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Introduction: Fracture of an acrylic resin complete denture base after aging, poses problem for patients, dentists and dental laboratory technicians. This study was performed to determine the effect of thermocycling on the flexural strength of a commercially available, heat-polymerized acrylic denture base material reinforced with glass fibers, carbon fibers, aramid fibers and high (HI) impact resins. Materials and Methods: Forty specimens were made of similar dimension from five groups of materials. Each group had eight specimens. A commercially available heat polymerized P.M.M.A denture base resin was selected as control and PMMA reinforced with glass, carbon, aramid fibres and HI impact resin were compared. All specimens were then subjected to thermocycling before testing. Flexural strength was evaluated with universal testing machine. The results were analyzed with Analysis of Variance (ANOVA) followed by Turkey HSD test. Results: All reinforced specimens and HI impact resins showed better flexural strength than the conventional acrylic resin after thermocycling. Specimens reinforced with glass fibers showed the highest flexural strength, followed by HI impact resin, carbon fibers and aramid fibers. After artificial aging, a significant improvement in the flexural strength of conventional acrylic resin was observed when it was reinforced with glass fibers. Conclusion: Within the limitations of this study, incorporation of 2% by weight of glass fibre in PMMA resin exhibited statistically significant maximum flexural strength followed by high impact resin, carbon, polyaramid reinforced P.M.M.A denture base resin. These can readily be used in the fabrication of dentures subjected to heavy masticatory loads.
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Objetivo: O presente trabalho avaliou a resistência flexural em barras de resina acrílica variando o tratamento superficial e o comprimento das fibras de vidro. Material e Método: Nove grupos experimentais foram criados (N = 10), tendo como fatores em estudo o comprimento da fibra de vidro pura (Unidirecional 23 mm (Uni23) e Picotada 3 mm (Pic3)) e o tipo de tratamento de superfície (sem tratamento (Crtl), silanização (Sil), impregnação com adesivo a base de bisGMA (Imp) e silanização + impregnação com adesivo a base de bisGMA (Imp/Sil)). Amostras (25 x 2 x 2 mm) foram produzidas e testadas a 0,5 mm/min obtendo-se os valores de resistência flexural em Mpa. Resultados: A análise estatística demonstrou diferença significante (p = 0,001) para os fatores: tratamento superficial (Imp: 297,95 ± 73,86A; Sil/Imp: 265,3 ± 64,21AB; Sil: 229,2 ± 72,47B; Controle: 164,9 ± 34,92C) e comprimento de fibra (Uni23: 266,5 ± 89,57a;Pic3: 212,17 ± 57,31b). A interação entre os dois em fatores em estudo não apresentou diferença estatisticamente significante (p = 0,098). Conclusão: As fibras de vidro, independente do seu comprimento, promovem o reforço significativo de resinas acrílicas quando tratadas superficialmente com adesivo bis-GMA, silano ou a combinação de ambos.
Objective: This study evaluated the flexural strength of acrylic resin bars by varying the surface treatment and the length of glass fiber. Material and Methods: Nine experimental groups were established (N = 10), with factors in study the length of the pure glass fiber (Unidirectional 23 mm (Uni23) and short 3mm (Pic3)) and the type of surface treatment (untreated(Ctrl), silanization (Sil), impregnation with BisGMA adhesive (Imp) and silanization + impregnation with BisGMA adhesive (Imp / Sil)). Samples (25 x 2 x 2 mm) were produced and tested at 0.5 mm / min ontaining flexural strength values in MPa. Results: Statistical analysis showed a significant difference (p = 0.001) for the factors: surface treatment (Imp: 297.95 ± 73.86 A; Sil / Imp: 265.3 ± 64.21 AB; Sil: 229.2 ± 72.47 B; control: 164.9 ± 34.92 C) and fiber length (Uni 23: 266.5 ± 89.57 a; Pic3: 212.17 ± 57.31 b).The interaction between the two factors in the study showed no statistically significant difference (p = 0.098). Conclusion: Glass fibers, independent of its length, promotes a significant reinforcement of acrylic resins when its surface are treated with bis-GMA adhesive, silane or a combination of both.
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Objectives: Different fiber types are available for reinforcing composite restorations. Little information exists regarding flexural strength of various fiber used to reinforce direct composites. This in vitro study examined the flexural strength of polyethylene and glass fibers when used to reinforce composite and influence of moisture exposure on the same materials. Materials and methods: The two types of fiber were used to reinforce blocks of composite (RX Flow, Dental Life Sciences) prepared to test flexural properties and compared with the unreinforced controls. Mean flexural strengths values were determined in a 3-point bend test at a crosshead speed of 8 mm/min by use of a universal testing machine. Results: Significant increases in mean flexural strength were found for all fiber-reinforced groups in comparison to the unreinforced controls at both before and after moisture exposure. The polyethylene fiber gave the greatest reinforcing effect. After 1 month of storage in an artificial saliva substitute, a significant decline occurred in the mean flexural strength of all the groups tested. Conclusion: Within the limitations of this study, the choice of fiber type was shown to have a significant increase on the flexural properties of the fiber-reinforced composite. Polyethylene fibers increased the flexural strength of the composite the most.
Objetivo: Diferentes tipos de fibras estão disponíveis para reforçar restaurações em resinas compostas. Há pouca informação sobre a resistência flexural de fibras usadas para reforçar compósitos diretos. Este estudo in vitro avaliou a resistência à flexão de fibras de polietileno e de vidro, quando usadas para reforçar resina composta e a influência da exposição à umidade sobre os mesmos materiais. Materiais e métodos: Os dois tipos de fibras foram usados para reforçar blocos de resina composta (RX Flow, Dental Life Sciences), preparados para testar as propriedades mecânicas e comparados com os controles não reforçados. Os valores médiosde flexão foram determinados em um ensaio de flexão de três pontos a uma velocidade de 8 mm/min em uma máquina de ensaio universal. Resultados: Um aumento significativo na resistência à flexão média foi encontrado para todos os grupos reforçados com fibras, em comparação com os controles não reforçadas, tanto antes quanto depois da exposição à umidade. A fibra de polietileno forneceu o maior efeito de reforço. Após 1 mês de armazenamento em saliva artificial, houve uma diminuição significativa na força média de flexão de todos os grupos testados. Conclusão: Dentro das limitações do presente estudo, o tipo de fibra demonstrou exercer um aumento significativo sobre as propriedades de flexão do compósito reforçado com fibras. Fibras de polietileno aumentaram mais a resistência à flexão do compósito.
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Polyethylene/chemistry , Composite Resins/chemistry , Glass/chemistry , Analysis of Variance , Materials Testing , Tensile Strength , Time FactorsABSTRACT
PURPOSE: The aim of this in-vitro investigation was to describe the effect of reinforcement with different fibers on impact strength of heat polymerized polymethyl methacrylate (PMMA) denture base resin and to analyze the effect of surface treatment of the fibers on the impact strength. MATERIALS AND METHODS: The specimens were fabricated from the dies formed as per standard ASTM D4812. 2% by weight of glass, polyethylene and polypropylene fibers were incorporated in the PMMA resin. The Izod impact testing was performed on the unnotched specimens and the values obtained were analyzed using appropriate one way ANOVA, followed by unpaired t-test. Fractured ends of the samples were subjected to the SEM analysis. RESULTS: The polypropylene fibers with plasma treatment showed the highest impact strength (9.229 x 10(2) J/m) followed by the plasma treated polyethylene fibers (9.096 x 10(2) J/m), untreated polypropylene fibers (8.697 x 10(2) J/m), untreated polyethylene fibers (7.580 x 10(2) J/m), silane treated glass fibers (6.448 x 10(2) J/m) and untreated glass fibers (5.764 x 10(2) J/m). Also the surface treatment of all the fibers has shown the significant improvement in impact strength. Findings of the SEM analysis justified the improvement in impact strength after surface treatment. CONCLUSION: Reinforcement with the fiber is an effective method to increase the impact strength of PMMA denture base resin. The surface treatment of fibers further increases the impact strength significantly.
Subject(s)
Denture Bases , Dentures , Glass , Hot Temperature , Plasma , Polyethylene , Polymers , Polymethyl Methacrylate , Polypropylenes , Reinforcement, PsychologyABSTRACT
PURPOSE: The aim of this in-vitro investigation was to describe the effect of reinforcement with different fibers on impact strength of heat polymerized polymethyl methacrylate (PMMA) denture base resin and to analyze the effect of surface treatment of the fibers on the impact strength. MATERIALS AND METHODS: The specimens were fabricated from the dies formed as per standard ASTM D4812. 2% by weight of glass, polyethylene and polypropylene fibers were incorporated in the PMMA resin. The Izod impact testing was performed on the unnotched specimens and the values obtained were analyzed using appropriate one way ANOVA, followed by unpaired t-test. Fractured ends of the samples were subjected to the SEM analysis. RESULTS: The polypropylene fibers with plasma treatment showed the highest impact strength (9.229 x 10(2) J/m) followed by the plasma treated polyethylene fibers (9.096 x 10(2) J/m), untreated polypropylene fibers (8.697 x 10(2) J/m), untreated polyethylene fibers (7.580 x 10(2) J/m), silane treated glass fibers (6.448 x 10(2) J/m) and untreated glass fibers (5.764 x 10(2) J/m). Also the surface treatment of all the fibers has shown the significant improvement in impact strength. Findings of the SEM analysis justified the improvement in impact strength after surface treatment. CONCLUSION: Reinforcement with the fiber is an effective method to increase the impact strength of PMMA denture base resin. The surface treatment of fibers further increases the impact strength significantly.
Subject(s)
Denture Bases , Dentures , Glass , Hot Temperature , Plasma , Polyethylene , Polymers , Polymethyl Methacrylate , Polypropylenes , Reinforcement, PsychologyABSTRACT
Background and objectives : The fracture of acrylic maxillary complete dentures is a commonly seen clinical problem which usually occurs due to heavy occlusal forces or accidental damage.The objectives of the study were to measure the impact strength of maxillary complete dentures fabricated with high impact acrylic resin and to evaluate the effect of woven E-glass fiber and silane treated glass fiber reinforcement on the impact strength of the Maxillary complete dentures. Methods :One commercially available heat cured acrylic resin (Trevalon HI) was selected. Preimpregnated woven E-glass fibers (Stick Net) and Silane treated glass fibers were used to reinforce ten maxillary complete dentures each. Ten unreinforced complete dentures served as the control group. The impact strength in Joules of the dentures were measured with a falling-weight impact test. Results : The mean impact strength of the control dentures was 75.22+/ - 10.392 J at crack initiation, and 84.62+/- 11.495 J at complete fracture. The mean impact strength of dentures reinforced with preimpregnated woven E-glass fibers was 165.91+/- 12.929 J at crack initiation, and 187.06+/- 17.972 J at complete fracture. The mean impact strength of dentures reinforced with silane treated glass fibers was 112.30+/- 8.709 J at crack initiation, and at complete fracture was 126.43 +/- 8.709 J. Interpretation and Conclusion :The impact strength of maxillary complete dentures fabricated with high impact acrylic resin increased significantly after reinforcement with preimpregnated woven Eglass fibers and silane treated glass fibers. The best improvement, however , was obtained by preimpregnated woven Eglass fibers.
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In the past, direct stabilization and splinting of teeth using an adhesive technique required the use of wires, pins, or mesh grids. Problems with the current fiber reinforcement materials are their inherent thickness when embedded within composite resin, their availability in fixed widths and their high cost. This paper discusses the use of silane-coated industrial grade glass fibers, which can be bundled in the form of ribbon according to the required thickness and length. Of the three patients discussed in this paper, none has exhibited debonding or recurrent caries over 1-year period. By reinforcing composite splints with these industrial grade glass fibers, dentists can provide patients with restorations and splints that are economical, fracture resistant, and more durable than most alternative splinting materials of the past.
Subject(s)
Acid Etching, Dental/methods , Adult , Coated Materials, Biocompatible/chemistry , Composite Resins/chemistry , Cuspid/pathology , Dental Materials/chemistry , Dental Prosthesis Design , Female , Follow-Up Studies , Glass/chemistry , Humans , Incisor/pathology , Periodontal Splints , Resin Cements/chemistry , Silanes/chemistry , Surface Properties , Tooth Mobility/therapyABSTRACT
OBJECTIVE: To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin. MATERIAL AND METHODS: Ninety-six rectangular specimens (64x10x2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2x3.5x21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification8 for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests. RESULTS: The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity. CONCLUSION: Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion.