Infiltração marginal em restaurações de resina composta após tratamento dentinário com abrasão a ar e sistemas adesivos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Low shrinkage composite resins: influence on sealing ability in unfavorable C-factor cavities

The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep) surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA) and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA) (G1); Filtek Z-350 (3M/ESPE,St Paul, MN, USA) (G2); Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA) (G3); Premisa (KERR Corporation, Orange, CA, USA) (G4). Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA) + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA). After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54) or depth (p = 0.8364) of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.

Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations

O objetivo deste estudo foi determinar o efeito da polimerização gradual, mediante a utilização de aparelhos de Quartzo-Tungustênio-Halógena (QTH) e Arco de Plasma de Xenônio (PAC), no selamento marginal de restaurações classe V em resina composta com margens localizadas em dentina. Setenta e cinco incisivos bovinos receberam preparos de cavidades classe V, na raiz, com o intuito de situar as margens cavitárias em dentina. Os dentes foram divididos em cinco grupos de acordo com o método de fotoativação. As cavidades, depois de condicionadas, foram tratadas com o sistema adesivo Single Bond (3M Dental) e restauradas com a resina composta Z100 (3M Dental) pela técnica incremental. A fotoativação foi realizada para cada grupo como descrito a seguir: Grupo I: PAC pelo método de fotoativação constante: 1600mW/cm² – 3s; Grupo II: PAC pelo método de fotoativação por passos (800mW/cm² – 2s, subindo automaticamente para 1600mW/cm² – 4s); Grupo III: QTH pelo método de fotoativação constante: 400 mW/cm² – 40s; Grupo IV: QTH pelo método de fotoativação em rampa: 100 a 600 mW/cm² – 15s, permanecendo a 600mW/cm² por mais 25s; Grupo V: QTH pelo método de fotoativação por pulso: 200 mW/cm² – 3s, tempo de espera de 3min.e a seguir 600mW/cm² – 30s. Os dentes foram armazenados em água destilada a 37ºC por 30 dias e então submetidos à ciclagem térmica, por 500 ciclos à 5 ºC e 55 ºC. Os ápices dos dentes foram selados com resina composta e os dentes foram cobertos com duas camadas de esmalte para unha, antes da sua imersão em fucsina básica a 0,5%. Os dentes foram seccionados e os cortes foram escaneados para avaliação da área infiltrada por corante por um programa de computador (Image Tools). Os cortes foram também visualizados com lupa para a determinação do grau de penetração do corante na interface dente-restauração por escores. Diferenças estatisticamente significantes foram observadas entre os grupos quanto ao grau e à área de penetração de corante (p < 0,05). Os grupos I e II apresentaram valores significantemente mais altos de infiltração e penetração do corante que os grupos III, IV e V. Em conclusão, o uso da fonte de PAC, no modo constante e por passos, resultou em valores significantemente maiores de infiltração marginal quando comparados com a intensidade de luz média emitida pelos aparelhos de QTH. Os métodos de fotoativação por pulso, rampa e continuo com a fonte de QTH resultaram num grau similar de microinfiltração.

Estudo da infiltração marginal em restaurações de resinas compostas para dentes posteriores: efeito de material, preparo cavitário e condicionamento do esmalte a nível cervical

Pós-graduação em Odontologia Restauradora - ICT

Reliability of marginal microleakage assessment by visual and digital methods

The aim of this study was to investigate the reliability of visual and digital methods to assess marginal microleakage in vitro. Materials and Methods: Typical Class V preparations were made in bovine teeth and filled with composite resin. After dye penetration (0.5% basic fuchsin), teeth were sectioned and the 53 obtained fragments were assessed according to visual (stereomicroscope) and digital methods (Image Tool Software ® -ITS) (University of Texas Health Science Center-San Antonio Dental School, USA). Two calibrated examiners (A and B) evaluated dye penetration, by means of a stereomicroscope with ×20 magnification (scores), and by the ITS (millimeters). The intra- and inter-examiner agreement was estimated according to Kappa statistics (κ), and intraclass correlation coefficient (ρ). Results: In relation to the visual method, the intra-examiner agreement was almost perfect (κA = 0.87) and substantial (κB = 0.76), respectively to the examiner A and B. The inter-examiner agreement showed an almost perfect reliability (κ = 0.84). For the digital method, the intra-examiner agreement was almost perfect for both examiners and equal to ρ = 0.99, and so was the inter-examiner agreement value. Conclusion: Visual (stereomicroscope) and digital methods (ITS) showed high levels of intra- and inter-examiner reproducibility when marginal microleakage was assessed.

Avaliação da capacidade seladora apical de um adesivo dentinário, acrescido ou não de hidróxido de cálcio, comparada à de um cimento endodôntico à base de hidróxido de cálcio, na obturação de canais radiculares

Pós-graduação em Odontologia Restauradora - ICT

Influence of ultrasound or halogen light on microleakage and hardness of enamel adjacent to glass ionomer cement

Background. The use of external sources of energy may accelerate the setting rate of glass ionomer cements (GICs) allowing better initial mechanical properties. Aim. To investigate the influence of ultrasound and halogen light on the microleakage and hardness of enamel adjacent to GIC restorations, after artificial caries challenge. Design. Cavities were prepared in 60 primary canines, restored with GIC, and randomly distributed into three groups: control group (CG), light group (LG) - irradiation with a halogen lightcuring unit for 60 s, and ultrasonic group (UG) application of ultrasonic scaler device for 15 s. All specimens were then submitted to a cariogenic challenge in a pH cycling model. Half of sample in each group were immersed in methylene blue for 4 h and sectioned for dye penetration analysis. The remaining specimens were submitted to Knoop cross-sectional microhardness assessments, and mineral changes were calculated for adjacent enamel. Results. Data were compared using Kruskal-Wallis test and two- way ANOVA with 5% significance. Higher dye penetration was observed for the UG (P < 0.01). No significant mineral changes were observed between groups (P = 0.844). Conclusion. The use of halogen light- curing unit does not seem to interfere with the properties of GICs, whereas the use of ultrasound can affect its marginal sealing.

Microhardness and marginal adaptation of pre-warmed composites

Objectives: The aim of this study was to examine the effect of pre-warmed composite on the microhardness and marginal adaptation. Methods: Ninety six identical class II cavities were prepared in extracted human molars and filled/cured in three 2 mm increments using a metal matrix. Two composites (Tetric Evo Ceram (IvoclarVivadent) and ELS(Saremco)) were cured with a LED curing unit (Bluephase (IvoclarVivadent)) using curing cycles of 20 and 40 seconds. The composite was used at room temperature or pre-warmed at 54.5ºC (Calset(AdDent)). Twelve teeth were filled for every composite-curing time-composite temperature combination. The teeth were thermocycled (1000 cycles at 5º and 55ºC) and then stored at 37° C for seven days . Dye penetration (basic fuchsine 5% for 8 hours) was measured using a score scale. Knoop microhardness was determined 100, 200, 500, 1000, 1500, 2500, 3500, 4500 and 5500µm from the occlusal surface at a distance of 150 and 1000µm from the metal matrix. The total degree of polymerization of a composite specimen was determined by calculating the area under the hardness curve. Results: Statistical analyses showed no difference in marginal adaptation (p>0.05). Hardness values at 150µm from the matrix were lower than those at 1000µm. There was an increase of the microhardness at the top of each increment and decrease towards the bottom of each increment. Longer curing times resulted in harder composite samples. Multiple linear regression showed that only the curing time (p<0.001) and composite material (p<0.001) had a significant association with the degree of polymerization. The degree of polymerization was not influenced by pre-warming the composite at a temperature of 54.5ºC (p=4.86). Conclusion: Polymerization time can not be reduced by pre-warming the composite on a temperature of 54.5ºC. The marginal adaptation is not compromised by pre-warming the composite.

Analysis of Hyporheic Flow Induced by a Bar in a Gravel Stream: an Experimental Study

Thesis (Master, Civil Engineering) -- Queen's University, 2016-06-01 00:03:02.939

ANALYSIS OF HYPORHEIC FLOW INDUCED BY A BAR IN A GRAVEL STREAM: AN EXPERIMENTAL STUDY

Pipelines are one of the safest means to transport crude oil, but are not spill-free. This is of concern in North America, due to the large volumes of crude oil shipped by Canadian producers and the lengthy network of pipelines. Each pipeline crosses many rivers, supporting a wide variety of human activities, and rich aquatic life. However, there is a knowledge gap on the risks of contamination of river beds due to oil spills. This thesis addresses this knowledge gap by focussing on mechanisms that transport water (and contaminants) from the free surface flow to the bed sediments, and vice-versa. The work focuses on gravel rivers, in which bed sediments are sufficiently permeable that pressure gradients caused by the interactions of flow with topographic elements (gravel bars), or changes in direction induce exchanges of water between the free surface flow and the bed, known as hyporheic flows. The objectives of the thesis are: to present a new method to visualize and quantify hyporheic flows in laboratory experiments; to conduct a novel series of experiments on hyporheic flow induced by a gravel bar under different free surface flows. The new method to quantify hyporheic flows rests on injections of a solution of dye and water. The method yielded accurate flow lines, and reasonable estimates of the hyporheic flow velocities. The present series of experiments was carried out in a 11 m long, 0.39 m wide, and 0.41 m deep tilting flume. The gravel had a mean particle size of 7.7 mm. Different free surface flows were imposed by changing the flume slope and flow depth. Measured hyporheic flows were turbulent. Smaller free surface flow depths resulted in stronger hyporheic flows (higher velocities, and deeper dye penetration into the sediment). A significant finding is that different free surface flows (different velocities, Reynolds number, etc.) produce similar hyporheic flows as long as the downstream hydraulic gradients are similar. This suggests, that for a specified bar geometry, the characteristics of the hyporheic flows depend on the downstream hydraulic gradients, and not or only minimally on the internal dynamics of the free surface flow.

Desinfeção aplicada aos cones de guta-percha

Introdução: Ao longo do tempo o Tratamento Endodôntico Não Cirúrgico tem sido das áreas da Medicina Dentária que mais tem evoluído. Todos os passos do tratamento têm sido revistos de forma a aumentar a taxa de sucesso. O controlo microbiológico é crucial para que o tratamento seja um sucesso a curto, médio e longo prazo. A assepsia deve ser mantida em todas as fases deste tratamento para que este seja um sucesso. Objetivo: Ao longo do meu percurso académico pude concluir que a fase da descontaminação dos cones, aquando a obturação (fase final do Tratamento Endodôntico Não Cirúrgico) era desvalorizada, o que me levou a efetuar uma revisão bibliográfica de modo a poder melhorar os meus conhecimentos e técnica. Material e Métodos: Para a elaboração deste trabalho foi realizada uma pesquisa bibliográfica recorrendo aos seguintes motores de busca: B-on, PubMed, Scielo e ScienceDirect, com as seguintes palavras-chave: “decontamination in endodontics”;” disinfection in endodontics”; “root canal irrigants”; “endodontics microbiology”; “Candida albicans“; “Enterococcus faecalis”; “sodium hypochlorite ”; “alcohol”; “contamination during Obturation”; “clorohexidine”; “filling materials endodontics”; “termoplastic gutta-percha”; “obturation material”; “Mineral Trioxide Aggregate”; “resilon”; “resin cement”; “resin material for root canal obturation”; “resin sealer”; “root canal”; “root canal sealing”; “root canal filling materials”; “condensation in endodontics”; “lateral condensation”; “gutta-percha”; “microlekeage”; “system B”; “fluid filtration model”;“dye penetration”. Como critério de inclusão estabeleceu-se que os artigos deveriam ser em Português, Inglês ou Espanhol e publicados entre 1995 e 2015. Dos resultados apresentados foram utilizados 110 artigos, pesquisados entre Maio de 2015 e 20 de Outubro de 2015. Foram ainda consultados livros de referência nestes mesmos locais. Conclusão: a presença de bactérias e os seus subprodutos no sistema tridimensional de canais está diretamente implicado com o insucesso do Tratamento Endodôntico. A descontaminação dos cones de guta-percha, é, portanto, um processo importante no Tratamento Endodôntico pois impede que os cones sejam colocados nos canais radiculares, estando contaminados por microorganismos que inviabilizam o tratamento efetuado. A submersão dos cones durante um minuto em clorohexidina a 2% ou hipoclorito a 5,25% está indicado e comprovado como um processo eficiente de desinfeção dos cones.

Absorbance kinetics of dye-doped systems with photochemical first order kinetics

Often it is assumed that absorbance decays in photochromic materials with the time dependence of the photochemical kinetics, i.e. exponentially for first order kinetics. Although this may hold in the limiting case of vanishing absorbance, deviations are to be expected for realistic samples, because the local photochemical kinetics slows down with increasing initial absorption and penetration depth of the radiation. We discuss the theory of the kinetics of initially homogeneous photochromic samples and derive analytical solutions. In extension of Tomlinson's theory we find an analytical solution that holds with good approximation even for samples that exhibit a small residual absorption in the saturation limit. The theoretical time dependence of the absorbance originating from photochemical first order kinetics of dye-doped systems is compared with experimental data published by Lafond et al. for fulgides doped in different polymer matrices. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hand-held spectroscopic device for in vivo and intraoperative tumor detection: contrast enhancement, detection sensitivity, and tissue penetration.

Surgery is one of the most effective and widely used procedures in treating human cancers, but a major problem is that the surgeon often fails to remove the entire tumor, leaving behind tumor-positive margins, metastatic lymph nodes, and/or satellite tumor nodules. Here we report the use of a hand-held spectroscopic pen device (termed SpectroPen) and near-infrared contrast agents for intraoperative detection of malignant tumors, based on wavelength-resolved measurements of fluorescence and surface-enhanced Raman scattering (SERS) signals. The SpectroPen utilizes a near-infrared diode laser (emitting at 785 nm) coupled to a compact head unit for light excitation and collection. This pen-shaped device effectively removes silica Raman peaks from the fiber optics and attenuates the reflected excitation light, allowing sensitive analysis of both fluorescence and Raman signals. Its overall performance has been evaluated by using a fluorescent contrast agent (indocyanine green, or ICG) as well as a surface-enhanced Raman scattering (SERS) contrast agent (pegylated colloidal gold). Under in vitro conditions, the detection limits are approximately 2-5 × 10(-11) M for the indocyanine dye and 0.5-1 × 10(-13) M for the SERS contrast agent. Ex vivo tissue penetration data show attenuated but resolvable fluorescence and Raman signals when the contrast agents are buried 5-10 mm deep in fresh animal tissues. In vivo studies using mice bearing bioluminescent 4T1 breast tumors further demonstrate that the tumor borders can be precisely detected preoperatively and intraoperatively, and that the contrast signals are strongly correlated with tumor bioluminescence. After surgery, the SpectroPen device permits further evaluation of both positive and negative tumor margins around the surgical cavity, raising new possibilities for real-time tumor detection and image-guided surgery.

Effects of atmospheric pressure plasma on dye uptake by the surface of wool

A woven pure wool fabric has been exposed to atmospheric pressure plasma for 30 seconds using a pilot-scale. commercial machine. X-ray photoelectron spectral data revealed large increases in oxygen and nitrogen. and a large reduction in carbon. on the surfaces of the plasma-treated fibres. A CIN ratio of 3.55 for plasma-treated wool was consistent with removal of the covalently-bound fatty acids from the surface of the cuticle cells. resulting in exposure of the proteinaceous epicuticle. Dye staining experiments revealed that the back of the fabric had received the same, uniform level of treatment as the face, despite the fact that only the face had been directly exposed to the plasma. Dyes (1 % oww) were applied to fabric at 50°C (liquor ratio =40: 1) and pH values from 3 to 6. The relatively low temperature of 50°C was selected in order to accentuate the effects of plasma on the rate of dye uptake. Under these conditions, dye was adsOibed onto the fibre surfaces, with very little penetration into the fibres. Effects of the plasma treatment on the rate of dyes adsorption were dyespecific. No significant effects of plasma on the rate of dye uptake were observed with relatively hydrophobic dyes, but hydrophilic dyes were adsorbed more rapidly by the plasmatreated fabric. It would appear that for more hydrophobic dyes, hydrophobic effects are more important for the adsorption of dyes by the plasma-treated fibres, even though these fibres were quite hydrophilic. On the other hand. it is concluded that for more hydrophilic dyes, electrostatic effects are more important for adsorption by the plasma-treated fibre.