A influencia do material de revestimento sobre as propriedades fisico-quimicas das resinas acrilicas polimerizadas com energia de microondas

Tese (livre-docencia) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O efeito do material silicone para inclusão sobre as propriedades das resinas acrílicas polimerizadas em microondas é pouco conhecido Este estudo avaliou a influência de dois materiais Gesso pedra tipo III (G) e silicone para inclusão (S) sobre a dureza Knoop (MD), resistência transversal (RT) e monômero liberado em água (ML) de duas resinas (Acron MC (A) e OndaCryl (O)) polimerizadas com microondas. Foram confeccionados 144 espécimes, divididos em quatro grupos (AG, AS, OG e OS), cada um contendo 12 espécimes para cada análise. A RT foi avaliada segundo a especificação n° 12 da ADA A MD foi mensurada nos tempos 24, 48, 72 horas e 30 dias e o ML em períodos de 24 ou 48 horas, num total de 288 horas. As resinas foram polimerizadas segundo as instruções dos fabricantes. Os resultados obtidos foram submetidos à analise de variância (p=0,05). A partir dos resultados obtidos pode ser verificado que os grupos AS e OS apresentaram os maiores valores (p0,05) para MD entre os grupos estudados. Ambos os materiais estudados afetaram (p>0,05) a RT das resmas. Os autores concluem que a utilização de silicone de inclusão possibilitou polimerização adequada das resinas estudadasAbstract: Little research has been completed on silicones used for the processing of microwave acrylic resins. This study evaluated residual monomer (RM), Knoop micro hardness (MH) and transverse strength (TS) of two microwave-cured acrylic resins (Acron MC (A) and OndaCryl (O)) processed with a silicone-gypsum molding technique (S) or an all-type III gypsum one (G). 144 specimens were made and equally distributed into four groups (AG, AS, OG, OS). TS test was carried out as ADA specif. 12. MH was measured after 24, 48, 72 h and 30 days of water storage (37°C), and RM during a period of 288 h. All materials were prepared according to the manufacturer's directions. Data from all tests were analyzed using two-way ANOVA (p0.05) (AG= 105.719.1 ,45=101.817.7 00=92.118.4 05=97.219.3). It was concluded that silicone-gypsum technique is useful in the construction of dentures with the microwave acrylic resins studiedLivre DocênciaPrótese DentalLivre Docente em Clinica Odontológic

Influence of abutment collar height and implant length on stress distribution in single crowns

This in silico study evaluated the influence of the abutment collar height and implants length on the biomechanical behavior of morse taper single dental implants with different crown-to-implant ratio. Six virtual models were constructed (S11, M11, L11, S13, M13 and L13) by combining short (S: 2.5 mm), medium (M: 3.5 mm) or long (L: 4.5 mm) abutment collar heights with different implant lengths (11 or 13-mm). An upper central incisor of 11-mm height was constructed on top of each abutment. Each set was positioned in a virtual bone model and exported to analyze mathematically. A 0.60-mm mesh was created after convergence analysis and a 49 N load was applied to the cingulum of the crown at an angle of 45°. Load-generated stress distribution was analyzed in the prosthetic components according to von Mises stress criteria (σvM) and in the cortical and cancellous bone by means of shear stress (εmax). The use of longer collar abutments (L11) increased the stress on the abutment by 250% and resulted in 40% higher stresses on the screw and 92% higher cortical shear stresses compared to short collared abutments (S11). Increasing the implant length produced a slight stress reduction on cortical bone. Cancellous bone was not affected by the crown-to-implant ratio. Longer abutment collars concentrate stresses at the implant level and cortical bone by increasing the crown-to-implant ratio303238243COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES33003033008P

Short term evaluation of interocclusal distance during speech after new removable prosthesis insertion

The aim of this study was to evaluate the interocclusal distance during the pronunciation of /m/ and /s/ sounds from Portuguese Language, in partially edentulous patients before and after new partial and total prosthesis installation. The subjects were divided into two groups: Experimental group, consisting of 9 patients entirely edentate in the upper maxillary arch and classified as Kennedy Class I in the lower arch; and Control group, consisting of 9 totally dentate patients. The subjects from the first group had their worn out dentures changed and the occlusal vertical dimension (OVD) corrected. A magnetic method of jaw tracking was used to measure the interocclusal distance (mm) during pronunciation of those phonemes. Comparison between groups, by t test, showed significant difference (pO objetivo deste estudo foi avaliar a distância interoclusal durante a pronúncia dos fonemas /m/ e /s/ da Língua Portuguesa em pacientes parcialmente desdentados antes e após a instalação de novas próteses parciais inferiores e totais superiores. Os voluntários foram divididos em dois grupos: Grupo Experimental: composto por 9 pacientes totalmente desdentados na arcada dentária superior, e classificados como classe I de Kennedy na arcada dentária inferior; e Grupo Controle, composto por 9 pacientes totalmente dentados. Os voluntários do primeiro grupo tiveram suas próteses antigas substituídas e a dimensão vertical de oclusão (DVO) corrigida. O método eletromagnético do traçado dos movimentos mandibulares foi utilizado para mensurar a distância interoclusal (mm) durante a pronúncia dos referidos fonemas. A comparação dos resultados entre os grupos (teste "t") demonstrou diferença significante (

Influence of a cobalt-chromium metal framework on surface roughness and Knoop hardness of visible light-polymerized acrylic resins

Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 x 4.0 ± 0.5 mm of a microwave- (Onda Cryl), a visible light- (Triad) and a water-bath-polymerized (Clássico) (control) acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1-µm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700) and Knoop hardness (Kg/mm²) was assayed using a microhardness tester (Shimadzu HMV 2000) at distances of 50, 100, 200, 400 and 800 µm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p;0.05). Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins.Resinas acrílicas polimerizadas por luz visível têm sido indicadas para a confecção de próteses parciais removíveis. Entretanto, não há estudos determinando se a presença de estrutura metálica interfere ou não na polimerização, considerando que essa estrutura pode refletir a luz e afetar propriedades como rugosidade e dureza e, consequentemente, facilitar o acúmulo de biofilme bacteriano. O objetivo deste trabalho foi comparar os valores de rugosidade e dureza Knoop de uma resina polimerizada por luz visível com resinas acrílicas polimerizadas por microondas ou banho de água, na presença de estrutura metálica. Para tanto, trinta e seis espécimes nas dimensões de 30,0 x 4,0 ± 0,05 mm de resina acrílica polimerizada por microondas (Onda Cryl), luz visível (Triad) e banho de água (Clássico) (controle), contendo barra metálica de cobalto cromo foram preparadas. Após a polimerização, os espécimes foram acabados e polidos com lixas abrasivas de 360 a 1000 de granulação em politriz, seguidas de pasta de diamante e disco de feltro. A rugosidade foi avaliada em perfilômetro mecânico (Surfcorder SE 1700) e a dureza Knoop (Kg/mm²) em microdurômetro (Shimadzu HMV 2000) a 50, 100, 200, 400 e 800 µm de distância da barra metálica. Os valores de rugosidade e dureza Knoop foram submetidos a ANOVA a dois critérios e comparadas com os testes Tukey e Kruskal Wallis ao nível de significância de 5%. Diferenças estatisticamente significantes foram encontradas (p;0.05). Dentro das limitações deste estudo in vitro, concluiu-se que a presença de metal não influenciou nos valores de rugosidade e dureza das resinas

Environmental pH influences Candida albicans biofilms regarding its structure, virulence and susceptibility to fluconazole

Candida albicans colonizes sites with different environmental pH. However, it is unclear how these conditions can interfere on biofilms. This study aimed to evaluate the influence of environmental pH on behavior of C. albicans regarding its structure, virulence and susceptibility to fluconazole (FLZ). Minimal inhibitory concentration, minimal fungicidal concentration and time kill were used to evaluate the susceptibility to FLZ in planktonic cells under three pH values (4.0, 5.5, 7.0). These pH values were used for biofilms analysis. C. albicans ATCC 90028 was developed on poly(-methlymethacrylate) resin for 48 h. Then, 2.56 mu g/mL of FLZ was added to experimental groups for 24 h, and biofilms were analyzed by cell quantification, bioactivity, secretion of proteinases and phospholipases and structure. All data were analyzed by two-way ANOVA, followed by Tukey's test (alpha = 0.05). For planktonic cells, changes in environmental pH decreased the susceptibility to FLZ. C. albicans biofilms developed at pH 5.5 showed higher cell counts, bioactivity, bio-volume, average thickness and roughness coefficient (p 0.05), but increased secretion of proteinase and phospholipase (p < 0.05). Within the conditions studied, it was shown that environmental pH modulates the structure, virulence and susceptibility of C albicans to FLZ69-703944CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ132399/2012-1; 2006-7/30814

Influence Of Substratum Position And Acquired Pellicle On Candida Albicans Biofilm.

The purpose of this study was to evaluate the influence of the substratum position and the saliva acquired pellicle (AP) on Candida albicans biofilm development. Poly(methylmethacrylate) (PMMA) disks were fabricated and randomly allocated to experimental groups: HNP (disks placed in a horizontal position and uncoated by pellicle), VNP (disks placed in a vertical position and uncoated by pellicle), HCP (disks placed in a horizontal position and coated by pellicle), and VCP (disks placed in a vertical position and coated by pellicle). Disks were placed in a 24-well plate and a suspension of 107 cells/mL of Candida albicans was added to each well for biofilm development. The plates were aerobically incubated at 35°C. The biofilms were evaluated at 1.5 (adhesion time point), 24, 48, 72, and 96 hours. The number of viable cells was quantified in terms of the colony-forming units per milliliter (CFU/mL). Metabolic activity was measured by the XTT assay. The biofilm structure was analyzed by scanning electron microscopy. The data were analyzed by three-way ANOVA followed by Tukey's test, with significance set at 5%. The vertical groups showed less biofilm formation and lower metabolic activity than the horizontal groups (p0.05). It can be concluded that the substratum position influenced biofilm development.27369-7

Salivary pellicles equalise surfaces’ charges and modulate the virulence of candida albicans biofilm

Numerous environmental factors influence the pathogenesis of Candida biofilms and an understanding of these is necessary for appropriate clinical management. Aims To investigate the role of material type, pellicle and stage of biofilm development on the viability, bioactivity, virulence and structure of C. albicans biofilms. Methods The surface roughness (SR) and surface free energy (SFE) of acrylic and titanium discs was measured. Pellicles of saliva, or saliva supplemented with plasma, were formed on acrylic and titanium discs. Candida albicans biofilms were then generated for 1.5 h, 24 h, 48 h and 72 h. The cell viability in biofilms was analysed by culture, whilst DNA concentration and the expression of Candida virulence genes (ALS1, ALS3 and HWP1) were evaluated using qPCR. Biofilm metabolic activity was determined using XTT reduction assay, and biofilm structure analysed by Scanning Electron Microscopy (SEM). Results Whilst the SR of acrylic and titanium did not significantly differ, the saliva with plasma pellicle increased significantly the total SFE of both surface. The number of viable microorganisms and DNA concentration increased with biofilm development, not differing within materials and pellicles. Biofilms developed on saliva with plasma pellicle surfaces had significantly higher activity after 24 h and this was accompanied with higher expression of virulence genes at all periods. Conclusion Induction of C. albicans virulence occurs with the presence of plasma proteins in pellicles, throughout biofilm growth. To mitigate such effects, reduction of increased plasmatic exudate, related to chronic inflammatory response, could aid the management of candidal biofilm-related infections66129140COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP007355/2013-002012/07436-

Alteração dimensional linear de resinas para bases de próteses polimerizadas com microondas

This study examined the influence of three polymerization cycles (1: heat cure - long cycle; 2: heat cure - short cycle; and 3: microwave activation) on the linear dimensions of three denture base resins, immediately after deflasking, and 30 days after storage in distilled water at 37± 2ºC. The acrylic resins used were: Clássico, Lucitone 550 and Acron MC. The first two resins were submitted to all three polymerization cycles, and the Acron MC resin was cured by microwave activation only. The samples had three marks, and dimensions of 65 mm in length, 10 mm in width and 3 mm in thickness. Twenty-one test specimens were fabricated for each combination of resin and cure cycle, and they were submitted to three linear dimensional evaluations for two positions (A and B). The changes were evaluated using a microscope. The results indicated that all acrylic resins, regardless of the cure cycle, showed increased linear dimension after 30 days of storage in water. The composition of the acrylic resin affected the results more than the cure cycles, and the conventional acrylic resin (Lucitone 550 and Clássico) cured by microwave activation presented similar results when compared with the resin specific for microwave activation.A proposta deste estudo foi comparar as alterações dimensionais de 3 resinas submetidas à polimerização com os seguintes ciclos: 1) banho d&#146;água em 73ºC durante 12 horas - ciclo longo, 2) banho d&#146;água durante 3 horas - ciclo curto, 3) energia de microondas por 3 minutos a potência de 500 W, após armazenamento em água destilada a 37 ± 2ºC durante 30 dias. As resinas usadas foram Clássico, Lucitone 550 e Acron MC. As resinas Clássico e Lucitone 550 foram submetidas aos três ciclos, enquanto a resina Acron-MC somente ao ciclo 3. Amostras medindo 65,0 x 10,0 x 3,0 mm e com marcas iguais em três pontos eqüidistantes foram confeccionadas a partir da inclusão de matrizes de aço em gesso-pedra tipo III. Foram confeccionados 21 corpos-de-prova para cada combinação resina/ciclo de polimerização e que foram submetidos a 3 leituras para cada posição (A e B), com o auxílio do microscópio de mensuração (precisão de 0,001 mm), imediatamente após a polimerização e depois do período de imersão em água por 30 dias. Os resultados mostraram que todas as resinas, independendo do ciclo a que tenham sido submetidas e das medidas avaliadas, apresentaram expansão dimensional após terem sido mantidas em água; a composição da resina interferiu na expansão dimensional mais do que o ciclo de polimerização ao qual as resinas foram submetidas; a resina convencional, quando polimerizada com energia de microondas, apresentou alteração dimensional semelhante à resina desenvolvida para a polimerização em microondas

Salivary pellicles equalise surfaces' charges and modulate the virulence of Candida albicans biofilm

Numerous environmental factors influence the pathogenesis of Candida biofilms and an uderstanding of these is necessary for appropriate clinical management. Aims: To investigate the role of material type, pellicle and stage of biofilm development on the viability, bioactivity, virulence and structure of C. albicans biofilms. Methods: The surface roughness (SR) and surface free energy (SFE) of acrylic and titanium discs was measured. Pellicles of saliva, or saliva supplemented with plasma, were formed on acrylic and titanium discs. Candida albicans biofilms were then generated for 1.5 h, 24 h, 48 h and 72 h. The cell viability in biofilms was analysed by culture, whilst DNA concentration and the expression of Candida virulence genes (ALS1, ALS3 and HWP1) were evaluated using qPCR. Biofilm metabolic activity was determined using XTT reduction assay, and biofilm structure analysed by Scanning Electron Microscopy (SEM). Results: Whilst the SR of acrylic and titanium did not significantly differ, the saliva with plasma pellicle increased significantly the total SFE of both surface. The number of viable microorganisms and DNA concentration increased with biofilm development, not differing within materials and pellicles. Biofilms developed on saliva with plasma pellicle surfaces had significantly higher activity after 24 h and this was accompanied with higher expression of virulence genes at all periods. Conclusion: Induction of C. albicans virulence occurs with the presence of plasma proteins in pellicles, throughout biofilm growth. To mitigate such effects, reduction of increased plasmatic exudate, related to chronic inflammatory response, could aid the management of candidal biofilm-related infections