrochantetic fracture was 57 cases(40.7%),and other was 32 cases (22.8%).The patients were divided into the two groups according to the age:60 ~75 years group(n =62)and >75 years group(n =78),femoral neck fracture was 37.2%,and intertrochantetic fracture was 52.6% in the group that more than 75 years old,which were 35.5% and 25.8%,respectively in 60 ~75 years group,there was statistically significant difference between the two groups(χ2 =18.337,P <0.01).The hemoglobin,serum albumin weight,weight,BMI in the fracture group were (117.44 ±20.25)g/L,(34.96 ±4.95)g/L,(60.81 ±10.63)kg,(22.83 ±3.54)kg/m2 , and those in the normal control group were (136.99 ±17.10)g/L,(37.27 ±5.85 )g/L,(64.47 ±11.23)kg, (24.24 ±3.88)kg/m2 respectively.The commonly used nutritional indicators:hemoglobin(t =-8.908),serum albu-min(t =-3.619),weight(t =-2.837)and BMI(t =-3.218)were lower than the normal control group(all P <0.01 ),serum phosphate was lower than the normal control group,the difference was statistically singnificant (t =-2.047,P <0.05).The blood calcium(t =0.630)and ALP(t =-0.550)had no statistically singnificant differences between the two groups(all P >0.05).Conclusion The proportion of intertrochantetic fracture and femo-ral neck fracture were higher in hospitalized elderly patients,and malnutrition,such as lower hemoglobin,lower serum albumin,lower weight,and lower BMI were,important factors in the fragile fracture in the geriatric inpatients.

Objective The purpose of this study was to evaluate the disinfection effectiveness and properties of acrylic resin via microwave irradiation. Methods Forty acrylic resin base dentures fabricated in a standardized procedure were chosen and divided into Group A,B,C and D randomly. Group A,B and C were immersed in 200ml distilled water and submitted to microwave irradiation at 700W for 3,4,5 minutes individually. Group D was used as positive control. Bacteria specimens from each group were got for culture and numbers were calculated. Then the four groups were tested for the flexural strength and impact strength by universal test machine before and after microwave irradiation sterilization. Results The germicidal ratio of Group B was more than 90% ,while the ratio of group C was 100%. There was no significant difference in flexural strength and impact strength between group C and group D. Conclusions Microwave irradiation for 5 minutes at 700W produced sterilization of dentures contaminated with all bacteria whereas the denture strength is not affected. Microwave irradiation at 700W solution for 5 minutes was effective to sterilize acrylic resin base dentures.

AIM:To investigate the roles of ClC-3 chloride channels in the regulation of cell cycle and the re-lationship between ClC-3 chloride channels and the cell cycle regulators , such as cyclin D1, cyclin-dependent kinase (CDK)4, CDK6, P21 and P27 in the HeLa cells.METHODS:ClC-3 genes were silenced by the siRNA technique in the HeLa cells.The transfection efficiency of ClC-3 siRNA was detected by real-time PCR.The cell cycle distribution was ana-lyzed by the flow cytometry .The protein expression of ClC-3, P21, P27, CDK4, CDK6 and cyclin D1 was determined by Western blot .RESULTS:ClC-3 was knocked down by ClC-3 siRNA in the HeLa cells .Transfection of the cells with ClC-3 siRNA arrested the cells at G0/G1 phases, decreased the expression of cyclin D1, CDK4 and CDK6, and increased the expression of P21 and P27.CONCLUSION:ClC-3 plays an important role in the cell cycle of HeLa cells through the G 1-S transition point.ClC-3 may regulate the cell cycle progression by up-regulation of cyclin D1, CDK4 and CDK6 expression and/or by down-regulation of P21 and P27 expression.

OBJECTIVETo investigate the effect of three different impression methods on the marginal fit of all-ceramic crowns. The three methods include scanning silicone rubber impression, cast models, and direct optical impression.

METHODSThe polymethyl methacrylate (PMMA) material of a mandibular first molar in standard model was prepared with 16 models duplicated. The all-ceramic crowns were prepared using three different impression methods. Accurate impressions were made using silicone rubber, and the cast models were obtained. The PMMA models, silicone rubber impressions, and cast models were scanned, and digital models of three groups were obtained to produce 48 zirconia all-ceramic crowns with computer aided design/computer aided manufacture. The marginal fit of these groups was measured by silicone rubber gap impression. Statistical analysis was performed with SPSS 17.0 software.

RESULTSThe marginal fit of direct optical impression groups, silicone rubber impression groups, cast model groups was (69.18±9.47), (81.04±10.88), (84.42±9.96) µm. A significant difference was observed in the marginal fit of the direct optical impression groups and the other groups (P<0.05). No statistically significant difference was observed in the marginal fit of the silicone rubber impression groups and the cast model groups (P>0.05).

CONCLUSIONAll marginal measurement sites are clinically acceptable by the three different impression scanning methods. The silicone rubber impression scanning method can be used for all-ceramic restorations.

Computer-Aided Design ; Crowns ; Dental Marginal Adaptation ; Dental Porcelain ; Dental Prosthesis Design ; Zirconium

OBJECTIVEThis study aims to evaluate the bond strength of a self-adhesive resin cement to dentin by ethylene diamine tetraacetic acid (EDTA) and NaClO.

METHODSTwenty-seven freshly extracted non-carious human premolars were prepared to expose the buccal dentin and randomly divided into three groups: control group (A group), EDTA group (B group) and NaClO group (C group). All teeth were bonded to dentin using a self-adhesive resin cement after the teeth in the A group were processed with distilled water. The B and C group were processed with 3%EDTA and 1%NaClO, respectively. After 24 hours at 37 °C water, the shear bond strengths of the twenty-four specimens were measured. All statistical analysis was performed using SPSS 17.0 software package. Each fractured specimen was examined under dental microscope. Three new specimens were cut, and the morphologies of the cement-dentin interface were observed under scanning electron microscope (SEM).

RESULTSThe shear bond strength in the A group, B group and C group was (8.55±0.63), (8.47±0.56) and (12.97± 0.59) MPa, respectively. The difference between A group and B group was no statistically significant (P>0.05), whereas the difference between C group and B group (or A group) was statistically significant (P<0.05). SEM observation of the cement-dentin interface in the C group showed good adaptation, but resin tags were not observed. The other two groups showed poor bonding interface. Most of the fractured adhesive dentin surfaces exhibited cohesive failure in the A group and B group. All the fractured adhesive dentin surfaces exhibited cohesive failure in the C group.

CONCLUSION1% NaClO can increase the bond strength of self-adhesive resin cement to dentin, but 3%EDTA has no effect.

Adhesives ; Dental Bonding ; Dental Stress Analysis ; Dentin ; chemistry ; Dentin-Bonding Agents ; Detergents ; chemistry ; Humans ; Resin Cements

OBJECTIVETo investigate the shear bond strength between veneering ceramic and zirconia core in different all-ceramic systems.

METHODSTwenty disk-shaped specimens with 8 mm in diameter and 3 mm in height for each zirconia system (Lava, Cercon, IPS e.max ZirCAD, Procera) were fabricated respectively and divided into four groups: Lava group, Cercon group, IPS e.max ZirCAD group, Procera group. For each group, 10 specimens were sintered with 1 mm corresponding veneering ceramic, while the other were sintered with 2 mm corresponding veneering ceramic respectively. The shear bond strength and fracture mode of specimens were observed and determined.

RESULTSThe values of shear bond strength for Lava, Cercon, IPS e.max ZirCAD and Procera were (13.82 +/- 3.71), (13.24 +/- 2.09), (6.37 +/- 4.15), (5.19 +/- 5.31) MPa in the group of 1 mm thicked veneering ceramics, respectively, while the values in the group of 2mm thicked veneering ceramics were (38.77 +/- 1.69), (21.67 +/- 3.34), (12.70 +/- 4.24), (9.94 +/- 6.67) MPa. The values of Lava and Cercon groups were significantly higher than that of IPS e.max ZirCAD and Procera groups (P < 0.05). And the values of 2 mm thicked veneering ceramic group were significantly higher than that in 1 mm thicked groups (P < 0.05). Adhesive fracture between core and veneering ceramics were observed in the fracture modes of most specimens.

CONCLUSIONThe shear bond strength of veneering ceramic to the zirconia framework are different from the zirconia system we chose, and the thickness of veneering ceramic has a great impact on its shear bond strength.

Ceramics ; Dental Bonding ; Dental Porcelain ; Dental Stress Analysis ; Dental Veneers ; Humans ; In Vitro Techniques ; Materials Testing ; Metal Ceramic Alloys ; Shear Strength ; Surface Properties ; Titanium ; Zirconium

To investigate the effects of ATRA, acitretin and tazarotene on the growth and apoptosis of human tongue squamous cell carcinoma cell line Tca8113. The effect of retinoids on growth of Tca8113 cells in vitro was examined by MTT assay and Trypan blue exclusion assay. Cell cycle analysis, early apoptosis analysis with double staining with Annexin V-FITC and PI, and active caspase-3 analysis with the staining of FITC-conjugated monoclonal rabbit anti-active caspase-3 antibody were made by flow cytometer. Streptavidin-biotin complex (SABC) immunocytochemical assays were employed for the detections of Bax/Bcl-2 proteins expressions. Our results showed that the retinoids inhibited growth of Tca8113 cells in a dose- and time-dependent manner with maximal inhibition 24 h after treatment of 10-5 mol/L. 10-5 mol/L retinoids altered cell cycle distribution of Tca8113 cells, revealing an increase in G0/G1-phase population, a decrease in S-phase population and the inhibition of G1/S switching. 10-5 mol/L retinoids significantly induced apoptosis of Tca8113 cells (all P<0.05), elevated the cells population with detectable active caspase-3 (P<0.05 for all), increased the number of cells forming Bax and decreased the number of cells forming Bcl-2 significantly (all P<0.05). Acitretin played a most prominent role among the retinoids. It is concluded that the inhibition of cell cycle progress of Tca8113 cells by ATRA, acitretin and tazarotene is one of the possible mechanisms for proliferation arrest of Tca8113 cells elicited by the retinoids. The retinoids mediate apoptosis in Tca8113 cells that may be caspase-dependent through mitochondria pathway. High concentration retinoids inhibit growth of Tca8113 cells in vitro by interfering with proliferation and inducing apoptosis of cells. Acitretin may be an alternative medicine for the prevention and treatment of tongue squamous cell carcinoma.

OBJECTIVEThis study aims to identify highly accurate quantitative methods for evaluating the occlusal vertical dimension by using cephalometric radiographs to analyze the craniofacial hard tissue landmarks in 30 cases with normal occlusions.

METHODSA total of 30 subjects with normal occlusions and aged between 20 and 30 years old were included in the study. Cephalometric radiographs were obtained and analyzed using the Winceph 8.0 measurement software. Landmark points were identified and measured.

RESULTSThe mean distribution difference of the center angle (CA) and lower angle (LA) of the face was not statistically significant (t = -1.490, P = 0.147). The CA and LA had a significantly linear correlation (r = 0.976, P = 0.000), and the regression equation was y = 0.298 + 0.997x.

CONCLUSIONThe CA can be used to assess and quantify the occlusal vertical dimension in clinical practice.

Adult ; Cephalometry ; Face ; Female ; Humans ; Male ; Pilot Projects ; Vertical Dimension ; Young Adult

Objective To investigate the relationship among Helicobacter pylori(H.pylori),CD4 positive cells and CD8 positive cells in gastric mucosa of the AIDS patients with gastritis.Methods Fiftyeight AIDS patients with upper abdominal pain were diagnosed with chronic gastritis through gastroscopy.The gastric biopsies from them were used for H.pylori detection with rapid urease test and Giemsa staining,pathology examination with HE staining,and immunohistochemistry analysis for CD4,CD8 positive cells in Gastric mucosa.And the application of flow cytometry was for the detection of peripheral blood CD4 and CD8 lymphocytes from the patients.Results H.pylori was positive in 26 cases,and negative was in 32 cases.CD8 cell expression in gastric mucosa of the AIDS patients with H.pylori positive was significantly higher than H.pylori negative patients(P＜0.05).There is no difference CD4 cell expression in gastric mucosa between the AIDS patients with H.pylori positive and H.pylori negative patients.Moreover,CD8 positive lymphocytes in gastric mucosa of those patients with H.pyloriinfection were significantly stronger than the CD4 positive lymphocytes.However,the peripheral blood CD4 lymphocytes from the patients with H.pylori infection were more than those from H.pylorinegative patients significantly(P＜0.05).Conclusion The expression level of CD8 cells in gastric mucosal tissues of AIDS patients with H.pylori infection were higher than those without H.pylori infection.The CD4 lymphocytes from the peripheral blood of the patients with H.pylori infection were more than those without H.pylori negative patients.