ABSTRACT
Objective:To evaluate the effects of magnetron-sputtered ZrSiN/ZrO2 gradient coating on the bonding strength of commercially pure titanium to porcelain.Methods:50 cast titanium specimens were prepared according to the ISO 9693 standard,and divided into 2 groups(n =25).The ZrSiN/ZrO2 gradient coating was deposited on specimens by magnetron sputtering technique,and subsequently a low-fusing porcelain was applied for the samples in the expermental group,the samples in the control group were treated by surface sandblasting.The roughness and surface energy of the samples were measured(n =10).The bonding strength of titanium-porcelain specimens was analyzed by three-point bending test (n =10).Scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDS) were employed to examine the properties of the delaminated and cross-sectioned surfaces.The results were analyzed by paired t-test (α =0.05) with SPSS 1 1.0 software.Results:The roughness of the experimantal group was lower(P ＜ 0.05) and the contact angle was larger(P ＜ 0.05) than those in the control group.The titanium-porcelain bond strength of gradient-coated group was greater than that of control group(P ＜0.05).The SEM and EDS examination results of delaminated and cross-sectioned surfaces also indicated that the gradient-coated group showed more porcelain residues.Conclusion:The bonding strength of porcelain-fused-to-titanium can be improved by magnetron sputtered ZrSiN/ZrO2 gradient coating.
ABSTRACT
BACKGROUND: Because of complicated physiological environment and difficulty to control experimental conditions, it is difficult to get satisfactory results from in vivo studies of cell mechanics.OBJECTIVE: To study the action and mechanism of p38MAPK signaling pathways on myoblast apoptosis based on successful construction of in vitro mechanical stimulation models.METHODS: The C2C12 cells cultured in vitro were divided into control group and SB203580 treatment group. Cyclic tensile stress was applied on the C2C12 myoblast cells for 0, 6, 12 and 24 hours in each group. The Flexcell Strain Unit-5000T was used to expose C2C12 myoblast cell to an equiaxial cyclic of 15% magnitude and a frequency of 10 cycles/min, each cycle including the 3 s stretch and 3 s relaxation. Hoechst 33258 fluorescent staining and optical microscope were used to detect cell apoptosis. RT-PCR, flow cytometric analysis were used to observe the apoptosis of C2C12 myoblast cells and Western blotting were used to detect the activity of p38MAPK and p-p38MAPK. RESULTS AND CONCLUSION: The optical microscope tested the change in the morphology. Hoechst 33258 staining showed that after treatment with cyclic stress, the cell took the typical appearance of apoptosis with chromatin condensation and apoptotic bodies. RT-PCR and flow cytometry showed that with the extension of time the rate of the apoptosis of C2C12 myoblast cell increased. And cells imposed SB203580 before imposing cyclical tensile stress, the results showed that the apoptosis was markedly affected, and the p-p38MAPK expression declined apparently. These findings demonstrate that p38MAPK signaling pathways in stress mediated into C2C12 myoblast cell apoptosis plays an important role.
ABSTRACT
BACKGROUND: The initial stability of implantable distractor depends on the stress distribution of bone-distractor interface. The understanding of the biomechanical change in initial stage can improve the clinical success ratio of implantable distractor used in alveolar crest.OBJECTIVE: To evaluate the influence of bone quality on stress distribution and deformation in initial distraction stage.METHODS: Four three-dimensional models with 10 079-11 456 cells and 17 299-20 101 nodes were prepared by finite element methods (11 mm in length and 3.7-4.1 mm diameter). Implantable distractor was embedded in a segment of mandible. The elastic modulus of cancellous bone and the thickness of cortical bone, stress and deformation of bones and distractor were calculated.RESULTS AND CONCLUSION: The highest stress in the bone was concentrated in transportable section and the maximum deformation of transportable section was observed at the edge of the cortical bone, both of which were increased with bone quality decreased. The subsidence of distractor was observed with bone quality decreased. Bone quality influenced the initial stability and the result of the implantal distraction. The decrease of bone elastic modulus would increase the failure risk of distraction osteogenisis.
ABSTRACT
BACKGROUND:Using Twin-block appliance to treat mandibular retrusion,the mandible position changes greatly.The influence of this change on temporomadibular joint and the effect of Twin-block appliance on condylar growth remain unclear.OBJECTIVE:To observe the effect of Twin-block appliance on condylar process location during mandible forward positioning.PARTICIPANTS:A total of 20 patients with mandible retraction (Angel Ⅱ) malocclusion were selected from Department of Stomatology,First Sanatorium of Qingdao,Jinan Military Area Command of Chinese PLA,comprising 13 males and 7 females,aged 10.8 years (range 9-13 years).All patients were treated with Twin-block appliance.Four median joint pantomograms were taken before treatment,1 week after treatment,1 week and 1 year after treatment finish to measure the condylar process location.RESULTS AND CONCLUSION:In all cases,neutroclusion were obtained.No clicking,pain or other temporomadibular joint symptoms were observed.The condylar process position altered significantly.The anterior space distance was decreased,the superior space distance was increased,and posterior space was enlarged (P<0.05-0.01),i.e.condylar process moved downward and forward.The condylar process position was consistent with preoperative,and joint superior,anterior and posterior space distributed balancedly.Twin-block appliance could restore normal and harmonious process-fossa relationship through growth remodeling,but maintenance is necessary till the remodeling accomplish.