ABSTRACT
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.
Subject(s)
Polyethylene/chemistry , Composite Resins/chemistry , Glass/chemistry , Analysis of Variance , Materials Testing , Tensile Strength , Time FactorsABSTRACT
Endodontic therapy, today, forms an integral part of everyday dental practice. The large number of teeth being treated endodontically makes it imperative for the dentists to provide satisfactory restoration for those teeth to remain intact within the dental arch as an integral functioning component. So this study was carried out to check the reinforcement of composite with polyethylene fibers placed in two different technique in root filled mandibular molar teeth with mesio-occlusodistal tooth preparation. Fifty freshly extracted molars were divided into five groups of ten teeth each. Group I: Intact teeth (positive control). Group II: Unrestored MOD prepared tooth (negative control). Group III: MOD tooth preparation restored with posterior composite resin. Group IV: Ribbond fiber was placed over the composite resin restoration and exposed fiber was covered with composite resin. Group V: Ribbond fiber was placed on the floor of the tooth preparation and the remaining prepared tooth was restored with composite resin restoration. The samples were subjected to compressive loading on Hounsfield tensometer until failure. The data were recorded and subjected to statistical analysis. Group-IV showed significantly higher fracture resistance than Group-V.