Soil ecological effect of attapulgite and its application prospect in ecological planting of Chinese materia medica / 中国中药杂志

The long-term and extensive use of chemical fertilizers and pesticides in the cultivation of Chinese materia medica has resulted in serious soil ecological and environmental problems such as secondary salinization, soil consolidation, soil acidification, continuous cropping obstacles, micro-ecological imbalance, and serious soil pests and diseases in the production areas of Chinese materia medica. Therefore, promoting the ecological planting of Chinese materia medica is the only way for the production of Chinese materia medica. Attapulgite(ATP) is a kind of water-rich magnesium-rich aluminosilicate clay mineral with layered and chain structure. It has abundant reserves in China, possesses nano-material properties, strong adsorption and ion exchange properties, and has huge high value utilization space. ATP and its functional products have the potential of water and fertilizer conservation, regulating soil structure and micro-ecology, and are widely used in ecological planting of Chinese materia medica. This paper reviews the resource distribution, structural characteristics, the research and application progress in soil ecological effects of ATP, and prospects the application prospects of it in the ecological planting of Chinese materia medica.

Protocolo de cementación indirecta de aparatología ortodóncica fija utilizando materiales de uso común / Indirect cementation protocol for fixed orthodontic appliances using commonly used materials

Introducción: La técnica de arco recto es una de las técnicas más utilizadas para la corrección de maloclusiones en ortodoncia; sin embargo, el éxito de la técnica radicará en la exactitud en que se posicionan los brackets. Este artículo presenta un protocolo de cementación indirecta, el cual, adicionalmente, permite una mayor accesibilidad a los materiales requeridos para este procedimiento. Objetivo: Presentar un protocolo efectivo y accesible de cementación indirecta. Material y métodos: Para este protocolo se ha utilizado materiales como resina de cementación de brackets (Transbond XT, 3M Unitek, EEUU), aislante de acrílico para separar los brackets del modelo de yeso y silicona líquida, utilizada habitualmente para autos (Kit Silicona, Johnson, Chile), para separar los brackets del soporte termoplástico, el cual fue realizado con silicona termofusible. Conclusión: El protocolo de cementación indirecta permite un buen posicionamiento de los brackets, reduciendo la posibilidad de reposicionar durante las fases de alineamiento y nivelado (AU)

Introduction: The straight arch technique is one of the most used techniques for the correction of malocclusions in orthodontics; however, the success of the technique will lie in the accuracy in which the brackets are positioned in the correct position. This article presents an indirect cementation protocol which additionally allows greater accessibility to the materials required for this procedure. Objective: Present an effective and accessible indirect cementation protocol. Material and methods: For this protocol, materials such as brace cementation resin (Transbond XT, 3M Unitek, USA), acrylic insulator have been used to separate the brackets from the gypsum and liquid silicone model, usually used for cars (Silicone Kit, Johnson, Chile), to separate the brackets from the thermoplastic support, which was made with hot melt silicone. Conclusion: The indirect cementation protocol allows a good positioning of the brackets, reducing the possibility of repositioning during the alignment and leveling phases (AU)

Use of silicon for skin and hair care: an approach of chemical forms available and efficacy

Abstract Silicon is the second most abundant element on Earth, and the third most abundant trace element in human body. It is present in water, plant and animal sources. On the skin, it is suggested that silicon is important for optimal collagen synthesis and activation of hydroxylating enzymes, improving skin strength and elasticity. Regarding hair benefits, it was suggested that a higher silicon content in the hair results in a lower rate of hair loss and increased brightness. For these beneficial effects, there is growing interest in scientific studies evaluating the efficacy and safety of using dietary supplements containing silicon. Its use aims at increasing blood levels of this element and improving the skin and its annexes appearance. There are different forms of silicon supplements available and the most important consideration to be made in order to select the best option is related to safety and bioavailability. Silicon supplements are widely used, though there is wide variation in silicon bioavailability, ranging from values below 1% up to values close to 50%, depending on the chemical form. Therefore, the aim of this study was to evaluate the scientific literature related to the different chemical forms of silicon supplements available and the limitations and recent progress in this field. According to reported studies, among the different chemical forms available, the orthosilicic acid (OSA) presents the higher bioavailability, whereas the others forms have absorption inversely proportional to the degree of polymerization. However, clinical studies evaluating safety and efficacy are still lacking.

Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

AbstractSome weaknesses of conventional glass ionomer cement (GIC) as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved.Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol%) of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitrorat dental pulp stem cells (rDPSCs) viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min) specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05) and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

Micromorphological evaluation of dentin treated with different desensitizing agents

The purpose of a desensitizing agent is a permanent coating or filling of dentin surface. Morphological analysis in vitro of this treated surface is essential to understand the interaction between desensitizing agent and hypersensitive dentin. The aim was to evaluate the morphology of four dentin surface treated with desensitizing agents. This was an in vitro laboratory study, where fifteen specimens from extracted human premolars were obtained. The enamel was removed to expose the dentin surface, polished with silicon carbide abrasive papers and etched with 6% citric acid for 2 min. The specimens were randomly divided into 5 groups: G1 - without treatment [control] [C], G2 - fluoride varnish [FV], G3 - potassium oxalate [PO], G4 - 2-step self-etching adhesive system [AS], G5 - diode laser [DL]. The specimens were cleaved in the lingualbuccal direction, prepared for analysis by Scanning Electron Microscope and the surface and interior of the dentinal tubules were observed at 1500 X magnification. In the control group, the dentin etching promoted smear layer removal and exposure of dentinal tubules. In the group of fluoride varnish, a film was observed on the surface, with plugs of varnish into tubules. In the group of oxalate, partial obliteration of the tubular entrances was observed. In the group of the adhesive system, the tubules were obstructed through the formation of hybrid layer and a physical barrier on the surface. In the group of the diode laser, dentin melting and solidification with partial occlusion of dentinal tubules were observed. All desensitizing agents evaluated demonstrated ability to modify the surface of dentin, with partial or total occlusion of dentinal tubules. Thus, it is suggested to do more clinical studies to verify the effectiveness of the findings

Shear bond strength of resin cement to an acid etched and a laser irradiated ceramic surface

PURPOSE: To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic. MATERIALS AND METHODS: Fifty-five ceramic blocks (5 mm x 5 mm x 2 mm) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at 37degrees C for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (alpha=0.05). RESULTS: Adhesion was significantly stronger in Group 2 (3.88 +/- 1.94 MPa) and Group 3 (3.65 +/- 1.87 MPa) than in Control group (1.95 +/- 1.06 MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 (3.59 +/- 1.19 MPa) and Control group. Shear bond strength was highest in Group 1 (8.42 +/- 1.86 MPa; P<.01). CONCLUSION: Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique.

Shear bond strength of three self-adhesive resin cements to dentin.

Context: The result of the studies concerning the bonding of self-adhesive resin cements to dentin is controversial. Aims: To assess in vitro shear bond strength (SBS) of three self-adhesive dual-cured resin cements to dentin compared to a currently used dual-cured resin cement, using SBS test. Settings and Design: The extant study is an experimental in vitro one on extracted human third molars dentin. Material and Methods: 40 intact human third molars were selected and randomly divided into 4 groups of 10. Buccal dentin surfaces were exposed perpendicular to the long axis and prepared with SiC papers. A translucent plastic ring, was placed over the dentin surfaces. Group I (Control group): After 15 s of etching and application of Excite DSC Bond (Ex), Variolink II (Var II) resin cement was injected into the plastic ring and was light cured for 40 s. Group II: RelyX Unicem (RX) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group III: Maxcem (Mc) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group IV: Multilink Sprint (MS) was injected into the plastic ring and after 30 s, was light cured for 40 s. After thermal cycling, SBS were measured with a universal testing machine. Statistical Analysis Used: Statistical computations were conducted according to Student's t-test. Results: The mean SBS and standard deviations (in parentheses) for groups I, II, III, and IV were 12.95 (2.64), 6.73 (0.79), 3.01 (0.90), 4.60 (0.75) MPa, respectively. Statistical analysis, revealed that: (1) the mean SBS of Var II were significantly higher than the other groups (P<0.05). (2) The mean SBS of Mc and MS were significantly lower than RX (P<0.05). (3) The mean SBS of Mc and MS did not show significant difference (P>0.05). Conclusion: Bond strength of three self-adhesive resin cements was significantly lower than the conventional total-etch resin cement. RX significantly performed better SBS than Mc and MS to dentin.

The effect of urea on the corrosion behavior of different dental alloys.

Objective: Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Materials and Methods: Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Results: Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. Conclusion: The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

Changes in surface roughness and color stability of two composites caused by different bleaching agents

The objective of this study was to evaluate the effect of two bleaching agents (10% and 35% hydrogen peroxide) on the color stability and surface roughness of two composites, one nanohybrid and one nanoparticle. Specimens were polished, aged, stained, bleached and polished again. The action of the bleaching agents on the composites was analyzed using a profilometer (surface roughness) and a spectrophotometer (color stability). The effect of polishing the composites on the surface roughness and the resumption of the composite color was also evaluated. The results were analyzed statistically by ANOVA and Tukey's test at 5% significance level. The analysis indicated that the nanohybrid composite was more affected by staining. The bleaching agents were not able to promote bleaching of either composite over the evaluation period. Surface polishing returned nanohybrid composite to its original color condition, which did not occur for the nanoparticle composite. Additionally, polishing did not return the surface roughness of either composite to its original value. It may be concluded that polishing surface after bleaching should not be the treatment of choice, as it was not possible to reverse the roughness of the composites to their original values, suggesting that a more extensive and irreversible degradation might have occurred.

O objetivo deste estudo foi avaliar o efeito de dois agentes clareadores (peróxido de hidrogênio a 10% e 35%) sobre a estabilidade de cor e rugosidade superficial de dois compósitos, um nanohíbrido e um nanoparticulado. Os espécimes foram polidos, envelhecidos, manchados, clareados e polidos novamente. A ação dos agentes clareadores sobre os compósitos foi analisada em perfilômetro (rugosidade) e um espectrofotômetro (estabilidade de cor). A ação de polimento dos compósitos sobre a rugosidade superficial e a retomada da cor dos compósitos também foi avaliada. Os resultados foram analisados estatisticamente por ANOVA e teste de Tukey (5% de significância). A análise indicou que o compósito nanohíbrido foi mais afetado pelo manchamento. Os agentes clareadores não foram capazes de promover o clareamento dos compósitos ao longo do período de avaliação. O polimento da superfície retornou o compósito nanohíbrido à sua condição de cor original, o que não foi observado para o nanoparticulado. Além disso, o polimento não retornou a rugosidade de superfície dos compósitos para os valores originais. Os autores concluíram que o polimento da superfície após o clareamento não deve ser a opção de tratamento, uma vez que não foi possível inverter a rugosidade dos compósitos à sua rugosidade original, sugerindo que uma degradação mais extensa e irreversível pode ter ocorrido.

Evaluación de la deformación de dos siliconas para prótesis faciales, influencia de la pigmentación y desinfección química / Assessment of initial and the permanent deformation of two silicones (Silved Selant and Brascoved) for facial prostheses under the pigmentation and chemical disinfection influence

La propuesta de este estudio fue analizar el efecto de la pigmentación y de la desinfección química sobre la deformación inicial y permanente de dos siliconas (Silved Selant y Brascoved) utilizadas en la confección de prótesis faciales. Las muestras para los analisis de deformación inicial y permanente (20 mm × 12,5 mm) fueron confeccionadas de acuerdo con las instrucciones del fabricante. Para cada silicona (n= 40), diez muestras fueron pigmentadas con polvo de maquillaje, diez con óxido de hierro, diez con polvo de cerámica y diez sin pigmentación. Cinco muestras de cada grupo fueron sometidas a desinfección química, con clorhexidina al 2 por ciento por aspersión. Todas las muestras fueron inmersas en suero fisiológico y almacenado en estufa a 35 º ± 1 ºC. Después de 90 días, las muestras fueron sometidas a los exámenes de deformación inicial y permanente. Para ambas propiedades, los datos fueron analizados por el test de Tukey (a= 0,05). Los resultados mostraron que todos los materiales presentaron deformación inicial y permanente independiente de la desinfección química y pigmentación. Los grupos pigmentados con óxido de hierro fueron los que presentaron menor deformación, inicial y permanente, cuando fueron sometidos a desinfección química, independientemente de la silicona usada(AU)

The purpose of present study was to analyze the effect of pigmentation and chemical disinfection on the initial and the permanent deformation of two silicones (Silved Selant and Brascoved) for facial prosthesis. Initial and permanent deformation tests samples (20 mm × 12.5 mm) were made following the manufacturer's instructions. For each silicone (n= 40), ten samples were used for pigmentation with make up power, ten with iron oxide, ten with ceramics power and tem were tested without pigmentation. Five samples of each group were submitted to chemical disinfection using a 2 percent Chlorhexidine spray. All samples were immersed in physiological saline and stored in an oven at 35 º ± 1 ºC. After 90 days, the samples were submitted to initial and permanent deformation tests using a dial indicator. For both properties, data were analyzed by Tukey's test (a= 0.05). The results showed that all the materials had initial and permanent deformation regardless of pigmentation and chemical disinfection. The groups were used for pigmentation with iron oxide showed less initial and permanent deformation when were submitted to the chemical disinfection regardless the silicone used(AU)

Effect of filler particles on surface roughness of experimental composite series

OBJECTIVE: The purpose of this study was to evaluate the effect of different filler sizes and shapes on the surface roughness of experimental resin-composite series. MATERIAL AND METHODS: Thirty-three disc-shaped specimens of the series (Spherical-RZD 102, 105, 106, 107, 114 and Irregular-RZD 103, 108, 109, 110, 111, 112) were prepared in a split Teflon mold and irradiated with an halogen light-curing unit (450 mW/cm² for 40 s) at both top and bottom surfaces. The specimens were stored for 3 months in distilled water. The surface roughness values in form of surface finish-vertical parameter (Ra), maximum roughness depth (Rmax) and horizontal roughness parameter (Sm) were recorded using a contact profilometer. The data were analyzed by one-way ANOVA and the means were compared by Scheffé post-hoc test (a=0.05). RESULTS: The lowest surface roughness (Ra) was observed in S-100 (0.079±0.013), while the roughest surface was noted in I-450/700/1000 (0.125±0.011) and I-450/1000 (0.124±0.004). The spherical-shape series showed the smoothest surface finish compared to the irregular-shape ones with higher significant difference (p>0.05). The vertical surface roughness parameter (Ra) values increased as the filler size increased yielding a linear relation (r²=0.82). On the contrary, the horizontal parameter (Sm) was not significantly affected by the filler size (r²=0.24) as well as the filler shape. CONCLUSIONS: Filler particle's size and shape have a great effect on the surface roughness parameters of these composite series.

Synthesis and biocompatibility of an experimental glass ionomer cement prepared by a non-hydrolytic sol-gel method

The aims of this study were to demonstrate the synthesis of an experimental glass ionomer cement (GIC) by the non-hydrolytic sol-gel method and to evaluate its biocompatibility in comparison to a conventional glass ionomer cement (Vidrion R). Four polyethylene tubes containing the tested cements were implanted in the dorsal region of 15 rats, as follows: GI - experimental GIC and GII - conventional GIC. The external tube walls was considered the control group (CG). The rats were sacrificed 7, 21 and 42 days after implant placement for histopathological analysis. A four-point (I-IV) scoring system was used to graduate the inflammatory reaction. Regarding the experimental GIC sintherization, thermogravimetric and x-ray diffraction analysis demonstrated vitreous material formation at 110oC by the sol-gel method. For biocompatibility test, results showed a moderate chronic inflammatory reaction for GI (III), severe for GII (IV) and mild for CG (II) at 7 days. After 21 days, GI presented a mild reaction (II); GII, moderate (III) and CG, mild (II). At 42 days, GI showed a mild/absent inflammatory reaction (II to I), similar to GII (II to I). CG presented absence of chronic inflammatory reaction (I). It was concluded that the experimental GIC presented mild/absent tissue reaction after 42 days, being biocompatible when tested in the connective tissue of rats.

O objetivo deste estudo foi demonstrar a sinterização pelo método sol-gel não-hidrolítico de um cimento de ionômero de vidro experimental (CIV) e avaliar sua biocompatibilidade em relação a um cimento de ionômero de vidro convencional (Vidrion R). Quatro tubos de polietileno contendo os cimentos testados foram implantados no dorso de 15 ratos, da seguinte maneira: GI - CIV Experimental e GII - CIV Convencional. A lateral do tubo foi considerada Grupo Controle. Os ratos foram sacrificados em 7, 21 e 42 dias pós-implantação para análise histopatológica. Uma escala de I a IV foi utilizada como sistema de score para graduar a reação inflamatória. Em relação à sinterização do CIV experimental, as análises termogravométrica e por difração de raio-x demonstraram a formação de material vítreo aos 110oC pelo método sol-gel. Para o teste de biocompatibilidade, os resultados mostraram uma reação inflamatória moderada para o GI (III), severa para o GII (IV) e branda para o Grupo Controle (II) aos 7 dias. Após 21 dias, GI apresentou uma reação branda (II); GII, moderada (III) e Grupo Controle, branda (II). Aos 42 dias, GI apresentou uma reação inflamatória branda/ausente (II a I), similar ao GII (II a I). O Grupo Controle demonstrou ausência de reação inflamatória (I). Concluiu-se que o CIV Experimental apresentou reação tecidual branda/ausente após 42 dias, sendo biocompatível quando testado em tecido conjuntivo de ratos.

Effect of self-adhesive resin cement and tribochemical treatment on bond strength to zirconia / 国际口腔科学杂志·英文版

<p><b>AIM</b>To evaluate the interactive effects of different self-adhesive resin cements and tribochemical treatment on bond strength to zirconia.</p><p><b>METHODOLOGY</b>The following self-adhesive resin cements for bonding two zirconia blocks were evaluated: Maxcem (MA), Smartcem (SM), Rely X Unicem Aplicap (UN), Breeze (BR), Biscem (BI), Set (SE), and Clearfil SA luting (CL). The specimens were grouped according to conditioning as follows: Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 microm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment--silica coating + silanization. Specimens were stored in distilled water at 37 degrees C for 24 hours before testing shear bond strength.</p><p><b>RESULTS</b>Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, BI, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP-containing self-adhesive resin cement CL had the highest bond strengths to zirconia.</p><p><b>CONCLUSION</b>Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.</p>

Effect of temperature variation on the cytotoxicity of cast dental alloys and commercially pure titanium

Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. OBJECTIVE: The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. MATERIAL AND METHODS: Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37ºC and thermocycling (37ºC/5ºC/37ºC/55ºC/37ºC). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (α=0.05). RESULTS: The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling. CONCLUSION: Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.

Embolismo pulmonar por silicona: reporte de caso y revisión de literatura / Silicone pulmonary embolism: report of a case and review of the literature

Presentamos el caso de un paciente de 24 años, con disnea súbita progresiva y antecedentes de inyecciones de silicona en regio glútea 24 horas antes del ingreso hospitalario. Al examen físico se encontraron disminuidos los ruidos respiratorios, taquipnea, en la gasimetria arterial trastorno de la oxigenación; los hallazgos de la tomografía computarizada de tórax y del lavado bronco alveolar fueron compatibles con embolismo pulmonar por silicona. La mortalidad en esta entidad es elevada debido al trastorno severo en la oxigenación y perfusión. El uso de este compuesto para fines cosméticos es, en la mayoría de los casos, practicado de manera ilegal, poniendo en riesgo la vida de los usuarios de este tipo de terapia. La evolución de este caso fue favorable.

Biocompatibility study of a hydroxyapatite-aiumina and silicon carbide composite scaffold for bone tissue engineering

To date, several scaffolds have been fabricated for application in bone tissue repair. However, there remains a need for synthesis of scaffolds with better mechanical properties, which can be applied to defects in weight-bearing bones. We constructed a composite ceramic bioscaffold of hydroxyapatite-alumina and silicon carbide [HA-Al2O3- SiC] to take advantage of the mechanical properties of this combination and show that it supports osteoblast-like cell attachment and growth. Ceramic composite microporous scaffolds were synthesized using an organic template [commercial polyurethane sponge with an open, interconnected microporosity]. Osteoblast-like cells [Saos-2] were then cultured on the scaffold and their growth pattern and viability were compared with those cultured in cell culture-treated flasks. Scanning electron microscopy [SEM] was used to assess cell attachment and migration. The fabricated scaffold shows fairly uniform pore morphologies. Cell growth and viability studies show that the scaffold is able to support osteoblast attachment and growth. However, SEM images indicated that the cells do not spread optimally on the scaffold surfaces. Our data suggest that that a ceramic hydroxyapatite-alumina and silicon carbide composite scaffold is a viable option for bone tissue repair. However, its surface properties should be optimized to maximise the attachment of osteoblasts

[Die dimension variation in three impression taking methods]

Dimensional stability of die plays very important role in fixed prosthodontic treatments. Different impression taking techniques may be the main source of die dimensional changes. However, in this regards, contradictory results have been reported in the literature. This study was designed to assess the dimensional accuracy of master casts prepared by means of three impression techniques using Speedex silicone impression material. This quasi-experimental study was carried out using laboratory stainless steel master models that contained three complete crown abutment preparations. The one-step, two-step with and without relief methods were the three putty-wash impression techniques used in this investigation. Fifteen impressions were taken for each technique and velmix casting material was used to prepare stone models. Profile Projector and micrometer were used to measure the final die's height, diameter and different dimensions in order to compare them with laboratory model. ANOVA and paired samples t-test were used for data analyses. The two step technique with spacer was the most accurate method with zero LC distance [distance between left and middle abutment]. However, in the other two techniques, the mean difference was 0.22 [ +/- 0.01], [P<0.05]. Regarding the distances between abutments, there was no significant difference when comparing one-stage and two-stage technique without spacer. Although, the height of abutment was more accurate in two-stage technique without spacer than one-stage. The two-step technique with spacer was the most accurate technique when using Speedex impression material

Effects of silicon carbide on the cure depth, hardness and compressive strength of composite resin / 生物医学工程学杂志

The hardness, compressive strength and cure depth are important indices of the composite resin. This investigation was made with regard to the effects of silicon carbide on the cure depth, hardness and compressive strength of the light-curing composite resin. Different amounts of silicon carbide were added to the light-curing composite resin, which accounted for 0 wt%, 1 wt%, 0.6 wt%, 0.3 wt%, 0.1 wt%, 0.05 wt% and 0.005 wt% of the composite resin, respectively. The hardness, compressive strength and cure depth of the six afore-mentioned groups of composite resin were measured by the vernier caliper, the vickers hardness tester and the tensile strength of machine, respectively. The results showed that silicon carbide improved the hardness and compressive strength of the light-curing composite resin,when the concentration was 0.05 wt%. And the cure depth was close to that of control.

Inductively coupled plasma-optical emission spectroscopy [ICP-OES] study of ion release from raw and acid washed fluoroaluminosilicate [glass ionomer] glasses

To measure the release of ions from fluoroaluminosilicate glasses, LG125, into deionised water and to compare the ion release from raw and acid washed glasses, taking account of the effect of acid wash on the ion release. Randomized Control Trials [RCT] Study was conducted at Department of Biomaterials in relation to Dentistry, Queen Mary University of London from Nov 2004 to Jun 2005. Specimens of experimental glasses, LG125 raw and acid washed [aw], were stored in polyethylene [PE] tubes at 37 °C in deionised water for a storage period of 1 to 28 days. Glass free solutions were collected after 1, 3, 7, 14, 21 and 28 days. The ions released were analyzed by Inductively Coupled Plasma-Optical Emission Spectroscopy [ICP-OES]. ICP-OES is a very powerful tool for trace metal analysis that uses the phenomenon of atomic and ionic excitation to determine concentration of ions in aqueous solutions. [a] Ions releases from the glasses were observed at all time intervals. The amounts of ion release were decreased over time and minimal quantities were seen in week four. [b] After acid wash the amount of release of fluoride [F] and aluminum [Al] ions were increased from the glasses while the release of Strontium [Sr] and Calcium [Ca] were decreased. [c] It was also seen that the acid washing enhances the release of F ions more than Al ions. Although the amount of Al was increased after acid wash but the concentration was too lower as compared to F ions. [a] Under both conditions substantial amounts of ions were released from the glasses but the release of ion were decreased after reaching a peak value. [b] F and Al were released more from aw glasses as compared to raw. [c] Release of Sr and Ca were greater from raw than aw

The micro-tensile bond strength of two-step self-etch adhesive to ground enamel with and without prior acid-etching / 대한치과보철학회지

STATEMENT OF PROBLEMS: Self-etch adhesives exhibit some clinical benefits such as ease of manipulation and reduced technique-sensitivity. Nevertheless, some concern remains regarding the bonding effectiveness of self-etch adhesives to enamel, in particular when so-called 'mild'self-etch adhesives are employed. This study compared the microtensile bond strengths to ground enamel of the two-step self-etch adhesive Clearfil SE Bond (Kuraray) to the three-step etchand-rinse adhesive Scotchbond Multi-Purpose (3M ESPE) and the one-step self-etch adhesive iBond (Heraeus Kulzer). PURPOSE: The purpose of this study was to determine the effect of a preceding phosphoric acid conditioning step on the bonding effectiveness of a two-step self-etch adhesive to ground enamel. MATERIAL AND METHODS: The two-step self-etch adhesive Clearfil SE Bond non-etch group, Clearfil SE Bond etch group with prior 35% phosphoric acid etching, and the one-step self-etch adhesive iBond group were used as experimental groups. The three-step etch-and-rinse adhesive Scotchbond Multi-Purpose was used as a control group. The facial surfaces of bovine incisors were divided in four equal parts cruciformly, and randomly distributed into each group. The facial surface of each incisor was ground with 800-grit silicon carbide paper. Each adhesive group was applied according to the manufacturer's instructions to ground enamel, after which the surface was built up using Light-Core (Bisco). After storage in distilled water at 37 degreesC for 1 week, the restored teeth were sectioned into enamel beams approximately 0.8*0.8mm in cross section using a low speed precision diamond saw (TOPMET Metsaw-LS). After storage in distilled water at 37 degreesC for 1 month, 3 months, microtensile bond strength evaluations were performed using microspecimens. The microtensile bond strength (MPa) was derived by dividing the imposed force (N) at time of fracture by the bond area (mm(2)). The mode of failure at the interface was determined with a microscope (Microscope-B nocular, Nikon). The data of microtensile bond strength were statistically analyzed using a one-way ANOVA, followed by Least Significant Difference Post Hoc Test at a significance level of 5%. Results: The mean microtensile bond strength after 1 month of storage showed no statistically significant difference between all adhesive groups (P>0.05). After 3 months of storage, adhesion to ground enamel of iBond was not significantly different from Clearfil SE Bond etch (P>0.05), while Clearfil SE Bond non-etch and Scotchbond Multi-Purpose demonstrated significantly lower bond strengths (P<0.05), with no significant differences between the two adhesives. CONCLUSION: In this study the microtensile bond strength to ground enamel of two-step selfetch adhesive Clearfil SE Bond was not significantly different from three-step etch-and-rinse adhesive Scotchbond Multi-Purpose, and prior etching with 35% phosphoric acid significantly increased the bonding effectiveness of Clearfil SE Bond to enamel at 3 months.