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Edge chipping test on microhybrid and nanocomposites
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without compromising mechanical properties. Introduction of reinforcing filler does not interfere with the nanogel-based stress reduction potential. Support: NIH/NIDCR-R01DE022348.
Matrix composition
Percentage of cells viability (mean ± s.d.)
Exp-1 group Exp-2 group Control group
67.73 ± 0.71 66.78 ± 0.20 64.36 ± 1.63
http://dx.doi.org/10.1016/j.dental.2013.08.124 124 Cytotoxicity evaluation of new resin matrix system on fiber-reinforced composites S. Sunarintyas 1,∗ , W. Siswomihardjo 1 , H. Suwarsohartono 1 , J.P. Matinlinna 2
http://dx.doi.org/10.1016/j.dental.2013.08.125 125
1
Universitas Gadjah Mada, Indonesia 2 University of Hong Kong, Hong Kong
Purpose: Recent commercial resin matrix systems use bisGMA as the basic matrix. A previous studies showed that bis-GMA affected the vitality of dental pulp and induced pulpal inflammation (Engelmann J, et al. Biomaterials 2004;25:4573), was able to disturb normal differentiation procedures of pulp fibroblasts (Imazato S, et al. J Biomed Mater Res Part B: Appl Biomater 2009;88B:378), and induced allergic contact stomatitis (Stoeva et al. J IMAB-Ann Proc 2008;book 2:45). A monomer alternative to bis-GMA, such as 1,6-hexanediol dimethacrylate (HDMA), is under current research. The purpose of this study was to determine the cytotoxicity property of HDMA on fibroblast cells by MTT method. Methods and materials: The materials used were bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), HDMA (Esstech, USA), CQ (Esstech, USA), CEMA (Esstech, USA), Eglass fibers (Stick Tech, Finland), Vero fibroblast cell line (UGM, Indonesia). Fifteen specimens of FRCs (2 × 2 × 25) mm were prepared and divided into 3 groups. The experiment groups were 78.4%HDMA + 19.6%MMA + 1.0%CQ + 1.0%CEMA (Exp-1 group) and 49.0%HDMA + 49.0%MMA + 1.0%CQ + 1.0%CEMA Exp-2 group), whilst the control group was 78.4%bisGMA + 19.6%MMA + 1.0%CQ + 1.0%CEMA. Specimens were milled and diluted in culture medium (0.1 mg powder/1 mL medium). Specimen solution of 100 L was added into 96-well plate containing fibroblast cells of 2 × 104 cells/100 L and incubated for 24 h. MTT of 10 L was added to the well, incubated for 4 h, then 100 L stop solution was added. The OD of the cells viability was determined by a ELISA reader with a wavelength of 550 nm. Cells viability was calculated in percentage and analyzed by ANOVA and LSD. Results: Analysis by one way ANOVA revealed significant differences of cells viability among the groups (p < 0.01). The LSD test showed a significant difference between exp-1 group and control group and also between exp-2 group and control group (p < 0.01), whilst no significant difference between exp-1 group and exp-2 group was found (p > 0.05). Conclusion: A resin matrix system based on HDMA–MMA (exp-1 group and exp-2 group) revealed a significant difference of fibroblast cells viability compared to a bis-GMA–MMA matrix system. The HDMA–MMA matrix system was less cytotoxic than bis-GMA–MMA matrix system. Average of fibroblast cells viability in percentage (%)
Edge chipping test on microhybrid and nanocomposites C.B. Tanaka 1,∗ , R.Y. Ballester 1 , G. De Souza 2 , Y. Zhang 3 , J.B.C. Meira 1 1
University of São Paulo, Brazil University of Toronto, Canada 3 New York University, USA 2
Purpose: The edge chipping test has been considered a practical and reliable test to evaluate “edge toughness” and “edge strength” of dental ceramics. The aim of this study was to investigate the influence of indenter type on the “edge toughness (Te)” of two different restorative composites. Methods and materials: A microhybrid composite, (Z250 – Filtek Supreme XT, 3M-ESPE, MN) and a nanocomposite (Z350 – Filtek Supreme XT, 3M-ESPE, MN) were used to prepare 3 bars (5 × 32 × 2.5 mm) samples for each material. The specimens were light-cured using a LED (light-emitting diode) with an irradiance of 1200 mW/cm2 (RADII CAL SDI, Bayswater, AUS). Three base increments were photo-activated for 20 s each and a final surface increment for 120 s. Specimens were kept for 7 days in water-storage at 37 ◦ C before being tested. The edge chipping tests were carried out using a universal testing machine, with a constant load (0.1 mm/min). Two indenter types were used: Rockwell (conical 120◦ ) and Vickers. The load was applied in different distances between the upper longitudinal edge and the indenter (da). Each specimen was chipped around twenty times, with five different da values, from 0.1 mm to 0.5 mm. An average force and standard deviation were calculated for each distance. The relationship between mean critical force (Fc) and edge distance (da) was plotted. Edge toughness (Te) was defined as the slope of the linear trend on these graphs. Results: The results showed that highest values of edge toughness was found using Vickers indenter. Differences between composite (Z250 Te = 335.9 N/mm and Z350 Te = 277.5 N/mm) were found with Vickers indenter, but not with Rockwell indenter (Z250 Te = 234.9 N/mm and Z350 Te = 235.0 N/mm). Conclusion: The type of indenter influences on edge toughness value. Vickers indenter was able to distinguish the different composite, while Rockwell indenter showed similar toughness for them.
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http://dx.doi.org/10.1016/j.dental.2013.08.126 126
127
The effect of 38% hydrogen peroxide on the fracture toughness of a composite resin
An experimental PVAc nanofiber: Electrospinning and characterization
L. Teodoro De Castro Cassanta 1,∗ , G.A. Borges 1 , M.M. Shimano 2 , B.A.S. Miranzi 1 , G.M. Santos E Souza 1 , A.M. Spohr 1,2,3
H.A. Vidotti 1,∗ , V. Leoung 2 , A.L. Valle 1 , F. Ko 2 , R.M. Carvalho 2 1
1
2
Uberaba University, Brazil 2 Federal University of Triangulo Mineiro, Uberaba, Brazil 3 Pontifical Catholic University of Rio Grande Do Sul, Brazil
Purpose: The aim of this study was to evaluate the influence of hydrogen peroxide at 38% on the fracture toughness of a restorative composite resin (Tetric-N-Ceram). Methods and materials: Twenty composite resin bars (25 mm in length × 2 mm wide × 4 mm thickness) were fabricated. Each specimen received a 2 mm long notch on one edge (the one that was tensile tested). Then, the specimens were divided into two groups (n = 10): (1) control – no additional procedure was performed; (2) the specimens received a bleaching agent (hydrogen peroxide) application (Opalescence® Xtra® Boost – Ultradent) using the office whitening procedure as instructed by the manufacturer. Then, all bars were tested using a three-point bending device in a universal testing machine (DL3000, EMIC, Brazil) until failure. The fracture data were recorded in Newton (N) and the crack length was measured after the fracture, and the fracture toughness (Kic) was calculated. The data were statistically analyzed with Student’s t test (p = 0.05). Results: The control group (3.35 ± 0.27) did not differ statistically from the bleached group (3.07 ± 0.37). Conclusion: According to the results obtained it could be concluded that the bleaching procedure used did not cause any changes in the fracture toughness of a restorative composite resin. http://dx.doi.org/10.1016/j.dental.2013.08.127
University of São Paulo, Bauru, Brazil University of British Columbia, Vancouver, Canada
Purpose: Electrospinning is a process by which polymer nanofibers with diameters from 50 to 500 nm can be produced using an electrostatically driven jet of a polymer solution. The objective of this study was to produce and evaluate the mechanical properties of an experimental polyvinyl acetate (PVAc) nanofiber. Methods and materials: A polymer solution consisting of PVAc and dimethylformamide was prepared. The PVAc nanofibers were produced by electrospinning the solution in an electrospinning setup with a rotating rod-like collector. Samples (5 mm in width × 50 mm in length) were mounted on a tensile machine and the tensile properties were determined from the average of six samples. Ultimate tensile stress (UTS), yield strength (YS – upon an offset of 0.3%) and elastic modulus (E) were calculated from the stress × strain plots. Morphological analysis was carried out by scanning electron microscopy. Results: The material presented a UTS of 29.5 ± 2.74 MPa, YS of 23.97 ± 3.87 MPa and E of 1.31 ± 0.05 GPa. It showed a typically plastic behavior as seen on the stress × strain plot. Conclusion: It is possible to produce PVAc nanofibers through the electrospinning process and it seems to be a promising material for the toughening of dental composites.
d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
without compromising mechanical properties. Introduction of reinforcing filler does not interfere with the nanogel-based stress reduction potential. Support: NIH/NIDCR-R01DE022348.
Matrix composition
Percentage of cells viability (mean ± s.d.)
Exp-1 group Exp-2 group Control group
67.73 ± 0.71 66.78 ± 0.20 64.36 ± 1.63
http://dx.doi.org/10.1016/j.dental.2013.08.124 124 Cytotoxicity evaluation of new resin matrix system on fiber-reinforced composites S. Sunarintyas 1,∗ , W. Siswomihardjo 1 , H. Suwarsohartono 1 , J.P. Matinlinna 2
http://dx.doi.org/10.1016/j.dental.2013.08.125 125
1
Universitas Gadjah Mada, Indonesia 2 University of Hong Kong, Hong Kong
Purpose: Recent commercial resin matrix systems use bisGMA as the basic matrix. A previous studies showed that bis-GMA affected the vitality of dental pulp and induced pulpal inflammation (Engelmann J, et al. Biomaterials 2004;25:4573), was able to disturb normal differentiation procedures of pulp fibroblasts (Imazato S, et al. J Biomed Mater Res Part B: Appl Biomater 2009;88B:378), and induced allergic contact stomatitis (Stoeva et al. J IMAB-Ann Proc 2008;book 2:45). A monomer alternative to bis-GMA, such as 1,6-hexanediol dimethacrylate (HDMA), is under current research. The purpose of this study was to determine the cytotoxicity property of HDMA on fibroblast cells by MTT method. Methods and materials: The materials used were bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), HDMA (Esstech, USA), CQ (Esstech, USA), CEMA (Esstech, USA), Eglass fibers (Stick Tech, Finland), Vero fibroblast cell line (UGM, Indonesia). Fifteen specimens of FRCs (2 × 2 × 25) mm were prepared and divided into 3 groups. The experiment groups were 78.4%HDMA + 19.6%MMA + 1.0%CQ + 1.0%CEMA (Exp-1 group) and 49.0%HDMA + 49.0%MMA + 1.0%CQ + 1.0%CEMA Exp-2 group), whilst the control group was 78.4%bisGMA + 19.6%MMA + 1.0%CQ + 1.0%CEMA. Specimens were milled and diluted in culture medium (0.1 mg powder/1 mL medium). Specimen solution of 100 L was added into 96-well plate containing fibroblast cells of 2 × 104 cells/100 L and incubated for 24 h. MTT of 10 L was added to the well, incubated for 4 h, then 100 L stop solution was added. The OD of the cells viability was determined by a ELISA reader with a wavelength of 550 nm. Cells viability was calculated in percentage and analyzed by ANOVA and LSD. Results: Analysis by one way ANOVA revealed significant differences of cells viability among the groups (p < 0.01). The LSD test showed a significant difference between exp-1 group and control group and also between exp-2 group and control group (p < 0.01), whilst no significant difference between exp-1 group and exp-2 group was found (p > 0.05). Conclusion: A resin matrix system based on HDMA–MMA (exp-1 group and exp-2 group) revealed a significant difference of fibroblast cells viability compared to a bis-GMA–MMA matrix system. The HDMA–MMA matrix system was less cytotoxic than bis-GMA–MMA matrix system. Average of fibroblast cells viability in percentage (%)
Edge chipping test on microhybrid and nanocomposites C.B. Tanaka 1,∗ , R.Y. Ballester 1 , G. De Souza 2 , Y. Zhang 3 , J.B.C. Meira 1 1
University of São Paulo, Brazil University of Toronto, Canada 3 New York University, USA 2
Purpose: The edge chipping test has been considered a practical and reliable test to evaluate “edge toughness” and “edge strength” of dental ceramics. The aim of this study was to investigate the influence of indenter type on the “edge toughness (Te)” of two different restorative composites. Methods and materials: A microhybrid composite, (Z250 – Filtek Supreme XT, 3M-ESPE, MN) and a nanocomposite (Z350 – Filtek Supreme XT, 3M-ESPE, MN) were used to prepare 3 bars (5 × 32 × 2.5 mm) samples for each material. The specimens were light-cured using a LED (light-emitting diode) with an irradiance of 1200 mW/cm2 (RADII CAL SDI, Bayswater, AUS). Three base increments were photo-activated for 20 s each and a final surface increment for 120 s. Specimens were kept for 7 days in water-storage at 37 ◦ C before being tested. The edge chipping tests were carried out using a universal testing machine, with a constant load (0.1 mm/min). Two indenter types were used: Rockwell (conical 120◦ ) and Vickers. The load was applied in different distances between the upper longitudinal edge and the indenter (da). Each specimen was chipped around twenty times, with five different da values, from 0.1 mm to 0.5 mm. An average force and standard deviation were calculated for each distance. The relationship between mean critical force (Fc) and edge distance (da) was plotted. Edge toughness (Te) was defined as the slope of the linear trend on these graphs. Results: The results showed that highest values of edge toughness was found using Vickers indenter. Differences between composite (Z250 Te = 335.9 N/mm and Z350 Te = 277.5 N/mm) were found with Vickers indenter, but not with Rockwell indenter (Z250 Te = 234.9 N/mm and Z350 Te = 235.0 N/mm). Conclusion: The type of indenter influences on edge toughness value. Vickers indenter was able to distinguish the different composite, while Rockwell indenter showed similar toughness for them.
e62
d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
http://dx.doi.org/10.1016/j.dental.2013.08.126 126
127
The effect of 38% hydrogen peroxide on the fracture toughness of a composite resin
An experimental PVAc nanofiber: Electrospinning and characterization
L. Teodoro De Castro Cassanta 1,∗ , G.A. Borges 1 , M.M. Shimano 2 , B.A.S. Miranzi 1 , G.M. Santos E Souza 1 , A.M. Spohr 1,2,3
H.A. Vidotti 1,∗ , V. Leoung 2 , A.L. Valle 1 , F. Ko 2 , R.M. Carvalho 2 1
1
2
Uberaba University, Brazil 2 Federal University of Triangulo Mineiro, Uberaba, Brazil 3 Pontifical Catholic University of Rio Grande Do Sul, Brazil
Purpose: The aim of this study was to evaluate the influence of hydrogen peroxide at 38% on the fracture toughness of a restorative composite resin (Tetric-N-Ceram). Methods and materials: Twenty composite resin bars (25 mm in length × 2 mm wide × 4 mm thickness) were fabricated. Each specimen received a 2 mm long notch on one edge (the one that was tensile tested). Then, the specimens were divided into two groups (n = 10): (1) control – no additional procedure was performed; (2) the specimens received a bleaching agent (hydrogen peroxide) application (Opalescence® Xtra® Boost – Ultradent) using the office whitening procedure as instructed by the manufacturer. Then, all bars were tested using a three-point bending device in a universal testing machine (DL3000, EMIC, Brazil) until failure. The fracture data were recorded in Newton (N) and the crack length was measured after the fracture, and the fracture toughness (Kic) was calculated. The data were statistically analyzed with Student’s t test (p = 0.05). Results: The control group (3.35 ± 0.27) did not differ statistically from the bleached group (3.07 ± 0.37). Conclusion: According to the results obtained it could be concluded that the bleaching procedure used did not cause any changes in the fracture toughness of a restorative composite resin. http://dx.doi.org/10.1016/j.dental.2013.08.127
University of São Paulo, Bauru, Brazil University of British Columbia, Vancouver, Canada
Purpose: Electrospinning is a process by which polymer nanofibers with diameters from 50 to 500 nm can be produced using an electrostatically driven jet of a polymer solution. The objective of this study was to produce and evaluate the mechanical properties of an experimental polyvinyl acetate (PVAc) nanofiber. Methods and materials: A polymer solution consisting of PVAc and dimethylformamide was prepared. The PVAc nanofibers were produced by electrospinning the solution in an electrospinning setup with a rotating rod-like collector. Samples (5 mm in width × 50 mm in length) were mounted on a tensile machine and the tensile properties were determined from the average of six samples. Ultimate tensile stress (UTS), yield strength (YS – upon an offset of 0.3%) and elastic modulus (E) were calculated from the stress × strain plots. Morphological analysis was carried out by scanning electron microscopy. Results: The material presented a UTS of 29.5 ± 2.74 MPa, YS of 23.97 ± 3.87 MPa and E of 1.31 ± 0.05 GPa. It showed a typically plastic behavior as seen on the stress × strain plot. Conclusion: It is possible to produce PVAc nanofibers through the electrospinning process and it seems to be a promising material for the toughening of dental composites.