Efeito de protocolos de cimentação na carga de fratura para uma cerâmica de dissilicato de lítio

Pós-graduação em Odontologia Restauradora - ICT

Efeito da limpeza pós-condicionamento e do tratamento térmico do silano na resistência de união de um cimento resinoso à cerâmica

Pós-graduação em Odontologia - FOA

Influência de três tratamentos de superfície para cerâmicas a base de zircônia na resistência adesiva e no comportamento à fadiga do material

Pós-graduação em Odontologia Restauradora - ICT

Interactions between restorative dentistry and periodontics: preparation and cementation of an onlay in Empress (Part III)

The relentless pursuit by cosmetic dentistry brought the evolution of materials ceramics. The IPS-Empress system was upgrading of indirect restorations based on lithium disilicate. The ceramic restoration posterior allow a new esthetic approach due to its translucency and resistance without any weakening of the remaining dental element, being an option more conservative when compared to conventional prosthetic restorations.

Surface roughness analysis of dental ceramics treated with hydrofl uoric acid and aluminum oxide jet

The aim of this study was to evaluate the surface roughness of 5 indirect restorative materials treated with hydrofluoric acid to 10%, with aluminum oxide jet and a combination of both. The specimens was prepared with 10 mm in diameter and 2 mm thickness, divided into fi ve groups: (1) Ceromer (CeseadII-Kuraray), (2) Leucite crystals ceramics (IPS EmpressIIIvoclarforcasket), (3) glass ceramic with fluorapatite (IPS D. Sign-Ivoclar), (4) lithium disilicate ceramic (IPS Empress II-Ivoclar restorations), (5) ceramics (Cergogold-Degussa). For all groups were performed the controls, and the surfaces with the 3 types of treatment. For testing roughness used the rugosimeter Taylor/Hobson-Precision, model form tracerSV-C525 high sensitivity. After confi rmation of variance analysis with a signifi cance level of 1% (p < 0.01), there was equality between the average roughness of materials from groups 1, 3 and 5, and the group 2 was different from the others. It was also found that the ceramics of the group 5 behaved similar to group 4. However the lowest average roughness was observed in group 2 ceramic. In the evaluation between the types of treatment, the aluminum oxide jet and associations and blasting with hydrofl uoric acid were similar, and different isolated hydrofl uoric acid, and 3 types of treatment signifi cantly higher than the control group. All treatments promoted superfi cial alterations in all tested materials.

Reabilitação estética do sorriso por meio do sistema cerâmico dissilicato de lítio: relato de caso

The reestablishment of a harmonious smile through dental ceramics, when properly conducted and with specific indications, can achieve extremely predictable results. For aesthetic and functional rehabilitation, many ceramic materials can be used such as zirconia, leucite, alumina, feldspar, and lithium disilicate. Among these materials the lithium disilicate stands out due to the following characteristics: its resistance to wear, to chemical attack, high temperatures and oxidation; low electrical conductivity; near zero thermal expansion; good optical properties and biocompatibility with periodontal; excellent esthetics; color stability and reinforcement of tooth structure. The indications for the use of lithium disilicate are not limited to multiple facets of teeth in cases where there was no favorable response to tooth whitening, and also comprehend teeth with multiple restorations, diastema closure, shape alteration, and dental contouring, replacement of missing or fractured teeth, among others. The versatility of lithium disilicate ceramics allows its utilization in several clinical situations. The concomitant use of lithium disilicate for veneers and over metal has satisfactory aesthetic results, as reported in the present studying cases that require both aesthetics and resistance.

O impacto do preparo, da cerâmica e do contato oclusal na distribuição de tensões em facetas

Pós-graduação em Odontologia Restauradora - ICT

Caracterização microestrutural e crescimento subcrítico de trincas em cerâmicas odontológicas

Pós-graduação em Odontologia Restauradora - ICT

Fetal kidney programming by severe food restriction: effects on structure, hormonal receptor expression and urinary sodium excretion in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

From acoustic waves to microwaves

We present here some results of our research related to the optoelectronics and photonics and show all the experimental setups used. Starting with a discussion on the importance of the waves, we demonstrate our achievements based on employment of acoustic, optical, and microwaves and their technological use. The results concern the acousto-optic and electro-optic effects. The generalized analysis of the electro-optic effect reveals a new high induced birefringence in lithium niobate. A patented optical fiber microphone is presented, and its applications to the measurements of acoustic wave velocity in gases and in the laser ultrasound non-destructive evaluation system are discussed. Finally, the generation of microwaves by an optical method with substantial cost reduction is presented.

Structural characterization of Li-MN doped powders prepared by Pechini's method

Pechini's method has been successfully used to prepare Li-doped MgNb2O6(MN) at short time and low temperature. It consists in the preparation of metal citrate solution, which is polymerized at 250°C to form a high viscous resin. This resin was burned in a box type furnace at 400°C/2h and ground in a mortar. Successive steps of calcination up to 900°C were used to form a crystalline precursor. SEM, DTA and XRD were used to characterize the powders. MN precursor powders containing from 0.1 to 5.0 mol% of LiNbO3 additive was prepared aiming better dielectric properties and microstructural characteristics of the PMN prepared from columbite route. SEM analysis showed that particles increased by sintering, forming large agglomerates. The surface area is also substantially reduced with the increase in additive amount above 1.0 mol%. In XRD pattern of the precursor material with 5.0 mol% of additive was observed the LiNbO3 phase of trigonal structure. XRD data were used for Rietveld refinement and a decrease in microstrain and pronounced increase in crystallite size with the increase of LiNbO3 were observed. It is in agreement with the particle morphologies observed by SEM analysis.

Prosthetic rehabilitation of a patient with gastroesophageal reflux disease: 4-year followup

The gastroesophageal reflux disease (GERD) is one of the main causes of dental erosion. The aim of this case presented is to describe the prosthetic rehabilitation of a patient with GERD after 4 years of followup. A 33-year-old male patient complained about tooth sensitivity. The lingual surface of the maxillary anterior teeth and the cusps of the upper and lower posterior teeth presented wear. It was suspected that the feeling of heartburn reported by the patient associated with the intake of sports supplements (isotonics) was causing gastroesophageal changes. The patient was referred to a gastroenterologist and was diagnosed with GERD. Dental treatment was performed with metal-free crowns and porcelain veneers after medical treatment of the disease. With the change in eating habits, the treatment of GERD and lithium disilicate ceramics provided excellent cosmetic results after 4 years and the patient reported satisfaction with the treatment.

Influence of Mg on the structural and optical properties of LiNbO3 thin films grown by polymeric precursor method

A polymeric precursor solution was used to deposit pure and Mg doped LiNbO3 thin films on sapphire substrates by spin-coating. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. Phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.

Oxygen Interstitial Dynamics in Bi(2)Sr(2)CaCu(2)O(8+delta) Oxides Measured by Mechanical Spectroscopy

Many researchers became interested in the discovery of Bi(2)Sr(2)CaCu(2)O(8+delta) oxides with critical temperature of around 80 K. It is known that the critical temperature is related to the CuO2 planes of the material. For this reason, the study of the interstitial oxygen in these oxides is of great relevance. The samples were prepared by means of conventional solid state reactions, through the stoichiometric mixture of precursory powders. After the sinterization, the samples were submitted to measurements of density, electrical resistivity, x-ray diffraction, scanning electron microscopy and energy dispersion spectroscopy, with the objective of performing their characterization. The measurements of mechanical spectroscopy were performed by a torsion pendulum. The results show three relaxation processes in the temperature range of 200 and 700 K, with activation energy of approximately 0.9 eV, which has been attributed to the dynamics of the interstitial oxygen present in the material.

Obtenção e caracterização óptica e elétrica de 'La''Ta'O IND.4' e LiTaO Ind.3 puros e dopados com Eu POT.3+

Eletronicalceramics are used in many applications such as: multilayer capacitor, transducer, pyroelectric sensors and electrooptic devices. In recent years there has been a growing demand for eletronicalceramics with better performance and functionality. This demand has accelerated the development of synthesis techniques to produce powders with well-defined particle size, shape and crystallinity. The eletronicalceramics in the form of bulk are determined by their performance characteristics of the powders used and the preparation process. So, physical and chemical properties of powders, such as chemical control of stoichiometry, purity, homogeneity, particle size and shape should be observed when choosing the methods of synthesis. Among the techniques used so far, the polymeric precursor method, also known as Pechini, has been considered ideal for the preparation of nanosized powders. Thus, this research project aims to use the polymeric precursor method to prepare powders of lithium tantalate and lanthanum tantalate, with good chemical stability. In this aspect is proposed to investigate the effects of variation of the concentration of europium about the properties of tantalate because doping with Eu3 + indicates that they may occupy different sites in the crystal structure, as in the case of LiTaO3. Effects of things like occupation sites, stability of phases and formation temperature have been previously investigated by the group, which motivated the formulation of this project. Our proposal aims to introduce the Eu3 + LaTaO4 and LiTaO3 and study the structural and optical properties of the powders obtained by Pechini method, as well as correlate these studies with the electrical properties of the material, mainly the Ironelectricty Hysteresis.