1.Effects of pins and bonding agents on the tensile strengths of Ni/Cr alloy bonded to enamel
Journal of Peking University(Health Sciences) 2004;0(01):-
Objective: To evaluate the effects of pin retention form and different bonding agents on the tensile bond and re-bond strength of Ni/Cr alloy to the enamel. Methods: Sixty bovine permanent incisors were randomly divided into 6 equal groups by the variables of the numbers (0, 1 or 2) of pins to be prepared and bonding agents (Panavia F and Super-Bond C&B). The pin 1mm in diameter and 1mm in depth was prepared vertically to each enamel surface in the groups to be with pins. Cast Ni/Cr alloys cy-linders were made and bonded to respective enamels using two different agents. Tensile strengths were tested. After residual visible resin on the debonded surfaces being removed, specimens were re-bonded and tested in the same way as initial bonding. Results: The tensile strength of Super-Bond C&B groups (11.82 MPa) was significantly higher than those of Panavia F groups (9.28 MPa, P
2.Case of depression.
Yadong WANG ; Qing YANG ; Zongbao YANG
Chinese Acupuncture & Moxibustion 2015;35(7):656-656
3.Influence of attachment type on stress distribution of implant-supported removable partial dentures
Xue YANG ; Qiguo RONG ; Yadong YANG
Journal of Peking University(Health Sciences) 2015;(1):72-77
Objective: To compare influences of different retention attachments on stress among supporting structures .Methods: By 3-dimensional laser scanner and reverse engineering computer aided design ( CAD) software , a basic partially edentulous digital model with mandibular premolar and molar missing was established .Implant attachment and removable partial dentures ( RPD) were added into the basic model to build three kinds of models: RPD only, RPD +implant +Locator attachment , and RPD +implant +Magfit attachment .Vertical and inclined loads were put on artificial teeth unilaterally . By means of 3-dimensional finite element analysis , the stress distribution and displacement of the main supportive structures were compared . Results: A complete 3-dimensional finite element model was established , which contained tooth structure , and periodontal structures .The displacement of the denture was smaller in Locator (9.38μm vertically, 45.48μm obliquely) and Magfit models (9.54μm vertically, 39.45 μm obliquely) compared with non-implant RPD model (95.27 μm vertically, 155.70 μm oblique-ly) .Compared with the two different attachments , cortical bone stress value was higher in Locator model ( Locator model 10.850 MPa vertically , 43.760 MPa obliquely;Magfit model 7.100 MPa vertically , 19.260 MPa obliquely).The stress value of abutment periodontal ligamentin Magfit model (0.420 MPa vertically) was lower than that in Locator model (0.520 MPa vertically).Conclusion:The existence of implant could reduce maximum von Mises value of each supportive structure when Kennedy Ⅰpartially edentulous mandible was restored .Comparing the structure of Magfit and Locator attachment , the contact of Magfit attachment was rigid , while Locator was resilient .Locator attachment could improve stability of the denture dramatical -ly.Locator had stronger effect on defending horizontal movement of the denture .
4.Influence of retention-form design on the retention of resin-bonded fixed partial dentures
Jian YANG ; Yadong YANG ; Hailan FENG
Journal of Peking University(Health Sciences) 2004;0(01):-
Objective: To evaluate the influence of retention-form design of resin bonded fixed partial dentures(RBFPDs). Methods: Forty-five metal replicas of posterior metal RBFPDs were divided into 3 groups(n=15):C shape(control group), C shape + axial groove, C shape + pin hole. All the replicas were luted with Panavia F cement and subgroup of 5 specimens were subject to 70 N compressive load cycling for 0 cycles, 240 000 cycles , and 1 200 000 cycles respectively .Half of the cycles was on the central fossa of the pontics and half on the buccal inclined surface of the lingual cusp. Forces for dislodgment of the specimens were applied along the long axis of the abutment at a crosshead speed of 1.0 mm /min. The separation forces were recorded as maxium retention force at the time of dislodgement. Results: Se-paration forces of the C shape group (566.82?71.59 N)0.05). After 1 200 000 cycles, the retention force of the RBFPDs decreased significantly (P
5.Case of metrorrhagia after delivery.
Hong WANG ; Yadong WANG ; Zongbao YANG
Chinese Acupuncture & Moxibustion 2016;36(4):380-380
6.Case of sleepiness.
Zongbao YANG ; Ni BAI ; Yadong WANG
Chinese Acupuncture & Moxibustion 2015;35(11):1154-1154
7.Three-dimensional degradable porous scaffolds made by silk fibroin-chitosan composite
Yadong YANG ; Wenyuan ZHANG ; Guojian FANG
Chinese Journal of Tissue Engineering Research 2009;13(51):10074-10078
BACKGROUND: Simply used natural materials-prepared scaffolds such as collagen, gelatin and fibrin solve problems of biocompatibility, but its degradation is rapid, and cannot induce new tissues, but collapse is found as cell scaffolds.OBJECTIVE: To explore and determine the property of biological degradable three-dimensional porous scaffolds using silk fibroin-chitosan composite.DESIGN, TIME AND SETTING: The material observational study was performed at the Institute of Bioengineering, Zhejiang Academy of Medical Science from June 2008 to June 2009.MATERIALS: Spring silk cocoon was presented by a silkworm farmer from Huangdunmiao village, Maqiao town, Haining City,Zhejiang Province, China. Chitosan was produced by Shanghai Bo'ao Biological Technology.METHODS: 15 g/L silk fibroin solution was made by degumming, salvation and dialysis. Chitosan was dissolved in 2% acetic acid solution to prepare 25 g/L chitosan-acetic acid solution. Two solutions were mixed to prepare six silk fibroin/chitosan solutions, and mass ratio was 10: 0, 5: 5, 4: 6, 3: 7, 2: 8, 0:10. These solutions were separately sucked in a 24-well plate. Following exhausting gas vacuole at 4 ℃, precooling was performed at -20 ℃ for 12 hours, followed by cryodesiccate for 30 hours. Samples were then hydrated in ethanol, neutralized in NaOH-alcohol for 1 hour, washed and then frozen to dry.MAIN OUTCOME MEASURES: Optical microscope and scanning electron microscope were used to observe pore size and structure of various mass ratio-prepared scaffold. Modified liquid substitution method was utilized to measure porosity of various scaffolds. The degradable rate of various scaffolds was determined at 4 weeks in vitro.RESULTS: Silk fibroin/chitosan of 10: 0 mass ratio-prepared scaffold had rough fluffy pore, was brittle, with high dissolve-loss rates. On the contrary, chitosan-prepared scaffold was hard, without enough elasticity following freeze-dry. The composite scaffold of 5: 5, 4: 6, 3: 7 and 2: 8 following freeze-dry was loose and soft, similar to sponge. With increased chitosan concentration,scaffold hardness increased. There were evenly distributed, detailed eyelets on the scaffold. Under the optical microscope,various pores were irregular; each pore closely connected and linked together; pore size was even, 20-100 μm. With increased chitosan concentration, pore size was gradually reduced. Scaffold porosity determination results displayed that mass ratio of silk fibroin/chitosan 4: 6 group > 5: 5 group > 3: 7 group > 2: 8 group. Compared with 2: 8 group, the porosity was significantly increased in the 5: 5 and 4: 6 groups (P < 0.05). No significant difference was detected in volume expansibility in the silk fibroin/chitosan composite scaffold of various mass ratios (P > 0.05). The degradation was slowest in the 2: 8 group, and fastest in the 5: 5 group at 4 weeks.CONCLUSION: Regarding physical and chemical properties, composite scaffold made by silk fibroin/chitosan showed significant superiority compared with scaffold made by silk fibroin or chitosan alone. Of them, silk fibroin/chitosan mass ratio of 5: 5 and 4: 6 are accorded with the requirement of cartilage tissue engineering.
8.The efficacy comparison between glargine and biphasic insulin aspart 30(BIAsp 30) after CSII in newly diagnosed type 2 diabetes mellitus
Yadong SUN ; Yan MA ; Le YANG
Chinese Journal of Diabetes 2009;17(12):908-910
Objective To compare the efficacy and safety of glargine(Lantus) versus biphasic insulin aspart 30 (30% free and 70% protamine-bound, BIAsp 30) after continuous subcutaneous insulin infusion treatment (CSII) in newly diagnosed type 2 diabetes mellitus. Methods A 20 week open and random study was performed. All 60 patients with newly diagnosed T2DM were randomly divided into two groups. Group B patients was treated by glargine and group A received treatment with BIAsp 30 administered immediately before dinner and breakfast. Blood glucose at 7 time points, glycosylated hemoglobin A1c(HbA1c) and hypoglycemia were observed. Results The postprandial glucose(PPG) was significantly lower in group B than in group A (P<0.05), and the frequency of hypoglycaemic episodes was lower in group B than in group A (P<0.05). The fasting blood glucose(FBG) was not different between two groups (P>0.05). And there was no difference between two groups in HbA1c and other adverse events. Conclusions Glargine is surperior to BIAsp30, not only in controlling the PPG but also in reducing the incidence of hypoglycemia.
9.Preparation of chitosan sustained release microspheres encapsulated with transforming growth factor beta 1
Yadong YANG ; Wenyuan ZHANG ; Guojian FANG
Chinese Journal of Tissue Engineering Research 2009;13(38):7481-7484
OBJECTIVE: To prepare chitosan microspheres encapsulated transforming growth factor β1 (TGFβ1), and to analyze its property. METHODS: The chitosan was dissolved in 2% acetic acid to prepare chitosan microspheres encapsulated TGFβ1 with emulsification cross-linking method, Tween 80 and sodium polyphosphate were served as emulsifying agent and cross-linking agent, respectively. Meanwhile, chitosan microspheres and containing bovine serum albumin chitosan microspheres were prepared as blank control and experimental control groups. The morphology and diameter of 3 kinds of microspheres were observed, and the dispersion and in vitro release of chitosan microspheres encapsulated TGFβ1 were detected, furthermore, the water absorption expansion rate of blank control and experimental control groups were measured. RESULTS: Scanning electron microscopy showed that the microspheres diameter in the blank group was approach 15 μm, with smooth surface and plenty of tiny pores. However, the microspheres in the other 2 groups were distributed uniformly with approximately 1 μm in diameter, the surface was smooth. The chitosan microspheres encapsulated TGFβ1 released fast at begin 12 hours, and then gentled gradually, with 53.5% release ratio within 6 days. The increased mass of microspheres in the blank control and experimental control groups reached a balance after 1 hour, both of which were over 700%,in particular larger in the acid environment. CONCLUSION: Chitosan microspheres encapsulated TGFβ1 prepared by emulsification cross-linking method exhibit high yield and good drug release. The strong water absorption expansion rate of chitosan microspheres requires aperture size, as well as intensity of bone tissue engineered scaffold.