Síntese por reação em estado sólido de pós cerâmicos multifuncionais à base de CaCu3Ti4O12 modificados com estrôncio

The study of ceramic materials is constantly evolving, especially in research related to advanced ceramics. Once these have many applications, this paper relates to synthesis by solid state reaction of calcium copper titanate (CCTO) ceramic material means doping with strontium. The powders were characterized using thermal analysis techniques such as TG (thermogravimetry), DTA (differencial thermal analysis), dilatometry, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The compositions have submitted weight loss at around 6% with respect to carbonates used, and was attributed a temperature of 950° C to perform the calcination according to thermogravimetric analysis. After the process of calcination and milling, the particles presented approximately spherical shapes and high percentages of substitution Ca2+ with Sr2+ was evident by the presence of necks between to particles due to the milling calcination. Analyses with Energy Dispersive Spectroscopy (EDS) showed stoichiometries in different samples very similar to the theoretical stoichiometry

Efeitos dos parâmetros de usinagem no acabamento superficial de materiais cerâmicos a verde

Pós-graduação em Engenharia Mecânica - FEB

Estudo clínico longitudinal de dentes restaurados com sistemas cerâmicos livres de metal: estudo prospectivo sobre a hipersensibilidade dental pós-operatória

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese e caracterização estrutural de pigmentos cerâmicos a base de cromita por método químico

The ceramic pigments are colored inorganic substances that during the process of dispersion in the ceramic glazes and subsequent calcination, are stable against physical and chemical attack. Therefore, they are crystalline compounds applied in the ceramic industry for coloring vitreous base. In this study, the Pechini method was used for obtaining the pigment CuCr2O4 with heat treatment at the temperatures of 800, 900 and 1000 ° C. The powder pigments were characterized on their structural, morphological and colorimetric aspects. The thermal analysis conducted on an amorphous precursor in a TG / DTA indicates the weight loss in the entire temperature range investigated, with characteristic exothermic peak of the elimination of the organic composition of the precursor around 300°C. The development of the crystalline phases were investigated by XRD, using a diffractometer with Cu Ka radiation and graphite monochromator, where it was observed the presence of crystalline phases corresponding to Cr2O3 and CuCr2O4.The measurements of the specific surface area of the powders pigments were carried out in an equipment Micromeritcs, model ASAP 2000, using N2 as gas of adsorption/desorption. The colorimetric measurements of the pigments were made in a colorimeter Gretac Macbeth Color-eye spectrophotometer 2180 / 2180UV in CIELAB standards. Based on the obtained results, it can be verified the thermal stability of the powder pigments of green coloration, which enables it as an alternative to the materials currently used in the manufacture of ceramic tiles.

Efeito da escovação dentária no manchamento de braquetes estéticos cerâmicos

Objective: this study aimed to analyze the in vitro effect of brushing on the color stability of ceramic brackets immersed in dye solutions. Materials and Methods: seven ceramic brackets of four commercial brands were tested: two monocrystalline and two polycrystalline. The parameters of color were obtained by spectrophotometer before and after 21 days of immersion of the brackets in coffee, red wine, Coca-Cola, black tea and artificial saliva. Another group of brackets of each brand were also immersed in the same solutions and for an equal time to the previous group, but with intervals of daily brushing performed by a toothbrushing machine (Mavtec). The data were evaluated by analysis of variance, multiple comparison tests for means and Student's t-test. Results: the mean color change of the brackets without brushing ranged from 0.46 to 7.61, while in the group with brushing these means ranged from 0.36 to 2.50. The staining still remained noticeable (change of color greater than 3.7) for all brackets when immersed in black tea. Conclusion: daily brushing helped significantly in the color stability of ceramic brackets, maintaining the color change to levels considered not visible to the human eye, except for the solution of black tea in which the staining remained relevant.

Sistemas cerámicos puros parte 1: una evolución basada en la composicíon

The continuing advances in technology, dental materials and equipment have contributed significantly to improve the level of esthetic dentistry today. Among these innovations, development of pure ceramic restorations has evolved to give different alternatives. Dental ceramics have presented a rapidly technological changing to improve mechanical and optical properties. Currently there are several systems of metal free ceramics with excellent mechanical and optical properties, for making crowns and plurals. These modern systems are presented with various compositions and different preparation techniques, making these more versatile. Within this perspective, the dental market offers a huge range of new indirect and metal-free materials for prostheses, providing new options, plus also new questions to decide among the available alternatives. The aim of this review is take a view of the different ceramic systems in terms of its composition and different techniques of production.

Sistemas cerámicos puros parte 2: materiales, propiedades ópticas y consideraciones clínicas

While dentistry continues to advance, the aesthetic techniques have evolved in proceedings more effective, functional and biocompatible. Meanwhile, cosmetic dentistry has become a bit more complex and technically difficult. With improvement of the properties (physical and optical) of the ceramics and the establishment of a working protocol, ceramic restorations have become increasingly popular. Currently there are several ceramic systems have excellent optical properties such as opalescence, fluorescence, translucency, chromaticity, which allow the restoration to mimic the tooth structure. From the physical point of view has restored biomechanical integrity and strengthening the remaining tooth structure. All this has led the profession to experience the use of new ceramic systems ranging from conventional feldspathic ceramics to modem ceramic reinforced, injected or computer-aid made. The material selection should be based on clinical need, aesthetic and functional requirements, restoration site, prosthetic design and laboratory techniques. In this article we will deal with the characteristics of the materials, their optical properties and clinical considerations for proper selection.

Fragmentos cerâmicos

Clínica - International Journal of Brazilian Dentistry

Desenvolvimento, implantação e avaliação do desempenho de biorreator anaeróbico de leito fluidizado e leito fixo com filtros biológicos em materiais diversos

This study aimed to develop, implement and evaluate the performance of a new type of bioreactor for anaerobic treatment of wastewater using different filling materials like trickling filters post-reactor. This bioreactor has mixed characteristics of the UASB reactors and horizontal flow from the point of view of removal of BOD (Biochemical Oxygen Demand) ssed (settled solids), TS (Total Solids), SS (Suspended Solid), SD (Dissolved Solids) and turbidity. The experimental model consists of a bioreactor with a volume of 12 m³, 2/3 filled by fluidized bed and 1/3 for fixed. The fluidized bed is made of polystyrene plates used as a system percolation and compartmentalized trickling filters, where each compartment was filled with a support medium with different characteristics (gravel number 4, plastic rings of polystyrene, PET and HDPE) . In addition, the output of a filter system was installed three entries filled with activated carbon. The bioreactor was installed in private residence in the city of Igarapava-SP (20° 02'40.18"S and 47° 45'01.36" W). The system was highly efficient as the removal of organic contaminant load 92% on average reducing the BOD, a significant result when compared to other anaerobic systems. For the other parameters, the mean reduction was 96% for turbidity, 99% ssed, 67.5% ST, 57% SD and 88% of SS. As for its operation the system was capable of operating in continuous flow without the need for maintenance during the entire period of evaluation and without energy, as it operates taking advantage of the natural slope of the terrain where it is installed. The environmental impacts were minimized due to the preservation of local vegetation allowing the ecosystem to remain unchanged beyond the prototype was completely sealed preventing exhalation of odors and therefore not causing inconvenience to neighboring populations. Given these facts it was concluded that the prototype is shown to be highly feasible deployed as a new alternative for treatment of sewage in rural and urban settings (individual homes, condos, farms, ranches, etc.) Due to ease of design and operability, and sustainability at all stages of execution.

Avaliação da tenacidade à fratura de diferentes sistemas cerâmicos

Although ceramics present high compressive strength, they are brittle materials due to their low tensile strength so they have lower capacity to absorb shocks. This study evaluated the fracture toughness of different ceramic systems, which refers to the ability of a friable material to absorb defformation energy. Three ceramic systems were investigated. Ten cylindrical samples (5,0mm x 3,0mm), were obtained from each ceramic material as follows: G1- 10 samples of Vitadur Alpha (Vita-Zahnfabrik); G2- 10 samples of IPS Empress2 (Ivoclar-Vivadent); G3- 10 samples of In-Ceram Alumina (Vita-Zahnfabrik). Fracture toughness values were collected upon indentation tests that were performed under a heavy load. A microhardness tester (Digital Microhardness Tester FM) utilized a 500gf load cell during 10seconds to perform four impressions on each sample. Statistically significant results were observed (ANOVA and Kruskal-Wallis tests). In-Ceram Alumina presented the highest median toughness values (2,96N/m3/2), followed by Vitadur Alpha (2,08N/m3/2) and IPS Empress2 (1,05N/m3/2). It may be concluded that different ceramic systems present distinct fracture toughness values, thus In-Ceram is capable of absorbing superior stress when compared to Vitadur Alpha and IPS Empress2.

Propriedades ópticas de nanopartículas de halogenetos de cobre preparadas in situ em filmes híbridos de sílica

The sol-gel process is a technique based on the hydrolysis and polycondensation of metal alkoxides have been investigated as an alternative for the preparation of vitreous or glassceramic materials, for allowing the obtaining of high-purity materials at low temperatures, and to obtain hybrid materials with different compositions. When ORMOSILs are doped with nanoparticles, are called nanocomposites, and its functionality arises when electrons confined in scale three-dimensional structures near zero are excited. In principle, such materials exhibit discrete energy level, with peaks in the absorption spectrum. Therefore, the glasses doped semiconductor nanocrystals are important candidates for the preparation of optical filters with sharp cut-off, and are being exploited commercially for coloring glasses. This study evaluates the optical properties presented by hybrid films of silica doped with copper nanoparticles. The matrix was prepared using the alkoxides 3-glycidoxypropyltrimethoxysilane (GPTS) and tetraethylorthosilicate (TEOS) doped with Cu2O and hydrolyzed under reflux conditions in two different acidic conditions (HCl and HBr). After thermal treatment at temperatures between 100 °C and 170 °C and/or under the action of commercial black light radiation, CuCl and CuBr present in the hybrid film are transformed into nanoparticles of CuCl or CuBr. The UV-VIS absorption identified the absorption bands, and its variation

Laminados cerâmicos em dentes tratados endodonticamente: considerações restauradoras e endodônticas com finalidade protética

A harmonia e beleza de um sorriso podem ser comprometidos pela presença de apenas um dente da região anterior que se apresente escurecido, mesmo que os demais elementos estejam alinhados e com forma adequada. A alteração de coloração, mesmo que mínima, sendo na região frontal é capaz de gerar um ponto de tensão e de desequilíbrio no sorriso, concentrando o olhar do observador no local1,2,3. Logo, a demanda dos pacientes por um sorriso estético, belo e harmonioso aumenta o desafio do profissional que visa integrar as características ópticas de um dente anterior despolpado e escurecido com os demais dentes polpados e sem manchamentos significativos. O clareamento é a alternativa mais conservadora para resolver o escurecimento em dentes despolpados. Apesar de resultados satisfatórios, alguns clínicos e autores relutam em assumir, como rotina, os procedimentos de clareamento para dentes despolpados, pelo alto índice de recidiva de escurecimento4,5. Mas, é importante lembrar que as recidivas descritas, normalmente, não contemplam um retorno aos valores inicias de manchamento. Deve ser feito um bom planejamento, levando em considerações fatores como a idade do paciente, o grau de escurecimento, o tempo em que o dente se encontra escurecido e a dificuldade em se alcançar o clareamento do dente, que são determinantes para o sucesso do tratamento clareador e para estabelecer a longevidade do clareamento obtido. Por isso, não são todos os dentes despolpados que apresentam alteração de cor que podem ser clareados, devendo ser avaliados com precisão os critérios estabelecidos3. Os dentes tratados endodonticamente e escurecidos, muitas vezes, necessitam da reintegração estética, associando as técnicas de clareamento com procedimentos restauradores ou, dependendo da condição do dente, a escolha imediata por procedimentos restauradores diretos ou indiretos.

Plástica gengival associada à laminados cerâmicos para resolução estética

Sometimes we face clinical situations in which the lack of harmony in the smile is caused by a major exhibition of the gingival tissue. In these cases the professional should be able to perform a detailed analysis of the static and dynamic components of the smile, in search of a satisfactory planning and treatment which may include different dental specialties. For these situations, the association of periodontics/prosthesis is a viable alternative that has been used positively in search of an aesthetic and functional condition that benefits the patient, without leaving aside the preservation of periodontal tissues and of the remaining structure of the tooth. Thus, the aim of this study was to describe a case in which the association between these two areas was proposed to correct gummy smile and dental vestibularization. Clinical results and the satisfaction of the patient indicate that this multidisciplinary treatment combining periodontal and prosthetic techniques is favorable to positive results in cases of compromised smile aesthetics due to excessive gum tissue.