Direct Esthetic Restorations Based on Translucency and Opacity of Composite Resins

Light dynamics is a relevant phenomenon with respect to esthetic restorations, as incorrect analysis of the optical behavior of natural dentition may lead to potential clinical failures. The nature of incident light plays a major role in determining the amount of light transmission or reflection, and how an object is perceived depends on the nature of the light source. Natural teeth demonstrate translucency, opalescence, and fluorescence, all of which must be replicated by restorative materials in order to achieve clinical success. Translucency is the intermediary between complete opacity and complete transparency, making its analysis highly subjective. In nature, the translucency of dental enamel varies from tooth to tooth, and from individual to individual. Therefore, four important factors must be considered when appraising translucency. Presence or absence of color, thickness of the enamel, degree of translucency, and surface texture are essential components when determining translucency. State-of-the-art resin composites provide varying shades and opacities that deliver a more faithful reproduction of the chromaticity and translucency/opacity of enamel and dentin. This enables the attainment of individualized and customized composite restorations. The objective of this article is to provide a review of the phenomena of translucency and opacity in the natural dentition and composite resins, under the scope of optics, and to describe how to implement these concepts in the clinical setting.CLINICAL SIGNIFICANCEChoosing composite resins, based on optical properties alone, in order to mimic the properties of natural tooth structures, does not necessarily provide a satisfactory esthetic outcome. In many instances, failure ensues from incorrect analysis of the optical behaviors of the natural dentition as well as the improper use of restorative materials. Therefore, it is necessary to implement a technique that enables a restorative material to be utilized to its full potential to correctly replicate the natural teeth.(J Esthet Restor Dent 23:73-88, 2011).

Road segment delineation using active testing principle and an edge-based post-processing strategy

This paper presents a semi-automated method for extracting road segments from medium-resolution images based on active testing and edge analysis. The method is based on two sequential and independent stages. Firstly, an active testing method is used to extract an approximated road centreline which is based on a sequential and local exploitation of the image. Secondly, an iterative strategy based on edge analysis and the approximated centreline is used to measure precisely the road centreline. Based on the results obtained using medium-resolution test images, the method seems to be very promising. In general, the method proved to be very accurate whenever the roads are characterized by two well-defined anti-parallel edges and robust even in the presence of larger obstacles such as trees and shadows.

Effect of Ceramic Thickness and Shade on Mechanical Properties of a Resin Luting Agent

Purpose: This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement.Materials and Methods: Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated. Disk specimens (diameter: 7 mm; thickness: 2 mm) of the resin cement were light cured under a ceramic block. Light-cured specimens without the ceramic block at distances of 1 and 3mm were also produced. The Knoop hardness number (KHN), density, and dynamic Young's moduli were determined. Statistical analysis was conducted using ANOVA and a Tukey B rank order test (p = 0.05).Results: The bleaching 1-mm-thick group exhibited significantly higher dynamic Young's modulus. Lower dynamic Young's moduli were observed for the 3-mm-thick ceramic groups compared to bleaching 3-mm-thick group, and no difference was found among the other 3-mm groups. For the KHN, when A3.5 3-mm-thick was used, the KHN was significantly lower than bleaching and A1 1-mm-thick ceramic; however, no difference was exhibited between the thicknesses of the same shade.Conclusions: The dual-cured resin cement studied irradiated through the 1-mm-thick ceramic with the lightest shade (bleaching ceramic) exhibited a better elastic modulus, and there was no effect in KHN of the resin cement when light cured under different ceramic shades and thicknesses (1 and 3 mm), except when the A3.5 3-mm-thick ceramic was used.Clinical Significance: Variolink II irradiated through ceramic with the lowest chroma exhibited the highest elastic modulus; therefore, the light activation method might not be the same for all clinical situations.

Morphological aspects of the liver of the Podocnemis expansa (Testudines, podocnemididae)

The liver of P. expansa was characterized morphohistologically. To this end, twenty livers from clinically healthy male and female Podocnemis expansa, weighing from 2.0 to 4,5 kg, supplied by the commercial breeder Fazenda Moenda da Serra, in Araguapaz, state of Goiás, Brazil, were analyzed macro-and microscopically. The coelomatic cavity was opened and the topography of the fresh organs was examined visually. After the histological preparation, the slides were stained with Hematoxylin and Eosin (HE), Periodic Acid-Schiff (PAS), Gomori Trichrome, Reticulin and Picrosirius. The liver of P. expansa is a voluminous organ with an approximately rectangular shape and brown coloration, varying from light to dark shades, and is divided into a right lobe, left lobe, and a central portion. The right lobe is the largest of the three portions. The gall bladder is located in a depression in the caudal portion of the right lobe, where the gall duct begins and empties into the duodenum. Histologically, the hepatocytes are arranged in the form of double cords surrounded by winding sinusoidal capillaries. In cross section, they resemble acini containing approximately two to five hepatocytes surrounding a probable central biliary canaliculus. The hepatocytes are polyhedral or pyramidal in shape, of uniform size, with a few central nuclei and others displaced peripherally, and the cytoplasm is little eosinophilic when analyzed by the HE staining technique. The parenchyma is supported by delicate reticular fibers surrounding hepatocytes and sinusoids. The parenchyma and perisinusoidal spaces contain large quantities of melanomacrophages, mainly close to the portal spaces.

Adesão e grau de conversão: efeito das cores da cerâmica e do agente de fixação resinoso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A cor do citrino: efeito de irradiação e tratamento térmico

Quartz crystals under natural or artificial irradiation can acquire dark shades and variations btween smoky, black and brown but when submitted at heat-treatment they can become greenish, yellowish or brownish, called citrine at gem shops. In this work a lot of samples was collected from different places in Brazil (Corinto - MG, Diamantina - MG, Sento Sé - BA and Santana do Araguaia – PA) and at first they were submitted at artificial irradiation resulting in dark colours. After that they were submitted at heat-treatment in differents temperatures and time of exposure to record when color change happened to light colours. It variated according to each origin, temperature, time of expousure and different aluminiun and other chemical elements content. Its was possible to define the ideal conditions to results better colours and related it with geology and chemical quartz composition.

A ocupação da terra na formação do municipio de Ourinhos-SP

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

Bond Strength of Different Resin Cement and Ceramic Shades Bonded to Dentin

Purpose: To evaluate the microtensile bond strength (MTBS) of ceramic cemented to dentin varying the resin cement and ceramic shades.Materials and Methods: Two VITA VM7 ceramic shades (Base Dentine 0M1 and Base Dentine 5M3) were used. A spectrophotometer was used to determine the percentage translucency of ceramic (thickness: 2.5 mm). For the MTBS test, 80 molar dentin surfaces were etched and an adhesive was applied. Forty blocks (7.2 x 7.2 x 2.5 mm) of each ceramic shade were produced and the ceramic surface was etched (10% hydrofluoric acid) for 60 s, followed by the application of silane and resin cement (A3 yellow and transparent). The blocks were cemented to dentin using either A3 or transparent cement. Specimens were photoactivated for 20 s or 40 s, stored in distilled water (37 degrees C/24 h), and sectioned. Eight experimental groups were obtained (n = 10). Specimens were tested for MTSB using a universal testing machine. Data were statistically analyzed using ANOVA and Tukey's post-hoc tests (alpha <= 0.05).Results: The percentage translucency of 0M1 and 5M3 ceramics were 10.06 (+/- 0.25)% and 1.34 (+/- 0.02)%, respectively. The lowest MTBS was observed for the ceramic shade 5M3. For the 0M1 ceramic, the A3 yellow cement that was photocured for 20 s exhibited the lowest MTBS, while the transparent cement that was photocured for 40 s presented the highest MTBS.Conclusions: For the 2.5-mm-thick 5M3 ceramic restorations, the MTBS of ceramic cemented to dentin significantly increased. The dual-curing cement Variolink II photocured for 40 s is not recommended for cementing the Base Dentine 5M3 feldspathic ceramic to dentin.

Community-wide spatial and temporal discordances of seed-seedling shadows in a tropical rainforest

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

The shadows of a ghost: a survey of canine leishmaniasis in Presidente Prudente and its spatial dispersion in the western region of São Paulo state, an emerging focus of visceral leishmaniasis in Brazil

Visceral leishmaniasis is an emerging zoonosis and its geographic distribution is restricted to tropical and temperate regions. Most of the individuals infected in Latin America are in Brazil. Despite the control measures that have been adopted, the disease is spreading throughout new regions of the country. Domestic dogs are involved in the transmission cycle and are considered to be the main epidemiologic reservoir of Leishmania infantum (syn. L. chagasi). Our aim was to determine the prevalence of canine leishmaniasis (CL) and Ehrlichiosis infection in Presidente Prudente as well as the spatial dispersion of the disease in the western region of São Paulo state. Dogs underwent clinical examination and symptoms related to CL were recorded. Anti- Leishmania antibodies were detected using ELISA, rK39-immunocromatographic tests (DPP), and an indirect fluorescent antibody test (IFAT). Anti-E. canis antibodies were detected by IFAT. A follow-up was conducted in dogs that were positive in the ELISA at the baseline study. Data on the spatial distribution of L. longipalpis and CL in São Paulo state were obtained from Brazilian public health agencies. Serum samples from 4547 dogs were analyzed. The seroprevalence of CL was 11.2 % by ELISA and 4.5 % by IFAT. In the follow-up, seroprevalence was 32.9 % by ELISA, 15.3 % by IFAT, 11.8 % by DPP test, and 66.5 % for E. canis. There was a significant positive association between Leishmania and E. canis infection (P < 0.0001). In the follow-up, clinical examinations revealed symptoms compatible with CL in 33.5 % of the dogs. L. longipalpis was found in 24 and CL in 15 counties of the Presidente Prudente mesoregion. The dispersion route followed the west frontier of São Paulo state toward Paraná state. Low CL and high ehrlichiosis prevalence rates were found in Presidente Prudente city. This emerging focus of CL is moving through the western region of São Paulo state toward the border of Paraná state. Integrated actions to fight the vector, parasites, infected dogs, and humans are needed to monitor the disease and implement strategies for epidemiologic control.

Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Increase in severity of molar-incisor hypomineralization and its relationship with the colour of enamel opacity: a prospective cohort study

Background. Predicting risk of posteruptive enamel breakdown (PEB) of molar-incisor hypomineralization (MIH) opacity is a difficult but important clinical task. Therefore, there is a need to evaluate these aspects through longitudinal studies.Objective. The aim of this longitudinal study was to analyse the relationship between colours of MIH opacity of children aged 6-12 (baseline) and other clinical and demographic variables involved in the increase in severity of MIH.Materials and methods. A blinded prospective 18-month follow-up was conducted with 147 individuals presenting mild MIH. Tooth-based incidence of increase in severity of MIH (PEB or atypical restorations) was used as dependent measurement. Enamel opacities were recorded according to colour shades of white, yellow and brown, allowing assessment of susceptibility to structural loss over time, according to colour of MIH opacity. Poisson regression models were used to adjust the results for demographic and clinical variables.Results. Brown and yellow MIH opacities were at higher risk for PEB and atypical restorations than those of white ones, even after adjustment for clinical and demographic variables.Conclusion. Teeth presenting mild MIH severity associated with yellow and brown enamel opacities were at high risk for increase in severity of MIH than lighter ones. This result could help clinicians determine a risk-based treatment for children with MIH.

Effect of diabetes mellitus and insulin therapy on bone density around osseointegrated dental implants: a digital subtraction radiography study in rats

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

Influence of the Light-Curing Unit, Storage Time and Shade of a Dental Composite Resin on the Fluorescence

The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 +/- 0.1 mm, thickness 1.0 +/- 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A(2)E, A(2)D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37 C and 100% humidity. The analysis of variance (ANOVA) and Tukey's post-hoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) (P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage (P < 0.05). The colors had difference significant between them (shades: A2D < A2E < TC) (P < 0.05). The Ultraled (LED) and Ultralux (QTH) when used the TC shade showed higher than Radii (LED), however to A2E shade and A2D shade any difference were found (P > 0.05).

Almost strict total positivity and a class of Hurwitz polynomials

We establish sufficient conditions for a matrix to be almost totally positive, thus extending a result of Craven and Csordas who proved that the corresponding conditions guarantee that a matrix is strictly totally positive. Then we apply our main result in order to obtain a new criteria for a real algebraic polynomial to be a Hurwitz one. The properties of the corresponding extremal Hurwitz polynomials are discussed. (C) 2004 Elsevier B.V. All rights reserved.