scholarly journals Impact of the light-curing source and curing time on the degree of conversion and hardness of a composite

2013 ◽  
Vol 1 (1) ◽  
pp. 91
Author(s):  
Anderson Catelan ◽  
Caetano Tamires ◽  
Boniek Castillo Dutra Borges ◽  
Giulliana Panfiglio Soares ◽  
Bruno de Castro Ferreira Barreto ◽  
...  
Keyword(s):  
Physical Properties ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
High Irradiance ◽  
Degree Of Conversion ◽  
Curing Time ◽  
Light Emitting ◽  
Light Curing ◽  
Ft Ir ◽  
The Impact

Adequate physical properties of the resinous materials are related to clinical longevity of adhesive restorations. The aim of this investigation was to assess the impact of light-curing source and curing time on the degree of conversion (DC) and Knoop hardness number (KHN) of a composite resin. Circular specimens (5 x 2 mm) were carried out (n = 7) of the Filtek Z250 (3M ESPE) composite. The specimens were light-cured by quartz-halogen-tungsten (QTH) XL 3000 (3M ESPE, 450 mW/cm2) or light-emitting diode (LED) Bluephase 16i (Vivadent, 1390 mW/cm2) for 20, 40, or 60 s. After 24 h, absorption spectra of composite were obtained using Spectrum 100 Optica (Perkin Elmer) FT-IR spectrometer in order to calculate the DC and, KHN was performed in the HMV-2T (Shimadzu) microhardness tester under 50-g load for 15 s dwell time. DC and KHN data were subjected to 2-way ANOVA and Tukey’s test at a pre-set alpha of 0.05. The LED showed highest DC and KHN values than QTH (p < 0.05). The increase of curing time improved the DC and KHN, all curing times with statistical difference (p < 0.05). The use of light-curing units with high irradiance and/or the time of cure increased may improve the physical properties of resin-based materials.

scholarly journals Effect of different light sources on degree of conversion, hardness and plasticization of a composite

2013 ◽  
Vol 1 (2) ◽  
pp. 134
Author(s):  
Bruno de Castro Ferreira Barreto ◽  
Anderson Catelan ◽  
Ricardo Coelho Okida ◽  
Gisele Fernanda Gonçalves ◽  
Gisele Rodrigues da Silva ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Composite Resins ◽  
Degree Of Conversion ◽  
Light Sources ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Light Curing ◽  
Ft Ir

Clinical performance of composite resins depends largely on their mechanical properties, and those are influenced by several factors, such as the light-curing mode. The purpose of this study was to evaluate the influence of different light sources on degree of conversion (DC), Knoop hardness (KHN) and plasticization (P) of a composite resin. Disc-shaped specimens (5 x 2 mm) of Esthet-X (Dentsply) methacrylate-based microhybrid composite were light-cured using quartz-tungsten-halogen (QTH) Optilight Plus (Gnatus) or light-emitting diode (LED) Ultraled (Dabi Atlante) curing units at 400 and 340 mW/cm2 of irradiance, respectively. After 24 h, absorption spectra of composite were obtained using Nexus 670 (Nicolet) FT-IR spectrometer in order to calculate the DC. The KHN was measured in the HMV-2000 (Shimadzu) microhardness tester under 50 g loads for 15 s, and P was evaluated by percentage reduction of hardness after 24 h of alcohol storage. Data were subjected to t-Student test (alpha = 0.05). QTH device showed lower P and higher KHN than LED (p < 0.05), and no difference between the light-curing units was found for DC (p > 0.05). The halogen-curing unit with higher irradiance promoted higher KHN and lower softening in alcohol than LED.

Effectiveness of Second-generation Light-emitting Diode (LED) Light Curing Units

2007 ◽  
Vol 8 (2) ◽  
pp. 35-42 ◽  
Author(s):  
Fabrício Aulo Ogliari ◽  
Ulisses Bastos Campregher ◽  
Susana Maria Werner Samuel ◽  
Carmen Beatriz Borges Fortes ◽  
Alberth David Correa Medina ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Second Generation ◽  
Light Emitting Diode ◽  
Strength Properties ◽  
Knoop Hardness ◽  
Curing Time ◽  
Light Emitting ◽  
Led Light ◽  
Three Samples ◽  
Light Curing

Abstract Aim The purpose of this study was to evaluate the effectiveness of three commercially available light emitting diode (LED) light curing units (LCU) (Elipar FreeLight - 3M ESPE; UltraLume LED2 - Ultradent; and Single V - BioArt) for polymerizing Z250-A3 composite (3M ESPE) using Knoop hardness, polymerization depth, and flexural strength properties. Methods and Materials The XL 2500 (3M ESPE) LCU, which is a conventional halogen unit, was used as a control. In all cases the curing time was 20 seconds. Hardness was determined 24 hours after composite cure for 10 samples of 8 mm diameter and 2 mm height for each LCU tested. Samples were stored dry in a lightproof container prior to testing. The depth of cure of the composite was measured immediately after composite polymerization for each LCU using three samples 4 mm in diameter and 6 mm in height. Flexural strength was determined for five samples 24 hours after immersion in distilled water at 37°C. Each sample measured 25 mm in length, 2 mm in width, and 2 mm in height for each LCU tested. Conclusion The results were treated statistically for comparison of the LCUs. In all cases the results obtained by LED LCUs were not different or were higher than a conventional halogen LCU. Clinical Significance Second generation LED LCUs were as effective as/or more effective than a halogen LCU for polymerization of the used composite. The present study shows second generation LEDs have the potential to replace halogen LCUs. Citation Campregher UB, Samuel SMW, Fortes CBB, Medina ADC, Collares FMC, Ogliari FA. Effectiveness of Second-generation Light-emitting Diode (LED) Light Curing Units. J Contemp Dent Pract 2007 February;(8)2:035-042.

scholarly journals The Influence of Distance on Radiant Exposure and Degree of Conversion Using Different Light-Emitting-Diode Curing Units

2019 ◽  
Vol 44 (3) ◽  
pp. E133-E144 ◽  
Author(s):  
AO Al-Zain ◽  
GJ Eckert ◽  
JA Platt
Keyword(s):  
Strong Correlation ◽  
Light Emitting Diode ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Degree Of Conversion ◽  
Light Emitting ◽  
Radiant Exposure ◽  
Light Curing ◽  
Irradiance Data ◽  
Resin Curing

SUMMARY Objectives: To investigate the influence of curing distance on the degree of conversion (DC) of a resin-based composite (RBC) when similar radiant exposure was achieved using six different light-curing units (LCUs) and to explore the correlation among irradiance, radiant exposure, and DC. Methods and Materials: A managing accurate resin curing-resin calibrator system was used to collect irradiance data for both top and bottom specimen surfaces with a curing distance of 2 mm and 8 mm while targeting a consistent top surface radiant exposure. Square nanohybrid-dual-photoinitiator RBC specimens (5 × 5 × 2 mm) were cured at each distance (n=6/LCU/distance). Irradiance and DC (micro-Raman spectroscopy) were determined for the top and bottom surfaces. The effect of distance and LCU on irradiance, radiant exposure, and DC as well as their linear associations were analyzed using analysis of variance and Pearson correlation coefficients, respectively (α=0.05). Results: While maintaining a similar radiant exposure, each LCU exhibited distinctive patterns in decreased irradiance and increased curing time. No significant differences in DC values (63.21%-70.28%) were observed between the 2- and 8-mm distances, except for a multiple-emission peak LCU. Significant differences in DC were detected among the LCUs. As expected, irradiance and radiant exposure were significantly lower on the bottom surfaces. However, a strong correlation between irradiance and radiant exposure did not necessarily result in a strong correlation with DC. Conclusions: The RBC exhibited DC values &gt;63% when the top surface radiant exposure was maintained, although the same values were not reached for all lights. A moderate-strong correlation existed among irradiance, radiant exposure, and DC.

scholarly journals Effect of the increase of energy density on knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc

2005 ◽  
Vol 16 (3) ◽  
pp. 218-224 ◽  
Author(s):  
Américo Bortolazzo Correr ◽  
Mário Alexandre Coelho Sinhoreti ◽  
Lourenço Correr Sobrinho ◽  
Rubens Nisie Tango ◽  
Luis Felipe Jochims Schneider ◽  
...  
Keyword(s):  
Energy Density ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Composite Resins ◽  
Plasma Arc ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Light Curing ◽  
Cylindrical Cavities ◽  
Hardness Values

The aim of this study was to evaluate the effect of the increase of energy density on Knoop hardness of Z250 and Esthet-X composite resins. Cylindrical cavities (3 mm in diameter X 3 mm in depth) were prepared on the buccal surface of 144 bovine incisors. The composite resins were bulk-inserted and polymerized using different light-curing units and times: conventional QTH (quartz-tungsten-halogen; 700 mW/cm²; 20 s, 30 s and 40 s); LED (light-emitting diode; 440 mW/cm²; 20 s, 30 s and 40 s); PAC (xenon plasma arc; 1700 mW/cm²; 3 s, 4.5 s and 6 s). The specimens were stored at 37°C for 24 h prior to sectioning for Knoop hardness assessment. Three measurements were obtained for each depth: top surface, 1 mm and 2 mm. Data were analyzed statistically by ANOVA and Tukey's test (p<0.05). Regardless of the light source or energy density, Knoop hardness of Z250 was statistically significant higher than that of Esthet-X (p<0.05). Specimens cured with PAC had lower hardness than those cured with QTH and LED (p<0.05). Higher Knoop hardness was obtained when the energy density was increased for LED and PAC (p<0.05). No statistically significant differences (p>0.05) were found for QTH. Knoop hardness values decreased with the increase of depth. The increase of energy density produced composites with higher Knoop hardness means using LED and PAC.

Influence of Different Cordless Light-emitting-diode Units and Battery Levels on Chemical, Mechanical, and Physical Properties of Composite Resin

2019 ◽  
Vol 45 (4) ◽  
pp. 377-386 ◽  
Author(s):  
IO Cardoso ◽  
AC Machado ◽  
DNR Teixeira ◽  
FC Basílio ◽  
A Marletta ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Composite Resin ◽  
Light Emitting Diode ◽  
Pearson Correlation ◽  
Composite Resins ◽  
Degree Of Conversion ◽  
Light Emitting ◽  
Mechanical And Physical Properties ◽  
Diametral Tensile Strength

Clinical Relevance Irradiance may decrease as the light-emitting diode (LED) is discharged. Therefore, the LED must be charged carefully to prevent the possibility of influencing the chemical, mechanical, and physical properties of composite resin. SUMMARY The aim of this study was to evaluate the influence of different light-emitting diode (LED) curing units and battery levels on the chemical, mechanical, and physical properties of composite resins. The irradiance for each cycle from full to completely discharged battery level was evaluated, for five different new cordless LED units: Optilight Color (Gnatus), Bluephase (Ivoclar), Valo (Ultradent), Radii Plus (SDI), and Radii Xpert (SDI). After the irradiance evaluation, composite resin specimens were prepared and light cured, while varying the battery level for each LED unit: high level (HL, 100%), medium level (ML, 50%), and low level (LL, 10%). The degree of conversion, diametral tensile strength, sorption, and solubility were also evaluated. Data were checked for homoscedasticity and submitted to two-way and three-way analysis of variance, depending on the test performed, followed by the Tukey test with a significance level of 95%. A negative correlation was found between irradiance and cycles of light curing, which was checked by the Pearson correlation test. Valo and Radii Xpert were not influenced by the battery level in any test performed. However, different battery levels for some LED units can influence the degree of conversion, diametral tensile strength, sorption, and solubility of composite resins.

scholarly journals Light curing time reduction: in vitro evaluation of new intensive light-emitting diode curing units

2005 ◽  
Vol 27 (4) ◽  
pp. 408-412 ◽  
Author(s):  
A. Mavropoulos ◽  
C. B. Staudt ◽  
S. Kiliaridis ◽  
I. Krejci
Keyword(s):  
Light Emitting Diode ◽  
Curing Time ◽  
In Vitro Evaluation ◽  
Light Emitting ◽  
Light Curing ◽  
Time Reduction

scholarly journals Light-curing Time and Aging Effects on the Nanomechanical Properties of Methacrylate- and Silorane-based Restorations

2014 ◽  
Vol 39 (4) ◽  
pp. 389-397 ◽  
Author(s):  
A Catelan ◽  
T Pollard ◽  
AK Bedran-Russo ◽  
PH dos Santos ◽  
GMB Ambrosano ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Curing Time ◽  
Aging Effects ◽  
Hybrid Layer ◽  
Light Emitting ◽  
Nanomechanical Properties ◽  
Bonded Interface ◽  
Light Curing ◽  
Double Time ◽  
Fluid Cell

SUMMARY The aim of this study was to assess the influence of light-curing time on the nanohardness (H) and reduced elastic modulus (Er) of components (underlying dentin, hybrid layer, adhesive, and composite) of methacrylate- and silorane-based restorations after 24 hours and six months of storage. Class II slot preparations were carried out in human molars (n=3) and restored with methacrylate (Clearfil SE Bond [Kuraray] + Filtek Z250 [3M ESPE]) or silorane (LS restorative system [3M ESPE]) restorative systems and light-cured using light-emitting diode at 1390 mW/cm2 for the recommended manufacturers' time or double time. Restorations were sectioned, and bonded dentin-resin interfaces were embedded in epoxy resin and polished for evaluation with a Berkovich fluid cell tip (TI 700 Ubi-1 nanoindenter, Hysitron). Data were statistically analyzed by analysis of variance and Tukey's test (alpha=0.05). Overall, the H and Er values were higher for methacrylate-based restorations than for silorane materials (p≤0.05), an increase in curing time did not improve the H and Er of the bonded interface components of either material (p&gt;0.05), and aging significantly decreased the mechanical properties of interface components of both resin-based restorative systems (p≤0.05). In general, nanomechanical properties decreased after six months of storage, the methacrylate restorative system exhibited higher H and Er than silorane, and light-curing time did not influence the properties tested.

Composite Resin Microhardness: The Influence of Light Curing Method, Composite Shade, and Depth of Cure

2008 ◽  
Vol 9 (4) ◽  
pp. 43-50 ◽  
Author(s):  
Cesar Henrique Zanchi ◽  
Flávio Fernando Demarco ◽  
Camila Silveira de Araújo ◽  
Marcelo Thomé Schein ◽  
Sinval Adalberto Rodrigues
Keyword(s):  
Composite Resin ◽  
Light Emitting Diode ◽  
Curing Time ◽  
Light Emitting ◽  
Depth Of Cure ◽  
Quartz Tungsten Halogen ◽  
Light Curing ◽  
Curing Method ◽  
Hardness Values ◽  
Knoop Indenter

Abstract Aim The aim of this study was to investigate the influence of light curing method, composite shade, and depth of cure on composite microhardness. Methods and Materials Forty-eight specimens with 4 mm of depth were prepared with a hybrid composite (Filtek Z-100, 3M ESPE); 24 with shade A1 and the remaining with shade C2. For each shade, two light curing units (LCUs) were used: a quartz-tungsten-halogen (QTH) LCU (Optilight Plus - Gnatus) and a light emitting diode (LED) LCU (LEC 470 II - MM Optics). The LED LCU was tested using two exposure times (LED 40 seconds and LED 60 seconds). After 24-hour storage, three indentations were made at mm depth intervals using a Knoop indenter. Data were submitted to three-way analysis of variance (ANOVA) and Tukey's test (p<0.05). Results The three factors tested (light curing method, shade, and depth) had a significant influence on the composite microhardness (p<0.05). All groups presented similar hardness values in the first mm, except for composite shade C2 cured with LED for 40 seconds. The hardness decreased with depth, especially for shade C2 for 40 seconds. Increasing light-curing time with LED produced hardness values similar to the QTH. Conclusions The light curing method including variations of time, the depth of cure, and the composite shade influence the composite microhardness. Clinical Significance Clinicians should avoid thicker increments when working with composite restorations. Extended light-curing time might be indicated depending on the composite shade and on the light-curing device. Citation de Araújo CS, Schein MT, Zanchi CH, Rodrigues SA Jr, Demarco FF. Composite Resin Microhardness: The Influence of Light Curing Method, Composite Shade, and Depth of Cure. J Contemp Dent Pract 2008 May; (9)4:043-050.

scholarly journals Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

2009 ◽  
Vol 20 (5) ◽  
pp. 410-413 ◽  
Author(s):  
Rogério Vieira Reges ◽  
Ana Rosa Costa ◽  
Américo Bortolazzo Correr ◽  
Evandro Piva ◽  
Regina Maria Puppin-Rontani ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Resin Cement ◽  
Light Emitting ◽  
Ceramic Disc ◽  
Quartz Tungsten Halogen ◽  
Cure Time ◽  
Light Curing ◽  
Effect Of Light ◽  
Made In

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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