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Biodegradable hydrogels have become very promising materials for a number of biomedical applications, including tissue engineering and drug delivery. For optimal tissue engineering design, the mechanical properties of hydrogels should match those of native tissues as closely as possible because these properties are known to affect the behavior and function of cells seeded in the hydrogels. At the same time, high water-contents, large mesh sizes and well-tuned degradation rates are favorable for the controlled release of growth factors and for adequate transport of nutrients through the hydrogel during tissue regeneration. With these factors in mind, the goal of this research was to develop and investigate the behavior of injectable, biodegradable hydrogels with enhanced stiffness properties that persist even at high degrees of swelling. In order to do this, degradable functionalities were incorporated into photo-crosslinkable poly(ethylene glycol) and poly(acrylic acid) hydrogels, and these two components were used to make a series of double-network hydrogels. Synthesis of the precursor macromers, photopolymerization of the hydrogels, and structural parameters of the hydrogels were analyzed. The composition and the molecular weight between crosslinks (Mc) of the hydrogel components were varied, and the degradation, swelling, thermal and mechanical properties of the hydrogels were characterized over various time scales. These properties were compared to corresponding properties of the component single-network hydrogels.

Les travaux de recherche présentés ici avaient pour objectif principal la synthèse de copolymères statistiques à base d’éthylène et d’acide acrylique (AA). Pour cela, la déprotection des groupements esters d’un copolymère statistique précurseur, le poly(éthylène-co-(tert-butyl)acrylate), a été effectuée par hydrolyse à l’aide d’iodure de triméthylsilyle. La synthèse de ce précurseur est réalisée par polymérisation catalytique en présence d’un système à base de Palladium (Pd). Le deuxième objectif a été d’étudier et de caractériser des polymères synthétisés à l’état solide et en suspension colloïdale. Plusieurs copolymères précurseurs comprenant différents pourcentages molaires en tert-butyl acrylate (4 à 12% molaires) ont été synthétisés avec succès, puis déprotégés par hydrolyse pour obtenir des poly(éthylène-coacide acrylique) (pE-co-AA) avec différentes compositions. Seuls les copolymères comprenant 10% molaire ou plus de AA sont solubles dans le Tétrahydrofurane (THF) et uniquement dans ce solvant. De telles solutions peuvent être dialysées dans l’eau, ce qui conduit à un échange lent entre cette dernière et le THF, et l’autoassemblage du copolymère dans l’eau peut ensuite être étudié. C’est ainsi qu’ont pu être observées des nanoparticules stables dans le temps dont le comportement est sensible au pH et à la température. Les polymères synthétisés ont été caractérisés par Résonance Magnétique Nucléaire (RMN) ainsi que par spectroscopie Infra-Rouge (IR), avant et après déprotection. Les pourcentages molaires d’AA ont été déterminés par combinaison des résultats de RMN et ii de titrages conductimètriques. A l’état solide, les échantillons ont été analysés par Calorimétrie différentielle à balayage (DSC) et par Diffraction des rayons X. Les solutions colloïdales des polymères pE-co-AA ont été caractérisées par Diffusion dynamique de la lumière et par la DSC-haute sensibilité. De la microscopie électronique à transmission (TEM) a permis de visualiser la forme et la taille des nanoparticules. / The first objective of this research is to synthesize random linear copolymers of ethylene and acrylic acid (AA). The synthesis relies on the deprotection of the functional groups in the copolymer’s precursor, which is represented by poly(ethylene-co-tertbutyl acrylate). The synthesis of the precursor was realized by the catalytic approach, where Pd-based catalytic systems are frequently utilized nowadays. The deprotection was carried out by hydrolysis of the ester functionality using trimethylsilyl iodide agent. The second objective is to investigate and characterize the synthesized polymers in the bulk and in colloidal solution. A set of different precursor polymers with various degrees of molar incorporation of tertbutyl acrylate (from 4 to 12 mol %) was successfully synthesized and deprotected. The resulting poly(ethylene-co-acrylic acid) copolymers were found to be soluble in tetrahydrofuran THF, when the molar incorporation of AA reaches the value of 12 and more. This aspect gave the possibility to study the self-assembly of this copolymer in aqueous medium by slow THF to water exchange (dialysis). It was found that the copolymers self-assemble into nano-sized structures and these nanoparticles remain stable in colloidal solution for extended periods of time. Moreover, it was shown that the nanoparticles formed by the discussed copolymer possess thermo- and pH-responsive behaviour. The polymers synthesized were characterized by nuclear magnetic resonance (NMR) and infrared spectroscopies (IR) before and after deprotection. The bulk samples were analyzed by conventional differential scanning calorimetry and by X-ray diffraction iv technique. The molar percentages of AA were determined using a combination of NMR and conductimetric titration. Colloidal solutions of pE-co-AA copolymers were analyzed by dynamic light scattering and high-sensitivity differential scanning calorimetry techniques. The nanoparticles formed were visualized and characterized by transmission electron microscopy.

The objectives of work presented in this thesis are to understand droplet and particle formulation processes in order to make useful polymer-polymer hybrids in aqueous dispersions and use our fundamental understanding of these processes to: 1. Improve monomer conversion as much as possible. 2. Understand impact of these processes on hybrid film properties. Specific case studies of interest under commercially feasible conditions (i.e. solids content of 50wt %) were done based on two systems namely alkyd-acrylic and polyurethane-acrylic. Miniemulsification, miniemulsion polymerisation and characterisation of hybrid latex, chemical incorporation of alkyd and polyurethane to acrylic monomers were studied in detail. We have been able to successfully synthesise and characterise hybrid latex of about 100nm in particle diameter and high solids content (50wt %) to be used in coating and adhesive applications

A higienização das próteses parciais ou totais removíveis é fundamental para a durabilidade do tratamento e prevenção de patologias orais. O objetivo deste estudo foi avaliar o efeito de agentes higienizadores de prótese na cor, corrosão e rugosidade superficial do titânio c.p., ligas metálicas e resina acrílica termopolimerizável, simulando um período de 180 dias de higienização. Espécimes em formato de discos (12 mm x 3 mm) foram confeccionados em: titânio comercialmente puro (Tritan - Ti c.p.), liga de níquel-cromo-molibdênio-titânio (Vi-Star), liga de níquel-cromo (Fit Cast-SB Plus) e liga de níquel-cromo-berílio (Fit Cast-V). Cada disco fundido foi incluído em mufla previamente preparada por matrizes retangulares de teflon (38 mm x 18 mm x 4 mm), incorporando-se o disco metálico à resina acrílica termopolimerizável. Os corpos-de-prova (n=5) foram imersos em soluções dos agentes higienizadores: hipoclorito de sódio a 0,05%, Periogard, Cepacol, pastilha Corega Tabs, pastilha Medical Interporous e pastilha Polident 3 Minute. Como controle, foi utilizada a água deionizada. Foram realizados ensaios de estabilidade de cor por meio de espectrocolorímetro (Color-guide 45/0), resistência à corrosão por meio da análise visual da presença de manchas no metal e análise da alteração de massa (balança eletrônica analítica), e rugosidade superficial por meio de rugosímetro (Surftest SJ-201P). Além disso, foi realizada análise quantitativa de liberação de íons metálicos por meio de espectrometria de massa com plasma indutivamente acoplado (ICP-MS - ELAN DRC II). Os resultados de estabilidade de cor, alteração de massa e rugosidade foram submetidos à ANOVA e teste de Tukey (p< 0,05). Quanto à estabilidade de cor da resina acrílica termopolimerizável (E), houve diferença estatisticamente significante entre o titânio c.p. e as ligas. A resina associada ao Ti c.p. apresentou menor alteração de cor, enquanto que a resina associada à Fit Cast-SB Plus apresentou a maior alteração de cor (1,33 ± 1,11 e 5,06 ± 1,96, respectivamente). Com relação à presença de manchas no metal, o hipoclorito de sódio causou manchamento nos espécimes das ligas Vi-Star e Fit Cast-V. Quando avaliada a alteração de massa (g), o Cepacol e a pastilha Corega Tabs propiciaram maior perda de massa. Entre os metais, a amostra do Ti c.p. apresentou maior perda de massa. Quanto à rugosidade (Ra, µm) da resina, o Cepacol causou maior rugosidade, enquanto que a pastilha Corega Tabs e o Periogard propiciaram maior lisura no corpo-de-prova. A resina associada ao Ti c.p. e ao Fit Cast-SB Plus apresentaram maior rugosidade. Quanto à rugosidade do metal, os produtos de imersão não influenciaram nos resultados, mas a liga Fit Cast-SB Plus apresentou maior rugosidade após a imersão. A liberação de íons mais expressiva foi constatada nas ligas Vi-Star e Fit Cast-V após a imersão na pastilha Medical Interporous. Pode-se concluir que as ligas Vi-Star e Fit Cast-V podem ser consideradas seguras para a confecção de aparelhos protéticos removíveis, mas com a condição de não utilizar o hipoclorito de sódio a 0,05% ou a pastilha Medical Interporous para a higienização, pois causaram corrosão e maior liberação de íons, respectivamente. / The hygiene care of the removable partial and complete dentures is required for the longevity of the treatment and prevention of oral diseases. The aim of this study was to evaluate the effect of denture cleansers on color, corrosion and surface roughness of the commercially pure titanium, metal alloys and heat-polymerized acrylic resin, simulating a period of 180 days of hygiene. Disk-shaped specimens (12 mm x 3 mm) had been fabricated with commercially pure titanium (Tritan - Ti c.p.), nickel-chromium-molybdenum-titanium alloy (Vi-Star), nickel-chromium alloy (Fit Cast-SB Plus) and nickel-chromium-beryllium alloy (Fit Cast-V). Each cast disc was invested in the flasks previously prepared by Teflon rectangular matrices (38 mm x 18 mm x 4 mm), incorporating the metal disk to the heat-polymerized acrylic resin. The specimens (n= 5) had been immersed in the solutions: sodium hypochlorite 0.05%, Periogard, Cepacol, Corega Tabs, Medical Interporous and Polident 3 Minute. As a control, it was used deionized water. It was accomplished assays of color stability by means of a colorimeter (Color-guide 45/0), corrosion resistance by means of visual analysis of tarnishes on the metal and mass alteration analysis (analytical electronic balance), and surface roughness by means of a surface analyzer (Surftest SJ-201P). Besides, the quantitative analysis of metal ions release was accomplished by means of inductively coupled plasma mass spectrometry (ICP-MS - ELAN DRC II). Color stability, mass alteration and roughness results were submitted to ANOVA and Tukey test (p<0.05). Considering the color stability of the heat-polymerized acrylic resin (E), there were statistically significant difference between the titanium c.p. and the alloys. The resin associated with the Ti c.p. showed lesser color alteration, whereas the resin associated with Fit Cast-SB Plus showed the higher color alteration (1,33 ± 1,11 e 5,06 ± 1,96, respectively). In relation to the presence of tarnishes on the metals, the sodium hypochlorite caused tarnishes on specimens of the Vi-Star and Fit Cast-V alloys. When evaluated the mass alteration (g), Cepacol and Corega Tabs propitiated higher weight loss. Between the metals, the Ti c.p. samples showed greater weight loss. Considering the resin roughness (Ra, µm), Cepacol caused higher roughness, whereas Corega Tabs and Periogard propitiated greater smoothness on the specimens. The resin associated with the Ti c.p. and Fit Cast-SB Plus showed higher roughness. Considering the metal roughness, the immersion products did not influence on the results, but the Fit Cast-SB Plus showed greater roughness after immersion. The ionic release most significant was with the Vi-Star and Fit Cast-V alloys after immersion in Medical Interporous. It could be concluded that the Vi-Star and Fit Cast-V alloys can be considered safe for removable prosthesis finish, but with the condition of do not use sodium hypochlorite 0.05% or Medical Interporous tablet for hygiene, because they caused corrosion and greater ionic release, respectively.

Made available in DSpace on 2014-06-11T19:28:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-25Bitstream added on 2014-06-13T18:58:04Z : No. of bitstreams: 1 pellizzaro_d_me_arafo.pdf: 501665 bytes, checksum: 45c7da463c0ecbc1bda09d0615a81f92 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A Candida albicans tem sido considerada o principal agente etiológico da estomatite protética, uma das infecções mais comumente observadas em pacientes usuários de próteses removíveis. A adesão de C. albicans à superfície das próteses é o primeiro passo para o desenvolvimento da estomatite protética. Assim, uma adequada higienização das próteses é essencial para prevenir a formação de biofilme microbiano sobre a superfície protética e, conseqüentemente, o início e propagação desta infecção. O objetivo deste estudo foi avaliar a efetividade da escovação com diferentes soluções (água destilada, dentifrício, digluconato de clorexidina a 2%, hipoclorito de sódio a 1% e Polident fresh cleanse®) na redução da viabilidade de um biofilme maduro de C. albicans, desenvolvido sobre uma resina termopolimerizável para base de prótese. Para isso, 90 corpos-de-prova circulares foram confeccionados, esterilizados e inoculados com uma suspensão de 107 células/mL de C. albicans. Para a formação do biofilme, todos os corpos-de-prova foram incubados por 48 h a 37 °C sob agitação. A seguir, os corpos-de-prova foram aleatoriamente divididos (n=9) e individualmente submetidos à escovação ou exposição por 90 s nas diferentes soluções avaliadas. Os espécimes imersos em água destilada pelo mesmo período de tempo foram utilizados como controle positivo. Para verificar a efetividade da escovação e dos agentes de limpeza, os corpos-de-prova foram submetidos à avaliação da atividade metabólica das células não removidas de C. albicans por meio do teste do XTT. Os resultados obtidos foram analisados estatisticamente pelos testes de Mann-Whitney e Kruskal-Wallis (α=0.05). A escovação com todos os agentes de limpeza apresentou redução significativamente superior (p<0,0001) na viabilidade do biofilme quando comparada à exposição dos corpos-de-prova... / The adhesion of C. albicans to surfaces is the prerequisite for occurrence of denture stomatitis, a common disease diagnosed among denture wearers. Therefore, a strict routine of denture cleansing is essential to prevent biofilm formation on the acrylic denture surface and the onset of this infection. Thus, the aim of the current study was to investigate the effectiveness of combining toothbrushing and cleansing agents (dentifrice, 2% chlorhexidine gluconate, 1% sodium hypochlorite, and Polident fresh cleanse®) in inactivating C. albicans biofilm. Circular specimens (10 x 2 mm) of acrylic resin denture base material were made, sterilized, and individually inoculated with C. albicans (1x107 colony-forming units/mL). After incubation (37 °C/48 h), the specimens were divided into 10 experimental groups (n=9): 5 subjected to toothbrushing with different cleansing agents and 4 exposed to the cleansing agents without toothbrushing. Non–cleansed specimens were used as positive controls. The viability of cells was evaluated by XTT reduction method. Mann-Whitney and Kruskal-Wallis tests were used for comparative analysis between the two methods of cleansing and the cleansing agents, respectively (α=0.05). Toothbrushing with all agents was significantly more effective (p<0.0001) in reducing biofilm viability than exposure to the cleansing agents only. Exposure to all cleansing agents reduced significantly (p<0.0001) the biofilm viability, with 2% chlorhexidine gluconate being most effective (p<0.0001). Toothbrushing with 2% chlorhexidine gluconate and 1% sodium hypochlorite resulted in 100% inactivation of the biofilm. The use of cleansing agents as an adjunct to toothbrushing is an effective method to reduce C. albicans biofilm viability on denture base resins.

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-07Bitstream added on 2014-06-13T20:37:53Z : No. of bitstreams: 1 zequetto_mm_me_araca.pdf: 764308 bytes, checksum: f9f1ab6ade3df1b1023440b60d0137eb (MD5) / Pro-Line Servicos Produtos Odontologicos Ortopedicos Ltda. / O presente trabalho avaliou a desadaptação marginal de infra-estruturas metálicas de coroas metalo-cerâmicas obtidas com técnicas de fundição convencional (T1) e rápida (T2), utilizando para inclusão os revestimentos: aglutinado por fosfato Termocast (R1) e a base de cerâmica granulada Micro Fine 1700 (R2), confeccionando padrões em cera escultura Galileo (P1) e padrões em resina acrílica Duralay (P2), com n=56, sobre um troquel metálico. Para a construção dos padrões, utilizou-se uma matriz de silicone e realizou-se a fundição com liga de Ni-Cr. Verificou-se a desadaptação marginal por meio de um microscópio comparador digital Mitutoyo em 12 diferentes pontos de cada infra-estrutura. Os dados obtidos foram submetidos à análise de variância (ANOVA) e teste de Tukey com p<0.05, demonstrando os menores valores de desadaptação marginal e, estatisticamente similares (p<0.05), em ordem crescente, para os grupos: P2R2T2 (55,4æm), P2R1T2 (55,6æm), P2R1T1 (57,4æm), P1R2T2 (59,4æm), P1R2T1 (86æm), P1R1T1(104,4æm); e os maiores valores para P1R1T2 (166,9æm) e P2R2T1 (185,3æm). Os resultados obtidos permitiram concluir que as infra-estruturas metálicas obtidas com padrões, tanto de cera quanto de resina acrílica, apresentaram valores aceitáveis em ambas as técnicas de fundição realizadas, desde que as interações e recomendações dos fabricantes dos revestimentos sejam respeitadas. / The present study evaluated the marginal unfit of metallic infrastructures of metallic-ceramic crowns obtained through the conventional (T1) and accelerated (T2) casting techniques, using for investing the investments: agglutinated by phosphate Termocast (R1) and the base of granulated ceramic Micro Fine 1700 (R2), making patterns in sculpture wax Galileo (P1) and patterns in acrylic resin Duralay (P2), with n=56, on a metallic die with shoulder in chamfer. For the construction of the patterns, a matrix of silicone was used and the casting was made with Ni-Cr alloy. The marginal unfit was verified through the comparing microscope Mitutoyo in 12 different points of each infrastructure. The values obtained were submitted to analysis of variance (ANOVA) and Tukey s test with p<0.05, showed smaller values and statistically similar, in increasing order, for the groups: P2R2T2 (55,4ìm), P2R1T2 (55,6ìm), P2R1T1 (57,4ìm), P1R2T2 (59,4ìm), P1R2T1 (86ìm), P1R1T1(104,4ìm); and the largest values for P1R1T2 (166,9ìm) and P2R2T1 (185,3ìm). Taking obtained results into account, it was possible to conclude that the metallic infrastructures obtained from patterns, of wax as well as of acrylic resin, presented acceptable values of marginal fit in both casting techniques, providing the interactions and the recommendations of the investments manufacturers are respected.

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-15Bitstream added on 2014-06-13T20:18:38Z : No. of bitstreams: 1 mazaro_jvq_me_araca.pdf: 2035782 bytes, checksum: e67d1a0017e9c678266d158062acc962 (MD5) / Universidade Estadual Paulista (UNESP) / A relação existente entre os métodos de processamento das resinas acrílicas e a espessura de resina das bases de dentaduras, bem como a associação com o tamanho e forma do arco maxilar, tem sido um assunto bastante discutido no que diz respeito à possíveis alterações no posicionamento dos dentes e selamento posterior de próteses totais maxilares. Sendo assim, o propósito desse trabalho foi avaliar a movimentação dentária que ocorre durante o processamento de próteses totais maxilares com três diferentes espessuras de base, frente a dois métodos de inclusão e submetidas à polimerização por microondas. Quarenta e duas (42) amostras foram aleatoriamente divididas em 6 grupos de 7 amostras cada, respeitando, evidentemente, a espessura da base (1,25 mm - 2,50 mm - 3,75 mm) e o tipo de revestimento em mufla (silicone e gesso pedra). Pontos foram demarcados sobre os dentes artificiais para permitir a mensuração das R ee ssum o amostras através do software AutoCad. A diferença das médias dos segmentos entre o modelo encerado e demuflado de cada grupo foi submetida à analise de variância (ANOVA) e teste de Tukey. De acordo com os resultados obtidos pode-se concluir que: todas as técnicas de processamento juntamente com as diferentes espessuras de base de prótese total avaliadas apresentaram alteração na posição dos dentes artificiais após o processamento. A técnica de inclusão com barreira de silicone foi a que apresentou as maiores alterações dimensionais, independentemente da espessura. Na análise dos segmentos, houve uma maior alteração dos segmentos A/B/C (Triângulo maior) com relação aos segmentos D/E/F (Triângulo menor). Independente do tipo de inclusão, não houve diferença estatística entre as espessuras das bases (p<0,059), entretanto, analisando o comportamento de alteração, as prótese totais com bases mais finas apresentaram maior... . / The existent relationship between the methods of processing of the acrylic resins and the thickness of dentures bases resin, as well as the association with the size and form of the maxillary arch, it has been a subject quite discussed with regard to possible alterations in the teeth positioning and maxillary complete denture postdamming. So that, the aim of the study was to evaluate the dental movement that it happens during the processing of maxillary complete dentures with three base thickness different, front of two inclusion methods and submitted to the microwaves polymerization. Forty two (42) samples were randomly divided in 6 groups of 7 samples each, respecting, evidently, the base thickness (1,25 mm - 2,50 mm - 3,75 mm) and the type in flask investment (silicone and plaster stone). Points were demarcated on the artificial teeth to allow the measurement of the samples through the AutoCad software. The averages difference of the segments between the Ab ss tt rr a cc tt waxed model and deflasked of each group was submitted to it analysis of variance (ANOVA á=0,05) and Tukey test. In agreement with the obtained results it can be conclusion that: all the processing techniques together with the different thickness of complete denture base evaluated, presented alteration in the artificial teeth positionig after the processing. The silicone flasking technique was that presented the largest dimensional alterations, independently of the thickness. In the segments analysis, there was a larger alteration of the segments A/B/C (larger Triangle) regarding the segments D/E/F (smaller Triangle). Independent of the flasking type, there was not difference statistics among the thickness of the bases (p <0,059), however, analyzing the alteration behavior, thinner bases presented larger movement in the position of the artificial teeth than thicken base that complete denture them. The completed... (Complete abstract, click electronic address below).

Resumo: A energia por microondas tem sido recomendada para desinfetar próteses totais. Entretanto, os ciclos de desinfecção podem afetar a estabilidade dimensional das bases de próteses. Assim, o objetivo deste estudo clínico foi avaliar o efeito de dois protocolos de desinfecção por microondas na estabilidade dimensional de próteses totais, analisando a estabilidade dimensional linear, o percentual de força oclusal obtido a partir dos contatos oclusais cêntricos e as ocorrências clínicas. Foram confeccionadas próteses totais para quarenta pacientes totalmente edêntulos. Todas as próteses foram prensadas com a resina Lucitone 550. Após a colocação, aguardou-se 30 dias para submeter as próteses às condições experimentais como a seguir: Grupo 1 (G1)- 20 pacientes tiveram as próteses maxilares submetidas a desinfecção por microondas (650 W / 3 minutos), uma vez por semana, durante 4 semanas. Grupo 2 (G2)- 20 pacientes tiveram as próteses maxilares submetidas a desinfecção por microondas (650 W / 3 minutos), três vezes por semana, durante 4 semanas. Para avaliar a estabilidade dimensional linear, mensurações foram realizadas entre quatro pontos de referência (primeiros pré-molares e segundos molares bilateralmente) antes da primeira desinfecção por microondas (baseline) e após cada semana de desinfecção. Um software foi utilizado para mensurar as distâncias entre os pontos de referência a partir de fotografias padronizadas. As dimensões médiolateral e anteroposterior e a área foram calculadas. Os dados foram analisados pelos testes ANOVA two-way, Tukey e t-Student (_=0,05). O sistema T-Scan III foi utilizado para avaliar o percentual de força oclusal obtido a partir dos contatos oclusais cêntricos. Os contatos oclusais cêntricos foram capturados, antes da primeira desinfecção por microondas (baseline) e após cada semana de desinfecção, por meio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Microwave energy has been recommended for disinfecting complete dentures. However, the microwave disinfection cycles may affect the dimensional stability of denture bases. Therefore, the purpose of this clinical study was to evaluate the effect of two microwave disinfection protocols on the dimensional stability of complete dentures, analyzing the linear dimensional stability, the percent occlusal force obtained from centric occlusal contacts and the clinical events. Complete dentures were constructed for forty totally edentulous patients. All dentures were conventionally processed with heat-polymerized acrylic resin (Lucitone 550). After insertion of complete dentures, it was expected 30 days to submit the dentures to the experimental conditions as follows: Group 1 (G1)- 20 patients had the maxillary complete dentures submitted to microwave disinfection (650 W/ 3 minutes), once a week, for four weeks. Group 2 (G2)- 20 patients had the maxillary complete dentures submitted to microwave disinfection (650 W/ 3 minutes), three times a week, for four weeks. To evaluate the linear dimensional stability, measurements were taken across four reference points (first premolars and second molars bilaterally) before of first microwave disinfection (baseline) and after each week of disinfection. Software was used to measure distances between reference points from standardized photographs. Mediolateral and anteroposterior dimensions and area between reference points were calculated. The dimensional data obtained were analyzed using two-way ANOVA, Tukey test and t test (_ = .05). To evaluate the percent occlusal force obtained from centric occlusal contacts, the T-Scan III system was used. The centric occlusal contacts were measured, before of first microwave disinfection (baseline) and after each week of disinfection, using pressure-sensitive sheets and studied in T-Scan software. The occlusal data... (Complete abstract click electronic access below) / Orientador: Eunice Teresinha Giampaolo / Coorientador: Marco Antonio Compagnoni / Banca: Raphael Freitas de Souza / Banca: Claudia Helena Lovato da Silva / Banca: Ana Claudia Pavarina / Banca: João Neudenir Arioli Filho / Doutor

O Brasil, à semelhança de outros países, está envelhecendo rapidamente. Os indivíduos com mais de 60 anos compõem hoje o segmento que mais cresce em termos proporcionais, mostrando um incremento da ordem de 500%, em 40 anos. A estimativa para o ano de 2020 é de que o Brasil tenha em torno de 32 milhões de indivíduos idosos, e desta população, uma parcela significativa será parcial ou totalmente desdentada, necessitando de aparelhos protéticos. Apesar da Odontologia apresentar avanços científicos notáveis na reabilitação da saúde bucal, muitos ainda usarão estes aparelhos. Sabe-se que o uso contínuo de próteses pode propiciar o desenvolvimento da estomatite protética, cuja etiologia é multifatorial, destacando-se principalmente a má higiene bucal e da prótese, e geralmente associada à presença de Candida albicans. Desta forma, há necessidade de se propor um método de desinfecção, que se mostre eficaz, que seja seguro quanto à toxicidade, que represente baixo risco ocupacional, que seja de fácil manuseio e que não interfira nas propriedades dos materiais utilizados na confecção destes aparelhos. Portanto, a proposição deste trabalho foi avaliar a influência de dois métodos de desinfecção, nas propriedades das resinas acrílicas empregadas na confecção das próteses.As propriedades avaliadas foram: resistência e módulo de flexão, resistência ao impacto Izod, microdureza Knoop, rugosidade, massa específica e grau de inchamento, grau de conversão do monômero, temperatura de transição vítrea, sorção e solubilidade. Os corpos de prova foram confeccionados de acordo com os requisitos de cada ensaio, tanto para os grupos controle (sem tratamento), quanto para os tratados (submetidos a um dos processos de desinfecção). Os tratamentos de desinfecção consistiram de: a) irradiação com energia de microondas na potência de 840 W, durante 1 minuto; b) imersão em ácido peracético durante 5 minutos. A eficácia da desinfecção foi avaliada através de ensaios microbiológicos que consistiram em verificar o crescimento no meio de cultura e na superfície do corpo de prova de Candida albicans, após a desinfecção dos corpos de prova, previamente contaminados com uma cepa conhecida do fungo (ATCC 10231). Como as resinas acrílicas são materiais muito utilizados em todas as áreas de atuação da Odontologia, o conhecimento das suas propriedades é de interesse do cirurgião-dentista. As resinas acrílicas tipo 1 (de termopolimerização), tipo 2 (quimicamente ativada) e tipo 5 (ativada por microondas) foram avaliadas neste trabalho. Os resultados mostraram que as resinas acrílicas tipo 1 e tipo 5 apresentam valores semelhantes em todas as propriedades analisadas. A resina acrílica tipo 2 apresentou valores inferiores àqueles encontrados nas tipo 1 e 5. O ciclo de polimerização com melhores resultados foi aquele proposto pelo respectivo fabricante daresina acrílica. A presença de fibras de nylon e de corante não influenciou as propriedades da resina acrílica tipo 5. Das técnicas de desinfecção, a imersão em ácido peracético apresentou os melhores resultados para todas as propriedades avaliadas ao longo do tempo de 20 meses. Por outro lado a irradiação de microondas, a longo prazo, apresentou os piores resultados para todas as propriedades avaliadas. Ambas as técnicas de desinfecção foram eficazes do ponto de vista microbiológico. Mas, para o uso prolongado, a técnica de desinfecção com ácido peracético pode ser recomendada com toda a segurança, no que diz respeito às propriedades avaliadas neste trabalho. / Brazil, similar to other countries, is aging quickly. The individuals with more than 60 years old compose today the segment that more grows in proportional terms, showing an increment of about 500% in 40 years. The estimate for 2020 is that Brazil has around 32 million elderly and a significant parcel of them will be partial or totally toothless, needing prosthetic equipments. In spite of notable scientific advance in the rehabilitation of the oral health, many people still will use these equipments. The continuous use of the prosthesis can propitiate the development of denture stomatitis, whose etiology is multifactorial, being generally, associated to the presence of fungus Candida albicans. Bad oral hygiene and prosthesis is still distinguished as factor of risk. Therefore, it very necessary for the elderly a efficient, safe and easy handling method of disinfection with low occupational risk and that doesn’t intervene with the properties of the materials used in the confection of these prosthetic equipments. The aim of this work is to evaluate the influence of two disinfection methods on the properties of acrylic resin used in the confection of dental prosthesis. Samples had been confectioned in accordance with the requirements of each test for the control groups (without treatment), as for the treated (submitted to one of the disinfection process). The evaluated properties had been resistance and module of flexure, Izod impact, Knoop microhardness, rugosity, specific mass and degree of swelling, degree of conversion of monomer, glass transition temperature, sorption and solubility. The treatments of disinfection had consisted of: a) irradiation with energy of microwaves, in the power of 840 W, during 1 min, or b) immersion in peracetic acid during 5 min. The effectiveness of the disinfection was evaluated by means of microbiological tests, in which was verified the occurrence of growth of Candida albicans through of culture and sample surface. For that, the samples were previously contaminated with one type of fungus (known as ATCC 10231) and, after, submitted to one of the two considered processes of disinfection. The work was studied the behavior of three commercial acrylic resins of dental use: acrylic resins of thermal polymerization, self-polymerization and polymerization for energy of microwaves (type 1, 2 and 5 respectively) from two different suppliers The results had shown that the acrylic resins of type 1 and type 5 presented similar values in all the analyzed properties. The acrylic resins of type 2 had also similar values in all the properties, but statistically lower than ones of type 1 and 5. The best polymerization cycle, which did not modify the resin properties, was that one considered by the respective manufacturer of the acrylic resin. The nylon fiber presence and colouring did not influence the properties of the acrylic resin of type 5. The first irradiation with microwaves significantlyincreased the evaluated properties and the first immersion in peracetic acid did not modify these properties, in comparison to the control groups. After 20 months, the immersion in peracetic acid did not modify the properties of the material, while the microwave irradiation showed alterations in some properties. Both disinfection techniques had been efficient of the microbiological point of view. On the basis of these results, can be concluded that the microwave irradiation after the polymerization of the material (first cycle), can be recommended, since it increased all the values of the evaluated properties, specially to the conversion degree monomer/polymer. Nevertheless, for prolonged use, the disinfection by means of the immersion in peracetic acid must be recommended, it is efficient for elimination of fungal microorganism and security, characterized for the maintenance of the properties of the acrylic resin evaluated in this work.