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 investigate the role of phosphatidylinositol 3-kinase (PI3K)/protein-serine-threonine kinases(Akt) signal transduction pathway in EphB receptor-mediated neuropathic pain in rats.Methods Forty-eight pathogen-free male SD rats aged 2-3 months weighing 150-180 g were randomly divided into 6 groups (n =8 each):groups sham operation (groups S1 and S2 ); groups chronic constrictive injury (CCI) (groups C1and C2 ) and groups EphBI-Fc (EphB receptor antagonist) + CCI (groups E1 and E2 ).Neuropathic pain was induced by placing 4 ligatures on left sciatic nerve at 1 mm intervals with 5-0 silk thread in groups C1,C2,E1 and E2.EphBI-Fc 0.5 μg in 5 μl normal saline was injected intrathecally 1 h before operation and at 1 and 2 d after operation (group E1 ) or on 5th day after operation (group E2).Normal saline 5 μl was injected intrathecally instead of EphBI-Fc 1 h before operation and at 1 and 2 days after operation (groups S1 and C1 ) or on 5th day after operation (groups S2 and C2 ).Pain withdrawal latency to noxious thermal stimulation (PWL) and pain withdrawal threshold to noxious mechanical stimulation (PWT) were measured before operation and at 1,3 and 5 d after operation.The animals were sacrificed at 5 d after operation after measurement of pain threshold.The lumbar segment of spinal cord (L4-6) was removed for determination of c-Fos,PI3K and phosphorylated Akt(p-Akt) expression.Results CCI significantly reduced PWL and PWT and up-regulated spinal c-Fos,PI3K and p-Akt expression in groups C1 and C2 as compared with groups S1 and S2.EphB1-Fc significantly decreased hyperalgesia and the upregulated spinal Fos,PI3K and p-Akt protein expression induced by CCI in groups E1 and E2 as compared with groups C1 and C2.Conclusion Spinal EphB receptor is involved in the development and maintenance of neuropathic pain through PI3K/Akt signal transduction pathway.
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 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: The purpose of this study is to investigatc the effects of the HAB/DBP composite in the restoration of restoring bone defects. Methods: The HAB/DBP composiite, HAB or DMB samples were grafted into the defects of rabbit's radii respectively and the samples were examined 2 weeks, 4 weeks, 8 weeks and 12 weeks after operation with general, radiological and histological observations respectively.Results: In the group of HAB/DBP composssite implanted area , mesenchymal cells and new bone stromas were observed assembling 2 weeks after the operation. New bone formation and bone trabeculation were found 4 weeks after transplantation. A lot of bone trabeculation and composite degrad ation were observed 8 weeks after operation. The defects were completely restored 12 weeks after the surgery.Conclusion: The HAB/DBP composite has the properties of osteoconduction and osteoinduction, and its osteogenic ability is similar to that of DMB.
ABSTRACT
0.05),and both of them were significantly lower than that of Clearfil DC Core in the coranal region(P
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.
ABSTRACT
The role of oxygen free radical's scavenger systems in the protection of cellular damages during total ischemia and reperfusion was studied in isolated Langendorff perfused rat hearts. The changes of myocardial enzymes(superoxide dismutase and glutathione peroxidase)and ultrastructure were used as indexes of cellular damage. The hearts were perfused in total ischemia for 40, 60, 80 min and reperfusion for an additional 20 min resulted in a decrease in both SOD and GSH-Px activity. SOD activty decreased continuously when the hearts perfused in total ischemia for periods of 40 and 60min were reperfused for an additional 20min. GSH-Px activity was much lower during reperfusion(total ischemia 40 min and reperfusion 20 min) than that during total ischemia(60 min) and ultrastrcture damage in this phase was the most severe. Both sodium selenite(Na_2SeO_3 3?10~(-8)M)and DS-182(4?10~(-6)g/ml, one of the effective components of salvia miltiorrhiza bunge) could increase the activity in both SOD and GSH-Px and protect the ultrastreture of myocardium from reperfusion injury. The DS-182 is more effective than Na_2SeO_3 in the protection of myocardium from reperfusion damage.