Radiant exposure effects on physical properties of methacrylate - and silorane-composites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desgaste e rugosidade superficial de um cimento de ionômero de vidro nanoparticulado

To compare the abrasion wear resistance and superficial roughness of different glass ionomer cements used as restorative materials, focusing on a new nanoparticulate material. Material and Method: Three glass ionomer cements were evaluated: Ketac Molar, Ketac N100 and Vitremer (3M ESPE, St. Paul, MN, USA), as well as the Filtek Z350 (3M ESPE, St. Paul, MN, USA). For each material were fabricated circular specimens (n=12), respecting the handling mode specified by the manufacturer, which were polished with sandpaper disks of decreasing grit. The wear was determined by the amount of mass (M) lost after brushing (10,000 cycles) and the roughness (Ra) using a surface roughness tester. The difference between the Minitial and Mfinal (ΔM) as well as beroughness of aesthetic restorative materials: an in vitro comparison. SADJ. 2001; 56(7): 316-20. 11. Yip HK, Peng D, Smales RJ. Effects of APF gel on the physical structure of compomers and glass ionomer cements. Oper. Dent. 2001; 26(3): 231-8. 12. Ma T, Johnson GH, Gordon GE. Effects of chemical disinfectants on the surface characteristics and color of denture resins. J Prosthet Dent 1997; 77(2): 197-204. 13. International organization for standardization. Technical specification 14569-1. Dental Materials – guidance on testing of wear resistance – PART I: wear by tooth brushing. Switzerland: ISO; 1999. 14. Bollen CML, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater.1997; 13(4): 258-9. 15. Kielbassa AM, Gillmann C, Zantner H, Meyer-Lueckel H, Hellwig E, Schulte-Mönting J. Profilometric and microradiographic studies on the effects of toothpaste and acidic gel abrasivity on sound and demineralized bovine dental enamel. Caries Res. 2005; 39(5): 380-6. 16. Tanoue N, Matsumara H, Atsuta M. Wear and surface roughness of current prosthetic composites after toothbrush/dentifrice abrasion. J Prosthet Dent. 2000; 84(1): 93-7. 17. Heath JR, Wilson HJ. Abrasion of restorative materials by toothpaste. J Oral Rehabil. 1976; 3(2): 121-38. 18. Frazier KB, Rueggeberg FA, Mettenburg DJ. Comparasion of wearresistance of class V restorative materials. J Esthet Dent. 1998; 10(6): 309-14. 19. Momoi Y, Hirosakil K, Kohmol A, McCabe JF. In vitro toothebrushdentifrrice abrasion of resin-modified glass ionomers. Dent Mater. 1997; 13(2): 82-8. 20. Turssi CP, Magalhães CS, Serra MC, Rodrigues Jr.AL. Surface roughness assessment of resin-based materials during brushing preceded by pHcycling simulations. Oper Dent. 2001; 26(6): 576-84. 21. Wang L, Cefaly DF, Dos Santos JL, Dos Santos JR, Lauris JR, Mondelli RF, et al. In vitro interactions between lactic acid solution and art glassionomer cements. J Appl Oral Sci. 2009; 17(4): 274-9. 22. Carvalho FG, Fucio SB, Paula AB, Correr GM, Sinhoreti MA, PuppinRontani RM. Child toothbrush abrasion effect on ionomeric materials. J Dent Child (Chic). 2008; 75(2): 112-6. 23. Coutinho E, Cardoso MV, De Munck J, Neves AA, Van Landuyt KL, Poitevin A, et al. Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer. Dent Mater. 2009; 25(11): 1347-57. tween Rainitial and Rafinal (ΔRa) were also used for statistical analysis (α=0.05). Results: Except for the composite, significant loss of mass was observed for all glass ionomer cements and the ΔM was comparable for all of them. Significant increase in roughness was observed only for Vitremer and Ketac N100. At the end of the brushing cycle, just Vitremer presented surface roughness greater than the composite resin. Conclusion: All glass ionomer cements showed significant weight loss after 10,000 cycles of brushing. However, only Vitremer showed an increase of roughness greater than the Z350 resin, while the nanoparticulate cement Ketac N100 showed a smooth surface comparable to the composite.

Indirect resin onlay cemented with self-adhesive resin cement: a comprehensive clinical overview

Advances in adhesive technology and esthetic dental materials have permitted clinicians to perform conservative preparation of the dentition for onlay restorations. Indirect resin onlays are a great alternative to dental crowns for reestablishment the function and esthetic in teeth with great destruction.

Dentinogenesis imperfecta type II: approach for dental treatment

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Caries formation around restorative composite and glass ionomer cement

This in vitro study evaluated the demineralization around restorations class V made on the buccal and lingual surfaces of teeth when using different restorative materials. Thirty extracted teeth were randomly divided into 3 groups (n=10) according to the restorative material: Group I - Fuji II LC (GC America Inc., Alsip, Illinois, USA), Group II - Tetric (Ivoclar Vivadent AG, Schaan, Liechtenstein) and Group III - Chelon Fil (3M/ESPE., Seefeld, Germany). The teeth were submitted to a pH-cycling model associated to a thermocycling model. Sections were made and the specimens were analyzed under a polarized light microscopy as for the presence of demineralization. Measurements were performed and the results were subjected to statistical analysis using Anova and Tukey´s Test (α=0.05). Mean values of demineralization depth (µm) according to each positions showed that the demineralization was significantly reduced when Chelon Fil (Group III) was used for all depths, when compared to fluoridated resin materials. Also, it was verified that non-fluoridated resin material, composite resin Tetric, had the lowest inhibitory effect on the development of demineralization.

Avaliação da resistência de união de reparos em resinas compostas convencionais e bulkfill

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do comprimento do pino de fibra de vidro na resistência à fratura de raízes fragilizadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do comprimento do pino de fibra de vidro na resistência à fratura de raízes fragilizadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Compressive strength of dental composites photo-activated with different light tips

The aim of this study was to evaluate the compressive strength of microhybrid (FiltekTM Z250) and nanofilled (FiltekTM Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm-2 when using the fiber optic light tip and 596 mW cm-2 with the polymer. After storage in distilled water at 37± 2 °C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min-1. The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane’s test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p < 0.001) between the microhybrid composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth.

Improved column-based radiochemical processing of the generator produced 68Ga

An improved chemical strategy for processing of the generator produced 68Ga was developed based on processing of the original 68Ge/68Ga generator eluate on a micro-column. Direct pre-concentration and purification of the eluted 68Ga is performed on a cation-exchange resin in hydrochloric acid/acetone media. A supplementary step based on a second micro-column filled with a second resin allows direct re-adsorption of 68Ga eluted from the cation exchanger. 68Ga is finally striped from the second resin with a small volume of pure water. For this purpose a strong anion exchanger and a novel extraction chromatographic resin based on tetraalkyldiglycolamides are characterized. The strategy allows online pre-concentration and purification of 68Ga from the original generator eluate. The supplementary column allows transferring 68Ga with high radionuclide and chemical quality in the aqueous solution with small volume and low acidity useful for direct radiolabeling reactions.

Cytotoxic effects of polycarbonate-based orthodontic brackets by activation of mitochondrial apoptotic mechanisms

OBJECTIVES: The aim of the study was to evaluate the biological effects of water eluents from polycarbonate based esthetic orthodontic brackets. METHODS: The composite polycarbonate brackets tested were Silkon Plus (SL, fiber-glass-reinforced), Elan ME (EL, ceramic particle-reinforced) and Elegance (EG, fiber-glass-reinforced). An unfilled polyoxymethylene bracket (Brilliant, BR) was used as control. The brackets' composition was analyzed by ATR-FTIR spectrometry. The cytotoxicity and estrogenicity of the eluents obtained after 3months storage of the brackets in water (37°C) were investigated in murine fibroblasts (NIH 3T3), breast (MCF-7) and cervical cancer (CCl-2/Hela) cell lines. RESULTS: SL and EG were based on aromatic-polycarbonate matrix, whereas EL consisted of an aromatic polycarbonate-polyethylene terepthalate copolymer. A significant induction of cell death and a concurrent decrease in cell proliferation was noted in the EG eluent-treated cells. Moreover, EG eluent significantly reduced the levels of the estrogen signaling associated gene pS2, specifically in MCF7 cells, suggesting that cell death induced by this material is associated with downregulation of estrogen signaling pathways. Even though oxidative stress mechanisms were equally activated by all eluents, the EG eluents induced expression of apoptosis inducing factor (AIF) and reduced Bcl-xL protein levels. SIGNIFICANCE: Some polycarbonate-based composite brackets when exposed to water release substances than activate mitochondrial apoptosis.

Desenvolvimento de um painel sanduíche com carga de particulado oriundo de resíduo lignocelulósico para aplicação em produtos na área de equipamentos de proteção

This work aims to study and investigate the use of a hybrid composite polymer formed with blanket aramid (Kevlar 29) fiber blanket flax fiber and particulate dry endocarp of coconut (Cocos nucifera Linn), using as matrix an epoxy resin based thermoset for use in areas of protective equipment. Besides such material is used an aluminum plate, joined to the composite by means of glue based on epoxy and araldite commercial. The manufacturing process adopted was manual lamination (Hand Lay Up) to manufacture the hybrid composite. After the composite is prepared, an aluminum plate is subjected to pressure and glued to cure the adhesive. Layers of veil will also be used to separate the particulate from the linen blanket layer without disturbing the alignment of the fibers of the blankets. To characterize the mechanical and physical behavior was manufactured a plate of 800 x 600 mm of the hybrid composite, which were removed specimens for tests of water absorption to saturation; density; impact test (Charpy) and two test specimens for ballistic testing 220 mm x 200 mm to make a comparative study between the dry state and saturated water absorption and thus see the ballistic performance of these two conditions. The test was applied to make a comparative study of fracture in these two conditions, caused by penetrating ballistic missile (38 and 380). To test the impact (Charpy) will analyze the absorbed energy, fracture appearance and lateral contraction, also in dry condition and saturation of absorbed water, thereby analyzing situations where the impact load is relevant, such as bumps and shocks produced by stone, metal or wooden bars among others. The proposed configuration, along with the tests, has the purpose, application in the fields of equipment against ballistic impact, such as helmets; bullet proof vests; shields; protective packaging and other items to be identified in this research.

Compressive strength of dental composites photo-activated with different light tips

The aim of this study was to evaluate the compressive strength of microhybrid (FiltekTM Z250) and nanofilled (FiltekTM Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm−2 when using the fiber optic light tip and 596 mW cm−2 with the polymer. After storage in distilled water at 37 ± 2 "C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min−1. The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane’s test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p < 0.001) between the microhybrid composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth.

Interaction of fluorescence of resin cements with glass ceramics

Poster presented at the 24th Annual Meeting of the Portuguese Dental Association, Lisbon, 12-14 November 2015.

Evaluation of polycaprolactone scaffold degradation for 6 months in vitro and in vivo

The use of polycaprolactone (PCL) as a biomaterial, especially in the fields of drug delivery and tissue engineering, has enjoyed significant growth. Understanding how such a device or scaffold eventually degrades in vivo is paramount as the defect site regenerates and remodels. Degradation studies of three-dimensional PCL and PCL-based composite scaffolds were conducted in vitro (in phosphate buffered saline) and in vivo (rabbit model). Results up to 6 months are reported. All samples recorded virtually no molecular weight changes after 6 months, with a maximum mass loss of only about 7% from the PCL-composite scaffolds degraded in vivo, and a minimum of 1% from PCL scaffolds. Overall, crystallinity increased slightly because of the effects of polymer recrystallization. This was also a contributory factor for the observed stiffness increment in some of the samples, while only the PCL-composite scaffold registered a decrease. Histological examination of the in vivo samples revealed good biocompatibility, with no adverse host tissue reactions up to 6 months. Preliminary results of medical-grade PCL scaffolds, which were implanted for 2 years in a critical-sized rabbit calvarial defect site, are also reported here and support our scaffold design goal for gradual and late molecular weight decreases combined with excellent long-term biocompatibility and bone regeneration. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 90A: 906-919, 2009