Effects of plasma on polyethylene fiber surface for prosthodontic application

ABSTRACT Plasma technology has the potential to improve the adherence of fibers to polymeric matrices, and there are prospects for its application in dentistry to reinforce the dental particulate composite. Objectives This study aimed to investigate the effect of oxygen or argon plasma treatment on polyethylene fibers. Material and Methods Connect, Construct, InFibra, and InFibra treated with oxygen or argon plasma were topographically evaluated by scanning electron microscopy (SEM), and chemically by X-ray photoelectron spectroscopy (XPS). For bending analysis, one indirect composite (Signum) was reinforced with polyethylene fiber (Connect, Construct, or InFibra). The InFibra fiber was subjected to three different treatments: (1) single application of silane, (2) oxygen or argon plasma for 1 or 3 min, (3) oxygen or argon plasma and subsequent application of silane. The samples (25x2x2 mm), 6 unreinforced and 60 reinforced with fibers, were subjected to three-point loading tests to obtain their flexural strength and deflection. The results were statistically analyzed with ANOVA and the Bonferroni correction for multiple comparison tests. Results SEM analysis showed that oxygen and argon plasma treatments promote roughness on the polyethylene fiber surface. X-ray photoelectron spectroscopy (XPS) analysis shows that both plasmas were effective in incorporating oxygenated functional groups. Argon or oxygen plasma treatment affected the flexural strength and deflection of a fiber reinforced composite. The application of silane does not promote an increase in the flexural strength of the reinforced composites. Conclusions Oxygen and argon plasma treatments were effective in incorporating oxygenated functional groups and surface roughness. The highest strength values were obtained in the group reinforced with polyethylene fibers treated with oxygen plasma for 3 min.

Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations

Objective: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. Material and Methods: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p<0.05). Results: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. Conclusions: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus. .

Effect of different disinfecting procedures on the hardness and color stability of two maxillofacial elastomers over time

Objective Disinfection procedures often cause deterioration in a maxillofacial prosthesis. Color and hardness alterations could lead to a replacement of the prosthesis. Material and Methods An experimental chlorinated polyethylene (CPE) and a commercial polydimethyl siloxane (PDMS) sample were treated with four different disinfection procedures for a period which simulates 1 year of clinical service. The applied disinfection procedures included microwave exposure and immersion in three solutions, sodium hypochlorite, neutral soap and a commercial disinfecting soap. Shore A hardness (∆H) and color differences (∆E) were determined before and after each procedure. All data were analyzed by Two Way Analysis of Variance (ANOVA) and Tukey's post hoc tests at a level of α=0.05. Results The samples presented significant alterations in color and hardness after the different disinfection treatments. The color differences (∆E) were at least eye detectable in all cases and clinically unacceptable in most of the cases, with values ranging from 1.51 to 4.15 and from 1.54 to 5.92 for the PDMS and CPE material, respectively. Hardness was decreased after all the disinfection procedures in the PDMS, while for the CPE, a decrement was observed after disinfection with sodium hypochlorite and neutral soap and an increment after microwave exposure and the disinfection with a commercial antimicrobial agent. The PDMS samples presented greater alterations in color and hardness after disinfection with sodium hypochlorite solution, while the microwave exposure caused negligible effects. The CPE samples were affected most after disinfection when treated with neutral soap, and more slightly when disinfected with sodium hypochlorite solution. Conclusions The disinfection procedures caused alterations in color and hardness of the examined materials. The most suitable disinfection procedure for ...

Effect of moisture on flexural strength of fiber-reinforcedcomposites used as splinting materials / Efeito da umidade na resistência flexural de resinas compostas reforçadas por fibras usadas como material de esplintagem

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.

In vitro comparative evaluation of the effect of two different fiber reinforcements on the fracture toughness of provisional restorative resins.

Background: Fracture of provisional fixed partial denture (FPD) may jeopardize the success of provisional prosthodontic treatment phase and cause patient discomfort. Aim: The aim of this study was to compare the fracture toughness of the Polymethyl Methacrylate (PMMA) resin and Bis-Acryl Composite (BAC) resin reinforced with the Polyethylene and Glass fibers. Materials and Methods: Three groups (N=10) of each of the two materials were prepared for the fracture toughness test. Two groups had the different reinforcements and group without reinforcement served as the control. The mean fracture toughness (MPa.m½ ) was compared by One-way ANOVA, followed by the Scheffe analysis. Fracture toughness between fiber-reinforced PMMA and BAC resin was compared by the independent samples t test. Results: For the controls, the fracture toughness for PMMA resin (0.91) was significantly lower than for the BAC resin (1.19). Glass fiber reinforcement produced significantly higher fracture toughness for both, PMMA (1.48) and BAC (1.82) resin, but the Polyethylene fibers did not (0.95 for PMMA and 1.23 for BAC resin). Among the reinforced groups, Silane impregnated Glass fibers showed highest fracture toughness for the BAC resin (1.82). Conclusion: Of two fiber reinforcement methods evaluated, Glass fiber reinforcement for the PMMA and BAC resin produced highest fracture toughness. Clinical Implications: On the basis of this in--vitro study, the use of Glass and Polyethylene fibers tested may be an effective way to reinforce resins used to fabricate fixed provisional restorations.

Odontología restaurativa directa. Usos de RIBBOND para restaurar dientes tratados endodónticamente / Direct restorative dentistry. Uses of RIBBOND to restore endodontically treated teeth

El uso de postes convencionales en odontología, puede traer algunos compromisos que tienen efectos desfavorables, por ej., fractura de raíz y estética (transmisión de luz). El uso de sistemas de fibras de refuerzo, ofrece una oportunidad de evitar esos compromisos