Avaliação da correlação entre o grau de instruções e qualidade de higiene de usuários de próteses totais com a presença de estomatite protética / Correlation between the level of instructions and the quality of hygiene of complete denture wearers with presence of denture stomatitis

Objetivo: Avaliar a correlação entre tempo de uso da prótese, idade do paciente, grau de instrução dos pacientes e qualidade observada da higiene das próteses totais com a presença de estomatite protética. Material e método: Foi aplicado questionário para levantamento dos dados. A presença de biofilme na superfície interna das próteses totais superiores foi inspecionada visualmente. O exame clínico da região palatina nos pacientes foi realizado para avaliar a presença de estomatite protética. Os dados foram analisados por meio dos testes de Correlação de Spearman (tempo de uso da prótese e idade do paciente x estomatite protética), U de Mann-Whitney (gênero e frequência de escovação x inflamação da mucosa; uso contínuo da prótese e instruções do cirurgião-dentista x presença de estomatite protética; instrução do cirurgião-dentista x necessidade de consultas periódicas) e Tau-B de Kendall (higiene da superfície interna da prótese x estomatite protética). Todas as análises foram feitas considerando- se α=5%. Resultados: A maioria dos pacientes não tira a prótese para dormir (91,10%) e relata higienizar esta três vezes ao dia (44,40%). Porém, a higiene das próteses foi considerada precária (53,30%). Nenhum dos fatores investigados relacionados aos relatos dos pacientes influenciou na presença/severidade da estomatite (p>0,05). Entretanto, a higiene observada internamente nas próteses foi inversamente proporcional à presença/severidade da estomatite (p<0,001). Conclusões: Não foi observada correlação entre idade, tempo de uso da prótese, grau de instrução dos pacientes e estomatite protética. Porém, a qualidade observada da higiene das próteses foi considerada precária, estando negativamente relacionada com a prevalência da estomatite protética.

Objective: To evaluate the correlation between patients denture using time, age, degree of instruction and observed quality of complete dentures with the prevalence of denture stomatitis. Material and method: It was applied a questionnaire to data collection. The biofilm in the inner surface of superior dentures were accessed visually. A clinical examination of the palatal area of the patients was performed to classify the presence of denture stomatitis. Data were analyzed by the following tests: Spearman correlation (time of prosthesis usage and patient age x denture stomatitis), Mann-Whitney U (patient gender and prosthesis hygiene x mucosal inflammation; continuous usage of prosthesis and dentist instructions x denture stomatitis; dentist instructions x periodic consult needs) and Kendall Tau-B (hygiene of internal surface of prosthesis x denture stomatitis). All analyses were done considering α=5%. Results: Most patients relate to do not remove the dentures before sleeping (91.10%) and to clean up them three times a day (44.40%), however, the overall hygiene of the dentures was considered poor (53.30%). None of the factors related to patients relates influences stomatitis presence/severity (p>0.05). However, it was found an inverse correlation between the denture surface hygiene and denture stomatitis (p<0.001). Conclusion: It was not found any correlation among patients age, denture using time and degree of instruction with denture stomatitis. However, the overall hygiene of the dentures investigated, which was considered to be poor, were negatively correlated with the denture stomatitis prevalence.

Antimicrobial activity and surface properties of an acrylic resin containing a biocide polymer.

OBJECTIVE: To evaluate the antimicrobial activity and surface properties of an acrylic resin containing the biocide polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA). BACKGROUND: Several approaches have been proposed to prevent oral infections, including the incorporation of antimicrobial agents to acrylic resins. MATERIALS AND METHODS: Specimens of an acrylic resin (Lucitone 550) were divided into two groups: 0% (control) and 10% PTBAEMA. Antimicrobial activity was assessed by adherence assay of one of the microorganisms, Staphylococcus aureus, Streptococcus mutans and Candida albicans. Surface topography was characterised by atomic force microscopy and wettability properties determined by contact angle measurements. RESULTS: Data of viable cells (log (CFU + 1)/ml) for S. aureus (control: 7.9 ± 0.8; 10%: 3.8 ± 3.3) and S. mutans (control: 7.5 ± 0.7; 10%: 5.1 ± 2.7) showed a significant decrease with 10% of PTBAEMA (Mann-Whitney, p < 0.05). For C. albicans (control: 6.6 ± 0.2; 10%: 6.6 ± 0.4), there was no significant difference between control and 10% of PTBAEMA (Kruskal-Wallis, p > 0.05). Incorporating 10% PTBAEMA increased surface roughness and decreased contact angles. CONCLUSION: Incorporating 10% PTBAEMA into acrylic resins increases wettability and roughness of acrylic resin surface; and decreases the adhesion of S. mutans and S. aureus on acrylic surface, but did not exhibit antimicrobial effect against C. albicans.

Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation

OBJECTIVES: The purpose of this study was to evaluate the antimicrobial activity of an acrylic resin combined with an antimicrobial polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA) to inhibit Staphylococcus aureus, Streptococcus mutans and Candida albicans biofilm formation. MATERIAL AND METHODS: Discs of a heat-polymerized acrylic resin were produced and divided according to PTBAEMA concentration: 0 (control), 10 and 25%. The specimens were inoculated (10(7) CFU/mL) and incubated at 37ºC for 48 h. After incubation, the wells were washed and each specimen was sonicated for 20 min. Replicate aliquots of resultant suspensions were plated at dilutions at 37ºC for 48 h. The number of colony-forming units (CFU) was counted and expressed as log (CFU+1)/mL and analyzed statistically with α=.05. RESULTS: The results showed that 25% PTBAEMA completely inhibited S. aureus and S. mutans biofilm formation. A significant reduction of log (CFU+1)/mL in count of S. aureus (control: 7.9±0.8A; 10%: 3.8±3.3B) and S. mutans (control: 7.5±0.7A; 10%: 5.1±2.7B) was observed for the group containing 10% PTBAEMA (Mann-Whitney, p<0.05). For C. albicans, differences were not significant among the groups (control: 6.6±0.2A; 10%: 6.6±0.4A; 25%: 6.4±0.1A), (Kruskal-Wallis, p>0.05, P=0.079). CONCLUSIONS: Acrylic resin combined with 10 and 25% of PTBAEMA showed significant antimicrobial activity against S. aureus and S. mutans biofilm, but it was inactive against the C. albicans biofilm.

Improving patient care: alternative rubber dam isolation methods / Melhorando o cuidado ao paciente: métodos alternativos de isolamento absoluto

Adhesive techniques are more sensitive than conventional techniques and it is mandatory to isolate the operatory . To accomplish this goal, rubber dam isolation is the gold standard procedure. In root canal treatment, use of a rubber dam is found to be the standard of care, however, it is usually abandoned by professionals as time progresses from graduation to professional life, since the prevalence of rubber dam use is found to be low in many studies. To increase the use of rubber dams, adaptations of traditional techniques have been suggested. One possible way of reducing gingival trauma and pain promoted by isolation clamps during rubber dam usage would be the application of a thin layer of a soft material between the clamp and the tooth/gingival tissue. Objective: The purpose of the present work is to present alternative methods of rubber dam isolation, thus improving patient care. Description: Two methods are described: 1- Dam Coverage Method- Clamping the rubber dam over the tooth (putting the clamp over the dam and the teeth at the same time, without including the clamped tooth in the operatory ); 2- Silicone Coverage Method: Inter positioning of a heavy (high viscosity) silicone impression material between the tooth and the clamp. Conclusions: The current authors purposed two simple methods for absolute operatory isolation using a rubber dam. These methods reduce sensitivity, provide little or no gingival trauma and better comfort to the patient during rubber dam isolation as well as in the postoperative period, thus improving patient care.

Técnicas adesivas são mais sensíveis do que as convencionais, neste contexto, isolar o campo operatório é fundamental e o isolamento absoluto é o procedimento padrão-ouro. No tratamento endodôntico, o uso de um dique de borracha é reconhecido como padrão em cuidado de atendimento, no entanto, este é geralmente abandonado com o passar do tempo. Para aumentar a utilização de diques de borracha, adaptações das técnicas tradicionais têm sido sugeridas. Uma maneira possível de reduzir o trauma e a dor gengivais promovidos por grampos de isolamento seria a aplicação de uma fina camada de um material macio entre o grampo e o tecido dentário / gengival. Objetivo: O objetivo do presente trabalho é apresentar métodos alternativos de isolamento absoluto, melhorando assim o atendimento ao paciente. Descrição: Dois métodos são descritos: 1 - Cobertura com o Dique, que consiste na apreensão do dique de borracha sobre o dente (colocando o grampo sobre o dique de borracha e os dentes, ao mesmo tempo, sem a inclusão do dente no campo operatório), 2 - Cobertura com Silicona: consiste no posicionamento da silicona de condensação ou adição do tipo massa densa (alta viscosidade) entre o dente e o grampo. Conclusões: Os autores apresentaram dois métodos simples para o isolamento absoluto do campo operatório usando um dique de borracha que podem reduzir a sensibilidade e minimizar ou até mesmo evitar o trauma gengival provocado pelos grampos de isolamento, oferecendo assim conforto para o paciente durante e após o procedimento, melhorando a qualidade do atendimento prestado ao mesmo.

Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation.

OBJECTIVES: The purpose of this study was to evaluate the antimicrobial activity of an acrylic resin combined with an antimicrobial polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA) to inhibit Staphylococcus aureus, Streptococcus mutans and Candida albicans biofilm formation. MATERIAL AND METHODS: Discs of a heat-polymerized acrylic resin were produced and divided according to PTBAEMA concentration: 0 (control), 10 and 25%. The specimens were inoculated (10(7) CFU/mL) and incubated at 37ºC for 48 h. After incubation, the wells were washed and each specimen was sonicated for 20 min. Replicate aliquots of resultant suspensions were plated at dilutions at 37ºC for 48 h. The number of colony-forming units (CFU) was counted and expressed as log (CFU+1)/mL and analyzed statistically with α=.05. RESULTS: The results showed that 25% PTBAEMA completely inhibited S. aureus and S. mutans biofilm formation. A significant reduction of log (CFU+1)/mL in count of S. aureus (control: 7.9±0.8A; 10%: 3.8±3.3B) and S. mutans (control: 7.5±0.7A; 10%: 5.1±2.7B) was observed for the group containing 10% PTBAEMA (Mann-Whitney, p<0.05). For C. albicans, differences were not significant among the groups (control: 6.6±0.2A; 10%: 6.6±0.4A; 25%: 6.4±0.1A), (Kruskal-Wallis, p>0.05, P=0.079). CONCLUSIONS: Acrylic resin combined with 10 and 25% of PTBAEMA showed significant antimicrobial activity against S. aureus and S. mutans biofilm, but it was inactive against the C. albicans biofilm.

Complete denture wearing and fractures among edentulous patients treated in university clinics.

OBJECTIVE: The prevalence of wearing and fracture of complete dentures was evaluated among edentulous patients treated in two dental schools in Brazil. BACKGROUND: Acceptance and wearing of complete dentures are related to adaptive behaviour of edentulous patients. However, one reason that could interfere with the wearing dentures is their potential to fracture, which is still a common complication in denture rehabilitation practice. MATERIAL AND METHODS: Two hundred and twenty-four edentulous patients rehabilitated with complete dentures from 2000 to 2005 in Araçatuba and Araraquara Dental School, University of State of São Paulo, were assessed in 2006 and 2007 to answer a questionnaire about wearing and fracture of their dentures. Statistical analysis were performed using Epi Info software and chi-squared test to compare maxillary and mandibular data (α = 0.05). RESULTS: Almost 26% of the patients did not wear their dentures, and among the remainder, the majority wore the maxillary denture. About 30% of the dentures were fractured, with higher prevalence in the maxillary arch (p = 0.003). CONCLUSIONS: Discontinuation of wearing dentures was quite high, especially considering the treatment which was carried out in university clinics. Prevalence of fractures was also high, greater for the maxillary denture, and was one of the main reasons for non-wearing of complete dentures.

Caracterização química e resistência à flexão de uma resina acrílica após a incorporação de um polímero com atividade antimicrobiana / Chemical characterization and flexural strength of an acrylic resin after the incorporation of a polymer with antimicrobial activity

Introdução: Resinas acrílicas com atividade antimicrobiana poderiam oferecer aos pacientes usuários de próteses parciais e totais melhorias na sua saúde oral por meio de um melhor controle de biofilme. Objetivo: O objetivo deste estudo foi caracterizar quimicamente uma resina acrílica para base protética (Onda-Cryl), à qual foi incorporado o polímero antimicrobiano 2-tert-butilaminoetil (PTBAEMA), além de avaliar a resistência à flexão dessa resina. Material e método: Foram confeccionados espécimes de formato retangular a partir da resina acrílica contendo diferentes concentrações de PTBAEMA (0,5 e 10%). A superfície dos espécimes foi avaliada por meio de ESCA para detectar a presença de grupos amina, representada por índices de nitrogênio. As análises de FTIR e DSC foram utilizadas para avaliar o processo de polimerização e a influência da incorporação de PTBAEMA na Tgda resina, respectivamente. A resistência à flexão dos espécimes foi avaliada e os resultados foram analisados por meio de análise de variância a um fator (ANOVA), seguida pelo teste HSD de Tukey (α = 0,05). Resultado: Foram observados diferentes índices de nitrogênio para os grupos 0, 5 e 10% (0, 0,85 e 5,82%, respectivamente); houve copolimerização entre a resina e o PTBAEMA, e redução da Tg após incorporação. Foram encontradas diferenças significantes para a resistência à flexão (p < 0,05) cujos resultados foram 94,7 ± 9,4A, 21,8 ± 3,4B, 13,0 ± 1,5C MPa para os grupos 0,5 e 10%, respectivamente. Conclusão: A incorporação de PTBAEMA resultou em copolimerização,presença de grupos amina na superfície dos espécimes e diminuição da Tg e da resistência à flexão.

Introduction: Acrylic resins with antimicrobial activity could offer patients complete denture and partial wearers? improvement in their oral health by means of a better control of biofilm formation. Objective: The objective of this study was chemically characterize a denture base acrylic resin (Onda-Cryl) that was incorporated the antimicrobial polymer 2-tert-butylaminoethyl (PTBAEMA) and to evaluate the flexural strength of this resin. Material and method: Rectangular specimens were from a denture base acrylic resin with different concentrations of PTBAEMA(0,5 and 10%). Specimens' surfaces were assessed by ESCA to detect the presence of amine groups, represented by nitrogen ratios. Analysis of FTIR and DSC were used to evaluate the polymerization process and the influence of the incorporation of PTBAEMA in Tg of the resin, respectively. Flexural strength was evaluated and the results were analyzed by ANOVA/Tukey HSD test (α = 0,05). Result: Different nitrogen ratios were observed for groups 0, 5 and 10% (0, 0.85 and 5.82% respectively), there was copolymerization between the resin and PTBAEMA,and reduction of Tg after incorporation of PTBAEMA. Significant differences were found for flexural strength (p < 0.05), the mean values were 94.7 ± 9.4A, 21.8 ± 3.4B, 13.0 ± 1.5C MPa for groups 0,5 and 10%, respectively.Conclusion: The incorporation of PTBAEMA resulted in copolymerization, presence of amine groups on specimens? surfaces, and in decrease of Tg and flexural strength.

Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin.

UNLABELLED: Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. OBJECTIVES: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. MATERIAL AND METHODS: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2%. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (α=0.05). RESULTS: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33% for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Significant differences were found for flexural strength (p<0.001). The mean flexural strength values were 98.3±3.9, 93.3±3.2, 83.9±2.1, 82.8±5.2, 71.2±5.1 and 17.3±3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. CONCLUSION: Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.

Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. OBJECTIVES: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. MATERIAL AND METHODS: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2 percent. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (α=0.05). RESULTS: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33 percent for groups 0, 0.5, 1.0, 1.5, 1.75, and 2 percent, respectively. Significant differences were found for flexural strength (p<0.001). The mean flexural strength values were 98.3±3.9, 93.3±3.2, 83.9±2.1, 82.8±5.2, 71.2±5.1 and 17.3±3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2 percent, respectively. CONCLUSION: Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.

Reliability of a method for evaluating porosity in denture base resins.

BACKGROUND: The method of porosity analysis by water absorption has been carried out by the storage of the specimens in pure water, but it does not exclude the potential plasticising effect of the water generating unreal values of porosity. OBJECTIVE: The present study evaluated the reliability of this method of porosity analysis in polymethylmethacrylate denture base resins by the determination of the most satisfactory solution for storage (S), where the plasticising effect was excluded. MATERIALS AND METHODS: Two specimen shapes (rectangular and maxillary denture base) and two denture base resins, water bath-polymerised (Classico) and microwave-polymerised (Acron MC) were used. Saturated anhydrous calcium chloride solutions (25%, 50%, 75%) and distilled water were used for specimen storage. Sorption isotherms were used to determine S. Porosity factor (PF) and diffusion coefficient (D) were calculated within S and for the groups stored in distilled water. anova and Tukey tests were performed to identify significant differences in PF results and Kruskal-Wallis test and Dunn multiple comparison post hoc test, for D results (α=0.05). RESULTS: For Acron MC denture base shape, FP results were 0.24% (S 50%) and 1.37% (distilled water); for rectangular shape FP was 0.35% (S 75%) and 0.19% (distilled water). For Classico denture base shape, FP results were 0.54% (S 75%) and 1.21% (distilled water); for rectangular shape FP was 0.7% (S 50%) and 1.32% (distilled water). FP results were similar in S and distilled water only for Acron MC rectangular shape (p>0.05). D results in distilled water were statistically higher than S for all groups. CONCLUSIONS: The results of the study suggest that an adequate solution for storing specimens must be used to measure porosity by water absorption, based on excluding the plasticising effect.

Atividade antimicrobiana de uma resina acrílica para base protética combinada a um polímero antimicrobiano sobre a formação de biofilme / Antimicrobial activity of a denture base acrylic resin combined with a biocide polymer on biofilm formation

Por ser considerada um ambiente propício para proliferação de microrganismos bucais e formação de biofilme, possibilitando o aparecimento de estomatite protética, a adição de um polímero com ação antimicrobiana à resina acrílica poderia favorecer a saúde bucal do paciente edentado e torná-la menos suscetível à formação de biofilmes. Dessa forma, o objetivo deste estudo foi avaliar a atividade antimicrobiana de uma resina acrílica termopolimerizável para base protética combinada ao polímero antimicrobiano poli(2 tert-butilaminoetil) metacrilato (PTBAEMA) sobre formação de biofilme de Staphyloccocus aureus, Streptococcus mutans e Candida albicans. Trinta espécimes de formato circular foram confeccionados a partir da resina acrílica termopolimerizável (Lucitone 550) e divididos em três grupos de acordo com as diferentes concentrações de PTBAEMA 0, 10 e 25%. Os espécimes foram inoculados e incubados a 37ºC por 48h. Após esse período, cada espécimes foi transferido para tubos contendo solução salina. Em seguida, foram realizadas diluições seriadas da suspensão resultante e alíquotas dessas diluições foram semeados em placas de Petri e incubadas a 37ºC por 48h. Os dados obtidos foram transformados em log(UFC+1)/ml e analisados pelos testes de Mann-Whitney e Kruskal-Wallis (α=0,05). Os resultados demonstraram que o grupo contendo 25% de PTBAEMA inibiu completamente a formação de biofilme de S. aureus e S. mutans. Uma redução significativa na contagem de log(UFC+1)ml de S. aureus (P=0,001) e S. mutans (P=0,001) para o grupo contendo 10% de PTBAEMA foi observada quando comparada aos valores encontrados nos respectivos grupos controle. Para C. albicans não foi encontrada diferença significante entre grupos contendo PTBAEMA e o grupo controle (P=0,079). Conclui-se que a resina acrílica Lucitone 550 contendo 10% e 25% de PTBAEMA apresentaram, respectivamente, um efeito bacteriostático e bactericida na formação de biofilme de S. aureus e S. mutans. Entretanto não teve efeito significante na formação de biofilme de C. albicans

Denture base acrylic resins have been shown to be reservoirs for microorganisms and are a potential to support the formation of biofilm, which may result in the development of denture stomatitis. Thus, the addition of a polymer with antimicrobial activity to the acrylic resin could inhibit biofilm growth on denture base. The aim of this study was to evaluate the antimicrobial activity of an acrylic resin combined with antimicrobial polymer poly (2-tertbutylaminoethyl) methacrylate (PTBAEMA) to inhibit biofilm formation of three species of microorganisms (Staphylococcus aureus, Streptococcus mutans and Candida albicans). Thirty discs of a heat-polymerized acrylic resin (Lucitone 550) were produced and divided into three groups, according to the concentration of PTBAEMA: 0% (control), 10% and 25%. The specimens were individually inoculated with appropriate media containing one of the tested microorganisms and incubated for 37ºC for 48h under aerobic or anaerobic conditions. After incubation, each specimen was transferred to sterile tube containing sterile distilled water. Replicate aliquots of resultant suspensions were plated at dilutions for 48h at 37ºC. After incubation, the mean microbial counts were expressed as log (CFU + 1)/mL and analyzed statistically with Denture base acrylic resins have been shown to be reservoirs for microorganisms and are a potential to support the formation of biofilm, which may result in the development of denture stomatitis. Thus, the addition of a polymer with antimicrobial activity to the acrylic resin could inhibit biofilm growth on denture base. The aim of this study was to evaluate the antimicrobial activity of an acrylic resin combined with antimicrobial polymer poly (2-tertbutylaminoethyl) methacrylate (PTBAEMA) to inhibit biofilm formation of three species of microorganisms (Staphylococcus aureus, Streptococcus mutans and Candida albicans). Thirty discs of a heat-polymerized acrylic resin (Lucitone 550) were produced and divided into three groups, according to the concentration of PTBAEMA: 0% (control), 10% and 25%. The specimens were individually inoculated with appropriate media containing one of the tested microorganisms and incubated for 37ºC for 48h under aerobic or anaerobic conditions. After incubation, each specimen was transferred to sterile tube containing sterile distilled water. Replicate aliquots of resultant suspensions were plated at dilutions for 48h at 37ºC. After incubation, the mean microbial counts were expressed as log (CFU + 1)/mL and analyzed statistically with =.05. The results showed that the group containing 25% of PTBAEMA completely inhibited biofilm formation of S. aureus and S. mutans. A significant reduction in count of log (CFU +1) ml of S. aureus (P=0.001) and S. mutans (P=0.001) was observed for the group containing 10% PTBAEMA when compared to respective control groups. For C. albicans, differences were not significant between groups containing PTBAEMA and control group (P=0.079). It was concluded that 10% and 25% of PTBAEMA showed, respectively, a bacteriostatic and bactericidal effect in biofilm formation of S. aureus and S. mutans. However, had no significant effect on biofilm formation of C. albicans Denture base acrylic resins have been shown to be reservoirs for microorganisms and are a potential to support the formation of biofilm, which may result in the development of denture stomatitis. Thus, the addition of a polymer with antimicrobial activity to the acrylic resin could inhibit biofilm growth on denture base. The aim of this study was to evaluate the antimicrobial activity of an acrylic resin combined with antimicrobial polymer poly (2-tertbutylaminoethyl) methacrylate (PTBAEMA) to inhibit biofilm formation of three species of microorganisms (Staphylococcus aureus, Streptococcus mutans and Candida albicans). Thirty discs of a heat-polymerized acrylic resin (Lucitone 550) were produced and divided into three groups, according to the concentration of PTBAEMA: 0% (control), 10% and 25%. The specimens were individually inoculated with appropriate media containing one of the tested microorganisms and incubated for 37ºC for 48h under aerobic or anaerobic conditions. After incubation, each specimen was transferred to sterile tube containing sterile distilled water. Replicate aliquots of resultant suspensions were plated at dilutions for 48h at 37ºC. After incubation, the mean microbial counts were expressed as log (CFU + 1)/mL and analyzed statistically with =.05. The results showed that the group containing 25% of PTBAEMA completely inhibited biofilm formation of S. aureus and S. mutans. A significant reduction in count of log (CFU +1) ml of S. aureus (P=0.001) and S. mutans (P=0.001) was observed for the group containing 10% PTBAEMA when compared to respective control groups. For C. albicans, differences were not significant between groups containing PTBAEMA and control group (P=0.079). It was concluded that 10% and 25% of PTBAEMA showed, respectively, a bacteriostatic and bactericidal effect in biofilm formation of S. aureus and S. mutans. However, had no significant effect on biofilm formation of C. albicans α=.05. The results showed that the group containing 25% of PTBAEMA completely inhibited biofilm formation of S. aureus and S. mutans. A significant reduction in count of log (CFU +1) ml of S. aureus (P=0.001) and S. mutans (P=0.001) was observed for the group containing 10% PTBAEMA when compared to respective control groups. For C. albicans, differences were not significant between groups containing PTBAEMA and control group (P=0.079). It was concluded that 10% and 25% of PTBAEMA showed, respectively, a bacteriostatic and bactericidal effect in biofilm formation of S. aureus and S. mutans. However, had no significant effect on biofilm formation of C. albicans

Measurement of interfacial porosity at the acrylic resin/denture tooth interface.

PURPOSE: Small pores of almost uniform shape and size are common in polymeric materials; however, significant porosity can weaken a denture base resin and promote staining, harboring of organisms such as Candida albicans, and bond failures between the artificial tooth and denture base resin. The aim of this study was to investigate the porosity at the interface of one artificial tooth acrylic resin (Trilux, copolymer of polymethyl methacrylate, ethylene glycol dimethacrylate, and color pigments) and three denture base resins: Acron MC (microwave-polymerized), Lucitone 550 (heat-polymerized), and QC-20 (heat-polymerized). MATERIALS AND METHODS: Ten specimens of each denture base resin with artificial tooth were processed. After polymerization, specimens were polished and observed under a microscope at 80x magnification. The area of each pore present between artificial tooth and denture base resin was measured using computer software, and the total area of pores per surface was calculated in millimeter square. The Kruskal-Wallis test was performed to compare porosity data (alpha= 0.05). RESULTS: Porosity analysis revealed the average number of pores (n), area range (S, mm(2)), and diameter range (d, mum) for Acron MC (n = 23, S = 0.001 to 0.0056, d = 35 to 267), Lucitone 550 (n = 13, S = 0.001 to 0.005, d = 35 to 79), and QC-20 (n = 19, S = 0.001 to 0.014, d = 35 to 133). The analyses showed that there were no statistically significant differences among the groups (p= 0.7904). CONCLUSIONS: Within the limitations of this in vitro study, it was concluded that the denture base resins evaluated did not affect porosity formation at the artificial tooth/denture base resin interface.

Evaluation of the bond strength of denture base resins to acrylic resin teeth: effect of thermocycling.

PURPOSE: The purpose of this study was to evaluate the thermocycling effects and shear bond strength of acrylic resin teeth to denture base resins. MATERIALS AND METHODS: Three acrylic teeth (Biotone, Trilux, Ivoclar) were chosen for bonding to four denture base resins: microwave-polymerized (Acron MC), heat-polymerized (Lucitone 550 and QC-20), and light-polymerized (Versyo.bond). Twenty specimens were produced for each denture base/acrylic tooth combination and were divided into two groups (n = 10): without thermocycling (control groups) and thermocycled groups submitted to 5000 cycles between 4 and 60 degrees C. Shear strength tests (MPa) were performed with a universal testing machine at a crosshead speed of 1 mm/min. Statistical analysis of the results was carried out with three-way ANOVA and Bonferroni's multiple comparisons post hoc analysis for test groups (alpha = 0.05). RESULTS: The shear bond strengths of Lucitone/Biotone, Lucitone/Trilux, and Versyo/Ivoclar specimens were significantly decreased by thermocycling, compared with the corresponding control groups (p < 0.05). The means of Acron/Ivoclar and Lucitone/Ivoclar specimens increased after thermocycling (p < 0.05). The highest mean shear bond strength value was observed with Lucitone/Biotone in the control group (14.54 MPa) and the lowest with QC-20/Trilux in the thermocycled group (3.69 MPa). CONCLUSION: Some acrylic tooth/denture base resin combinations can be more affected by thermocycling; effects vary based upon the materials used.

Determinação dos períodos de secagem e sorção de água em resina acrílica para base protética: aplicabilidade de um método de análise da porosidade / Determination of the drying and water sorption periods of denture base resins in order to apply a method for analyzing porosity

O estudo da porosidade em resina acrílica para base protética tem sido realizado por meio de diversos métodos, entre os quais o método que associa a porosidade com a sorção de água pela resina acrílica, tendo como base o Princípio de Arquimedes. A determinação do momentoexato da pesagem do espécime para a avaliação da porosidade é necessária na aplicabilidade desta metodologia. O objetivo do presente estudo consiste em determinar o tempo mínimo necessário para que ocorra a estabilização da massa do espécime de resina acrílica durante os períodos de secagem e sorção de água, em função do tipo de resina (Acron MC e Clássico), da solução de armazenamento (soluções de cloreto de cálcio anidro a 25, 50, 75% e água destilada pura) edo formato do espécime (retangular e base protética maxilar). Os espécimes foram submetidos às etapas de secagem e sorção nas diferentes soluções e pesados a cada 24 horas. A partir domomento em que a estabilização das massas foi alcançada, um período três vezes maior foi aguardado, seguindo-se as pesagens, para confirmação desse período de estabilidade. Os dadosforam descritos por meio de curvas temporais de secagem e sorção de água dos espécimes. Os resultados sugerem que os períodos de secagem e sorção de água não sofreram influência do tipo de resina acrílica e da solução de armazenamento. Apenas o formato do espécime interferiu na determinação desses períodos: para o formato retangular, o período de secagem foi de 20 dias e o período de sorção de água, 30 dias; para a base protética maxilar, esses períodos foram de 30 e 40 dias, respectivamente.

Various methods have been used to study the porosity of denture base resin, among them the method that associates porosity with water sorption by the acrylic resin, based on the Archimedes Principle. When applying this method for evaluating porosity, it is necessary todetermine the exact moment of weighing the specimen. The aim of this study was to determine the minimum time necessary for stabilization of the acrylic resin mass of the specimen to occur, during the periods of drying and water sorption, as a function of the type of acrylic resin (Acron MC and Clássico), the storage solution (25, 50, 75% anhydrous calcium chloride solutions and pure distilled water) and specimen shape (rectangular and maxillary denture base). The specimens were submitted to the drying and sorption stages in the different solutions, and weighed every 24 hours. From the time when stabilization of the masses was reached, a three times longer period was waited, during which weighing continued, to confirm this period of stability. The data weredescribed by means of temporal drying and water sorption curves of the specimens. The results suggested that the period of drying and water sorption were not influenced by the type of acrylic resin and storage solution. Only the shape of specimens interfered in the determination of these periods. For the rectangular shape, the drying period was 20, and 30 days for water sorption. For the maxillary denture base these periods were 30 and 40 days respectively.

Maxillary complete denture movement during chewing in mandibular removable partial denture wearers.

OBJECTIVES: To evaluate the pattern of maxillary complete denture movement during chewing for free-end removable partial dentures (RPD) wearers, compared to maxillary and mandibular complete denture wearers. MATERIALS AND METHODS: Eighteen edentulous participants (group I) and 10 volunteers with bilateral posterior edentulous mandibles (group II) comprised the sample. Measures of mean denture movement and its variability were obtained by a kinesiographic instrument K6-I Diagnostic System, during the mastication of bread and a polysulphide block. Data were analysed using two-way ANOVA (alpha = 0.05). RESULTS: Upper movement during chewing was significantly lower for group II, regardless of the test food. The test food did not influence the vertical or lateral position of the denture bases, but more anterior dislocation was found when polysulphide blocks were chewed. Group II presented lower intra-individual variability for the vertical axis. Vertical displacement was also more precise with bread as a test food. CONCLUSION: It can be concluded that mandibular free-end RPD wearers show smaller and more precise movements than mandibular complete denture wearers.

Bond strength of denture teeth to acrylic resin: effect of thermocycling and polymerisation methods.

BACKGROUND: Failure of bonding between acrylic resin teeth and denture base material is a considerable problem for patients who wear complete dentures. OBJECTIVE: The purpose of this study was to evaluate the bond strength between acrylic resins and resin denture teeth with different thermocycling and polymerisation methods. MATERIALS AND METHODS: Microwave-polymerised (Onda-Cryl), heat-polymerised (Clássico) and autopolymerising (Jet) acrylic resins and resin denture tooth (Biotone) were used. The acrylic resins were polymerised according to the following: (A) microwave - fast cycle, Onda-Cryl; (B) microwave - long cycle, Onda-Cryl; (C) microwave - manufacturer's cycle, Onda-Cryl; (T) water bath - long cycle, Clássico; and (Q) bench polymerisation cycle, Jet. Twenty specimens were prepared for each polymerisation method. Ten were thermocycled, and 10 did not receive thermocycling. For the purpose of the study, a shear test was used. Data were analysed with the Kruskal-Wallis test and Dunn's multiple comparisons test (p = 0.05). RESULTS: Cycles B, C and T were similar (p > 0.05), and had statistically higher bonding values than cycles A and Q (p < 0.05) for the thermocycled and non-thermocycled groups. For all cycles, there were no statistically significant differences between thermocycled and non-thermocycled groups (p > 0.05), except for cycle Q (p = 0.0038). CONCLUSION: Thermocycling decreased the bond strength, but not significantly for microwave and heat-polymerised cycles. Regarding the bond strength of denture teeth to acrylic resin, the fast microwave polymerisation cycle should be avoided when polymerising Onda-Cryl acrylic resin. In addition, Jet acrylic resin is not adequate for use in denture repair.

Análise da condição de higiene oral de pacientes usuários de prótese parcial fixa / Assessment of oral hygiene of partial fixed dentures weares

O objetivo deste estudo foi avaliar a condição de higiene oral de pacientes usuários de próteses parciaisfixas (PPFs) por meio de um questionário e exame clínico. O questionário abordava o histórico das PPFse os metodos de higiene oral empregados, e o exame clínico, o tipo de material utilizado para confecçãodas PPFs, a localização da linha cervical (LC), o índice gengival (IG) e o índice de placa (IP). O IP e o IGforam avaliados nos dentes remanescentes (G1) e nos dentes pilares da prótese (G2) conforme critériosde Lõe; para esses índices foram adotadas as medianas para análise estatística, sendo aplicado o teste deQui-quadrado. Foram avaliados 50 pacientes portadores de 65 PPFs das quais 78,5% tinham até 5 anos deuso sendo em sua maioria metalocerâmicas (64,6%). Com relação aos métodos de higiene, 58% dos pacientesutilizavam escova macia; 62% escovavam seus dentes 3 vezes/dia; 66% dos pacientes não tiveramdificuldades para higienizar após a instalação da prótese apesar de 80% não terem recebido instruçõesde higiene oral; a maioria não foi informada sobre retornos periódicos. Não houve diferença estatística significanteentre G1 e G2 com relação ao IP diferentemente da comparação entre o IG dos dois grupos, commaior inflamação gengival no G2 (p=0,0021). Coroas com linha cervical intra-sulcular apresentaram melhorIP (p=0,001) e as subgengivais pior IG (p=0,002). Concluiu-se que os pacientes usuários de PPFs apresentaramdificuldade para higienizar a prótese, evidenciando a necessidade de reforço dos métodos de higieneoral nesta região.

The aim of this study was to evaluate the oral hygienepractices of patient with fixed partial dentures(FPDs) using a questionnaire and a clinical examination.Fifty patients wearers of 65 FPDs wereevaluated. Each patient was questioned about theFPDs historical and the oral hygiene practices. Atthe clinical examination the material type of theFPDs, location of crown margins, gingival index (GI)and plaque index (PI) were recorded. The periodontalparameters of the uncrowned teeth (G1) werecompared with the abutment teeth (G2) accordingto Lõe. For these indexes the medians were usedfor statistical analysis and qui-square test was applied.Of the prostheses, 78.5% were up to 5 yearsof use; and 64.6% were metallo-ceramics.Regarding the oral hygiene practices, 66% of thepatients did not have difficulties of hygiene afterthe prosthesis insertion, although 80% of them didnot get hygiene instructions. Most of them were notinformed about regular maintenance care. The PIdid not differ between the crowned teeth (G1) andabutment teeth (G2). However G2 had significantlygreater gingival inflammation than G1 (p=.001). Intra-sulcular retainer margins showed the better PI(p=.001) and the subgingival retainer margins presentedthe worse GI (p=.002). It was concluded thatthe FPDs wearers had difficulties in the prostheseshygiene, and these findings suggest the necessityof oral hygiene reinforcement.

Flexural strength of acrylic resins polymerized by different cycles

Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico), a microwave-polymerized (Onda-Cryl) and a autopolymerizing acrylic (Jet) resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle - 500W/3 min, long - 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/3 min + 0W/3 min + 720W/3 min); T (Clássico, water bath cycle - 74ºC/9h) and Q (Jet, press chamber cycle - 50ºC/15 min at 2 bar). Ten specimens (65 x 10 x 3.3mm) were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5 percent level. The microwave-polymerized groups showed the highest means (p<0.05) for flexural strength (MPa) (A = 106.97 ± 5.31; B = 107.57 ± 3.99; C = 109.63 ± 5.19), and there were no significant differences among them. The heat-polymerized group (T) showed the lowest flexural strength means (84.40 ± 1.68), and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength.

Técnica para confecção de espécimes para teste de cisalhamento utilizando uma embutidora / A technique for fabrication specimens for shear bond test using an embedded machine

Este artigo descreve uma técnica alternativa para confecção de um espécime para teste de cisalhamento entre resina acrílica e dente artificial.

This article describes an alternative technique for fabricating a specimen for shear bond testing between acrylic resin and artificial teeth. The technique involves a special machine to embed the artificial tooth on which the acrylic resin is processed.

Flexural strength of acrylic resins polymerized by different cycles.

Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico), a microwave-polymerized (Onda-Cryl) and a autopolymerizing acrylic (Jet) resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle - 500W/3 min, long - 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/3 min + 0W/3 min + 720W/3 min); T (Clássico, water bath cycle - 74 degrees C/9h) and Q (Jet, press chamber cycle - 50 degrees C/15 min at 2 bar). Ten specimens (65 x 10 x 3.3mm) were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5% level. The microwave-polymerized groups showed the highest means (p<0.05) for flexural strength (MPa) (A = 106.97 +/- 5.31; B = 107.57 +/- 3.99; C = 109.63 +/- 5.19), and there were no significant differences among them. The heat-polymerized group (T) showed the lowest flexural strength means (84.40 +/- 1.68), and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength.