ABSTRACT
Objective:To explore a type of teaching teeth that can highly simulate natural teeth, and to investigate its application in the practice teaching of crown preparations.Methods:A total of 44 senior students majoring in stomatology Fourth Military Medical University were selected, and each student received the training of crown preparations using interpenetrating polymer network (IPN) enamel-like teaching teeth, extracted natural teeth, and traditional composite resin teeth. Operation assessment was performed, and the operation time of each crown preparation was recorded. According to the requirements for crown preparations, scores were determined from the five aspects of axial converging, space for repair, line angle, shoulder quality, and posture, with 10 points for each aspect and 50 points in total, and the total score was calculated. A questionnaire survey on IPN enamel-like teeth was performed for each student after assessment, and SPSS 23.0 was used to perform the least significant difference t-test and the Tambane's T2 test. Results:There was no significant difference in total assessment score between the IPN enamel-like teeth group and the natural teeth group (37.15±1.17 vs. 37.20±1.20, P>0.05), and both groups had a significantly higher total score than the resin teeth group (31.53±1.41) ( P<0.05). The IPN enamel-like teeth group and the natural teeth group had significantly higher scores than the traditional composite resin teeth group in terms of axial converging, space for repair, and shoulder quality ( P<0.05). The questionnaire survey of the students showed a relatively high score of 3.7-4.9 for each item. Conclusion:Compared with traditional composite resin teeth, IPN enamel-like teeth can more comprehensively and effectively simulate the operation and experience of natural teeth for crown preparations and thus have potential advantages in the practice teaching of crown preparations.
ABSTRACT
Septin 9 (SEPT9) gene, a member of the conserved framework protein genes family, has guanosine triphosphataseg (GTPase) activity and play an important role in a wide range of biological processes such as cell division, cell polarization and membrane remodeling.Accumulated evidence have confirmed that SEPT9is closely related to the generation and development of human diseases.And SEPT9has become the new aroused general interest in tumor related research at this stage.This article mainly reviews the structural features of SEPT9gene, action mechanism of SEPT9protein and the role of SEPT9gene in a variety of common oncogenesis, and explores the potential value of SEPT9as a marker in early tumor screening.
ABSTRACT
Objective@#To evaluate the effect of sandblasting on bending strength and subcritical crack growth (SCG) under cyclic loading of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics.@*Methods@#After being polished, sixty bar-shaped specimens of Y-TZP (Wieland zirconia ceramics) were assigned to two groups (n=30) according to the random number table, the sandblasting group (SG) which was treated with sandblasting and the control group (CG) which remained untouched. In each group, half of the specimens (n=15) were subjected to bending strength test, and the results were examined by Weibull statistics and analyzed with ANOVA. The other 15 specimens in each group were subjected to fatigue tests. The results were examined by Weibull statistics and subcritical crack propagation rates were calculated.@*Results@#The bending strengths of SG and CG were (1 291±133) and (1 140±124) MPa (F=10.117, P=0.004), and the Weibull modules of the two groups were 11.06 and 10.64 respectively. The crack growth rate of SCG of SG was lower than that of CG under the same cyclic loading.@*Conclusions@#Proper sandblasting on Y-TZP ceramic can increase its bending strength and resistance to SCG.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the F(-) releasing and recharging properties of six dental restorative materials.</p><p><b>METHODS</b>Disc specimens 10 mm in diameter and 1 mm in thickness were prepared from 6 different dental restorative materials: Fuji VII [glass ionomer cement (GIC)], Fuji II LC (light-curing, GIC), Beautifil (giomer), Compoglass F (compomer), Charisma (composite) and Experimental I (a fluoride releasing composite), with 10 discs for each material. Specimens were dipped in 5 ml deionized water and F(-) release was detected using a fluoride-specific ion electrode every day from 1-7 days and every three days from 8-28 days. On day 28, specimens were exposed to a fluoride foam for 4 min and then dipped in water, then the F(-) concentration was detected every day for a week. The specimens were exposed to fluoride foam and fluoride release was detected repeatedly for three times.</p><p><b>RESULTS</b>All materials presented the highest F(-) release on the first day after dipping and the F(-) release sharply decreased after 24 h and slowly decreased after 3 days. On the first day, Fuji VII presented the highest F(-) release[(99.68±15.21) µg×cm(-2)×d(-1)], followed by Fuji II LC [(37.12±1.67) µg×cm(-2)×d(-1)], Experimental I [(22.93±1.53) µg×cm(-2)×d(-1)], Compoglass F[(15.28±0.70) µg×cm(-2)×d(-1)], Beautifil[(2.40±0.52) µg×cm(-2)×d(-1)] and Charisma[(0.11±0.02) µg×cm(-2)×d(-1)]. Within 28 days of dipping, both Fuji VII and Fuji II LC released more F(-) than other materials did(P < 0.05), followed by Compoglass F and Experimental I, and Beautifil and Charisma released the least F(-)(P < 0.01). After F(-) uptake, all materials released the highest F- on the first day and presented sharply decrease after 24 h and slowly decrease after 2 days. On the first day after F(-) uptake, Fuji VII presented the highest F(-) release (>40 µg×cm(-2) ×d(-1)), much more than other materials(P < 0.01), followed by Fuji II LC(>25 µg×cm(-2) ×d(-1)). Beautifil, Compoglass F and Experimental I were close in F(-) release value(15- 20 µg × cm(-2) × d(-1)), and Charisma showed the lowest F(-) release.</p><p><b>CONCLUSIONS</b>Two glass ionomers were shown to have highest capacity in F(-) release and uptake, followed by compomer and fluoride releasing composite. Composite demonstrated the lowest F(-) release and uptake and Giomer was comparable to composite in F(-) release and to compomer and fluoride releasing composite in F(-) uptake.</p>
Subject(s)
Bisphenol A-Glycidyl Methacrylate , Chemistry , Compomers , Chemistry , Composite Resins , Chemistry , Curing Lights, Dental , Dental Materials , Chemistry , Fluorides , Pharmacokinetics , Glass Ionomer Cements , Chemistry , Resins, Synthetic , Chemistry , Time FactorsABSTRACT
Objective:To evaluate the reliability of flexural strength and subcritical crack growth(SCG)of WL and HT zirconia ce-ramics under cyclic loading.Methods:Bar-shaped speciments of WL(n =30)and HT(n =30)were fabricated and loaded in three-point bending and cyclically fatigued.The flexural strength and the number of cycles to fracture were obtained from three-point flexural test and cyclic fatigue test respectively.Data were examined using Weibull statistics.Pairs law was used to analysize the subcritical crack growth(SCG),the behavior of which was described in terms of crack velocity as a function of maximum stress intensity factor (KImax ).Results:The Weibull module(m)of WL and HT was 10.64 and 12.04,the stress corrosion cracking susceptive indexes(n) 23.71 and 32.87,the SCG 90% and 76.7%,the KImax 49.6% and 50.9% of its maximum stress intensity factor(KIC ),respectively. Conclusion:WL and HT produce pronounced SCG.The minimum fatigue crack growth rate of HT is lower than that of WL(νHT <νWL ).
ABSTRACT
Objective To observe the effect of propofol target controlled infusion with different blood plasma target concentration on stress reaction during the nasal endoscope operation. Methods Sixty patients with ASA Ⅰ - Ⅱ scheduled for the nasal endoscope operation were divided into three groups by random digits table: each group was 20 patients, group A, B, C was given propofol target controlled infusion with blood plasma target concentration 3,4,5 μ g/mi respectively. Heart rate (HR), mean arterial pressure (MAP), pulse oxygen saturation (SpO2), blood glucose, serum cortisol, bispectral index ( BIS ), extubation time were recorded before anesthesia,at 30 min after the operation starting and 60 min after the extubation.Results The descent degree of HR and MAP at 30 min after the operation starting were group C ＞ group B ＞ group A (P = 0.024,0.010 );the descent degree of MAP at 60 min after the extubation were group C ＞group B ＞ group A (P = 0.011 ). BIS and extubation time were 65 ± 8 and (25 ± 7) min in group A, 53 ± 11 and( 36 ± 13 ) min in group B, 45 ± 12 and(45 ± 9 ) min in group C, there were significant differences among three groups(t = 2.476,P= 0.023;t = 2.657,P= 0.012). The blood glucose was increased at 30 min after the operation starting and 60 min after the extubation, the ascensus degree were group A ＞ group B ＞ group C (P= 0.000、0.000);the serum cortisol was decreased at 30 min after the operation starting, the descent degree was group C ＞ group B ＞ group A (P= 0.000), increased at 60 min after the extubation, the ascensus degree was group A ＞ group B ＞ group C (P= 0.001 ). Conclusions Propofol target controlled infusion with blood plasma target concentration 4-5 μ g/ml can ensure eligible depth of anesthesia, decrease pain stimulus, remain stable vital sign,depress the stress reaction caused by nasal endoscope operation efficiently,with short extubation time. It is an eligible blood plasma target concentration.
ABSTRACT
OBJECTIVE: To provide reference for medical system reform in China. METHODS: According to Primary Medical Institutions Part of National Essential Drugs List (2009 edition), relevant aspects and reality of medical system reform and in China, policy connotation of Essential Drug System were analyzed to investigate the difficulties of implementation of Essential Drug System. RESULTS & CONCLUSION: Several problems should be resolved to implement essential drug system effectively, such as benefit assignment and financial support. The implementation of national essential drug system requires various efforts to achieve the goal of Medical Reform.
ABSTRACT
Objective To introduce the achievement in the research work of marine bio-adhesive used in medical fields in future.Methods The merits of marine bio-adhesive was elucidated and the requisition and remained defects of medical and dental adhesives were analyzed.The applicable prospects of mussel bio-adhesive were highlighted particularly on the components and functions.Results At present,gene reconstruction technique is the most useful and economic way to produce bio-adhesive protein from marine biomaterial.By that method,the problems of storage difficulty and resource limitation can be solved.Conclusion The marine bio-adhesive produced by gene reconstruction will be used in medical and dental treatment in the future.
ABSTRACT
This study aims to synthesize cis-butenedioic anhydride modified epoxy dimethacrylate resin and evaluate their physico-mechamical properties.Stoichiometric amounts of E51 type epoxy resin,methacrylate acid and cis-butenedioic anhydride were reacted with N,N-dimethylbenzylamine as a catalyst.The compressive strength,diametral tensile strength,surface hardness,cured depth,water uptake,and water solution of the composite resin with EAM monomers and those of EMA were measured.The composite resin with EAM monomers gave high value of compressive strength,diametral tensile strength,surface hardness and lower water uptake and water solution compared to EMA monomers.
ABSTRACT
This paper is toevaluate the shear bond strength(SBS)of six new dental adhesives tohuman enamel and dentin.120extracted human premaxillary teeth are randomly divided into12groups with10teeth in each.After24-hours immersion in water at37℃,all specimens are loaded in a shear mode in a tensile testing machine with a crosshead speed of10mm/min.The SBSof six adhesives toenamel are24.6?2.7,17.6?3.5,16.5?3.2,12.8?2.9,10.1?1.8and10.0?2.8Mpa for Clearfil SE Bond,Prompt L-Pop Single Bond,All Bond2,Prime&Bond and Opti Bond Sold respectively.Their SBStodentin are16.8?3.7,10.1?1.4,10.0?2.1,18.6?3.3,10.5?2.5and8.2?1.7Mpa respectively.Toenamel Clearfil SE Bond shows the highest mean SBSand Opti Bond Sold shows the lowest.Todentin the SBSof All Bond2is the highest and Opti Bond Sold is the lowest.
ABSTRACT
Objective:To evaluate the effects of primers on the bonding of an silicone elastomer to acrylic resin.Methods:Acrylic resin specimens were divided into eight groups.Six new primers and Cosmesil G611 primer were applied to the acrylic resin surfaces respectively.Untreated group was used as control.The shear bond strengths between silicone elastomer and acrylic resin were determined.D primer were measured by Forier transform infrared spectroscopy,and the bands were analyzed using spectrum method.Results:The experiment group with different concentration of ?-MPS showed different shear bond strengths between silicone elastomer and acrylic resin.Type D primer showed 2.20 MPa shear bond strength,which was significantly higher than that of other groups.While 1.44 MPa for Cosmesil G611 primer was found,there was no bond strength for untreated group.Conclusion:The concentration of ?-MPS is relative to the shear bond strength and type D primer can give the highest shear bond strength.
ABSTRACT
Objective: To explore the preparation methods of nanomete r powder of ZrO 2 for dental application. Methods:Zirconia gel wa s dehydrated by heterogeneous azeotropic distillation process and n-butanol was used as azeotropic solvent. The properties of ultrafine powder obtained via dec ompression (process b), atmosphere pressure (process c) and direct ethanol-wash ing (process a) were studied. Results: After drying and calcini ng the gel, the ultrafine powder obtained from process a,b and c was about 25 n m,22 nm and 17 nm respectively. 3Y-TZP ceramic prepared with the three kinds of nanometer powder had bending strength of 660 MPa,710 MPa and 640 MPa; fracture toughness of 4.34 MPa?m 1/2 ,4.77 MPa?m 1/2 and 4.24 MPa?m 1/2 , respectively. Conclusion: By the heterogeneous azeotropic dis tillation process, zirconia ultrafine powder without hard agglomeration (d BE T=17 nm) can be obtained.
ABSTRACT
Objective: To investigate the effect of ceramic bovine bone (CBB) combined with hydrogel complex (CBB/HG), ?-tricalcium phosphate (?-TCP) combined with hydrogel complex(?-TCP/HG) on the osteogenesis of bone marrow stromal cells (MSCs) in vitro. Methods: MSCs(induced by 50 mg/L ascorbic acid,10 -8 mol/L dexamethasone and 0.01 mol/L ?-sodium glycerylphosphate) were cultured on CBB/HG , ?-TCP/HG,CBB and ?-TCP respectively. 5 and 10 days after set up, marrow stromal cell attachment and morphology were observed by scanning electronic microscope, the proliferation of the cells was evaluated by cell counting, Alkaline phosphatase(ALP) activity was tested,typeⅠcollagen synthesis were examined by immunohistochemistry stainning. Results: On day 5 and 10 the marrow stromal cells on CBB/HG and on ?-TCP/HG were significantly more than those on CBB or ?-TCP. TypeⅠcollagen synthesis and ALP activity of the cells on CBB/HG and ?-TCP /HG were not different but significantly higher than those on CBB or ?-TCP. Conclusion: CBB/HG and ?-TCP /HG may stimulate bone marrow stromal cell proliferation, differentiation and extracellular matrix synthesis.
ABSTRACT
Objective To develop a new kind of auto thermal cycling machine,which can be used to test the chronic fatigue properties of dental materials.Methods The machine was designed and manufactured,the working parameters were set according to national standards YY/T0112-93.Results After 6-months testing,the machine ran stably,the precision of working parameters was consistent and reached the national standard.Conclusion The machine can be a credible device for the testing of dental materials.