Endodontic treatment with the use of dental operating microscope is a difficult part in teaching. We have applied cone beam computed tomography (CBCT) guided technology for microendodontic training of dental students who are in their 5th year of the 7 year course to pursue their master's degree. The process of teaching is constituted of preoperative analysis, operation guided by CBCT, postoperative therapeutic evaluation. And the result of teaching quality is acquired by questionnaire. This method improved student's capacities of analysis and solution in intractable cases and greatly motivated students' participa-tion, as well as promoting their learning efficiency. The application of this technique in teaching process compensates the deficiency of traditional teaching method by shaking off the fetters of experience-dependent pattern in the endodontic microscope teaching, and is worth to be popularized in endodontic education.

ObjectiveTo study the effect of menbranous milkvetch root parenteral solution on insulin resistance of gerontism cerebral infarction in recovery stage.Methods66 patients with gerontism cerebral infarction were randomly divided into therapy group(33 cases) which received membranous milkvetch root parenteral solution and control group(33 cases).Both groups adopted routine treatment at the same time, the period was 20 days. Insulin(Ins), free blood sugar(FBS), total cholesterol(CH), triglyceride(TG), hemorheology and insulin resistance(indicating by index of insulin sensitive) of blood on empty stomach were evalutated before and after treatment. ResultsAfter treatment there was decrease in CH, FBS, FINS in therapy group than in control group(P<0.01 or P<0.05); the clinical effect in therapy group was better than in control group(P<0.01).ConclusionMembranous milkvetch root parenteral solution can significantly decrease insulin resistance, blood lipin, blood viscosity in recovery stage of gerontism cerebral infarction, and improve clinical efficiency.

OBJECTIVETo investigate the effect of epigallocatechin-3-gallate (EGCG) on biomodification of demineralized dentine substrate, in its permeability, hydrophobicity, and inhibition ability to collagen enzymatic degradation.

METHODSThe dentine substrates were treated with simulated pulpal pressure created by mixtures of 0.02%, 0.1% EGCG/bovine serum albumin (BSA) in acidic environment (pH4.4) for 48 h. A fluid-transport model was used to measure the fluid permeability through demineralized dentine substrate. Positive replicas of dentine substrate were fabricated before and after being subjected to acidic environment for scanning electron microscope (SEM) examination. The blank group contained no EGCG and the positive group were treated with Gluma desensitizer. Static contact angle measurements on demineralized dentin and 0.1% EGCG primed dentin were performed by contact angle analyzer. The priming time were 60 s, 120 s, 0.5 h, 1 h. Dentine specimens bonded with Adper single bond 2 were subjected to 100 mg/L collagenase and observed under SEM. Resin-bonded specimens (with 0.02%, 0.1%, 0.5% EGCG priming, or without EGCG priming) were created for micro-tensile bond strength evaluation (MTBS). Resin-bonded specimens after thermol cycling were created for MTBS evaluation.

RESULTSThe fluid permeability in the blank control group increased ([151.3±22.3]%), the fluid permeability in 0.1% EGCG/BSA group decreased ([23.7±6.3]%). Compared to the blank control group, the contact angle of 120 s, 0.5 h, 1 h groups increased by 31.0%, 53.5%, 57.8% in deep dentin and 37.4%, 59.3%, 62.4% in shallow dentin. The SEM examination showed that 0.1% and 0.5% EGCG priming for 120 s significantly increased dentin collagen's resistance to collagenase. The immediate MTBS of 0.1% and 0.5% EGCG groups were (29.4±4.8) and (19.8± 4.9) MPa. After thermol cycling, the MTBS of 0.1% and 0.5% EGCG groups were (19.9±5.1) and (15.3± 6.3) MPa.

CONCLUSIONSUnder acidic environment (pH4.4), the 0.1% EGCG can reduce dentine permeability under acidic environment. The 0.1% EGCG can increase hydrophobicity of dentin substrate, and strengthen dentin substrate's resistance to collagenase hydrolysis, thus increased the resin-dentin bonding durability.

Acid Etching, Dental ; Catechin ; analogs & derivatives ; pharmacology ; Collagen ; chemistry ; drug effects ; Collagenases ; pharmacology ; Composite Resins ; Dental Bonding ; Dental Cements ; Dental Pulp ; Dentin ; chemistry ; drug effects ; Dentin Permeability ; drug effects ; Dentin-Bonding Agents ; Glutaral ; pharmacology ; Hydrogen-Ion Concentration ; Hydrolysis ; Methacrylates ; pharmacology ; Microscopy, Electron, Scanning ; Pressure ; Resin Cements ; Serum Albumin, Bovine ; pharmacology ; Tensile Strength ; Time Factors

Objective: To investigate the antibacterial activity to Streptococcus mutans of a nisin-containing single-bond universal adhesive. Methods: Nisin was mixed into the bonding agent to produce concentrations ranging from 0.01 g/mL to 0.05 g/mL for the experiments, and adhesive without nisin was used as the control. Dentin-resin specimens were prepared for the microtensile strength test to evaluate changes in the bonding strength. The proper concentrations were selected for more tests. ① An agar diffusion test was applied with filter paper to detect the release of nisin, and adhesive without nisin was used as the negative control, 0.01 g/mL Nisin aqueous solution was used as the positive control. ② Solidification; resin adhesive specimens were prepared for the assessment of direct contact inhibition activity. ③ Confocal laser scanning microscopy was used to examine the effect of the adhesive on the biological film activity and the ability of Streptococcus mutans to produce extracellular polysaccharides. Results : Nisin did not significantly reduce the bond strength of the modified adhesive at 0.01-0.03 g/mL (P < 0.05); these concentrations were selected for the subsequent antibiosis experiment. Rings could not be observed in the agar diffusion test, except for in the group of adhesive modified with 0.01-0.03 g/mL nisin. Resin adhesive with 0.01-0.03 g/mL nisin could significantly inhibit the proliferation of Streptococcus mutans on the surface of the specimens. The confocal laser scanning microscopy results indicate that only the adhesive resin modified with nisin could reduce the bacteria in the biofilm and the production of extracellular polysaccharides. Conclusion Single-bond universal adhesive with 0.01-0.03 g/mL nisin can inhibit the growth of Streptococcus mutans and its biofilms on the bonding interface, as well as decrease the production of extracellular polysaccharides, and thus has the potential to decrease the occurrence of secondary caries.

OBJECTIVETo investigate the functions of sodium tripolyphosphate (STTP) and polyacrylic acid (PAA) in the process of collagen biomimetic mineralization. This would allow future applications to other collagen matrices such as bone collagen or 3-D collagen scaffolds.

METHODSGlass cover slips and transmission electron microscopy (TEM) grids were coated with reconstituted typeIcollagen fibrils. Mineralization of the reconstituted collagens was demonstrated with scanning electron microscopy (SEM) and TEM using a Portland cement-containing resin composite and a phosphate-containing fluid in the presence of PAA and STTP. The rest were immersed in a biomimetic remineralization medium without PAA and/or STTP (control).

RESULTSIn the presence of PAA and STTP in the mineralization medium, intrafibrillar mineralization based on the non-classical crystallisation pathway could be identified. Mineral phases were evident within the collagen fibrils as early as 12 h after the initially-formed amorphous calcium phosphate nanoprecursors were transformed into apatite nanocrystals. Collagens at 72 h were heavily mineralized with periodically arranged intrafibrillar apatite platelets. Conversely, only large mineral spheres with no preferred association with collagen fibrils were observed in the absence of biomimetic analogues in the medium (control).

CONCLUSIONSIntrafibrillar apatite deposition can be achieved via biomimetic mineralization system containing PAA and STTP when amorphous calcium phosphate precursor is stabilized.

Acrylic Resins ; chemistry ; Apatites ; Biomimetics ; Bone and Bones ; Calcium Phosphates ; Collagen ; Collagen Type I ; chemistry ; Composite Resins ; Humans ; Microscopy, Electron, Transmission ; Minerals ; Phosphates ; Polyphosphates ; chemistry ; Tissue Scaffolds

OBJECTIVETo evaluate the sealing properties of three resin- based sealers, EndoREZ, RealSEAL and RealSEAL SE.

METHODSForthy-eight extracted human anterior teeth with single root and canal were prepared using ProTaper files with crown-down technique to F3. The teeth were filled with three sealer respectively with hot gutta- percha vertical condensation technique simulating the clinical situation. Leakage quantity was detected using computerized fluid filtration meter with 10 samples in each group. The cross section morphology of apical parts of roots of 5 mm was observed with scanning electron microscope and transmission electron microscope in 3 samples of each group, respectively.

RESULTSThe leakage quantity of EndoREZ, RealSEAL and RealSEAL SE were (2.61±0.60), (1.43±0.11) and (1.76±0.18) µl/min, respectively. The gaps between the the sealer and the canal wall were increased in in order of RealSEAL, RealSEAL SE and EndoREZ. No obvious demineralized dentin under EndoREZ and the smear layer was not completed removed. The partly demineralized dentin was observed under RealSEAL and the smear layer was totally removed. The partly demineralized dentin was seen under RealSEAL SE and the majority of smear layer was removed.

CONCLUSIONSAmong the three resin- based sealers, RealSEAL has the best sealing properties, followed by RealSEAL SE and EndoREZ.

Composite Resins ; Dental Leakage ; Dentin ; Epoxy Resins ; Gutta-Percha ; Humans ; Pit and Fissure Sealants ; Root Canal Filling Materials ; Tooth ; Tooth Root