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.

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 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.

Estandarización de una técnica de inyección de resinas poliéster para el estudio de la vasculatura cerebral / Standardization of a technique of injecting polyester resins for studying the brain vasculature

Introducción: La enfermedad cerebro vascular en nuestro medio tiene una alta tasa de morbi mortalidad. Dentro de las técnicas anatómicas utilizadas para el estudio de la irrigación de diversas estructuras y órganos se destaca la inyección de látex neopreno, acetato de vinilo y de diferentes polímeros tipo silicona, seguida de corrosión parcial o total de las estructuras anatómicas. Para poder establecer el patrón de irrigación de una muestra de población colombiana se desarrolló una técnica de inyección de resinas tipo poliéster. Materiales y métodos: Para la implementación de la técnica se analizaron 122 encéfalos de sujetos mestizos de sexo masculino provenientes de la ciudad de Bucaramanga, Colombia. Las edades de los sujetos variaron entre los 15 y 65 años que no presentaban ninguna patología que comprometiera el sistema nervioso. El procedimiento incluyó la cateterización de las arterias carótida interna (ACI) y vertebral en forma bilateral, lavado y prefijado del lecho vascular con 100 ce de formaldehído al 10% y la posterior inyección de 100 ce de resina de poíiésíer impregnada de color rojo mineral. Conclusiones: Esta técnica económica pennite por medio de la fácil manipulación de las muestras, conservar las características anatómicas de los vasos sanguíneos, su apariencia, relaciones estructurales externas, lo cual es de gran relevancia en la evaluación de las diferentes alteraciones.

Introducción: La enfermedad cerebrovascular en nuestro medio tiene una alta tasa de morbimortalidad. Dentro de las técnicas anatómicas utilizadas para el estudio de la irrigación de diversas estructuras y órganos se destaca la inyección de látex neopreno, acetato de vinilo y de diferentes polímeros tipo silicona, seguida de corrosión parcial o total de las estructuras anatómicas. Para poder establecer el patrón de irrigación de una muestra de población colombiana se desarrolló una técnica de inyección de resinas tipo poliéster. Material y métodos: Para la implementación de la técnica se analizaron 122 encéfalos de sujetos mestizos de sexo masculino provenientes de la ciudad de Bucaramanga, Colombia. Las edades de los sujetos variaron entre los 15 y 65 años que no presentaban ninguna patología que comprometiera el sistema nervioso. El procedimiento incluyó la cateterización de las arterias carótida interna (ACI) y vertebral en forma bilateral, lavado y prefijado del lecho vascular con 100 cc de formaldehído al 10 % y la posterior inyección de 100 cc de resina de poliéster impregnada de color rojo mineral. Conclusiones: Esta técnica económica permite por medio de la fácil manipulación de las muestras, conservar las características anatómicas de los vasos sanguíneos, su apariencia, relaciones estructurales externas, lo cual es de gran relevancia en la evaluación de las diferentes alteraciones.

Estudo prospectivo e randomizado de pacientes tratados com e sem stents revestidos com carbeto de silício amorfo para a prevenção da reestenose coronariana. Avaliação ultra-sonográfica / Randomized intravascular ultrasound comparison between endoprostheses with and without amorphous silicon-carbide

OBJETIVO: A reestenose intra-stent é a maior limitação das intervenções coronárias percutâneas. O carbeto de silício amorfo (SiC-a), substância antitrombótica e antiinflamatória capaz de reduzir a deposição de fibrina, plaquetas e leucócitos sobre o stent, apresenta potencial de prevenir a hiperplasia neo-intimal e a reestenose. MÉTODOS: Estudo prospectivo, randomizado e tipo rótulo aberto comparando pacientes com doença coronariana tratados com e sem stents revestidos com o SiC-a, utilizando a angiografia quantitativa e o ultra-som intracoronário. Foram incluídos 100 pacientes (50 em cada grupo) a fim de mensurar o volume de hiperplasia neo-intimal intra-stent/extremidades. Como os stents comparados apresentavam extensões diferentes, o volume de hiperplasia foi analisado em valores absolutos (por paciente) e relativos (por milímetro de extensão do stent). Avaliaram-se ainda os eventos cardíacos maiores e os resultados da angiografia quantitativa. RESULTADOS: Os grupos apresentaram características de base semelhantes. Todos os pacientes foram tratados com sucesso. No 6° mês de evolução foram reestudados 94 por cento dos casos dos dois grupos, obtendo-se ultra-som em 92 por cento. O volume de hiperplasia neo-intimal absoluto foi significativamente maior nos tratados com os stents revestidos (51.2 DP 18.8 mm³ vs 41.9 DP 16.4 mm³; p=0.014), porém o relativo foi semelhante (2.9 DP 1.0 mm³/mm stent vs 2.5 DP 0.9 mm³/mm stent; p=0.108). A obstrução volumétrica da luz também foi similar (36.4 DP 11.1 por cento vs 37.9 DP 10.9 por cento; p=0.505). O diâmetro mínimo da luz (1.9 DP 0.7 mm vs 1.8 DO 0.6 mm; p=0.552), a reestenose (19.1 por cento vs 17 por cento; p>0.999) e a revascularização do vaso-alvo (16 por cento vs 14 por cento; p>0.999) não diferiram. CONCLUSÃO: Os stents revestidos apresentaram resultados clínicos, angiográficos e ultra-sonográficos similares aos controles.

Comparação randomizada entre o implante de stents com e sem carbeto de silício amorfo para a prevenção da reestenose coronária / A randomized comparison of an amorphous silicon-carbide coated stent with an uncoated stent for the prevention of restenosis

Com o objetivo de avaliar se o revestimento de stents coronários com carbeto de silício amorfo é capaz de reduzir a hiperplasia neo-intimal em pelo menos 30 por cento, realizamos um estudo prospectivo e randomizado, que incluiu 100 pacientes com lesões primárias, tratados por meio dos stents Teneo® (revestido) e Bx Velocity® (não revestido). Aos seis meses de evolução analisaram-se: eventos coronários maiores e os resultados da angiografia e do ultra-som intracoronário. Demonstrou-se que as endopróteses revestidas apresentaram resultados clínicos, angiográficos e ultra-sonográficos semelhantes aos das convencionais.Silicon-carbide coating presents antithrombotic and anti-inflammatory properties, which improve stent hemocompatibility and biocompatibility. Thus, it could halt the trigger for smooth-muscle cell proliferation and subsequent restenosis after stent placement. A prospective, randomized, open label trial was conducted in 100 patients submitted to elective percutaneous intervention to compare the performance of the amorphous silicon-carbide coated stent Teneoâ with the uncoated stent Bx Velocityâ in 100 patients. Six-month clinical follow-up results as well as angiographic and intravascular ultrasound findings were similar in both groups...

Resultados del tratamiento con tubo de silicón en la dacrioestenosis del adulto / Results with silicone lacrimal tubes treatment in adults with acquired nasolacrimal duct obstruction

A lo largo de muchos años se ha intentado encontrar la mejor terapéutica para la dacrioestenosis, desde la irrigación y sondeo de la vía lagrimal hasta el uso de tubos de silicón. El objetivo de nuestro estudio fue definir la eficacia del uso de tubos de silicón en estos pacientes. Se realizó un estudio retrospectivo, en el que se incluyen pacientes adultos, con dacrioestenosis no traumática sometidos a dacriointubación cerrada con tubos de silicón.En un periodo de seguimiento de 10 meses de los 34 pacientes, 22 pacientes (64.70 por ciento), tuvieron un resultado posoperatorio eficaz y 12 pacientes (35.29 por ciento) tuvieron un resultado ineficaz. Las complicaciones posquirúrgicas que se tuvieron por el material de silicón fueron fístula en dos pacientes (5.88 por ciento) y desgarro del punto lagrimal en un paciente (2.94 por ciento). De acuerdo con la literatura nuestros resultados fueron similares.La dacriointubación cerrada ofrece la ventaja de permeabilizar la vía lagrimal de una manera natural, siendo un procedimiento recomendable antes de procedimientos más agresivos.