Microscópio odontológico como uma ferramenta útil para detectar foraminas na furca e no assoalho da câmara pulpar de dentes permanentes / Dental microscope as a useful tool to detect foramina in the furcation and pulp chamber floor of permanent teeth

This study assessed the influence of evaluation methods in the occurrence of foramina in the pulp chamber floor and in the furcation area of molars with complete and incomplete root formation. Methodology: A sample of 360 sound mandibular permanent molars was selected and prepared. A single experienced operator evaluated the whole sample using two methods: clinical inspection (with the naked eye) and dental microscope (at 30x magnification). Chisquare test was used to compare the detection of foramina between evaluation methods in both regions (p<0.05). Results: A limited number of specimens with foramina in the pulp chamber floor was observed, while there were more teeth with foramina in the furcation area, according both methods. The dental microscope identified significantly more molars with foramina in the furcation (p=0.000) and in the pulp chamber floor (p=0.031) than the clinical inspection. Conclusions: The presence of foramina in the furcation region is substantially greater than in the pulp chamber floor, regardless of the evaluation method. The presence of foramina is not influenced by the rhizogenesis stage. The dental microscope is an excellent tool to view dental anatomical details.

Este estudo avaliou a influência dos métodos de avaliação na ocorrência de foraminas no assoalho da câmara pulpar e na área de furca dos molares com formação radicular completa e incompleta. Metodologia: Uma amostra de 360 molares permanentes inferiores hígidos foi selecionada e preparada. Um único operador experiente avaliou toda a amostra utilizando dois métodos: exame clínico (a olho nu) e microscópio odontológico (com aumento de 30x). O teste do qui-quadrado foi utilizado para comparar a detecção de foraminas entre os métodos de avaliação em ambas as regiões (p<0,05). Resultados: Observou-se um número limitado de espécimes com foraminas no assoalho da câmara pulpar, enquanto que havia mais dentes com foraminas na área de furca, de acordo com ambos os métodos. O microscópio odontológico identificou significativamente mais molares com foraminas na furca (p=0,000) e no assoalho da câmara pulpar (p=0,031) do que na inspeção clínica. Conclusões: A presença de foraminas na região de furca é substancialmente maior do que no assoalho da câmara pulpar, independentemente do método de avaliação. A presença de foraminas não é influenciada pelo estágio de rizogênese. O microscópio odontológico é uma excelente ferramenta para ver detalhes anatômicos dentários.

Practice of physical activities is related to fine motor skills in elderly / Prática de atividades físicas estão relacionadas a motricidade fina de idosos

Objective: Evaluating the fine motor skills (M1) degree in a group of independent elders, checking its possible association with the weekly practice of physical activities. Methods: 139 independent elders of both genders, aged 60 and older, who responded to a survey about their weekly practice of physical activities and then, later on were subjected to M1 tests according to EMTI, which final scores determine each individual's M1. The elderly were categorized into two groups: 60­70 years­old and above 70 years­old. Results: the female gender was predominant in the sample. Most of the elders (46.56%) showed a M¹ Mean Normal, followed by Inferior levels (29.50%) and Superior levels (23.74%). About 6.5% of the elders do not practice any physical activity, 5% practice it once a week, 53% twice a week and 35.5% more than two times per week. It could be observed that those practicing physical activity at least three times a week have better score on the M1 test (Mann­Whitney Test; p = 0.039). On the other hand, the group older than 70 years had a worse performance (Mann­Whitney Test, p = 0.001). Conclusion: The M1 Normal Medium was the score achieved with the highest percentage in the two age groups analyzed, being the group older than 70 years the one that presented worse performance. In addition, sedentary elderly or those who report having physical activity only once a week also had the worst test results.

Objetivo: Avaliar o grau de Motricidade fina (M1) de um grupo de idosos independentes verificando a possível associação com a frequência semanal de atividade física. Métodos: 139 idosos independentes, de ambos os gêneros, com idade igual ou superior a 60 anos, que responderam um questionário relacionado a sua frequência semanal de atividade física, e, posteriormente, realizaram testes de M1 de acordo com a EMTI, cuja pontuação final determina a M1 de cada um. Os idosos foram categorizados em dois grupos: 60 a 70 anos e acima de 70 anos. Resultados: O gênero feminino foi predominante (88%) na amostra. A maioria dos idosos (46,56%) apresentaram M1 Normal Médio, seguido de níveis inferiores (29,50%) e superiores (23,74%). Em torno de 6,5% dos idosos da amostra não realizam atividade física, 5% praticam uma vez por semana, 53% duas vezes por semana e 35,5% acima de duas vezes. Foi observado que aqueles que praticam atividade física no mínimo três vezes por semana obtêm melhores pontos pelo teste de M1 (Teste Mann­Whitney; p = 0,039), já o grupo acima de 70 anos teve pior desempenho (Teste Mann­Whitney; p = 0,001). Conclusão: A M1 Normal Médio foi a classificação alcançada com maior percentual nos dois grupos etários analisados, sendo no grupo acima de 70 anos aquele que apresentou pior desempenho. Além disso, idosos sedentários ou que afirmam realizar atividade física apenas uma vez por semana também tiveram os piores resultados nos testes.

Surface change assessment of Co-Cr alloy subjected to immersion in denture cleansers

Choosing the right chemical cleanser for removable partial dentures is a challenge, because they present an acrylic and a metallic portion, which should be cleaned and not damaged. Aim: The aim of this study was to assess surface changes of cobalt chromium alloys immersed in diferente cleaners solutions: 0.05% sodium hypochlorite, 4.2% acetic acid, 0.05% sodium salicylate, sodium perborate (Corega Tabs®) and 0.2% peracetic acid. Material and Methods: One hundred and twenty circular specimens (10 mm in diameter) of two commercial available Co-Cr alloys were tested: GM 800 ® (Dentaurum) and Co-Cr® (DeguDent). The samples were randomly divided into tem experimental groups (n=10), according to the trend mark of alloy and cleaners solutions in which they were immersed, and two control groups, in which the samples of the two alloys were immersed in distilled water. Evaluations were performed through roughness measurement (rugosimeter Surftest 211, Mitutoyo), visual evaluation with stereomicroscope (Stereo Discovery 20, Carl Zeiss) and scanning electron microscope surface (JSM, 6360 SEM, JEOL), at experimental times T0 ­ before immersions, T1 - after one immersion, and T2 - after 90 immersions. Intergroup comparison for the effect of immersion in the different cleanser agents was evaluated through ANOVA/Tukey tests (p≤0.05). The effect of the time in the immersion of each alloy was evaluated by t-pared test (p≤0.05). The two alloys were compared using the t-Student test. Results: The analysis of roughness and microscopy showed that surface changes were significantly greater in groups submitted to 0.05% sodium hypochlorite after 90 immersions (T2). When comparing the two alloys, a similar behavior of roughness was observed for the cleaning agents. However, alloy GM 800® showed significant statistical difference for roughness variations in experimental times (Δ1 and Δ2), when immersed in sodium 0.05% hypochlorite. The number of exposures of the alloys to the cleaning agents showed a negative influence when using sodium hypochlorite solution. Conclusions: It is possible to conclude that 0.05% sodium hypochlorite has caused the greatest apparent damage to alloy surface. (AU)

Perception and Knowledge of Dentists in Southern Brazil Related to use of Atraumatic Restorative Treatment in the Public Health Service

Objective: To investigate the perception and knowledge of dentists regarding use of the Atraumatic Restorative Treatment (ART) in public health services of cities in the central region of Rio Grande do Sul (RS), Brazil. Material and Methods: A crosssectional study was conducted using a self-administered questionnaire with 60 dentists who work with public dentistry services. To evaluate possible associations between the use of ART and the independent variables we used the chi-square test and logistic regression models (α = 0.05). Results: Forty-four questionnaires were completed, resulting in a response rate of 73%. Of the respondents, 70.4% supported the use of ART and 81.8% reported having some training in the technique. However, 72.7% consider ART to be a temporary or urgent treatment. Professionals who do not advocate the use of ART were 76% less likely to use the technique when compared to their colleagues who defend the use of the technique (OR = 0.24, 95% CI = 0.06 to 0.98). Conclusion: While most dentists have knowledge and positive attitude towards ART, greater dissemination is required for this technique can be used effectively on the public service.

Behaviour of the Elderly with Regard to Hygiene Procedures for and Maintenance of Removable Dentures.

PURPOSE: To assess the behaviour of the elderly with regard to hygiene procedures for and maintenance of removable dentures. MATERIALS AND METHODS: 243 elderly people were interviewed using a semi-structured questionnaire, which was applied in the coverage area of Family Health Strategy in Urlandia district in the city of Santa Maria, Brazil. RESULTS: The majority of those interviewed were 60 to 69 years old, with a prevalence of women and incomplete primary school education. In general, the dentures had been worn for more than 10 years and 43.7% of them had been made by a dental prosthetic technician. More than half the study population had not received instructions on hygiene and maintenance of the dentures. CONCLUSION: This population was not aware of the importance of hygiene and maintenance of the removable dentures. It is worrying that a considerable number of elderly have sought dental prosthetic care from technicians who were not trained to promote and maintain health.

Impact of an extramural program in training dental students / Repercussões de um programa extramural na formação de estudantes de odontologia

Introduction: Extramural programs allow dental students to be trained facing the reality of people?s lives and their health needs. This study describes the experiences of an extramural program developed at the Federal University of Santa Maria, RS, Brazil. Methods: Professors and dentists participated in activities directed to a group of recyclable material collectors and their families, who are part of a singing group. The aim of the activities is to provide dental care, health promotion, health education and disease prevention. Results: Up until now, 80 people have been involved in the program. It was possible to observe that the collectors have gained confidence and self-esteem and positive changes in their behavior regarding health. The academic training was enriched by the educational, clinical and humanistic experience by interacting with the social context of the collectors. Conclusion: An endeavor to improve the health of these people has guaranteed an opportunity to train the health professional in a qualified teaching and learning environment in front of social reality.

Analysis of the effectiveness of different hygiene procedures used in dental prostheses.

PURPOSE: To compare the effectiveness of bacterial plaque removal of six denture hygiene procedures used by patients to clean their dentures. MATERIALS AND METHODS: Fifteen students randomly divided into groups G1, G2, G3, G4, G5 and G6 used maxillary intraoral appliances for 24 h without cleaning them. Afterwards, the appliances were submitted to the following procedures: P1: washing under running water for 20 s; P2 and P3: cleaning with alkaline peroxide (Corega Tabs®) for 5 and 30 min, respectively; P4: brushing with water and liquid soap for 40 s; P5: alkaline hypochlorite for 10 minutes; P6: home use chlorine solution (Q'boa® at 0.45% for 10 min), throughout a period of 6 consecutive weeks. The procedures followed a circulating scheme, so that all the appliances were submitted to all the hygiene methods studied. After the hygiene procedures, the appliances were stained, photographed and submitted to the weighing method. RESULTS: After ANOVA and Tukey's test, differences were observed: P5 = 0.73 ± 0.3 (b), P6 = 1.27 ± 0.4(b,c), P4 = 1.92 ± 0.5 (b,c), P3 = 2.24 ± 1.0 (b,c), P2 = 7.53 ± 2.5 (c) and P1 = 26.86 ± 15. 3 (a). CONCLUSION: From the results of the study, it could be concluded that the use of alkaline hypochlorite is the best way to remove bacterial plaque, followed by the home-use chlorine solution and brushing with water and liquid soap. Corega Tabs® must be used for 30 min of immersion to have a cleaning effectiveness similar to that of alkaline hypochlorite.

Evaluation of accessory furcation canals of permanent mandibular molars sing radiography and clearing / Avaliação do canal cavo-interradicular em molares inferiores permanentes através de Rx e diafanização

Purpose: To evaluate the presence of furcation canals of permanent mandibular teeth using radiography and a clearing technique. Methods: The sample comprised 344 extracted mandibular molars. The presence of furcation canals was assessed by a single trained observer using magnifying lens (4x) for the dental radiographs and a dental optical microscope (30x) for the cleared specimens. Scanning electron microscopy (SEM) was used to evaluate morphological differences in the pulp chamber floor. Results: Radiographs showed that 9% of the specimens had radiolucent areas, 2% had an image that suggested a canal, and 89% had no abnormal findings. Clearing techniques did not show any accessory canal. SEM images revealed dentin tubules in recently extracted teeth; the other specimens had small areas with dentin tubules. Conclusion: Radiography was not better than the clearing technique to diagnose furcation canals. The clearing technique can provide three-dimensional visualization of the internal tooth anatomy for in vitro studies.

Objetivo: Avaliar a presença do canal cavo-interradicular em molares inferiores permanentes através de radiografias e diafanização. Metodologia: A amostra foi constituída por 344 molares inferiores re-hidratados, preparados e armazenados individualmente em recipientes de vidro. A presença do canal cavo-interradicular foi investigada por um único operador treinado usando lupa (4x) para as radiografias e microscópio óptico odontológico (30x) para as amostras diafanizadas. Microscopia eletrônica de varredura (MEV) foi usada para verificar diferenças morfológicas do assoalho pulpar. Resultados: A análise radiográfica mostrou que 9% das amostras tinham uma zona levemente radiolúcida, 2% mostravam uma imagem sugestiva, e 89% das amostras não tinham nenhuma evidência. Pela diafanização, o canal não foi encontrado nas amostras avaliadas. Pela MEV, as amostras recém extraídas mostraram com canalículos dentinários uniformes; as demais apresentaram pequenos sítios com canalículos uniformes. Conclusão: O exame radiográfico não foi o melhor método de diagnóstico; a diafanização é um excelente método avaliativo, pois permite a visualização tridimensional da anatomia interna dental em pesquisas in vitro.

In vitro antifungal action of different substances over microwaved-cured acrylic resins.

OBJECTIVE: The presence of Candida albicans on the surfaces of denture-base acrylic resins is strongly related to the development of oral stomatitis. This study evaluated the antifungal action of different agents over microwave-cured acrylic resin without polishing specimens previously contaminated with Candida albicans. MATERIAL AND METHODS: Sixty specimens were immersed in BHI broth previously inoculated with the yeast and stored for 3 h at 37 degrees C. They were divided into 5 experimental groups (n=10): G1: 2% chlorhexidine solution (10 min); G2: 0.5% sodium hypochlorite (10 min); G3: modified sodium hypochlorite (10 min); G4: effervescent agent (5 min); G5: hydrogen peroxide 10 v (30 min). The specimens of the control group 1 (C1) were not disinfected. Ten additional specimens of the control group 2 (C2) were not infected with the yeast, aiming to check the asepsis during the experiment. The disinfection agents were neutralized and the acrylic resin specimens were immersed in BHI Broth for 24 h. Culture media turbidity was evaluated spectrophotometrically according to the transmittance degree, i.e. the higher the transmittance the stronger the antimicrobial action. Statistical analysis was performed (Kruskal-Wallis Test, p<0.05). RESULTS: The results, represented by the medians, were: G1 = 40; G2 = 100; G3 = 100; G4 = 90; G5 = 100; C1 = 40; C2 = 100. CONCLUSIONS: This in vitro study suggested that sodium hypochlorite-based substances and hydrogen peroxide are more efficient disinfectants against C. albicans than 2% chlorhexidine solution and the effervescent agent.

In vitro antifungal action of different substances over microwaved-cured acrylic resins

OBJECTIVE: The presence of Candida albicans on the surfaces of denture-base acrylic resins is strongly related to the development of oral stomatitis. This study evaluated the antifungal action of different agents over microwave-cured acrylic resin without polishing specimens previously contaminated with Candida albicans. MATERIAL AND METHODS: Sixty specimens were immersed in BHI broth previously inoculated with the yeast and stored for 3 h at 37ºC. They were divided into 5 experimental groups (n=10): G1: 2 percent chlorhexidine solution (10 min); G2: 0.5 percent sodium hypochlorite (10 min); G3: modified sodium hypochlorite (10 min); G4: effervescent agent (5 min); G5: hydrogen peroxide 10v (30 min). The specimens of the control group 1 (C1) were not disinfected. Ten additional specimens of the control group 2 (C2) were not infected with the yeast, aiming to check the asepsis during the experiment. The disinfection agents were neutralized and the acrylic resin specimens were immersed in BHI Broth for 24 h. Culture media turbidity was evaluated spectrophotometrically according to the transmittance degree, i.e. the higher the transmittance the stronger the antimicrobial action. Statistical analysis was performed (Kruskal-Wallis Test, p<0.05). RESULTS: The results, represented by the medians, were: G1 = 40; G2 = 100; G3 = 100; G4 = 90; G5 = 100; C1 = 40; C2 = 100. CONCLUSIONS: This in vitro study suggested that sodium hypochlorite-based substances and hydrogen peroxide are more efficient disinfectants against C. albicans than 2 percent chlorhexidine solution and the effervescent agent.

Evaluation of procedures employed for the maintenance of removable dentures in elderly individuals.

PURPOSE: The objective of the present study was to evaluate the behaviour of the wearers of removable dentures in relation to cleaning and maintaining the prosthesis. MATERIALS AND METHODS: Two hundred and thirty-one people were interviewed, most of whom were females, over 60 years of age and participants in the Center for Integrated Study and Support to the Elderly. RESULTS: After analysing the responses, it was verified that most people brush their dentures three times a day using dentifrice and only go to the clinician when they have a complaint. They do not receive follow-up appointments for checkups, do not use immersion cleaners for their dentures and do not remove their dentures during the night. CONCLUSIONS: It was concluded that the study sample did not receive proper orientation for the conservation of removable dentures, which may consequently reduce the useful life of dentures and cause social and functional problems.

Influência da imersão em água na porosidade de resina acrílica polimerizada por energia de microondas / Influence of water immersion on porosity of acrylic resin polymerized by microwave energy

Objetivo: Foi propósito deste trabalho avaliar se a imersão em água poderia alterar o grau de porosidade interna da resina acrílica processada em microondas. Metodologia: Foram confeccionados 50 corpos-de-prova (20x20x5mm) utilizando-se as resinas acrílicas incolores Vipi Cril® e Vipi Wave®. A polimerização do Grupo 1 (G1) foi obtida pela técnica convencional em banho de água quente (12h a 74ºC) e os grupos experimentais (G2, G3, G4 e G5) foram polimerizados por energia de microondas (ciclo de 20min a 180W, mais 5min a 540W). Os corpos-de-prova dos grupos G2 e G4 foram polimerizados imersos em água, enquanto que a polimerização dos grupos G3 e G5 ocorreu sem imersão. Todos os corpos-de-prova de resina acrílica incolor foram submetidos à avaliação visual a olho nu por um único observador calibrado, que atribuiu valores de 0 a 3 em uma escala crescente de porosidade. Resultados: Todos os corpos-de-prova receberam escore 0. A resina convencional (líquido Vipi Cril®) processada por energia de microondas não resultou em porosidade visível a olho nu. Conclusão: Os resultados permitiram concluir que não houve alteração na porosidade da resina polimerizada por energia de microondas, com ou sem imersão da mufla em água.

Purpose: The purpose of this investigation was to evaluate if immersion in water during polymerization would affect the porosity of acrylic resins polymerized by microwave energy. Methods: Fifty specimens (20x20x5mm) were fabricated with two types of colorless acrylic resin (Vipi Cril® and Vipi Wave®). Group 1 (G1) specimens were polymerized by conventional hot water bath (12h at 74ºC), and the experimental groups (G2, G3, G4 and G5) were polymerized by microwave energy (cycle of 20min at 180W, plus 5min at 540W). Groups G2 and G4 were immersed in water during the polymerization cycle in a microwave oven, and G3 and G5 were polymerized without water immersion. Specimens were subjected to visual evaluation without magnification by one calibrated observer, using a score system of porosity with values ranging from 0 to 3 in ascending order. Results: All specimens scored zero. The conventional resin (Vipi Cril liquid®) could be processed by microwave energy resulting no visible porosity. Conclusion: The results showed that immersion in water during microwave polymerization did not influence acrylic resin porosity.

Análise da rugosidade superficial de resinas acrílicas para coroas provisórias submetidas a diferentes tipos de polimento / Surface roughness analysis of temporary acrylic resin crowns submitted to different polishing methods

Neste trabalho foi avaliada a rugosidade superficial em noventa corpos-de-prova das resinas acrílicas Denkor, Vipi Cor e Duralay, submetidos ao polimento mecânico em torno de bancada, polimento mecânico com discos Sof-Lex e polimento químico (com fluido para polimento a 75 ± 2°C, por 10s). A rugosidade superficial (Ra) foi medida com um rugosimentro, sendo realizada seis leituras por corpo-de-prova, feitas em dois sentidos transversais entre si. os dois métodos mecânicos de polimento, utilizados nas três marcas de resina acrílica testadas, ofereceram resultados satisfatórios (Ra entre 0,21 e 0,37 µm). No entanto, apenas a resina acrílica Duralay apresentou lisura adequada quando polida quimicamente (Ra = 0,66 µm).

Reducing the negative effects of chemical polishing in acrylic resins by use of an additional cycle of polymerization.

STATEMENT OF PROBLEM: The chemical polishing of dentures and orthodontic appliances is an efficient and time-saving technique. However, the process may adversely affect the physical properties of resin. PURPOSE: This study evaluated the effect of an additional polymerization cycle in a microwave or water bath on the physical properties of an autopolymerized acrylic resin submitted to chemical polishing. MATERIAL AND METHODS: Control groups comprised acrylic resin specimens submitted to mechanical (group 1) and chemical (group 2) polishing. Experimental groups comprised chemically polished specimens submitted to an additional cycle of polymerization in a microwave at 450 W for 3 minutes (group 3) or in a hot water bath at 65 degrees C for 1 hour (group 4). For the residual monomer test, 10 standardized half-disc specimens (30 x 3 mm) were fabricated for each of the test groups, and daily ultraviolet spectrophotometric (206 nm) analyses were assessed for 13 days (microg/cm(2)). For transverse strength and internal Knoop hardness (KH) tests, 10 (65 x 10 x 2.5 mm) and 5 (32 x 10 x 2.5 mm) specimens were fabricated for each test group, respectively. Internal Knoop hardness (kg/mm(2)) was assessed at depths of 100, 700, and 1500 microm. Transverse strength (MPa) was measured with a 3-point bending test in a universal testing machine with a 10-kg load cell at a crosshead speed of 5 mm/min. The data were analyzed with 1-way analysis of variance, and the means were compared with Student's t test and Tukey-Kramer intervals (P<.05). RESULTS: At the end of the first day of the test, all groups showed significantly different residual monomer levels (P<.05). The groups in order of decreasing residual monomer were: group 2 (1315.7 +/- 225.5 microg/cm(2)), group 3 (848.2 +/- 150.4 microg/cm(2)), group 4 (295.1 +/- 81.6 microg/cm(2)), and group 1 (136.6 +/- 45.5 microg/cm(2)). After 13 days of water storage, the lowest residual monomer levels were recorded for group 1 (4.6 +/- 1.6 microg/cm(2)). There were no significant differences among group 2 (11.3 +/- 3.1 microg/cm(2)), group 3 (9.6 +/- 1.5 microg/cm(2)), and group 4 (12.3 +/- 1.7 microg/cm(2)). Group 1 demonstrated the highest transverse strength (78.1 +/- 6.1 MPa); the other groups were not significantly different from each other. All groups exhibited lower KH values at the 100-microm depth than at 700- and 1500-microm depths. At the latter depths, group 4 specimens demonstrated the highest hardness values (18.0 +/- 0.5 and 18.8 +/- 0.7 kg/mm(2), respectively). CONCLUSION: Within the limitations of this study, additional polymerization with hot water reduced residual monomer content of chemically polished acrylic resins on the first day. Although additional polymerization increased the internal hardness of the material, however, it did not recover the transverse strength that was decreased by the chemical polishing.

Alteraçäo dimensional linear de resinas para bases de próteses polimerizadas com microondas / Linear dimensional change of denture base resins cured by microwave activation

A proposta deste estudo foi comparar as alteraçöes dimensionais de 3 resinas submetidas à polimerizaçäo com os seguintes ciclos: 1) banho d'água em 73ºC durante 12 horas-ciclo longo, 2) banho d'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 ñ 2ºC durante 30 dias. As resinas usadas foram Clássico, Lucitone 550 e Acron MC. As resinas Clássico e Lucitone 550 foram submetidas aos três, 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 inclusäo de matrizes de aço em gesso-pedra tipo III. Foram confeccionados 21 corpos-de-prova para cada combinaçäo resina/ciclo de polimerizaçäo e que foram submetidos a 3 leituras para cada posiçäo (A e B), com auxílio do microscópio de mensuraçäo (precisäo de 0,001 mm), imediatamente após a polimerizaçäo e depois do período de imersäo 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 expansäo dimensional após terem sido mantidas em água; a composiçäo da resina interferiu na expansäo dimensional mais do que o ciclo de polimerizaçäo ao qual as resinas foram submetidas; a resina convensional, quando polimerizada com energia de microondas, apresentou alteraçäo dimensional semelhante à resina desenvolvida para a polimerizaçäo em micrrondas

Avaliaçäo in vitro da efetividade de polimerizaçäo da resina acrílica dental, ativada através de energia de microondas, quando em contato com metal / Use of microwave energy for processing acrylic resin near metal

Com o objetivo de verificar a efetividade da energia de microondas na polimerizaçäo da resina acrílica próxima ao metal, foram confeccionados 36 corpos-de-prova cilíndricos com 30,0mm de diâmetro X 4,0mm de espessura, contendo no seu interior uma sela metálica com 28,0mm X 8,0mm X 0,5mm, divididos aleatoriamente em 3 grupos e submetidos aos seguintes processamentos: G1) resina Clássico polimerizada em ciclo curto; G2) resina Acron-MC polimerizada em forno de microondas por 3 minutos a 500 W; G3) resina Clássico polimerizada em forno de microondas por 3 minutos a 500 W. Após a polimerizaçäo, cada amostra foi dividida em duas partes aproximadamente iguais, sendo que uma das partes foi utilizada para a avaliaçäo de monômero residual, enquanto a outra foi submetida aos testes de dureza e porosidade. A dosagem de monômero liberada na água durante doze dias consecutivos foi avaliada através da espectrofotometria...