Avaliação in vitro da adaptação cervical de coroas totais metálicas, variando os preparos dos términos cervicais, aliviando ou não as superfícies internas das coroas e empregando diferentes cimentos definitivos

Este trabalho avaliou a qualidade das adaptações cervicais de coroas totais metálicas, tendo como fonte de variação: a) o término do ombro cervical do preparo - biselado, inclinado em 1350; reto em 900, chanfro e gume de faca; b) o alívio ou não das superfícies internas das coroas; e, c) os tipos de agente de cimentação permanente, cimentos - fosfato de zinco Harvard; ionômero de vidro Ketac-Cem, policarboxilato de zinco Durelon e resinoso Panavia Ex. Inicialmente, foram confeccionados corpos-de-prova em modelos-padrão de aço inoxidável usinado, de acordo com o tipo de preparo dos términos cervicais experimentais. As cápsulas metálicas de aço inoxidável preparadas, tendo ou não alívio da superfície interna de 30 micrometros até a distância de 0,5 mm do limite do término cervical, justapunham-se precisamente e formavam um conjunto com adaptação e assentamento exatos. Estas foram cimentadas nos corpos-de-prova com os diferentes agentes cimentantes, os quais foram manipulados de acordo com as instruções dos fabricantes. Desenvolveram-se metodologias de reaproveitamento dos corpos-de-prova, estabilidade das cápsulas impedindo seu deslocamento durante a tomada das medidas e mensuração precisa. Concluiu-se que: a) as melhores médias de adaptações cervicais, semelhantes entre si, foram obtidas em modelos-padrão com ombros: lâmina de faca, ombro inclinado em 1350 e chanfro; b) as piores médias de adaptações cervicais, semelhantes entre si, foram obtidas em modelos-padrão com ombros reto em 900 e degrau em 900 com bisel de 450; c) houve melhora significativa na adaptação quando cápsulas metálicas foram cimentadas com alívio de sua superfície interna; d) os cimentos...(Resumo completo, clicar acesso eletrônico abaixo)

Doença periodontal em cães

Periodontal disease affects the periodontum which are tissues that support and protect the tooth and are composed by the gingiva, alveolar bone, cementum and periodontal ligament. Lesions in the periodontum have as main etiologic agent the presence of plaque or biofilm, which is formed in 24 hours and, basically, it consists of microorganisms surrounded by some bacteria rich matrix products and salivary glycoproteins. Gingivitis is the first clinical manifestation of periodontal disease and it is reversible if the etiologic agent (plaque) is removed. However, if it is not treated or controlled, it will lead to an irreversible periodontitis, and even evolve into alveolar bone, tissue destruction and, eventually, tooth loss

Caracterização física e mecânica de compensado produzido com dois diferentes adesivos em duas variações de pressão de prensagem

The adhesives used in the production of engineered boards have been object of study over the years in order to improve the properties of the boards with less energy consumption, lower production costs and reduced environmental impact. In addition to that, process variables may affect the properties of the board. The present study aimed to characterize sheets of plywood, manufactured with two types of adhesives, under two different pressing conditions. The adhesives used for the study were Phenol-formaldehyde and Polyurethane castor oil based. The pressure of pressing was varied in a range from 75 to 160 Bar, in order to verify how they influence the physical and mechanical properties of the board. The tests performed resulted in a conclusion that shows that the moister content of the veneers interferes on the physical and mechanical tests. In general, boards produced with polyurethane resin showed superior physical and mechanical results; although the ones produced with phenol formaldehyde at a pressure of 75 Bar had always equal or higher values, compared to what is found in literature

Produção e caracterização físico-mecânica de painel de compensado de Eucalyptus sp. e adesivo PVA

Studies on new adhesives and resins for bonding wood and wood products are being conducted with the intention of improving their properties, taking into account a lower environmental impact. For this reason new formulations of polyvinyl acetate (PVA) adhesives have been developed, because they have no chemicals in its composition extremely polluting and harmful to health, as is the case of formaldehyde-based resins, which in turn are the most commonly used today for wood panels production. This study tested three different formulations of PVA adhesives, with different times and temperatures of pressing for the production of Eucalyptus sp. Plywood, coming up in satisfactory results with respect to shear strength at the bondline, which was higher for the PVA adhesives compared with urea-formaldehyde and phenol. The results of MOE and MOR were lower than those values of the panels produced with urea and phenol-formaldehyde, and the results of physical tests showed to be close to the panels produced with these same adhesives

Uma revisão sobre a resina uréia-formadeído (RUF) empregada na produção de painéis de madeira reconstituída

According to ABIPA (2009), Brazil is currently among the major producers of reconstituted wood panels, with one of the main factors for this condition, its climate and its large land area, which allows the cultivation of forests, which provide raw materials for these industries. To establish that market as power, Brazil has invested about R$ 1.3 billion in the last 10 years, yet designed an investment of 0.8 billion dollars over the next three years (BNDES, 2008). With the new investments in this segment, we expect a growth of about 66% in the resin consumption of urea-formaldehyde (GPC, 2009) which should also result in major investments by the companies producing this polymer. Currently employees are mainly three types of resins in the production industry panels, as follows: Urea-Formaldehyde Resin (R-UF), melamine-formaldehyde resin (R-MF) and Phenol-Formaldehyde Resin (R-FF). Especially the cost factor, the urea-formaldehyde resin is the most used by companies producing reconstituted wood panels. The UF-R is a polymer obtained by condensation of urea and formaldehyde reactors (usually batch type), characterized by being a thermosetting polymer which makes it very efficient for bonding wood composites. The urea-formaldehyde polymer, to present a quite complex, it becomes very difficult to predict the exact chain resulting in the process of condensation of urea with formaldehyde, so that a greater knowledge of its characteristics and methods for their characterization can result in greater control in industrial processes and subsequent decrease cost and improve the quality of reconstituted wood panels produced in Brazil

Estudo da eficiência de reforços estruturais em vigas de concreto armado com o uso de chapas de aço coladas com resina epóxi: uma análise qualitativa

In civil engineering, a structure is the whole sustainment of a construction and, thus, it is important that it remains intact throughout its lifetime. An engineering construction must last for decades without losing its functionality. However its purpose may be altered and several times the original structure does not meet the new needs of use. Still, in new buildings, the functionality is altered due to possible flaws in execution and the structure, invariably does not reach the desired solicitation needs. In cases like this, the commonly adopted solutions are, basically, the demolishment followed by the reconstruction of the desired mold or the structural reinforcement. This second option, for long years, has not been put to practice due to certain factors such as the high costs for its implantation, use of inadequate reinforcement execution techniques, and the culture of people involved in the area regarding its use and, in this case, the option would always be the reconstruction. Thoughtout the years, some techniques were developed to allow the execution of structural reinforcements with low costs and in efficient ways. An interesting, fast, efficient and economical technique is the structural reinforcement through metal sheets put together with epoxy resin that can be applied in beams, slabs and pillars. In the present work the different behavior of beams reinforced with this technique. Steel is a very recommended material for these reinforcements due to its characteristics related to traction, compression and the effectiveness of the technique related to its cost. For the attachment the epoxy resin is recommended, since it allows the joining of two materials, in this case, steel and concrete. The efficiency of this union is so considerably high that it rarely produces any flaws in adherence and, normally, when it happens it is due to problems in the execution process, not in the union of materials

Marcadores de superfície de Células-tronco: estudo de reação cruzada inter-espécies

Mesenchymal stem cells (MSCs) are adult multipotent cells with fibroblastoid morphology and adherent to plastic. Furthermore, they can be obtained from different sources. Besides bone marrow, these cells are taken from umbilical cord blood, umbilical vein, saphenous vein, peripheral blood, arteries, liver and fetal pancreas, placenta, dental pulp and adipose tissue. MSCs derived from adipose tissue are important because of the abundant number of cells that can be obtained from this tissue, easy access and little discomfort to the patient. This study compared two techniques for obtaining MSCs from adipose tissue: mechanical dissociation (MD) and enzymatic digestion (ED). We also analyzed the inter-species cross-reactions using commercial monoclonal antibodies directed against surface antigens of stem cells from different species: mouse, horse, rabbit, monkey and human. We found that MD technique is favorable in relation to ED within 15 days of culture, and ED is more efficient in the first days of culture. The data also showed that MD causes less damage to cellular DNA. About inter-species cross-reactions, the monoclonal antibody A69 directed against stem cells from rabbits, which can be used in veterinary medicine, particularly in research involving horses

Estudo, desenvolvimento e concepção de uma célula de carga

In engineering projects, it’s fundamental to determine the active loads in components in order to guarantee acceptable values of safety and reliability according to project specifications. On the other hand, force measurement methods might be very complex and impracticable in some cases and, so that, load cells with eletric resistance strain gages can be applied as a simple and accurate option to measure the required load. The main purpose of this paper is to present the development of a load cell that measures uniaxial forces using electric resistance strain gages without being influenced by the location of the loading in a cantilever beam. For that, it was taken as basis a secondary purpose which is to present a general study of basic and wide concepts about transducers, load cells and extensometers primarily. Information such as: loading and measurements types, characteristics of the presented devices as well as factors that influence its functioning, the most common kinds of Wheatstone bridge links, the main points of a load cell project, cements used to fix extensometers and, finally, the project itself with the tests of the built transducer are presented. By the end of this paper, all the results are shown and analyzed, concluding about the designed load cell and the work itself

Processo de esmerilhamento, polimento e caracterização de um Shear Plate

Shearplate is an optical glass plate having two flat surfaces and a small angle between them. The use of a high quality shear plate is essential to implement shear interferometric technique . The shear interferometry is a technique used to evaluate the light beam collimation. In order to guarantee the shearplate quality , the complete manufacturing process must be thoroughly monitored. In the manufacturing process, the first step consisted of the glass selection. The selected glass has been submitted to the process of cutting, gluing, chamfering, grinding and polishing. Each phase has been strictly monitored. The quality of the final result depends extremely on an appropriate starting condition, which arises from the grinding process, as the polishing process only recovers the brightness of the part, acting on a small scale on the wearing off of the part, as well as not changing the structured obtained in the grinding process. Respecting all stages of the manufacturing process, the quality of the part has evolved to a good result. The best result obtained showed PV distance of 162 nm, slightly less than λ / 4. This result is significant because the dimensions of the piece with respect to the dimensions of the polisher what interferes directly in the results. The closer are the dimensions of piece and the dimensions of the polisher, the greater the difficulty in controlling the propagation of errors

Extensometria: estudo das microdeformações ao redor de três implantes de hexágono interno, com posicionamento linear, sob a influência da fundição de coifas plásticas e usinadas

The objective of this in vitro study was quantify the micro strain development around the internal hexagon implants, varying the type of prosthetic coping. For This reason, three implants of internal hexagon were inserted into one polyurethane block in line placement. Microunit abutments were screwed onto the implants. Tangentially the implants were bonded the strain gauges, two to the center implant. Ten structures, each one containing three copings were cast in Co-Cr alloy, that were divided into groups in the first group, plastic copings were used, and in the second group machined copings were used. The superstructure’s occlusal screws were tightened onto Microunit abutments with 10 Ncm torque, the magnitude of micro strain was recorded. The mean values of each strain gauge of each plastic copings were 363,37 ± 237,66 and the machined copings were 338,12 ± 223,01. The data were analyzed statistically by t- Student test. No statistically significant difference was found between the prosthetic copings (p= 0,867). It was concluded that to internal hexagon implants in line placement, the type of copings presented similar magnitude of micro strain after prosthetic occlusal screw was tightened

O ato alimentar em três espécies de Artibeus de grande porte (Chiroptera: Phyllostomidae) do Sudeste brasileiro

The alimentary act of three species of frugivorous bats of the genus Artibeus: A. lituratus, A. fimbriatus and A. planirostris, in a total of nine individuals, was studied by observations in field and captivity, during the months of May to September of 2008. With the objective to caracterize the form of consumption of two tipes of fruits (soft and consistent) and it relates with the dentary structure of this bats, the alimentary act was film and analysed later. It had little variation between the species. The fruits had been consumed in similar way, being that statistics analisis had demonstrated that consistent fruits had received more lateral bytes than the soft fruits. The dentary analisis shown that the posterior teeth (pre-molar and molar) present important characteristcs to triturate pieces of more consistent fruits and the incisors serve to scrape the pulp of the soft fruits. This study it served to describe the form of feeding of frugivorous bats, that little is explained in the studies of alimentary behavior

Dental caries and related factors in Brazilian children from fluoridated and non-fluoridated areas

PURPOSE: To compare the caries prevalence, saliva buffering capacity (SBC), oral hygiene (OH), dietary habits, family income (FI) and frequency of visits to a dental office (Do) between Brazilian children living in areas with and without fluoridated public water supply. METHODS: Forty-six 5-7-year-old preschoolers were selected in Itatiba, SP, Brazil; 19 were from a fluoridated area, and 27 were from a non-fluoridated area. The caries index was determined according to the World Health Organization criteria, and the SBC was assessed by titration with hydrochloric acid. The FI, frequency of OH and visits to Do were estimated by questionnaire. The dietary habits were assessed with a diet chart. The differences between the groups were analyzed with Mann-Whitney-U tests (α=0.05). RESULTS: Children from the non-fluoridated area showed significantly higher dmft/DMFT than those from the fluoridated area, but they showed significantly lower SBC, OH frequency and FI. No significant differences were observed between the areas for dietary habits and visits to Do. CONCLUSION: Children from fluoridated areas showed higher salivary buffering capacity, family income and oral hygiene frequency as well as lower caries prevalence, supporting the beneficial effect of fluoride in the tap water for caries prevention.

Aplicação de adesivos estruturais em painéis de carros

The automobile industry is increasingly interested in reducing vehicle weight for greater speed, lower fuel consumption and emissions, through innovation of materials and processes. One way to do this is to seek the replacement of conventional processes by the use of structural adhesives. Structural adhesives are highly resistant materials, which can replace rivets, bolts and welds allowing the substrate / adhesive assemble is stronger than the substrate itself. One of the major advantages of gluing with respect to welding is its esthetic appearance, since it does not leave marks. For this reason, parts to be soldered require a minimum thickness so that the marks do not appear, since the pieces from gluing have no restriction as to the thickness. By replacing the vibration welding process for gluing process of the instrument panel parts of an automobile, one obtains a reduction of the thickness of the parts and therefore it decreases the weight of the car. This work aims to study the various structural adhesives that already exist on the market to be applied on the instrument panel. The mechanical test performed to measure the maximum adhesive strength was the Lap Shear Test at 23°C (room temperature), -35°C and 85°C. The types of adhesives used were the hot-melt and the bi-component. By the results obtained, it is in favor using the bi-component for application to the union of instrument panel parts

Análise das microdeformações geradas ao redor de implantes de hexágono externo sob a aplicação de cargas verticais em pilares microunit retos e angulados

Pós-graduação em Odontologia Restauradora - ICT

Avaliação in vitro das microdeformações em implantes curtos, com conexão protética cone morse e diferentes desenhos de roscas, convencionais e platôs

Pós-graduação em Odontologia Restauradora - ICT