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Mario Alexandre Coelho Sinhoreti - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ceramic Interposition and Post-activation Times on Knoop Hardness of Different Shades of Resin Cement.
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p
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effect of ceramic interposition and post activation times on Knoop Hardness of different shades of resin cement
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop Hardness. Indirect activation through a ceramic material reduced significantly Knoop Hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop Hardness.
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influence of irradiance on Knoop Hardness degree of conversion and polymerization shrinkage of nanofilled and microhybrid composite resins
General dentistry, 2016Co-Authors: Ana Paula Piovezan Fugolin, Mario Alexandre Coelho Sinhoreti, Americo Bortolazzo Correr, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Simonides ConsaniAbstract:: The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microHardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop Hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the Hardness and DC, but not the polymerization shrinkage, of composite resins.
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Influence of the composition of different resin composites in the Knoop Hardness and bond strength between tooth/restoration
Applied Adhesion Science, 2014Co-Authors: Virginia Bosquiroli, William Cunha Brandt, Leticia Cristina Cidreira Boaro, Isaias D Silva, Mario Alexandre Coelho SinhoretiAbstract:The aim of this study was to evaluate the Knoop Hardness (KH) and bond strength (BS) among different resin composites. Three composites (Z100- 3 M/ESPE; Filtek Supreme-3 M/ESPE, Filtek Silorane-3 M/ESPE) were tested. Thirty bovine incisors (n = 10) were used. Conical cavities were prepared in the buccal surface of each tooth with a diamond bur (3131KG Sorensen, Barueri, SP, Brazil) with a high-speed water-cooled hand-piece in a standard cavity preparation appliance (2.0 x 2.0 x 1.5 mm), resulting in a C-Factor of 2.2. Two adhesive systems were used according to the manufacturer’s instructions (Single Bond 2 and Silorane System Adhesive - 3 M ESPE). The restorations were made respectively with Z100, Supreme and Silorane. The composites were inserted in a single increment and light cured with a LED unit, Freelight (3 M ESPE) for 40 s. After photo-activation the specimens were stored at 37°C in distilled water during 24 h. KH (HMV-2, Shimadzu) were performed in the top and bottom at each specimen. After that, the push-out test was performed with a universal testing machine (Model 4411, Instron). In the KH test the data were submitted to a two way ANOVA and Tukey’s test (α=5%). The mean of KHN and standard deviations were: Top - Z100 (74.1/9.0); Supreme (58.4/3.6); Silorane (42.8/6.2) and Bottom - Z100 (66.7/13.6); Supreme (61.2/3.6); Silorane (40.0/3.0). In the BS test the data were submitted to one way ANOVA and Tukey’s test (α=5%). The BS mean and standard deviations were: Z100 (12.6/5.2), Supreme (20.9/6.3), Silorane (29.7/9.0). Z100 had the highest KHN at the top and it was statistically different from the bottom. Supreme and Silorane had no differences between top and bottom. Silorane showed the highest BS mean differing statistically from the others. Differences in the composition of composite resins can to influence in the Knoop Hardness and bond strength of restorations.
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influence of the composition of different resin composites in the Knoop Hardness and bond strength between tooth restoration
Applied Adhesion Science, 2014Co-Authors: Virginia Bosquiroli, William Cunha Brandt, Leticia Cristina Cidreira Boaro, Isaias D Silva, Mario Alexandre Coelho SinhoretiAbstract:The aim of this study was to evaluate the Knoop Hardness (KH) and bond strength (BS) among different resin composites. Three composites (Z100- 3 M/ESPE; Filtek Supreme-3 M/ESPE, Filtek Silorane-3 M/ESPE) were tested. Thirty bovine incisors (n = 10) were used. Conical cavities were prepared in the buccal surface of each tooth with a diamond bur (3131KG Sorensen, Barueri, SP, Brazil) with a high-speed water-cooled hand-piece in a standard cavity preparation appliance (2.0 x 2.0 x 1.5 mm), resulting in a C-Factor of 2.2. Two adhesive systems were used according to the manufacturer’s instructions (Single Bond 2 and Silorane System Adhesive - 3 M ESPE). The restorations were made respectively with Z100, Supreme and Silorane. The composites were inserted in a single increment and light cured with a LED unit, Freelight (3 M ESPE) for 40 s. After photo-activation the specimens were stored at 37°C in distilled water during 24 h. KH (HMV-2, Shimadzu) were performed in the top and bottom at each specimen. After that, the push-out test was performed with a universal testing machine (Model 4411, Instron). In the KH test the data were submitted to a two way ANOVA and Tukey’s test (α=5%). The mean of KHN and standard deviations were: Top - Z100 (74.1/9.0); Supreme (58.4/3.6); Silorane (42.8/6.2) and Bottom - Z100 (66.7/13.6); Supreme (61.2/3.6); Silorane (40.0/3.0). In the BS test the data were submitted to one way ANOVA and Tukey’s test (α=5%). The BS mean and standard deviations were: Z100 (12.6/5.2), Supreme (20.9/6.3), Silorane (29.7/9.0). Z100 had the highest KHN at the top and it was statistically different from the bottom. Supreme and Silorane had no differences between top and bottom. Silorane showed the highest BS mean differing statistically from the others. Differences in the composition of composite resins can to influence in the Knoop Hardness and bond strength of restorations.
Simonides Consani - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ceramic Interposition and Post-activation Times on Knoop Hardness of Different Shades of Resin Cement.
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p
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effect of ceramic interposition and post activation times on Knoop Hardness of different shades of resin cement
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop Hardness. Indirect activation through a ceramic material reduced significantly Knoop Hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop Hardness.
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influence of irradiance on Knoop Hardness degree of conversion and polymerization shrinkage of nanofilled and microhybrid composite resins
General dentistry, 2016Co-Authors: Ana Paula Piovezan Fugolin, Mario Alexandre Coelho Sinhoreti, Americo Bortolazzo Correr, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Simonides ConsaniAbstract:: The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microHardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop Hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the Hardness and DC, but not the polymerization shrinkage, of composite resins.
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Temperature rise and Knoop Hardness promoted by different light-curing units
Brazilian dental science, 2010Co-Authors: Luis Felipe Jochims Schneider, Lourenco Correr Sobrinho, Mario Alexandre Coelho Sinhoreti, Rafael R. Moraes, Simonides ConsaniAbstract:This study characterized the light emitted by a quartz-tungsten-halogen (QTH) and three light-emitting diode (LED) light curing units (LCUs) and investigated the temperature rise and composite Hardness promoted by these sources. XL2500 QTH (3M ESPE), Freelight LED (3M ESPE), Ultrablue Is LED (DMC) and Cool Blue Wand LED (Milestone Scientific) were investigated. The irradiance was measured with a power meter, and the light spectral distribution obtained with a spectrometer. Temperature rise was recorded using a thermocouple connected to a digital thermometer during light-activation of Filtek Z250 (3M ESPE) resin composite. Data were submitted to ANOVA and Tukey’s test ( α =0.05). Knoop Hardness was assessed at different composite depths (20, 1000 and 1980 μ m), and data submitted to split-plot design two-way ANOVA and Tukey’s test ( α =0.05). Correlation between irradiance and temperature rise was investigated by Pearson’s test. All units presented 95% of irradiance between 400-515nm. Temperature rise means (oC) varied between 1.05 }0.16 and 2.74 }0.27. The Cool Blue LED presented significantly higher temperature increase than the other LCUs, and the QTH promoted significantly higher temperature rise than Ultrablue Is and Freelight LEDs. Significant relationship between irradiance and temperature increase was detected (r=0.867; p
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temperature rise and Knoop Hardness promoted by different light curing units
Brazilian dental science, 2010Co-Authors: Luis Felipe Jochims Schneider, Lourenco Correr Sobrinho, Mario Alexandre Coelho Sinhoreti, Rafael R. Moraes, Simonides ConsaniAbstract:This study characterized the light emitted by a quartz-tungsten-halogen (QTH) and three light-emitting diode (LED) light curing units (LCUs) and investigated the temperature rise and composite Hardness promoted by these sources. XL2500 QTH (3M ESPE), Freelight LED (3M ESPE), Ultrablue Is LED (DMC) and Cool Blue Wand LED (Milestone Scientific) were investigated. The irradiance was measured with a power meter, and the light spectral distribution obtained with a spectrometer. Temperature rise was recorded using a thermocouple connected to a digital thermometer during light-activation of Filtek Z250 (3M ESPE) resin composite. Data were submitted to ANOVA and Tukey’s test ( α =0.05). Knoop Hardness was assessed at different composite depths (20, 1000 and 1980 μ m), and data submitted to split-plot design two-way ANOVA and Tukey’s test ( α =0.05). Correlation between irradiance and temperature rise was investigated by Pearson’s test. All units presented 95% of irradiance between 400-515nm. Temperature rise means (oC) varied between 1.05 }0.16 and 2.74 }0.27. The Cool Blue LED presented significantly higher temperature increase than the other LCUs, and the QTH promoted significantly higher temperature rise than Ultrablue Is and Freelight LEDs. Significant relationship between irradiance and temperature increase was detected (r=0.867; p<0.001). Hardness means (kg/mm2) varied between 40.1 }3.6 and 92.7 }6.6. Samples activated by the Freelight LED presented significantly lower Hardness than samples activated by the others units.
Lourenco Corrersobrinho - One of the best experts on this subject based on the ideXlab platform.
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influence of irradiance on Knoop Hardness degree of conversion and polymerization shrinkage of nanofilled and microhybrid composite resins
General dentistry, 2016Co-Authors: Ana Paula Piovezan Fugolin, Mario Alexandre Coelho Sinhoreti, Americo Bortolazzo Correr, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Simonides ConsaniAbstract:: The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microHardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop Hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the Hardness and DC, but not the polymerization shrinkage, of composite resins.
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influence of the volume of composite and photoactivation method on push out bond strength and Knoop Hardness of a resin composite
Minerva stomatologica, 2012Co-Authors: Americo Bortolazzo Correr, Ana Rosa Costa, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Mario Alexandre Coelho SinhoretiAbstract:AIM: The aim of this paper was to evaluate the influence of modulated photoactivation methods and volume of composite on Knoop Hardness (KHN) and push-out bond strength (PBS) of Filtek Z350 to root dentin. METHODS: Three volumes (small, medium and large) of composite were bulk inserted in cavities prepared in 90 premolars. The specimens were photoactivated with continuous light, pulse-delay, or soft-start methods and submitted to PBS and KHN tests. The failure pattern was evaluated in stereomicroscope after the bond strength test. The data were submitted to two-way ANOVA and Tukey's test (P<0.05). RESULTS: Modulated photoactivation methods showed a higher PBS than continuous method (P<0.05). Medium volume of composite showed higher PBS than small and large volumes when photoactivated with continuous method (P<0.05). Pulse-delay significantly increased KHN for medium and large volumes in comparison to continuous method (P<0.05). Medium volume of composite showed KHN significantly higher than small and large volumes (P<0.05). CONCLUSION: The volume of composite influenced the PBS and KHN of resin composites. Pulse-delay showed the highest bond strength to dentin, as well KHN similar to the conventional method. The analysis of the failure pattern showed predominance of adhesive failure.
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can phenyl propanedione influence Knoop Hardness rate of polymerization and bond strength of resin composite restorations
Journal of Dentistry, 2011Co-Authors: William Cunha Brandt, Lourenco Corrersobrinho, Lucas De Oliveira Tomaselli, Mario Alexandre Coelho SinhoretiAbstract:Abstract Objectives The aim of this study was to evaluate the degree of conversion (DC), rate of polymerization (Rpmax), Knoop Hardness (KHN) and bond strength between tooth/restoration of composite resins containing different photo-initiators photo-activated by different light-curing units (LCUs). Materials and methods A mixture of BisGMA, UDMA, BisEMA and TEGDMA was prepared along with the following photo-initiators: camphorquinone (CQ), phenyl-propanedione (PPD) or the association (CQ/PPD) and 65 wt% of silanated filler particles. The LCUs included a halogen lamp XL 2500 and two LEDs: UltraBlueIS and UltraLume5. The conversion profiles during photo-polymerization were investigated using middle-infrared spectroscopy (mid-IR). Bond strength was evaluated using push-out test in ninety teeth with prepared cavities. Before the push-out test, Knoop Hardness (KH) was verified in the top and at the base of the restorations. Results PPD obtained lower Rpmax values, regardless of the LCU used. It also provided a greater bond strength than CQ when the LEDs LCUs were used. The degree of conversion after 40 s of irradiation was the same for all composite resins, except PPD photo-activated for XL 2500, which showed lower DC values than CQ and CQ/PPD. In the top and at the base of the restorations, PPD showed the lowest KH values when photo-activated with XL 2500. XL 2500 produced higher KH values than UltraBlueIS when used with CQ or CQ/PPD photo-initiators. Conclusion Because it increased the bond strength without compromising the properties of composite resins when photo-activated by an LED, PPD can be used as an alternative photo-initiator.
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effect of light curing units post cured time and shade of resin cement on Knoop Hardness
Brazilian Dental Journal, 2009Co-Authors: Rogerio Vieira Reges, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Evandro Piva, Regina Maria Puppinrontani, Lourenco CorrersobrinhoAbstract:The aim of this study was to evaluate the Knoop Hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm2, respectively. The Koop Hardness was measured using a microHardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (a=0.05). The QTH LCU provided significantly higher (p<0.05) KHN values than the LED LCU. When the post-cure times were compared for the same shade, QTH and LED at 24 h provided significantly higher (p<0.05) KHN values than at 15 min. It may be concluded that the Knoop Hardness was generally dependent on the LCU and post-cure time. The opaque shade of the resin cement showed lower Knoop Hardness than the other shades for both LCUs and post-cure times.
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influence of energy density of different light sources on Knoop Hardness of a dual cured resin cement
Journal of Applied Oral Science, 2008Co-Authors: Evandro Piva, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Lourenco Corrersobrinho, Flávio Fernando Demarco, John M. PowersAbstract:The purpose of this study was to evaluate the Knoop Hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm-2 (I/2x2T), 24 Jcm-2 (IxT) and 48 Jcm-2 (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop Hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (a=5%). Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8) and HAL (50.9±3.7) produced significantly higher KHN means (p<0.05) than the control (44.7±3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and Hardness increase.
Americo Bortolazzo Correr - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ceramic Interposition and Post-activation Times on Knoop Hardness of Different Shades of Resin Cement.
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p
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effect of ceramic interposition and post activation times on Knoop Hardness of different shades of resin cement
Brazilian Dental Journal, 2018Co-Authors: Marina Barreto Pereira Moreno, Frederick A. Rueggeberg, Simonides Consani, Mario Alexandre Coelho Sinhoreti, Ana Rosa Costa, Americo Bortolazzo Correr, Glaucia Maria Bovi Ambrosano, Lourenco Correr SobrinhoAbstract:: The aim of this study was to evaluate Knoop Hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microHardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 oC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p 0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop Hardness. Indirect activation through a ceramic material reduced significantly Knoop Hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop Hardness.
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influence of irradiance on Knoop Hardness degree of conversion and polymerization shrinkage of nanofilled and microhybrid composite resins
General dentistry, 2016Co-Authors: Ana Paula Piovezan Fugolin, Mario Alexandre Coelho Sinhoreti, Americo Bortolazzo Correr, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Simonides ConsaniAbstract:: The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microHardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop Hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the Hardness and DC, but not the polymerization shrinkage, of composite resins.
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Influence of the volume of composite and photoactivation method on push-out bond strength and Knoop Hardness of a resin composite.
Minerva stomatologica, 2012Co-Authors: Americo Bortolazzo Correr, Ana Rosa Costa, Lourenço Correr-sobrinho, Ricardo Danil Guiraldo, Mario Alexandre Coelho SinhoretiAbstract:AIM: The aim of this paper was to evaluate the influence of modulated photoactivation methods and volume of composite on Knoop Hardness (KHN) and push-out bond strength (PBS) of Filtek Z350 to root dentin. METHODS: Three volumes (small, medium and large) of composite were bulk inserted in cavities prepared in 90 premolars. The specimens were photoactivated with continuous light, pulse-delay, or soft-start methods and submitted to PBS and KHN tests. The failure pattern was evaluated in stereomicroscope after the bond strength test. The data were submitted to two-way ANOVA and Tukey's test (P
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influence of the volume of composite and photoactivation method on push out bond strength and Knoop Hardness of a resin composite
Minerva stomatologica, 2012Co-Authors: Americo Bortolazzo Correr, Ana Rosa Costa, Lourenco Corrersobrinho, Ricardo Danil Guiraldo, Mario Alexandre Coelho SinhoretiAbstract:AIM: The aim of this paper was to evaluate the influence of modulated photoactivation methods and volume of composite on Knoop Hardness (KHN) and push-out bond strength (PBS) of Filtek Z350 to root dentin. METHODS: Three volumes (small, medium and large) of composite were bulk inserted in cavities prepared in 90 premolars. The specimens were photoactivated with continuous light, pulse-delay, or soft-start methods and submitted to PBS and KHN tests. The failure pattern was evaluated in stereomicroscope after the bond strength test. The data were submitted to two-way ANOVA and Tukey's test (P<0.05). RESULTS: Modulated photoactivation methods showed a higher PBS than continuous method (P<0.05). Medium volume of composite showed higher PBS than small and large volumes when photoactivated with continuous method (P<0.05). Pulse-delay significantly increased KHN for medium and large volumes in comparison to continuous method (P<0.05). Medium volume of composite showed KHN significantly higher than small and large volumes (P<0.05). CONCLUSION: The volume of composite influenced the PBS and KHN of resin composites. Pulse-delay showed the highest bond strength to dentin, as well KHN similar to the conventional method. The analysis of the failure pattern showed predominance of adhesive failure.
Klaus D Jandt - One of the best experts on this subject based on the ideXlab platform.
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the influence of storage and indenter load on the Knoop Hardness of dental composites polymerized with led and halogen technologies
Dental Materials, 2004Co-Authors: Christian Michaelis, Robin W. Mills, Klaus D JandtAbstract:Abstract Objectives. The mechanical properties of light cured dental composites are greatly influenced by the light curing unit (LCU) used for the polymerization. Previous studies have shown that for some composites lower mechanical properties were obtained if light emitting diode (LED) LCUs were used for the polymerization instead of halogen LCUs. Previous studies have also shown that light cured composites improve their mechanical properties through a post-curing process after the initial illumination with the LCUs. Therefore, this study investigated the post-curing process, to ascertain if it can compensate for the lower mechanical properties of composites polymerized with LED LCUs. Methods. The Knoop Hardness was measured for four dental composites (Z100, Spectrum, Definite, Solitaire2) polymerized with an LED LCU (LED63 prototype) or a halogen LCU (Trilight), directly after the curing process and after 5 days of storage. In addition, the load on the indenter was varied from 200 to 400 gf to investigate the influence of the load on the measured Hardness on the top and bottom of the 2 mm thick samples. Results. In general the Knoop Hardness at the bottom of the stored samples, cured with the LED LCU, was the same or statistically significantly greater than for the samples cured with the halogen LCU. A statistically significantly lower (p Significance. The post-curing effect cannot compensate for the lower Hardness of composites containing co-initiators if polymerized with an LED LCU instead of a halogen LCU. The indenter load had a statistically significant influence on the measured Knoop Hardness of composites and has the potential to falsify results if not selected carefully.
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photoinitiator dependent composite depth of cure and Knoop Hardness with halogen and led light curing units
Biomaterials, 2003Co-Authors: Robin W. Mills, Klaus D JandtAbstract:Light curing units (LCUs) are used for the polymerization of dental composites. Recent trends in light curing technology include replacing the halogen LCUs with LCUs using light emitting diodes (LEDs) reducing curing times and varying the LCUs light output within a curing cycle. This study investigated the time dependence of the Knoop Hardness and depth of cure of dental composites polymerized with a halogen LCU (Trilight) and two LED LCUs (the commercial Freelight and custom-made LED LCU prototype). The halogen LCU was used in the soft-start (exponential increase of output power) and standard mode. Four dental composites (Z100, Spectrum, Definite, Solitaire2) were selected, two of them (Definite, Solitaire2) contain co-initiators in addition to the standard photoinitiator camphorquinone. The depth of cure obtained with the Trilight in the standard mode was statistically significantly greater (p<0.05) than that obtained with the LED LCUs for all materials and curing times. The custom made LED LCU prototype (LED63) achieved a statistically significantly greater depth of cure than the commercial LED LCU Freelight for all materials and curing times. There was no statistical difference in Knoop Hardness at the 95% confidence level at the surface of the 2 mm thick sample between the LED63 or Trilight (standard mode) for the composite Z100 for all times, and for Spectrum for 20 s and 40 s curing time. The composites containing co-initiators showed statistically significantly smaller Hardness values at the top and bottom of the samples if LED LCUs were used instead of halogen LCUs. The experiment revealed that the depth of cure test does not and the Knoop Hardness test does discriminate between LCUs, used for the polymerization of composites containing photoinitiators in addition to camphorquinone.
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Photoinitiator dependent composite depth of cure and Knoop Hardness with halogen and LED light curing units
Biomaterials, 2003Co-Authors: Axel Uhl, Robin W. Mills, Klaus D JandtAbstract:Light curing units (LCUs) are used for the polymerization of dental composites. Recent trends in light curing technology include replacing the halogen LCUs with LCUs using light emitting diodes (LEDs) reducing curing times and varying the LCUs light output within a curing cycle. This study investigated the time dependence of the Knoop Hardness and depth of cure of dental composites polymerized with a halogen LCU (Trilight) and two LED LCUs (the commercial Freelight and custom-made LED LCU prototype). The halogen LCU was used in the soft-start (exponential increase of output power) and standard mode. Four dental composites (Z100, Spectrum, Definite, Solitaire2) were selected, two of them (Definite, Solitaire2) contain co-initiators in addition to the standard photoinitiator camphorquinone. The depth of cure obtained with the Trilight in the standard mode was statistically significantly greater (p
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Knoop Hardness depth profiles and compressive strength of selected dental composites polymerized with halogen and led light curing technologies
Journal of Biomedical Materials Research, 2002Co-Authors: Robin W. Mills, Richard W Vowles, Klaus D JandtAbstract:After the first light-emitting diode (LED) light curing units (LCUs) became available commercially, a comparison of mechanical properties between materials polymerized with conventional halogen lamps and this new technology was required. This study, therefore, investigated the curing performance of two conventional commercial halogen LCUs (Translux CL, Spectrum800), a custom-made LED LCU prototype, and one of the first commercially available LED LCUs (LUXoMAX). The Spectrum800 was adjusted to a similar irradiance to the custom-made LED LCU prototype. Both technologies were compared by measuring compressive strength and Knoop Hardness depth profiles for selected dental composites polymerized for 20 or 40 s. Four dental composites (Z100, Spectrum TPH, Solitaire2, and Definite) were used. Two of these composites (Solitaire2 and Definite) contain co-initiators in addition to the standard photoinitiator camphorquinone. In general, the material Hardness obtained with the LUXoMAX was statistically significantly (p < 0.05) lower at the depths of 0.1, 1.0, 1.9, and 3.1 mm, for all composites and curing times, than for the other three LCUs. The LED LCU prototype achieved, with one exception, up to a depth of 1.9 mm a material Hardness for the composites Z100, Spectrum TPH and Solitaire2 that was not statistically significant different (p < 0.05) from the Hardness obtained with the halogen LCUs. At a greater depth (3.1 mm), however, the LED LCU prototype showed statistically significantly lower Hardness values than the halogen units. The compressive strength test showed at a 95% confidence level that similar compressive strengths were achieved with the LCUs LUXoMAX and Spectrum800, and the Translux and LED LCU prototype. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 729–738, 2002
