RESUMO
O cimento ósseo de polimetilmetacrilato é considerado um material padrão como carreador de antibiótico em cirurgias ortopédicas. A energia ultrassônica é um método capaz de gerar efeitos biológicos por mecanismos térmicos e não térmicos. Este estudo teve como objetivo analisar a dispersão de azul de metileno em pérolas de polimetilmetacrilato combinada com a exposição em campo acústico gerado por ultrassom não térmico. Foram utilizados 49 corpos-de-prova, cada um composto por uma pérola de polimetilmetacrilato (0,6 mm de diâmetro) dopada com azul de metileno e depositada em amostra de gelatina. Quarenta espécimes foram divididos em quatro grupos de 10 amostras com base nas intensidades de ultrassom (Grupo 1: 1,0 W/cm2; Grupo 2: 1,5 W/cm2) e profundidade (A - 2 cm; B - 3 cm) dos grânulos de polimetilmetacrilato na amostra de gelatina. Os outros nove espécimes constituíram o grupo controle. O grupo controle diferiu estatisticamente dos outros grupos. Todos os grupos irradiados com ultrassom apresentaram diferenças significativas, exceto os Grupos 2A e 2B. A dispersão de azul de metileno na gelatina entre os grupos foi: 1A> 1B; 2A> 1A; 2B> 1A; 2A> 1B; 2B> 1B. Ultrassom de baixa intensidade permitiu maior dispersão de azul de metileno com polimetilmetacrilato posicionado mais superficialmente, e não ocorreu influência da profundidade da pérola com ultrassom de alta intensidade.
Polymethylmethacrylate bone cement is a standard material used as antibiotic carrier in the orthopedic surgery. The ultrasonic energy method is capable of triggering biological effects based on both thermal and non-thermal mechanisms. The aim of the current study is to analyze methylene blue dispersion in polymethylmethacrylate beads, in association with the acoustic field generated by non-thermal ultrasound. Forty-nine specimens were used, and each specimen comprised one polymethylmethacrylate bead (0.6-mm diameter) doped with methylene blue and deposited in gelatin sample. Forty test specimens were divided into four groups comprising 10 samples, each, based on different ultrasound intensities (Group 1: 1.0 W/cm2; Group 2: 1.5 W/cm2) and polymethylmethacrylate bead depths (A - 2 cm; B - 3 cm) in gelatin sample. The control group comprised other nine specimens and statistically differed from the other groups. All groups irradiated with ultrasound have shown statistically significant differences in methylene blue dispersion, except for Groups 2A and 2B. Methylene blue dispersion in gelatin among groups was 1A> 1B; 2A> 1A; 2B> 1A; 2A> 1B; and 2B> 1B. Low-intensity ultrasound enabled the highest methylene blue dispersion when polymethylmethacrylate bead was positioned superficial; bead depth associated with high-intensity ultrasound did not influence methylene blue dispersion.
Assuntos
Azul de Metileno , Cimentos Ósseos , Fonoforese , Polimetil Metacrilato/efeitos da radiaçãoRESUMO
INTRODUCTION: While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. OBJECTIVE: The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials. MATERIAL AND METHODS: Thirty two specimens (32 mm x 10 mm x 2.5 mm) from polyamide (Valplast) and PMMA (Vertex Rapid Simplified) denture base materials were made. Eight specimens from each material were immersed in distilled water (control) and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE*) and translucency parameter (TP) were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%. RESULTS: Data analysis showed significant changes in length at baseline with an increasing number of cycles (p<0.05) and a significant interaction of cycle-material (p<0.001). The ΔΕ* parameter was significantly higher with a higher number of cycles (p<0.001), but it did not vary between materials (p>0.05). TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001). CONCLUSIONS: The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.
Assuntos
Bases de Dentadura , Micro-Ondas , Nylons/efeitos da radiação , Polimetil Metacrilato/efeitos da radiação , Pigmentação em Prótese , Análise de Variância , Cor , Colorimetria/métodos , Desinfecção/instrumentação , Desinfecção/métodos , Interferometria/métodos , Teste de Materiais , Nylons/química , Polimetil Metacrilato/química , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Fatores de Tempo , Água/químicaRESUMO
Abstract While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. Objective The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials. Material and Methods Thirty two specimens (32 mm x 10 mm x 2.5 mm) from polyamide (Valplast) and PMMA (Vertex Rapid Simplified) denture base materials were made. Eight specimens from each material were immersed in distilled water (control) and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE*) and translucency parameter (TP) were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%. Results Data analysis showed significant changes in length at baseline with an increasing number of cycles (p<0.05) and a significant interaction of cycle-material (p<0.001). The ΔΕ* parameter was significantly higher with a higher number of cycles (p<0.001), but it did not vary between materials (p>0.05). TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001). Conclusions The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.
Assuntos
Pigmentação em Prótese , Polimetil Metacrilato/efeitos da radiação , Bases de Dentadura , Micro-Ondas , Nylons/efeitos da radiação , Valores de Referência , Propriedades de Superfície , Fatores de Tempo , Teste de Materiais , Água/química , Desinfecção/instrumentação , Desinfecção/métodos , Reprodutibilidade dos Testes , Análise de Variância , Cor , Colorimetria/métodos , Polimetil Metacrilato/química , Interferometria/métodos , Nylons/químicaRESUMO
The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow-U (SDR), Tetric EvoCeram Bulk Fill-IVA (TEC) or Esthet-X HD-B1 (EHD), and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB) at the bottom of specimen stacks. Vickers hardness (VH) was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/ß)] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of ß, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.
Assuntos
Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária , Cura Luminosa de Adesivos Dentários/métodos , Análise de Variância , Testes de Dureza , Modelos Lineares , Teste de Materiais , Polimerização , Polimetil Metacrilato/química , Polimetil Metacrilato/efeitos da radiação , Doses de Radiação , Valores de Referência , Cimentos de Resina/química , Cimentos de Resina/efeitos da radiação , Propriedades de Superfície/efeitos da radiação , Fatores de TempoRESUMO
Abstract The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow-U (SDR), Tetric EvoCeram Bulk Fill-IVA (TEC) or Esthet-X HD-B1 (EHD), and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB) at the bottom of specimen stacks. Vickers hardness (VH) was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β)] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.
Assuntos
Resinas Compostas/efeitos da radiação , Resinas Compostas/química , Cura Luminosa de Adesivos Dentários/métodos , Lâmpadas de Polimerização Dentária , Doses de Radiação , Valores de Referência , Propriedades de Superfície/efeitos da radiação , Fatores de Tempo , Teste de Materiais , Modelos Lineares , Análise de Variância , Cimentos de Resina/efeitos da radiação , Cimentos de Resina/química , Polimetil Metacrilato/efeitos da radiação , Polimetil Metacrilato/química , Polimerização , Testes de DurezaRESUMO
PURPOSE: To determine the dimensional stability of a poly(methyl methacrylate) (PMMA) acrylic resin when subjected to multiple sessions of repeated microwave irradiation at power settings of 700 and 420 W. MATERIALS AND METHODS: Twenty standardized denture bases were fabricated using a PMMA resin. Points of measurement were marked on each denture base with a standardized template, and the distances between points were recorded using a digital microscope. The denture bases were randomly placed into two experimental groups of 10 bases each. Individual denture bases were placed into a glass beaker containing 200 ml of room temperature deionized water and then exposed to either 700 or 420 W of microwave radiation for 3 minutes. The denture bases were allowed to cool to room temperature, and measurements between points were recorded. This process was carried out for two microwave periods with measurements being completed after each period. The data were then analyzed for any significant changes in distances between points using a Student's t-test. RESULTS: All denture bases experienced 1.0 to 2.0 mm or approximately 3% linear dimensional change after each period of microwaving. Results were significant with all t-tests having values of p < 0.05. CONCLUSION: This report showed that the denture bases deformed significantly under experimental conditions at either 700 W for 3 minutes in 200 ml of water or 420 W for 3 minutes in 200 ml of water.
Assuntos
Resinas Acrílicas/efeitos da radiação , Materiais Dentários/efeitos da radiação , Bases de Dentadura , Dentaduras , Resinas Acrílicas/química , Resinas Acrílicas/uso terapêutico , Materiais Dentários/química , Materiais Dentários/uso terapêutico , Humanos , Micro-Ondas , Polimetil Metacrilato/química , Polimetil Metacrilato/efeitos da radiação , Polimetil Metacrilato/uso terapêuticoRESUMO
BACKGROUND: The microwave energy is an efficient disinfection method; however, it can generate high temperatures that can result in distortion of the dentures. OBJECTIVES: To evaluate whether the addition of an enzymatic cleanser to microwave disinfection regimen would disinfect dentures with shorter irradiation time. MATERIALS AND METHODS: Seven resin discs colonized with Candida albicans biofilm were placed on the palatal surface of sterile dentures to be randomly assigned to the following treatments: immersion in distilled water for 3 min with 0 (DW), 1 (DW + M1), 2 (DW + M2), or 3 min (DW + M3) of microwave irradiation; or immersion in denture cleanser for 3 min with 0 (DC), 1 (DC + M1), 2 (DC + M2) or 3 min (DC + M3) of irradiation. After the treatments, the viable cells were counted by a blinded examiner. The temperature was measured immediately after irradiation. The data were analyzed by ANOVA and Tukey post hoc tests (α = 0.05). RESULTS: No viable cells were found after DC + M2, DC + M3, and DW + M3 treatments, of which DC + M2 achieved the lowest temperature. No significant difference was found between the effectiveness of DW, DW + M1 and DC treatments (p > 0.05). CONCLUSION: Within the limits of this study, the association of a denture cleanser and microwave energy is efficient to disinfect dentures in lower irradiation time and temperature.
Assuntos
Desinfetantes de Equipamento Odontológico/uso terapêutico , Higienizadores de Dentadura/uso terapêutico , Dentaduras , Desinfecção/métodos , Micro-Ondas/uso terapêutico , Resinas Acrílicas/química , Resinas Acrílicas/efeitos da radiação , Biofilmes/efeitos dos fármacos , Biofilmes/efeitos da radiação , Candida albicans/efeitos dos fármacos , Candida albicans/efeitos da radiação , Contagem de Colônia Microbiana , Temperatura Alta , Humanos , Teste de Materiais , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Polimetil Metacrilato/química , Polimetil Metacrilato/efeitos da radiação , Propriedades de Superfície , Fatores de Tempo , Água/químicaRESUMO
OBJECTIVE: The aim of the study was to evaluate the effect of long-term disinfection procedures on the Vickers hardness (VHN) of acrylic resin denture teeth. MATERIAL AND METHODS: Five acrylic resin denture teeth (Vipi Dent Plus-V, Trilux-T, Biolux-B, Postaris-P and Artiplus-A) and one composite resin denture teeth (SR-Orthosit-O) were embedded in heat-polymerised acrylic resin within polyvinylchloride tubes. Specimens were stored in distilled water at 37°C for 48 h. Measurements of hardness were taken after the following disinfection procedures: immersion for 7 days in 4% chlorhexidine gluconate or in 1% sodium hypochlorite (CIm and HIm group, respectively) and seven daily cycles of microwave sterilisation at 650 W for 6 min (MwS group). In the WIm group, specimens were maintained in water during the time used to perform the disinfection procedures (7 days). Data were analysed with anova followed by the Bonferroni procedure (α = 0.01). RESULTS: Microwave disinfection decreased the hardness of all acrylic resin denture teeth (p < 0.001). Immersion for 7 days in 4% chlorhexidine gluconate or distilled water had significant effect on the hardness of the acrylic resin denture teeth A (p < 0.01), and 1% sodium hypochlorite on teeth T (p < 0.01). All disinfection procedures decrease the hardness of the composite resin denture teeth (p < 0.01). Teeth O exhibited the highest and teeth V the lowest hardness values in the control group (p < 0.01). CONCLUSIONS: Disinfection procedures changed the hardness of resin denture teeth.
Assuntos
Resinas Acrílicas/química , Materiais Dentários/química , Desinfecção/métodos , Dente Artificial , Resinas Acrílicas/efeitos da radiação , Clorexidina/análogos & derivados , Clorexidina/farmacologia , Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Desinfetantes de Equipamento Odontológico/química , Materiais Dentários/efeitos da radiação , Dureza , Humanos , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Micro-Ondas/uso terapêutico , Polimetil Metacrilato/química , Polimetil Metacrilato/efeitos da radiação , Poliuretanos/química , Poliuretanos/efeitos da radiação , Doses de Radiação , Hipoclorito de Sódio/química , Esterilização/métodos , Temperatura , Fatores de Tempo , Água/químicaRESUMO
PURPOSE: This study evaluated the cumulative effects of different microwave power levels on the physical properties of two poly(methylmethacrylate) (PMMA) denture base resins. MATERIALS AND METHODS: Eight sets of four PMMA specimens each (two polymerized in a water bath and two using microwave energy) were immersed in beakers containing 200 ml of distilled water. Each beaker was subjected to microwave irradiation for 3 minutes at a power level of 450,630, or 900 W. The surface roughness, surface hardness, linear stability, flexural strength, elastic modulus, impact strength, and fractographic properties were evaluated after either 6 or 36 simulated disinfection cycles. The data were statistically analyzed using ANOVA and the Tukey post hoc test (α= 0.05). RESULTS: The polymerization method did not influence any property (p > 0.05) except linear stability. The surface roughness (p < 0.001) and hardness (p= 0.011) increased after 36 irradiation cycles at 630 or 900 W. The resin polymerized using microwave energy exhibited greater linear distortion (p= 0.012), and there was a cumulative effect on linear stability for both resins (p < 0.001). No significant change (p > 0.05) was observed in flexural strength; however, the elastic modulus decreased (p= 0.008) after 36 disinfection cycles. The impact strength and crack propagation angles displayed no significant differences (p > 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that microwave disinfection at 450 W to 630 W for 3 minutes is safe for PMMA.
Assuntos
Bases de Dentadura , Desinfecção/métodos , Micro-Ondas , Polimetil Metacrilato/efeitos da radiação , Análise do Estresse Dentário , Módulo de Elasticidade , Dureza , Teste de Materiais , Maleabilidade , Polimerização , Propriedades de SuperfícieRESUMO
PURPOSE: This study evaluated the effect of different concentrations of ethanol on hardness, roughness, flexural strength, and color stability of a denture base material using a microwave-processed acrylic resin as a model system. MATERIALS AND METHODS: Sixty circular (14 x 4 mm) and 60 rectangular microwave-polymerized acrylic resin specimens (65 x 10 x 3 mm(3)) were employed in this study. The sample was divided into six groups according to the ethanol concentrations used in the immersion solution, as follows: 0% (water), 4.5%, 10%, 19%, 42%, and 100%. The specimens remained immersed for 30 days at 37 degrees C. The hardness test was performed by a hardness tester equipped with a Vickers diamond penetrator, and a surface roughness tester was used to measure the surface roughness of the specimens. Flexural strength testing was carried out on a universal testing machine. Color alterations (DeltaE) were measured by a portable spectrophotometer after 12 and 30 days. Variables were analyzed by ANOVA/Tukey's test (alpha= 0.05). RESULTS: For the range of ethanol-water solutions for immersion (water only, 4.5%, 10%, 19.5%, 42%, and 100%), the following results were obtained for hardness (13.9 +/- 2.0, 12.1 +/- 0.7, 12.9 +/- 0.9, 11.2 +/- 1.5, 5.7 +/- 0.3, 2.7 +/- 0.5 VHN), roughness (0.13 +/- 0.01, 0.15 +/- 0.07, 0.13 +/- 0.05, 0.13 +/- 0.02, 0.23 +/- 0.05, 0.41 +/- 0.19 mum), flexural strength (90 +/- 12, 103 +/- 18, 107 +/- 16, 90 +/- 25, 86 +/- 22, 8 +/- 2 MPa), and color (0.8 +/- 0.6, 0.8 +/- 0.3, 0.7 +/- 0.4, 0.9 +/- 0.3, 1.3 +/- 0.3, 3.9 +/- 1.5 DeltaE) after 30 days. CONCLUSIONS: The findings of this study showed that the ethanol concentrations of tested drinks affect the physical properties of the investigated acrylic resin. An obvious plasticizing effect was found, which could lead to a lower in vivo durability associated with alcohol consumption.