Estudo de cimentos comerciais e experimentais à base de MTA para obturação de canais radiculares

Orientador: Mário Alexandre Coelho SinhoretiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Os objetivos neste trabalho foram (1) avaliar e comparar propriedades físico-químicas de cimentos endodônticos, sendo um recentemente desenvolvido à base de mineral trióxido agregado (MTA Fillapex, Angelus, Londrina, Brasil) e outro à base de resina epóxica (AH Plus, Dentsply, Konstanz, Alemanha); e (2) desenvolver e avaliar propriedades físico-químicas de três cimentos endodônticos experimentais à base de MTA e uma resina de salicilato com diferentes fosfatos de cálcio (CaP). Os materiais foram manipulados de acordo com as instruções dos fabricantes. Os cimentos experimentais foram compostos de pastas bases e catalisadoras misturadas em 1:1. A pasta base foi composta de 60% de óxido de bismuto e 40% de butilenoglicol dissalicilato. Três diferentes pastas catalisadoras foram formuladas contendo: (1) 60% de MTA, 39% de Resimpol 8 e 1% de dióxido de titânio; (2) 40% de MTA, 39% de Resimpol 8, 20% de hidroxiapatita e 1% de dióxido de titânio e; (3) 40% de MTA, 39% de Resimpol 8, 20% de fosfato dibásico de cálcio diidratado e 1% de dióxido de titânio. MTA Fillapex foi usado como controle. O tempo de trabalho e escoamento foi testado de acordo com a ISO 6876:2001 e o tempo de presa de acordo com a ASTM C266 (n=3 para cada material e teste). Os materiais foram colocados em moldes de PVC (8 mm x 1,6 mm) e armazenados em recipientes contendo 20 ml (testes de solubilidade e absorção de água) ou 10 ml (ensaios de pH e liberação de cálcio) de água deionizada a 37ºC (n=10 para cada material e teste). Em 1, 7, 14 e 28 dias as amostras foram removidas dos recipientes e secas para aferiação da solubilidade e absorção de água. Após 3 e 24 horas e 4, 7, 14 e 28 dias, a água dos recipientes foi coletada para análises do pH e liberação de cálcio. Os dados foram analizados usando ANOVA um fator e teste de Tukey (5%). MTA Fillapex mostrou menores valores de escoamento e tempos de trabalho e presa em relação ao AH Plus (p<0,05). MTA Fillapex obteve os maiores valores de escoamento e tempos de trabalho e presa em comparação aos materiais experimentais (p<0,05). MTA Fillapex apresentou os menores valores de solubilidade e absorção de água (p<0,05). Todos os cimentos experimentais e o MTA Fillapex apresentaram pH básico e liberação de íons cálcio. MTA Fillapex e AH Plus mostraram valores de acordo com a ISO 6876:2001. Os materiais experimentais apresentaram propriedades físico-químicas satisfatóriasAbstract: The aims of this study were (1) to evaluate and to compare physicochemical properties of endodontic sealers, a recent calcium-silicate based sealer (MTA Fillapex, Angelus, Londrina, Brazil) and other an epoxy resin based sealer (AH Plus, Dentsply, Konstanz, Germany); and (2) to develop and to evaluate physicochemical properties of three experimental root canal sealers made by mineral trioxide aggregate (MTA) and a salicylate resin with different calcium phosphates (CaP). The materials were handled following the manufacturer's instructions. The experimental materials were composed of a base and a catalyst pastes mixed in a 1:1. The base paste was made by 60% bismuth oxide and 40% butyl ethylene glycol disalicylate. Three different catalyst pastes were formulated with: (1) 60% MTA, 39% Resimpol 8 and 1% titanium dioxide; (2) 40% MTA, 39% Resimpol 8, 20% hydroxyapatite and 1% titanium dioxide and; (3) 40% MTA, 39% Resimpol 8, 20% dibasic calcium phosphate dihydrate and 1% titanium dioxide. MTA Fillapex was used as control. The working time and flow were tested according to ISO 6876:2001 and the setting time according to ASTM C266 (n=3 for each material and test). The materials were placed into PVC molds (8 mm x 1.6 mm) and stored in containers with 20 mL (solubility and water absorption tests) or 10 mL (calcium release and hydroxyl ions tests) of deionized water at 37°C (n=10 for each material and test). At 1, 7, 14 and 28 days the samples were removed from the solutions and dry for solubility and water absorption tests. After 3 and 24 h and 4, 7, 14, 28 days the soaking water was collected for Ca and pH analysis. The data were analyzed using one-way ANOVA with Tukey's test (5%). MTA Fillapex showed lower values of flow and working and setting times when compared to AH Plus (p<.05). MTA Fillapex had the higher values of flow and working and setting times when compared to experimental materials (p<.05). MTA Fillapex presented the lowest values of solubility and water absorption (p<.05). All experimental cements and MTA Fillapex showed basifying activity and released calcium ions. MTA Fillapex and AH Plus showed values in according to the ISO 6876:2001. The experimental materials showed satisfactory physicochemical propertiesDoutoradoMateriais DentariosDoutor em Materiais Dentário

Dimensional evaluation of stone models in function of different techniques and elastomeric impression materials

Orientador: Mario Alexandre Coelho SinhoretiDissertação (mestrado) - Universidade EStadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo neste estudo foi medir e comparar a precisão dimensional de modelos de gesso confeccionados a partir de três técnicas de moldagem com dez diferentes elastômeros. Um modelo em cera, simulando um arco dental mandibular, teve retirados os dentes 44, 45 e 46 a fim de avaliar possíveis diferenças de precisão entre os lados direito e esquerdo, pelo maior volume de material de moldagem do lado direito, o que poderia acarretar em maior contração e conseqüentemente maior alteração desse lado. A partir desse modelo em cera foi obtido um modelo metálico padrão com pontos de referência nos dentes 33 (CE), 43 (CD), 37 (ME) e 47 (MD) que foi utilizado para a realização das moldagens. Foram medidas as distâncias entre os dentes CE-CD, ME-MD, CEME e CD-MD. Moldeiras metálicas de estoque foram usadas para as técnicas do reembasamento e dupla mistura. Já para a técnica da moldeira individual, moldeiras de resina acrílica foram confeccionadas com alívio interno de aproximadamente 2mm. Adesivos específicos para cada material foram usados nas moldeiras individuais, para promover adesão na moldeira. Todos os procedimentos de moldagem foram realizados em uma sala com temperatura e umidade relativa controladas. A manipulação dos materiais foi feita segundo as instruções dos fabricantes. O movimento de retirada da moldeira, após a presa do material de moldagem, foi padronizado por meio de um equipamento pneumático evitando possíveis distorções no molde. Os modelos de gesso foram vazados após trinta minutos da obtenção dos moldes, para promover a recuperação elástica dos materiais. Foram confeccionados cinco corpos-de-prova para cada marca comercial de elastômero e técnica de moldagem, totalizando cento e trinta amostras. Após 24 horas, foi feita a separação molde-modelo, sendo o modelo observado em microscópio comparador com 30x de aumento. Três leituras foram feitas em cada uma das distâncias analisadas, obtendo-se uma média que foi, posteriormente, analisada estatisticamente, por meio da análise de variância com três fatores ou com dois fatores e as médias comparadas pelo teste de Tukey (5%). Os resultados demonstraram que os silicones polimerizados por adição foram os materiais que mostraram melhores resultados de precisão dimensional dos modelos. Os silicones polimerizados por condensação apresentaram os piores resultados. Todas as distâncias mensuradas apresentaram alterações lineares negativas (contração), sendo que as distâncias ântero-posteriores (CEME e CD-MD) sofreram mais alterações quando comparadas com as distâncias transversais (CE-CD e ME-MD). Num contexto geral, não houve diferença entre as distâncias MD-CD e ME-CE. Também não foram encontradas diferenças entre as técnicas de moldagem. A precisão dos modelos de gesso foi mais afetada pelos materiais do que pela técnica de moldagem.Abstract: The aim of this study was assess and compare the dimensional accuracy of stone models made from of three impression techniques and ten different elastomeric materials. A wax model, simulating a lower dental arch, had removed the teeth 44, 45 and 46 in order to evaluate possible differences of accuracy between the right and left sides, by the bigger volume of impression material on the right side that could lead in bigger contraction and, consequently, bigger change in this side. From this wax model was obtained a metallic master model with reference points in the teeth 33 (LC), 43 (LM), 37 (RC) and 47 (RM) that was used for the accomplishment of the impressions. The distances were measured among the teeth LC-RC, LM-RM, LC-LM and RC-RM. Stock metallic trays were used for the putty/wash technique and double mix technique. For the single mix technique custom acrylic resin trays were made with internal relief of approximately 2mm. Specific adhesives for each material were used in the custom trays, to promote adhesion in the trays. All impressions procedures were made at room with temperature and relative humidity controlled. The materials handled were made following the manufacturers' instructions. The tray movement, after the impression aterial set, was standardized through of a pneumatic equipment avoiding possible distortions in the mold. The stone models were pouring after thirty minutes of the molds obtaining, to promote the materials elastic recovery. Five specimens were made for each elastomeric material commercial mark and impression technique, totaling one hundred thirty samples. After 24 hours, the separation mold/model was made, being the model observed in measuring microscope at 30x magnification. Three measurements were made in each one of the analyzed dimensions, getting a mean that was later analyzed statistically through of variance analysis three-way or two-way and the means compared by Tukey's test (5%). The results demonstrated that addition silicones were the materials that showed better results of models dimensional accuracy. The condensation silicones showed the worst results. All distances assessed showed negative linear change (contraction), being that the anteroposterior distances (LCLM and RC-RM) suffered more changes when compared with the transversal distances (LC-RC and LM-RM). In general, there wasn't difference between the distances LC-LM and RC-RM. There wasn't found differences between the impression techniques. The stone models accuracy was more affected by the materials than the impression technique.MestradoMestre em Materiais Dentário

Precisão Dimensional De Diferentes Técnicas De Moldagem De Uma Mandíbula Parcialmente Edêntulo

The purpose of this in vitro study was to assess and compare the dimensional accuracy of three impression techniques: 1-step putty/light-body, 2-step putty/light-body, and the monophase technique. Methods: A partially edentulous standard stainless steel mandibular arch cast with reference points on the teeth was used to make the impressions. The anteroposterior and transverse distances were measured. All impressions were made with a polyvinyl siloxane using stock metallic (1- and 2-step putty/light-body techniques) or acrylic resin (monophase technique) trays. The monophase impressions were made using a light-body material and the 1- and 2-step putty/light-body impressions with putty and light-body materials. After impression procedures, the accuracy of each technique was assessed measuring the stone casts (n = 5) poured from the impressions using a microscope at 30x magnification and at 0.5 µm accuracy. The data were analyzed statistically using 2-way ANOVA and Tukey's test (p&lt;0.05). Results: Stone casts made by all techniques had significantly negative linear changes (shrinkage). The anteroposterior distances showed more dimensional changes than the transverse distances. The edentulous side showed more shrinkage than the anteroposterior side. Conclusion: No differences between the impression techniques were found, but significant dimensional changes were observed.651252

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven

The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. MATERIAL AND METHODS: Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (

Bond strength of self-adhesive resin cement to dentin using different adhesion protocols

The treatment of dentin before the use of self-adhesive cements is still a crucial point to achieve the best bond strength values. The objective of this study was to evaluate the bond strength between dentin and com - posite resin using dif

Resistência à compressão, flexão e tração diametral de cimentos resinosos em tempos diferentes de armazenamento

Objetivos: O objetivo desse estudo foi avaliar a resistência à compressão, tração diametral e flexão de dois cimentos resinosos de presa dual. Métodos: foi utilizado o cimento autoadesivo RelyX U200 (3M ESPE) e o cimento convencional Variolink II (Ivoclar Vivadent). Foram confeccionados corpos de prova cilíndricos com 4mm de diâmetro x 6mm de altura para o teste de compressão, 6mm de diâmetro x 2mm de altura para o teste de tração diametral (ISO 9917-1:2007) e em forma de barra com 25mm de comprimento x 2mm de altura e largura para o teste de flexão três pontos (ISO 4049:2009). As amostras foram armazenadas por 24h (n = 10) e 45 dias (n = 10) em água destilada a 37ºC. Os testes foram realizados em uma máquina universal de ensaios EMIC (DL 2000) com uma célula de carga de 2000 Kgf para o teste de compressão e 200 Kgf para os testes de tração diametral e flexão, à uma velocidade de 0,5 mm/min. Os dados foram submetidos à análise de variância dois critérios (ANOVA) e as médias comparadas pelo teste de Tukey (5%). Resultados: os resultados mostraram valores estatisticamente similares para todas as propriedades mecânicas avaliadas entre todos os cimentos e tempos de armazenamento estudados. Conclusões: A composição química dos cimentos resinosos e o armazenamento em água por 45 dias não foram suficientes para ocasionar alterações nas propriedades mecânicas avaliadas nesse estudo

Resistência da união ao microcisalhamento de cimento resinoso e resina fluida à cerâmica de dissilicato de lítio

Objetivos: O objetivo neste estudo foi avaliar a resistência da união ao microcisalhamento de uma resina composta microhíbrida de baixa viscosidade (fluida) e de um cimento resinoso fotopolimerizável aplicados a uma cerâmica de dissilicato de lítio. Métodos: Discos de uma cerâmica de dissilicato de lítio (IPS e.max CAD, Ivoclar Vivadent) foram divididos em 2 grupos (n = 10), de acordo com material utilizado para a cimentação: cimento resinoso (Allcem Veneer, FGM) ou resina composta microhíbrida fluida (Opallis Fluida, FGM). Previamente a aplicação do material para cimentação, todas as cerâmicas receberam tratamento superficial padronizado: condicionamento com ácido fluorídrico a 10% (Condac Porcelana, FGM) por 20 s, lavagem com água por 60 s, secagem com ar por 30s e aplicação de silano (Prosil, FGM). Os materiais foram inseridos em uma matriz elastomérica (0,5 mm x 1,2 mm) sobre o bloco cerâmico. Quatro cilindros por grupo foram construídos e fotoativados por um aparelho de diodo emissor de luz (LED, Valo, Ultradent) por 40 s a uma irradiância de 1200 mW/cm2. O teste de microcisalhamento foi feito utilizando uma máquina de ensaio universal (EMIC) a uma velocidade de 0,5 mm/min. Os dados (MPa) foram submetidos ao teste de normalidade (Kolmogorov-Smirnov) e one-way ANOVA, sendo as médias comparadas pelo teste de Tukey (α=0,05). Resultados: O cimento resinoso apresentou resistência da união ao microcisalhamento estatisticamente superior à resina composta fluida (ρ=0,020). Conclusão: Melhor desempenho na união à cerâmica de dissilicato de lítio foi obtido utilizando cimento resinoso

Dimensional change of impression materials for dental prothesis using different measuring methods

The aim of this study was to verify the effectiveness of alternative techniques for measuring the linear dimensional change of molds obtained by different impression materials. A stainless-steel die containing three lines was used to get the impressions. The impression materials were handled according to the manufacturers' instructions. After gelation/polymerization time, the molds (n=12) were stored for 30 minutes and the lines were subsequently measured using: a microscope (Olympus Measuring Microscope STM; Olympus Optical Co) with a 30x magnification (MM, control group), a digital caliper (Mitutoyo Digimatic; Kawasaki) (DC) and digitization using a digital camera (Canon EOS Rebel 3Ti; Canon)  (DI). For each mold, a mean of the length of the lines was obtained. For each impression material, the difference in the length between the metallic matrix and the mold was considered as linear dimensional change (%). The data were submitted to the non-parametric Kolmogorov-Smirnov test, followed by one-way Analysis of Variance (ANOVA) for each material, and the means were compared by the Tukey test (α=0.05). The DI group promoted values of dimensional accuracy without significant differences with the control group (MM), except for the putty-body condensation silicone. The DC group showed significant differences for MM and DI groups for all impression materials tested. The DI group showed to be a reliable methodology (Standard error of the mean 10%) to measure the linear dimensional change of all impression materials. The DI group presented molds with linear dimensional change values without significant differences with MM group, except for the putty-body addition silicone. The digitization is a reliable methodology to evaluate the linear dimensional changes of molds made with impression materials, except for the putty-body elastomeric impression materials.Key words: Dimensional Measurement Accuracy; Dental impression materials; Microscopy

Polymerization depths of conventional and bulk fill composites photoactivated by different methods

The aim of this study was to evaluate the depth of cure of conventional (Filtek Z350 and Esthet-X HD) and bulk fill resins composites (Filtek bulk fill flow and SDR) using different photoactivation methods. Samples were made using five discshaped matrices (1 mm high and 8 mm central diameter) with interposed polyester strips. The samples were photoactivated using different methods [continuous high-irradiance light (LCA), continuous low-irradiance light (LCB), and soft-start (SS)], maintaining 24 J/cm² radiant exposure. After 24h, Knoop microhardness test was performed at 5 depths (surface, 1 mm, 2 mm, 3 mm and 4 mm). The Knoop microhardness were analyzed by ANOVA two-way and Tukey’s test (5%). Conventional resins presented the highest results up to 2 mm depth, except for Esthet-X photoactived by LCB, which showed significant lower Knoop hardness from 2 mm depth. Bulk fill resins photoactivated with LCA and SS had the highest results in 4 mm depth. The LCA and SS photoactivation methods produce suitable photoactivation in conventional composites up to 2 mm and bulk fill up to 4 mm depth and the bulk fill composites present higher polymerization depth than conventional composites.Keywords: Dental curing lights; hardness test; photoactivation; polymerization; resi

Light-Curing Units, Photoinitiators System, and Monomers on Physico-Mechanical Properties of Experimental Composite Resins

This study evaluated the physico-mechanical properties of experimental composite resins made with different resin matrix and light-curing units. Experimental composite groups were divided according to monomers (BisGMA + TEGDMA-BT and BisGMA + BisEMA + UDMA + TEGDMA-BBUT) and photoinitiator system (camphorquinone-CQ and 1-phenyl-1,2-propanedione-PPD). A quartz tungsten halogen (QTH) or light-emitting diode (LED) were used to light cure all materials. Knoop microhardness (n = 10) was determined using Knoop microhardness test. Compressive strength, diametral tensile strength, and Young modulus (n = 7) were obtained using a universal testing machine at crosshead speed of 1.0 mm/min. The data were submitted to a three-way ANOVA and the Tukey post-hoc test (α = 0.05). QTH presented the highest total irradiance values and similar total radiant exposure to LED. For the compressive strength test, BT-PPD light-cured with LED group showed the lowest mean value. BT-CQ light-cured with LED group exhibited the lowest diametral tensile strength results. The BBUT-composite resins presented lowest Young modulus values, with no statistical difference between light-curing units (QTH and LED) and photoinitiators system (CQ and PPD). Application of QTH or LED in BT-based composite resins with PPD photoinitiator generated suitable results regarding the physico-mechanical properties.Keywords: Biomaterials; blends; dental composites; polymerization; shrinkag