Effect of base curve aspheric orthokeratology lens on ocular surface of adolescents with myopia and moderate to high astigmatism / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To explore the effect of base curve aspheric orthokeratology lens in the treatment of adolescents with myopia and moderate to high astigmatism, and its influence on ocular surface morphology and tears.METHODS:A total of 232 adolescents(464 eyes)with myopia and moderate to high astigmatism treated in the hospital from December 2018 to March 2020 were selected as the research subjects. They were randomly divided into control group(116 patients, 232 eyes)and observation group(116 patients, 232 eyes). The control group was treated with base curve spheric orthokeratology lens, while the observation group was treated with base curve aspheric orthokeratology lens. Comparison was made between the two groups in terms of the correction effect, objective visual quality, ocular surface morphology, tears related indicators before and after wearing the lenses, and the incidence of complications after wearing the lenses for 12mo.RESULTS:After wearing the lenses, the uncorrected visual acuity(UCVA)and diopter of the two groups were significantly improved. The UCVA and diopter of the observation group were significantly better than those of the control group(all P<0.05). After wearing the lenses, the whole-eye and corneal coma, spherical aberrations and high-order aberrations were significantly increased, while Strehl ratio and modulation transfer function were decreased in the two groups. Trefoil aberrations was significantly increased(all P<0.05). These indicators in the observation group were better than those in the control group(all P<0.05). After wearing the lenses, the epithelium fluorescence staining scores, ocular surface disease index(OSDI)scores were significantly decreased in the two groups(P<0.05), but there was no statistically significant difference between the two groups(P>0.05); The noninvasive tear breakup time(NI-BUT)of the two groups were significantly decreased after wearing the lenses(P<0.05), but there was no statistically significant difference between the two groups(P>0.05). The Schirmer Ⅰ test and tear meniscus height of the two groups showed no statistically significant difference before and after wearing the lenses(P>0.05). The incidence rates of complications in the observation group and the control group after wearing the lenses were close(6.9% vs 6.0%, P >0.05).CONCLUSION:Base curve aspheric orthokeratology lens is superior to base curve spheric orthokeratology lens in the treatment of adolescents with myopia and moderate to high astigmatism in terms of correction effect and objective visual quality. The two lenses have similar influence on ocular surface morphology and tears.

Application prospect of silicon nitride ceramics in dental implants / 口腔疾病防治

@#Silicon nitride has high fracture toughness and compressive strength similar to human bone. It meets the basic mechanical requirements of implants and has good biocompatibility. The micrometer/nanometer morphology surface characteristics of silicon nitride give it good osteogenic activity and antibacterial properties, which are helpful to reduce the incidence of periimplant inflammation. Therefore, silicon nitride has good application potential in dental implants. In orthopedics, silicon nitride implants have been used in spine repair and joint implantation. However, there is a lack of research on silicon nitride as dental implant material. The evaluation of the osteogenic and antibacterial properties of silicon nitride bioceramics prepared using different sintering additives and sintering processes, the antibacterial properties of silicon nitride on different dominant oral pathogens, and the osteogenic activity and antibacterial properties of silicon nitride materials implanted into the jaw need to be further studied. Combined with the latest research results at home and abroad, this review discusses the application potential of silicon nitride materials in dentistry.

Research progress on tetrabutylammonium dihydrogen trifluoride as a substitute for hydrofluoric acid used for porcelain surface treatment / 口腔疾病防治

@#Hydrofluoric acid is a common surface treatment agent for glass ceramic restorations before bonding. However, the use of hydrofluoric acid has a high safety risk, so the search for hydrofluoric acid substitutes has been a research hotspot. Tetrabutylammonium dihydrogen trifluoride is a kind of fluoride, whose chemical activity is lower than that of hydrofluoric acid, so it’s safer, and the surface morphology changes on glass ceramics caused by it are smaller and more superficial. At present, the vast majority of laboratory studies and clinical case reports indicate that the mechanical strength and bonding strength of glass ceramics treated with tetrabutylammonium dihydrogen trifluoride can meet the clinical requirements. In the future, according to the research results, the performance of porcelain surface treatment agents containing tetrabutylammonium dihydrogen trifluoride can be further improved, and more hydrofluoric acid substitutes may be developed. In this review, the research progress of tetrabutylammonium dihydrogen trifluoride as a substitute for hydrofluoric acid is reviewed in terms of the influence of the surface morphology, mechanical strength, and bonding strength of glass ceramics.

Effects of changes in surface morphology of bone cement spacer on the expression of bone growth factor in induced membrane / 中国组织工程研究

BACKGROUND: At present, scholars at home and abroad try to promote the growth of bone graft by changing the types and morphology of implant materials, and improving the thickness and smoothness of induced membrane. OBJECTIVE; To compare the degree of vascularization and the expression of some osteogenic factors in the polymethylmethacrylate bone cement membrane with different surface roughness degrees at different femoral bone defects in rats. METHODS: Forty-eight male Sprague-Dawley rats (purchased from the Experimental Animal Center of Guangzhou University of Chinese Medicine) were used to establish rat models of critical-size femur defect. These rat modes were then randomly divided into groups A, B, C and D. Polymethylmethacrylate bone cement occupiers with surface roughness 0.05). Immunohistochemical staining revealed that the positive expression of bone morphogenetic protein 2, transforming growth factor (31 and vascular endothelial growth factor protein was similar among four groups (P>0.05). These findings suggest that the change of surface roughness of bone cement has no significant effect on the histomorphological structure of induced membrane and the expression of bone morphogenetic protein 2, transforming growth factor pi and vascular endothelial growth factor in induced membrane at 6 weeks after implantation of bone cement spacer.

Study on the mechanical properties of sutures in the process of suturing / 生物医学工程学杂志

Suture broken, knot slipping and tissue tearing are the main reasons of wound closure failure in clinical operation. Based on this, we simulated the suturing and healing operation by using a biological materials testing machine and investigated the tensile properties before and after knotting, relaxation property and friction property of three common sutures: silk, polyglactin 910 and polypropylene. Results show that the tensile property decreased after knotting. The tensile strength of polyglactin 910 and elongation of polypropylene were the largest. During the relaxation process, the sutures relaxed the most in the first 2 hours. The relaxation from less to more was: polyglactin 910, silk and polypropylene. Coating or monofilament could obviously reduce the surface roughness of sutures, and thus reduce the friction force of the suture-suture interface. The friction force of the suture-suture interface increased with the increasing load but did no change with the increasing velocity. The results can provide an important theoretical basis for the optimizations of suture design and knotting operation.

The effects of different Er: YAG laser parameters combined with dole fluorine on dentinal tubules / 口腔疾病防治

Objective@# To explore the effects of Er: YAG lasers with different pulse energies and of Er: YAG lasers combined with Duraphat on dentine surface morphology and the dentinal tubule exposure rate, thereby providing a theoretical basis and parameters for clinically treating dentine hypersensitivity with Er: YAG lasers.@*Methods @# Dentinal tubule exposure models were divided into five groups, namely, group A (single Er: YAG laser exposure), group B (Duraphat+ Er: YAG laser), and group C (Er: YAG laser+Duraphat), which were exposed to 6 levels of pulse energy (80 mJ/P- 250 mJ/P), and experimental control group D (Duraphat group) and blank control group E. Scanning electron microscopy was used to observe dentine surface morphology and dentinal tubule closure in these groups, and Image-Pro Plus 6.0 software was used for image analysis to measure the exposure rates of the five groups of dentinal tubules.@*Results@#The dentinal tubule exposure rates for the A-D groups were significantly lower than that of the E group (P < 0.001); when the Er: YAG laser pulse energy was less than 250 mJ/P, the dentinal tubule exposure rates for the A-C groups were all lower than that of the D group, but when the pulse energy was higher than 250 mJ/P, the dentinal tubule exposure rates for the A-C groups were higher than that of the D group, showing significant differences (P < 0.001); under the same handling method, when the pulse energy was 80~200 mJ/P, the dentinal tubule exposure rate decreased as the pulse energy increased. If the pulse energy reached 250 mJ/P, the exposure rate of the dentinal tubules increased instead. There were apparently no significant differences between 80 mJ/P, 100 mJ/P, 160 mJ/P and 200 mJ/P in the A and C groups or between 80 mJ/P and 100 mJ/P in the B group (P > 0.05), while significant differences existed among the other groups (P< 0.05). Under the same pulse energy, the dentinal tubule exposure rates were A group > C group >B group; under different pulse energies, there existed significant differences between the A and B groups (P < 0.05); when the pulse energy was 120~250 mJ/P, there were significant differences between the B and C groups (P < 0.05), while there were no significant differences among other groups (P＜0.05).@*Conclusion@#Er: YAG lasers can close the dentinal tubules and play a cooperative role if combined with Duraphat; the effects of laser exposure are better if fluorine is applied beforehand; and dentinal tubule closure is positively correlated with the pulse energy of Er: YAG lasers within a certain energy scope, but when the pulse energy reaches 200 mJ/P, the dentine surface is excessively fused and injured.

Characterization of Fluorotic Enamel After Microabrasion and Desensitizing Agent

ntroduction. Enamel microabrasion is a procedure used for removing a superficial layer of enamel that has some alteration of color and/or texture caused by dental fluorosis. The purpose of this study was to compare the microhardness and micromorphology of the fluorotic enamel surface after microabrasion with 6.6% hydrochloric acid and silica or 18% hydrochloric acid and evaluate the effect of desensitizing agent exposure on the treated enamel. Materials and Methods. Twenty anterior teeth with moderate fluorosis were divided into two groups: 1) Perla-Dent® group and 2) Opalustre® group. Each buccal surface of incisors was sectioned to obtain samples 3x3 mm. The samples were then mounted in acrylic blocks. The enamel surface of the blocks was polished, after the microabrasion materials and desensitizing agent were applied according to the manufacturer's instructions. All samples were analyzed by Vickers microhardness tester and scanning electron microscopy (SEM). Results. Both experimental groups presented a decrease in the microhardness values, with statistically significant differences (p<0.0001) when comparing the baseline and after treatments values. To compare the microhardness values after both microabrasion and desensitizing treatment in the study groups, it was observed that the Perla-Dent® group obtained lower values than the Opalescence® group with a statistically significant difference (p<0.0001). The representative images of study groups in SEM showed the enamel surface morphology after Perla-Dent® treatment more irregular and a very marked relief than that observed in enamel surface morphology after Opalustre® treatment. Conclusion. The surface of the enamel was more affected with Perla-Dent® treatment than with Opalustre® treatment and the placement of UltraEz® agent does not recover its baseline microhardness.

ntroducción. La microabrasión del esmalte es un procedimiento usado para remover la capa superficial de esmalte que tiene alguna alteración de color y / o textura causada por la fluorosis dental. El objetivo de este estudio fue comparar la microdureza y micromorfología de la superficie del esmalte fluorado después de microabrasión con ácido clorhídrico al 6,6% y sílice ó 18% de ácido clorhídrico y evaluar el efecto de la exposición del agente desensibilizante sobre el esmalte tratado. Materiales y métodos. 20 dientes anteriores con fluorosis moderada se dividieron en dos grupos: 1) grupo PerlaDent® y 2) grupo Opalustre®. La superficie bucal se seccionó para obtener muestras de 3x3 mm. Las muestras se montaron luego en bloques acrílicos. La superficie del esmalte de los bloques fue pulida, y posteriormente los materiales de microabrasión y el agente desensibilizante se aplicaron de acuerdo con las instrucciones del fabricante. Todas las muestras fueron analizadas por medio de microdureza Vickers y Microscopía electrónica de barrido (MEB). Resultados. Ambos grupos experimentales presentaron disminución de los valores de microdureza con diferencias estadísticamente significativas (p<0.0001) al comparar los valores de antes y después de los tratamientos. Al comparar los valores de microdureza después del tratamiento de microabrasión y desensibilizante en los grupos de estudio, se observó que el grupo Perla-Dent® obtuvo valores más bajos que el grupo Opalustre® con diferencia estadísticamente significativa (p<0.0001). Las imágenes representativas de los grupos de estudio en MEB mostraron la morfología de la superficie del esmalte después del tratamiento con Perla-Dent® más irregular y con un relieve más marcado que el observado en la superficie del esmalte después del tratamiento con Opalustre®. Conclusión. La superficie del esmalte se presentó más afectada posterior al tratamiento con Perla-Dent® que con Opalustre® y la colocación del agente UltraEz® no logró recuperar el grado de microdureza basal.

Electrochemical Characteristics of Nanotubular Ti-25Nb-xZr Ternary Alloys for Dental Implant Materials

PURPOSE: The purpose of this study was to investigate the electrochemical characteristics of nanotubular Ti-25Nb-xZr ternary alloys for dental implant materials. MATERIALS AND METHODS: Ti-25Nb-xZr alloys with different Zr contents (0, 3, 7, and 15 wt.%) were manufactured using commercially pure titanium (CP-Ti), niobium (Nb), and zirconium (Zr) (99.95 wt.% purity). The alloys were prepared by arc melting in argon (Ar) atmosphere. The Ti-25Nb-xZr alloys were homogenized in Ar atmosphere at 1,000℃ for 12 hours followed by quenching into ice water. The microstructure of the Ti-25Nb-xZr alloys was examined by a field emission scanning electron microscope. The phases in the alloys were identified by an X-ray diffractometer. The chemical composition of the nanotube-formed surfaces was determined by energy-dispersive X-ray spectroscopy. Selforganized TiO₂ was prepared by electrochemical oxidation of the samples in a 1.0 M H₃PO₄+0.8 wt.% NaF electrolyte. The anodization potential was 30 V and time was 1 hour by DC supplier. Surface wettability was evaluated for both the metallographically polished and nanotube-formed surfaces using a contact-angle goniometer. The corrosion properties of the specimens were investigated using a 0.9 wt.% aqueous solution of NaCl at 36℃±5℃ using a potentiodynamic polarization test. RESULT: Needle-like structure of Ti-25Nb-xZr alloys was transform to equiaxed structure as Zr content increased. Nanotube formed on Ti-25Nb-xZr alloys show two sizes of nanotube structure. The diameters of the large tubes decreased and small tubes increased as Zr content increased. The lower contact angles for nanotube formed Ti-25NbxZr alloys surfaces showed compare to non-nanotube formed surface. The corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface showed longer the passive regions compared to non-treatment surface. CONCLUSION: It is confirmed that corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface has longer passive region compared to without treatment surface.

Preparation and properties of polydopamine coating on the surface of C/C composites / 军事医学

Objective Carbon/carbon ( C/C) composites are a potential material for bone repair .To improve the hydrophilicity and biological activity of C/C composites , polydopamine coating was prepared on the surface of C /C composites.Methods By changing the coating time and coating environment ( oxygen or air atmosphere ), a series of polydopamine coating samples were prepared . The water contact angle test , scanning electron microscope , energy dispersive spectrometer , atomic force microscope and protein adsorption test were used to characterize the properties of different samples.Then, the data were analyzed to optimize preparation conditions .Results When the concentration of dopamine was 2.0 g/L,and the coating time was 30 min (oxygen atmosphere) +11.5 h (air atmosphere), the water contact angle was decreased from 64.0°(blank sample) to 25.9°, suggesting that the hydrophilicity was improved greatly . The results of the scanning electron microscope , energy dispersive spectrometer and atomic force microscope showed that the coating was uniform and dense .The amount of protein adsorption per sample was 0.2817 mg.Conclusion The polydopamine coating on the C/C composites improves its hydrophilicity and biological activity , which indicates that the polydopamine coated C/C composites will be a new potential material for bone tissue repair .

Relationship Between Surface Morphology and Performance of a Spirally Hierarchical Structure-based Electrochemical Glucose Sensor / 分析化学

Zinc oxide nanowires were hydrothermally synthesized on the surface of an Au cylindrical spiral formed by manually spiraling an Au fiber around an optical fiber core, glucose oxidase was immobilized on these nanowires by physical adsorption, and then a spirally hierarchical structure-based glucose enzymatic electrode was obtained. The surface morphologies of the spirally hierarchical structures and corresponding enzymatic electrodes were extracted, and the electrochemical performances of the enzymatic electrodes were characterized. It was concluded that the synthesizing parameters of zinc oxide nanowires significantly affected the surface morphologies and glucose oxidase immobilization on the spirally hierarchical structures, and further the performances of related glucose sensors. With Zn2﹢concentration of the growth solution set at 25 mmol/L, the roughness of surface morphology was determined to be 0. 10 μm and correlation length 0. 29 μm, resulting in a better immobilization of glucose oxidase upon zinc oxide nanowires. In this case the sensitivity of the glucose sensor was determined to be 2. 15 μA/(mmol/L·cm2), the linear range was 0-4. 50 mmol/L, the low detection limit was 9. 20 μmol/L and Michaelis-Menten constant was 3. 68 mmol/L. The results not only benefit the batch production of the spirally hierarchical structure-based enzymatic electrodes, but also significantly improve the performances of the glucose sensors.

Influence of fluoride-containing acidic artificial saliva on the mechanical properties of Nickel-Titanium orthodontics wires.

Objective: This study aimed to investigate the influence of fluoride and an acidic environment on the mechanical properties of NiTi orthodontic wires (NiTiW) in artificial saliva. Design: A prospective laboratory investigation. Setting: Department of Stomatology, First Affiliated Hospital, Zhejiang University, Hangzhou, China. Materials and Methods: Commercial, round 0.016-inch NiTiW were immersed in 0% or 0.05% Natrium-Fluoride-containing artificial saliva at a pH of 4 or 6 for one or three days, respectively. NiTiW were examined with a three-point bending test, Vickers' microhardness tests and surface morphology observation (SEM). Results: A pH of 4 increased microhardness and decreased the three-point bending strength significantly (P≤0.05), whereas immersion time and fluoride concentration had no significant influence on the microhardness or on the three-point bending strength (P>0.05). When examining the test group NiTiWs after three days of immersion at a pH of 4 the SEM revealed a rough surface morphology, a damaged oxide layer and signs of corrosion. Conclusions: The most influential factor for decreasing the unloading force and increasing the hardness seems to be the pH value, whereas immersion time and NaF addition do not have a major influence.

Effect of different sterilization methods on the surface morphology of PPDO-hybrid-PLGA nanofiber scaffold and attachments of PC12 cell

OBJECTIVES: the effect of different sterilization methods on the surface morphology of PPDO-hybrid-PLGA nanofiber scaffold and attachments of PC12 cell were investigated. METHODS: Poly (p-dioxone)-hybrid-Poly (lactide-glycolide) (PPDO-hybrid-PLGA) nanofiber scaffold, fabricated in a tube form with 1.5 mm internal diameter, 0.2 mm thickness and 5 mm length, was prepared using electrospinning method. To study the surface morphology using SEM, The study group and control group in respective were; Control:Non-sterilized scaffold, Group I:scaffold sterilized with 70% Alcohol, Group II: scaffold sterilized with Ethylene Oxide at 65 degrees C, and Group III: scaffold sterilized with Ethylene Oxide at 37 degrees C. To investigate viability of the PC12 cell on the scaffold, The study group and control group in respective were; Control: sterilized with 70% Alcohol, Group I: sterilized with Ethylene Oxide at 65 degrees C, and Group II: sterilized with Ethylene Oxide at 37 degrees C. RESULTS: 1. The surface morphology was slightly changed in Group I, II and GroupIII, compared with control. 2. The attachment of PC12 cells in Group I, II was not higher than in control DISCUSSION: The attachment of PC12 cell is not influenced by different sterilization methods.

Effects of acid etching times on enamel surface morphology and shear bond strength of orthodontic attachment to enamel / 대한치과교정학회지

The porpuse of this in vito study was to evaluate the effects of different acid etching times on the enamel srface morphology, shear bond strength and debinding failure mode of orthodontic attachment. Ninety six extracted human mandibular premolars were divided into eight groups of twelve teeth. The buccal surfaces were etched with 37% phosphoric acid 5, 10, 15, 30, 45, 60, 90 and 120 seconds, respectively. Two teeth from each group were used for scanning electron mocroscope examination. On the etched buccal aurfaces of remaining teeth, orthodontic attachments(lingual buttons) were bonded with light cured orthodontic adhesive. Twenty four hours after bonding, a Instron universal testing machine was used to determine shear bond strength of orhtodontic attachment to enamel. After debonding, bases of orthodontic attachments and enamel surfaces were examined under stereoscopic microscope to determine failure mode. Statistical analysis of the data was carried out with one way ANOVA and Duncan';s multiple range test. The results were as follows : 1. There was no statistically significant difference in shear bond strengths between the various etching times(p<0.05). 2. The failure modes of orthodontic attachments had some differences. In 5, 10 and 15 seconds etching groups, the percentage of adhesive/ enamel interface failure was higher than that of adhesive/attachment interface failure. On the contrary, 30, 45, 60, 90 and 120 seconds etching groups, the recults were reersed. 3. The etching parerns of enmel surfaces had a great variation. So, we could not find any correlation between etching pattern and bond strength. 4. The findings in this study indicate that in vito reduction of the etching time to 5 seconds maintains clinically acceptable bond strength. However, further study is required to determine the cause of failure mode in 5, 10 and 15 seconds groups.