RESUMO
PURPOSE: This study evaluated the effect of water storage (WS) on the shear bond strength (SBS) and shear bond fatigue limit (SBFL) between denture base and reline resins. In addition, a possible correlation between SBS and SBFL was evaluated. MATERIALS AND METHODS: Two denture base (Lucitone 550-L and Acron MC-AC) and two reline resins (Ufi Gel Hard- UGH and Tokuso Rebase Fast-TR) were selected. Cylinders (20 x 20 mm) of each denture base resin were processed, and the reline resins were packed on the bonding surfaces using a split mold (3.5 x 5.0 mm). Specimens of each denture base-reline resin combination were subjected to shear forces (0.5 mm/min) until fracture. A staircase approach was used to determine the SBFL. Specimens were submitted to either 10,000 cycles (5.0 Hz) or until fracture. For both SBS and SBFL, specimens were tested after relining (control) and after 30 days of WS. Data (MPa) were analyzed with 2-way ANOVA and Tukey's tests (α = 0.05). To test for a possible correlation between the SBS and SBFL, a linear regression analysis was performed. RESULTS: WS significantly increased (p < 0.05) the SBS of AC-TR and AC-UGH and the SBFL of AC-TR, AC-UGH and LUGH. After WS, UGH produced higher (p < 0.05) SBS than TR, regardless of the denture base resin used. Regardless of the experimental groups and the denture base resins used, UGH produced higher (p < 0.05) SBFL than TR specimens. A strong positive linear correlation (r(2) = 0.949) was observed between the SBS and SBFL. CONCLUSION: Overall, UGH promoted the highest SBS and SBFL. WS increased the SBS and SBFL of the AC relined specimens. A positive correlation was observed between the two variables.
Assuntos
Resinas Acrílicas , Colagem Dentária , Bases de Dentadura , Reembasadores de Dentadura , Metacrilatos , Elastômeros de Silicone , Análise de Variância , Falha de Restauração Dentária , Análise do Estresse Dentário , Reembasamento de Dentadura , Modelos Lineares , Teste de Materiais , Resistência ao Cisalhamento , Estatísticas não Paramétricas , ÁguaRESUMO
PURPOSE: This study evaluated the incorporation pattern of antifungal/antimicrobial agents added to a tissue conditioner by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis. MATERIALS AND METHODS: The nystatin dosages incorporated into the tissue conditioner (Softone, Bosworth Co., Skokie, IL) powder were 500,000 U (G1) and 1,000,000 U (G2). The addition of miconazole was at 125 mg (G3) and 250 mg (G4), and ketoconazole was at 100 mg (G5) and 200 mg (G6). Chlorhexidine diacetate was blended at levels of 5% (G7) and 10% (G8) w/w of the total amount (6.35 g) of the tissue conditioner. The drug powder concentrations were blended with the tissue conditioner powder at different concentrations before the addition of the tissue conditioner liquid (5 mL) to the mixture. One group (G0) without any drug incorporation was used as control. Specimens (n = 5) (36 x 7 x 6 mm(3)) were plasticized at room temperature for 10 minutes and carbon sputter coated. All specimens were submitted to SEM-EDS analysis. RESULTS: Nystatin and miconazole specimens exhibited particles with irregular shapes and sizes uniformly distributed. Ketoconazole specimens showed small spherical particles with a slight distribution throughout the matrix. Chlorhexidine specimens exhibited irregular particles up to approximately 50 mum in size randomly dispersed within the matrix. CONCLUSIONS: Within the limitations of this in vitro study, the modified tissue conditioner showed differences in the particle distribution and size of the antifungal/antimicrobial agent added to the plasticized matrix. Further studies would discriminate the most important particle features that may influence the drug leaching from the plasticized matrix.
Assuntos
Antifúngicos/química , Materiais Dentários/química , Miconazol/química , Nistatina/química , Ácidos Polimetacrílicos/química , Condicionamento de Tecido Mole Oral/métodos , Antifúngicos/administração & dosagem , Cristalização , Reembasadores de Dentadura , Relação Dose-Resposta a Droga , Sistemas de Liberação de Medicamentos/métodos , Cetoconazol/administração & dosagem , Cetoconazol/química , Miconazol/administração & dosagem , Microscopia Eletrônica de Varredura , Nistatina/administração & dosagem , Polímeros/química , Espectrometria por Raios XRESUMO
This study evaluated the effect of water-bath and microwave post-polymerization treatments on the flexural strength and Vickers hardness of four autopolymerizing reline resins (Duraliner II-D, Kooliner-K, Tokuso Rebase Fast-TR and Ufi Gel Hard C-UGH) and one heat-polymerized acrylic resin (Lucitone 550-L), processed using two polymerization cycles (short cycle - 90 minutes at 73ºC and 100ºC for 30 minutes; and long cycle - 9 hours at 71ºC). For each material, thirty specimens (64 x 10 x 3.3 mm) were made and divided into 3 groups (n=10). Specimens were tested after: processing (control group); water-bath at 55ºC for 10 minutes (reline materials) or 60 minutes (L); and microwave irradiation. Flexural strength tests were performed at a crosshead speed of 5 mm/min using a three-point bending device with a span of 50 mm. The flexural strengths values were calculated in MPa. One fragment of each specimen was submitted to Vickers hardness test. Data were analyzed by 2-way ANOVA followed by Tukey's HSD test (alpha=0.05). L microwaved specimens (short cycle) exhibited significantly higher flexural strength means than its respective control group (p<0.05). Water-bath promoted a significant increase (p<0.05) in flexural strength of K and L (long cycle). The hardness of the tested materials was not influenced by the post-polymerization treatments. Post-polymerization treatments could be used to improve the flexural strength of some materials tested.
RESUMO
STATEMENT OF PROBLEM: Microwave irradiation has been suggested as a method to disinfect denture bases. However, the effect of microwave heating on the dimensional stability of the relined denture bases is unknown. PURPOSE: The purpose of this study was to evaluate the dimensional stability of intact and relined acrylic resin denture bases after microwave disinfection. MATERIAL AND METHODS: A standard brass cast simulating an edentulous maxillary arch was machined and used to fabricate 2- and 4-mm-thick denture bases (n=200), which were processed with heat-polymerized acrylic resin (Lucitone 550). The 2-mm thick-specimens (n=160) were relined with 2 mm of autopolymerizing resin (Tokuso Rebase Fast, Ufi Gel Hard, Kooliner, or New Truliner). Distances between 5 removable pins on the standard brass cast were measured with a Nikon optical comparator, and the area (mm) formed by the distance between 5 pins was calculated and served as baseline. During fabrication, the pins were transferred to the intaglio surface of the specimens. Differences between the baseline area and those subsequently determined for the specimens were used to calculate the percent dimensional changes. The intact and relined denture bases were divided into 4 groups (n=10) and evaluated after: polymerization (control group P); 1 cycle of microwave disinfection (MW); daily microwave disinfection for 7 days (control group MW7); water storage for 7 days (WS7). Microwave irradiation was performed for 6 minutes at 650 W. Data were analyzed using 2-way ANOVA followed by Tukey's test (alpha=.05). RESULTS: Intact specimens and those relined with Kooliner and New Truliner showed increased shrinkage after 1 (P=.05, .018, and .001, respectively) and 7 (P <.001, .003, and <.001, respectively) cycles of microwave disinfection. With the exception of specimens relined with Kooliner, intact specimens showed greater shrinkage than the relined specimens after 7 cycles of microwave disinfection. CONCLUSIONS: Microwave disinfection produced increased shrinkage of intact specimens and those relined with New Truliner and Kooliner.
Assuntos
Bases de Dentadura , Reembasadores de Dentadura , Desinfecção/métodos , Micro-Ondas , Resinas Acrílicas/efeitos da radiação , Análise de Variância , Análise do Estresse Dentário , Reembasamento de Dentadura , Transição de FaseRESUMO
Fracture of dentures is a common clinical finding in daily prosthodontic practice, resulting in great inconvenience to both patient and dentist. A satisfactory repair should be cost-effective, simple to perform, and quick; it should also match the original color and not cause distortion to the existing denture. Different repair materials, surface designs, and mechanical and chemical surface treatments have been recommended in order to obtain stronger repairs. This article reviews some of the available literature with regard to the most important factors that may influence the strength of denture repairs.
Assuntos
Reparação em Prótese Dentária , Análise Custo-Benefício , Materiais Dentários/química , Reparação em Prótese Dentária/economia , Reparação em Prótese Dentária/métodos , Reparação em Prótese Dentária/normas , Estética Dentária , Humanos , Propriedades de Superfície , Fatores de TempoRESUMO
This study evaluated the effect of water-bath and microwave post-polymerization treatments on the flexural strength and Vickers hardness of four autopolymerizing reline resins (Duraliner II-D, Kooliner-K, Tokuso Rebase Fast-TR and Ufi Gel Hard C-UGH) and one heat-polymerized acrylic resin (Lucitone 550-L), processed using two polymerization cycles (short cycle - 90 minutes at 73 degrees C and 100 degrees C for 30 minutes; and long cycle - 9 hours at 71 degrees C). For each material, thirty specimens (64 x 10 x 3.3 mm) were made and divided into 3 groups (n=10). Specimens were tested after: processing (control group); water-bath at 55 degrees C for 10 minutes (reline materials) or 60 minutes (L); and microwave irradiation. Flexural strength tests were performed at a crosshead speed of 5 mm/min using a three-point bending device with a span of 50 mm. The flexural strengths values were calculated in MPa. One fragment of each specimen was submitted to Vickers hardness test. Data were analyzed by 2-way ANOVA followed by Tukey's HSD test (alpha=0.05). L microwaved specimens (short cycle) exhibited significantly higher flexural strength means than its respective control group (p<0.05). Water-bath promoted a significant increase (p<0.05) in flexural strength of K and L (long cycle). The hardness of the tested materials was not influenced by the post-polymerization treatments. Post-polymerization treatments could be used to improve the flexural strength of some materials tested.
RESUMO
Este estudo avaliou o efeito da desinfecção por irradiação de energia de microondas na porosidade superficial de quatro reembasadores rígidos (Kooliner - K, New Truliner - NT, Tokuso Rebase - TR, Ufi Gel Hard UGH) e uma resina termopolimerizável para base de prótese (Lucitone 550 - L). Vinte amostras de cada material (20 x 10 x 3mm) foram divididas em 4 grupos (n=5): G1 sem tratamento controle; G2 amostras imersas em 200 mL de água destilada e submetidas a 2 ciclos de irradiação (650W/6min) no mesmo dia; G3 1 ciclo diário de irradiação, por 7 dias, com as amostras imersas em água destilada entre os ciclos; e G4 amostras imersas em água destilada a 370 C, por 7 dias. As amostras foram fotografadas em microscópio eletrônico de varredura e as microfotografias analisadas em analisador de imagem Leica Qwin, para determinar o número e a área total de poros. Para avaliar a porosidade entre a região central e a periferia, foi utilizado o teste não-paramétrico de Wilcoxon ao nível de 5% de significância. Para avaliar a porosidade entre os grupos experimentais foi utilizado o teste de Kruskal Wallis, seguido por comparações múltiplas não-paramétricas, também ao nível de 5% de significância. Os resultados demonstraram que não houve diferença significativa (P>0,05) entre a região central e a periferia. A avaliação entre os grupos experimentais demonstrou que a porosidade do material K foi significantemente aumentada (P<0,05), após 7 ciclos de irradiação. Nenhuma diferença significante (P>0,05) foi encontrada para os materiais NT e L, em todas as condições avaliadas. Quando comparada ao grupo G1 (sem tratamento), a porosidade da TR e UGH foi significantemente diminuída (P<0,05), após 7 ciclos de irradiação. Concluiu-se que: 1) As irradiações por energia de microondas aumentaram o número de poros para o material K (P<0,05), quando este foi submetido a 7 ciclos, em relação ao G1. Entretanto, a área total de poros não exibiu essa influência (P>0,05) em todos os grupos avaliados. 2) O material NT não sofreu efeito das irradiações para o número de poros em todos os grupos. Entretanto, a área de poros foi reduzida (P<0,05), quando foram utilizados 7 ciclos (G3), em comparação a 2 ciclos (G2). 3) As microondas reduziram o número de poros para o material TR (P<0,05), quando este foi submetido a 7 ciclos, em comparação ao G1 e G2. Sua área total de poros, no G3, exibiu redução significativa, em relação aos demais grupos avaliados. 4) A resina UGH, quando submetida a 7 ciclos de irradiação (G3), teve o número de poros reduzido (P<0,05), em relação ao G1 e G4. Entretanto, a área total de poros foi estatisticamente igual para todos os grupos. 5) O número e a área de poros do material L não foram influenciados (P>0,05) pelas irradiações
This study evaluated the effect of microwave irradiation on the surface porosity of four hard chairside reline materials (Kooliner-K, New TrulinerNT, Tokuso Rebase-TR, Ufi Gel HardUGH) and one heat-polymerizing denture base acrylic resin (Lucitone 550-L) Twenty specimens (20X10X3mm) were made for each material and divided into four groups (n=5): G1-no treatment (control), G2specimens immersed in distilled water and submitted to 2 cycles of microwave irradiation (650W/6 min) consecutively on the same day; G3daily microwave irradiation for 7 days, with specimens immersed in distilled water at 370 C between exposures; G4specimens immersed in distilled water at 370 C for 7 days. Scanning electron microphotographs of the specimens (SEM) were analyzed using Leica Qwin image analyser software to determine the number and total area of porosities. Data were statistically analyzed with Wilcoxon test for paired analysis (P=0.05) to determine differences between the center and the periphery. Differences between the experimental groups were tested using the Kruskal-Wallis test. The results demonstrated that the number and the total area of pores did not differ significantly between the central and peripheral zones. The number and the total area of pores of K was significantly increased after 7 cycles (P<.05). Materials NT and L specimens showed no significant differences in the number of pores among all groups evaluated. However, for material NT, significant difference (P<.05) was observed between G2 and G3 in the total area of pores. The number of pores of TR and UGH was significantly decreased (P<.05) after 7 cycles when compared to G1. The area total of pores of the TR was significantly affected after 7 cycles. It was concluded that 1) Microwave irradiation promoted a significant increased (P<.05) in the number of pores for material K after 7 cycles; however, the total area of pores was not affect by irradiation in all groups evaluated. 2) Material NT was not affected by irradiation for the number of pores; however, the total area of pores was decrease after 7 cycles, when compared to G2. 3) For material TR, microwave irradiation decreased (P<.05) the number of pores after 7 cycles, compared to G1 and G2. The total area of pores of G3 was significantly decreased after 7 cycles. 4) Material UGH showed a significant decrease (P<.05) for number of pores when submitted to 7 cycles, compared to G1 and G4; however, the total area of pores was statically equal in all groups evaluated 5) For material L, the number and total area of pores were not affected by irradiations
Assuntos
Resinas Acrílicas , Desinfecção , Micro-Ondas , Reembasamento de DentaduraRESUMO
O estudo avaliou o efeito do reembasamento, da ciclagem mecânica, da ciclagem térmica e da desinfecção por microondas sobre a força máxima de fratura, a deformação, a energia de ruptura e a estabilidade dimensional de bases de prótese. O efeito das ciclagens mecânica e térmica foi avaliado utilizando 28 bases de prótese intactas com 3 mm de espessura e 56 bases de prótese com 2 mm de espessura. Estas bases foram obtidas a partir de um modelo padrão metálico do arco superior confeccionadas com a resina acrílica para microondas Acron MC (AC-MC), de acordo com as instruções do fabricante (500W por 3 minutos). Para verificar o efeito do reembasamento, as bases de prótese com 2 mm de espessura foram reembasadas com 1 mm de material reembasador (New Truliner - NTL ou Tokuyama Rebase Fast II - TRFII). Em seguida, as bases de prótese intactas ou reembasadas foram divididas aleatoriamente em 4 grupos (n=7) e o ensaio mecânico de resistência à compressão foi realizado após seguintes condições experimentais: sem tratamento (controle); 5.000 ciclos térmicos entre 5º e 55ºC; 10.000 ciclos mecânicos a um frequência de 0,8 Hz e uma força de 150N e; ciclagem térmica e posterior ciclagem mecânica. Todas as bases de prótese foram submetidas ao ensaio mecânico em uma máquina universal Instron 5565, utilizando-se uma velocidade de 5mm/min e uma célula de carga de 10 kN...
Assuntos
Resinas Acrílicas , Reembasamento de Dentadura , Desinfecção , Micro-OndasRESUMO
As próteses adesivas surgiram como uma alternativa protética, tendo em vista o seubaixo custo, ser uma técnica mais conservadora e facilidade laboratorial. Mais recentemente, emrazão da necessidade de soluções clínicas estéticas, novos materiais foram introduzidos no mercadoe utilizados na confecção de próteses adesivas sem metal. Os materiais utilizados são: resinascompostas reforçadas por fibras e sistemas cerâmicos de alta resistência. O objetivo deste trabalhofoi discutir, por meio de uma revisão de literatura, as formas de preparo, os tipos de materiais, asvantagens e desvantagens da utilização de próteses adesivas sem metal. Com base nas informaçõesda literatura, pôde-se concluir que as próteses adesivas sem metal são uma alternativa promissorana substituição de um elemento dental devido a sua superioridade estética, biocompatibilidade efacilidade de confecção, principalmente para compósitos reforçados por fibras. Além disso, suaresistência apresenta resultados satisfatórios in vitro. Entretanto, há poucas evidências científicascom relação a formas de preparo ideais para os retentores de ambos os materiais a serem utilizadosrotineiramente na clínica. Assim, acompanhamentos longitudinais deveriam ser realizados paraverificar o comportamento dessas próteses na cavidade bucal antes que possam ser indicadas comotratamento de rotina na prática clínica diária.
The resin bonded bridge sets up as prosthodontic alternative based on its costeffective,conservative techniques and easiness of laboratory manufacturing. Nowadays, theclinical practice has been requiring esthetic solutions and, consequently, new materials have beenintroduced and used in the metal free resin bonded bridge manufacture. The materials used arefibre-reinforced composite and high-strenght ceramic systems. The purpose of this study was todiscuss through a literature review the cavity design, types of materials used and the advantagesand disadvantages of the metal free resin bonded bridges. Based on the reviewed literature it couldbe concluded that the metal free resin bonded bridges are a promising solution for the replacementof a tooth because of their improved esthetics, biocompatibility and simple technique, specialyfor the fiber reinforced composite. Moreover, this kind of prosthesis presents satisfactory in vitrostrenght results. However, there is little scientific evidence about the adequated cavity and connectordesigns that offer support to use this prosthesis in clinical routine. Therefore, longitundinal studiesshould be performed in order to investigate the clinical behaviour of these prosthesis in the oralenvironment before their indication as a routine modality of treatment.
Assuntos
Estética Dentária , Preparo da Cavidade Dentária , Prótese AdesivaRESUMO
STATEMENT OF PROBLEM: Microwave postpolymerization has been suggested as a method to improve the mechanical strength of repaired denture base materials. However, the effect of microwave heating on the flexural strength of the autopolymerizing denture reline resins has not been investigated. PURPOSE: This study analyzed the effect of microwave postpolymerization on the flexural strength of 4 autopolymerizing reline resins (Duraliner II, Kooliner, Ufi Gel Hard, and Tokuso Rebase Fast) and 1 heat-polymerized resin (Lucitone 550). MATERIAL AND METHODS: For each material, 80 specimens (64 x 10 x 3.3 mm) were polymerized according to the manufacturer's instructions and divided into 10 groups (n = 8). Control group specimens remained as processed. Before testing, the specimens were subjected to postpolymerization in a microwave oven using different power (500, 550, or 650 W) and time (3, 4, or 5 minutes) settings. Load measurements (newtons) were made at a crosshead speed of 5 mm/min using a 3-point bending device with a span of 50 mm. The flexural strength values were calculated in MPa. Data analyses included 3-way and 2-way analysis of variance and the Tukey Honestly Significant Difference test (alpha = .05). RESULTS: The flexural strengths of resins Duraliner II and Kooliner were significantly increased (P = .0015 and P = .0046, respectively) with the application of microwave irradiation using different time/power combinations. The materials Lucitone 550, Tokuso Rebase Fast, and Ufi Gel Hard demonstrated no significant strength improvement compared to the corresponding control. Only after microwave postpolymerization irradiation for 3 minutes at 550 W did Lucitone 550 show significantly higher flexural strength (P =.001) than Tokuso Rebase Fast and Ufi Gel Hard relining resins. CONCLUSION: Microwave postpolymerization irradiation can be an effective method for increasing the flexural strength of Duraliner II (at 650 W) and Kooliner (at 550 W and 650 W for 5 minutes).