scholarly journals Analysis of the Effect of Dental Chair Light on the Knoop Hardness of Composite Resin While Light Curing with QTH and LED Light Units

2012 ◽  
Vol 3 (2) ◽  
pp. 156-160
Author(s):  
Bandish Parekh ◽  
Sucheta Sathe
Keyword(s):  
Composite Resin ◽  
Light Emitting Diode ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Degree Of Polymerization ◽  
Led Light ◽  
Group Iii ◽  
Dental Chair ◽  
Group I ◽  
Light Curing

ABSTRACT Dental chair lights have been known to rapidly polymerize lightcured composites beyond the point of workability. Often in our dental clinics we are advised to switch off the dental chair light while light curing of dental composites. The purpose of this study was to determine whether the dental chair light causes any effect on the degree of polymerization of light cured composites using the quartz tungsten halogen (QTH) and the light emitting diode (LED) light curing units (LCUs). Filtek Z350 composite samples of 2 × 5 mm were prepared in an acrylic mold. Four groups were made having 20 samples each. In group I and II light curing was done using QTH LCU with and without the dental chair light respectively. Similarly in group III and IV LED LCU was used. Microhardness was measured and compared using Knoop's hardness Test. Data was submitted to ANOVA and Tukey's test. Results showed that the average microhardness was significantly higher in group 4 (LED light curing with dental chair light on). Thus, it was concluded that the dental chair light can be left on while using QTH and LED LCU's during light curing of composite material. How to cite this article Parekh B, Sathe S, Hegde V. Analysis of the Effect of Dental Chair Light on the Knoop Hardness of Composite Resin While Light Curing with QTH and LED Light Units. World J Dent 2012;3(2):156-160.

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 Evaluation of Different Light-Curing Units—Light-Emitting Diodes and Quartz–Tungsten–Halogen-Based Light-Curing Units in Polymerization of Posterior Composite: An In Vitro Study

2018 ◽  
Vol 6 (02/03) ◽  
pp. 060-064
Author(s):  
R. Bansal ◽  
M. Bansal ◽  
S. Walia ◽  
C. Gupta ◽  
L. Bansal ◽  
...  
Keyword(s):  
Composite Resin ◽  
Light Emitting Diode ◽  
In Vitro Study ◽  
Hardness Test ◽  
Acrylic Resin ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Light Curing

Abstract Objective To assess the adequacy of various light-curing units to polymerize the posterior composite resin. Materials and Methods Specimens were prepared by placing a single increment of posterior composite resin in split cylindrical metallic mold of dimension (6.0 mm in diameter and 5 mm in depth). Polymerization was done by utilizing one quartz-tungsten-halogen and three light-emitting diode light-curing units of different powers. The specimens of composite resin were then mounted on metallic molds utilizing autopolymerizing acrylic resin. After polishing, the complete setting of composite resin material was analyzed using Vickers hardness test. Results Showed in each group, hardness reduced as we moved from upper to lower surface of composite resin. Furthermore, hardness increased as intensity of light was increased. The maximum hardness was detected when light-emitting diode light-curing unit having intensity of 1,250 mW/cm2 was utilized and least hardness was detected when halogen lamp having intensity 418 mW/cm2 was utilized and results were found to be highly significant (p < 0.01). Conclusion It was concluded that increased top and bottom hardness can be accomplished by utilizing the light-curing unit of high intensity.

scholarly journals In vitro Evaluation of Microleakage under Ceramic and Metal Brackets Bonded with LED and Plasma Arc Curing

2012 ◽  
Vol 13 (5) ◽  
pp. 644-649
Author(s):  
Abdolrahim Davari ◽  
Soghra Yassaei ◽  
Mariam Karandish ◽  
Fateme Zarghami
Keyword(s):  
Light Emitting Diode ◽  
Plasma Arc ◽  
Light Emitting ◽  
Group Iii ◽  
Gingival Margin ◽  
Group I ◽  
Ceramic Brackets ◽  
Light Curing ◽  
Ceramic Bracket

ABSTRACT Aim The aim of the present study was to evaluate these two high intensity light curing units regarding microleakage beneath metal and ceramic brackets. Materials and methods A total of 60 freshly extracted human premolar teeth were randomly divided into four groups of 15 samples; group I: Metal bracket + LED cured, group II: Ceramic bracket + LED cured, group III: Metal bracket + plasma arc cured, group IV: Ceramic bracket + plasma arc cured. After photopolymerization, the teeth were immersed in water and thermocycled (500 cycles between 5 and 55). Specimens were further sealed with nail varnish and stained with 5% basic fuchsin for 24 hours. All of the teeth were sectioned with two parallel longitudinal occlusogingival cuts and examined under a stereomicroscope. The microleakage was measured with a digital caliper and scored from 0 to 3 for marginal microleakage at the bracket-adhesive and adhesive-enamel interfaces from both the occlusal and gingival margins. Results Microleakage was detected in all groups. The plasma arc cured group showed less microleakage than light emitting diode (LED) cured in all samples at the enamel-adhesive interface at the gingival margin (ceramic brackets, p = 0.009 and metal brackets, p = 0.005). The plasma arc cured samples showed less microleakage than LED cured in metal brackets at the adhesive-brackets interface at the occlusal margin (p = 0.033). While curing with an LED unit, ceramic brackets displayed significantly less microleakage than metal ones at the gingival margin of adhesive-enamel interface (p = 0.013). The gingival margin in all groups exhibited higher microleakage compared with those observed in occlusal sides in all sample groups (p < 0.001). Conclusion 1. LED units cause more microleakage than plasma arc units. 2. In all groups the microleakage at the gingival margin is greater than the occlusal margin. Clinical significance The microleakage formation permits the passage of bacteria and oral fluids initiating white spot lesions beneath the bracket base. How to cite this article Davari A, Yassaei S, Karandish M, Zarghami F. In vitro Evaluation of Microleakage under Ceramic and Metal Brackets Bonded with LED and Plasma Arc Curing. J Contemp Dent Pract 2012;13(5):644-649.

scholarly journals The difference nanocomposite hardness level using LED photoactivation based on curing period variations

2011 ◽  
Vol 23 (1) ◽  
Author(s):  
Hasiana Tatian ◽  
Moch. Richata Fadil ◽  
Milly Armilia
Keyword(s):  
Physical And Mechanical Properties ◽  
Degree Of Polymerization ◽  
Curing Time ◽  
Group Iii ◽  
Hardness Level ◽  
Hardness Tester ◽  
Group I ◽  
Light Curing ◽  
The Difference

Polimerizatian is the critical stage to determine the quality of composites resin, this involves isolated monomer carbon double bonds being converted to an extended network of single bonds. Physical and mechanical properties of composites are influenced by the level of conversion attained during polymerization. An adequate light intensity and light curing time are important to obtain the degree of polymerization. The objective of this study is to evaluate the difference of the hardness nanocomposites which activated by LED LCU based on the variation of curing times. This study is a true experimental research. The samples were made from nanocomposites material with cylinder form of 4 mm in depth, 6 mm in diameter. This samples divided into 3 groups of curing times. Group, I was cured for 20's curing time as a control due to manufactory recommended; Group II was cured for 30's, and Group III was cured for 40's and the hardness (Rebound hardness tester) was determined using Rebound scale (RS) and converted by Mohs scale (MS). There was a very significant level of hardness rate from each group using ANOVA test. The result of the study concludes that there were the differences on the nanocomposites hardness level cured under different curing times 20, 30 and 40 sec. The longer of curing times, the higher level of hardness.

scholarly journals Effect of light-curing methods on resin cement knoop hardness at different depths

2007 ◽  
Vol 18 (4) ◽  
pp. 305-308 ◽  
Author(s):  
Mário Alexandre Coelho Sinhoreti ◽  
Izabella Paola Manetta ◽  
Rubens Nisie Tango ◽  
Nelson Tetsu Iriyama ◽  
Rafael Leonardo Xediek Consani ◽  
...  
Keyword(s):  
Chemical Reaction ◽  
Light Emitting Diode ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Resin Cement ◽  
Control Group ◽  
Light Emitting ◽  
Halogen Light ◽  
Curing Methods ◽  
Light Curing

This study evaluated, using Knoop hardness test, the polymerization depth of Rely-X dual-cured resin cement activated by chemical reaction alone (control group) or by chemical/physical mode with light curing through a 1.5-mm-thick ceramic layer (HeraCeram). Bovine incisors had their buccal surface flattened and hybridized. On this surface, a rubber mould (5 mm diameter; 1 mm high) was bulk filled with cement. Either a polyester strip or a 1.5-mm-thick disc of the veneering material was seated over this set. Light curing was performed with either conventional halogen light (QTH; XL2500) for 40 s, light-emitting diode (LED; Ultrablue Is) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. In a control group, cement setting occurred by chemical reaction alone. After storage dry in dark (24 h/37ºC), the specimens (n=5) were sectioned for hardness (KHN) measurements at three depths in a microhardness tester (50 gf load/15 s). Data were submitted to ANOVA and Tukey's test (a = 0.05). Rely-X cement presented higher Knoop hardness values when the QTH and LED LCUs were used, compared to the control group and PAC. Light curing with PAC resulted in lower hardness compared to the control group. Cement hardness was significantly lower in deeper regions.

scholarly journals A Comparative Evaluation of Curing Depth and Compressive Strength of Dental Composite Cured with Halogen Light Curing Unit and Blue Light Emitting Diode: An in vitro Study

2012 ◽  
Vol 13 (6) ◽  
pp. 834-837 ◽  
Author(s):  
R Divyashree ◽  
M Gururaj ◽  
CN Vijaya Kumar ◽  
Joseph Paul ◽  
L Krishnaprasada
Keyword(s):  
Compressive Strength ◽  
Light Emitting Diode ◽  
Dental Composite ◽  
Light Emitting ◽  
Led Light ◽  
Group I ◽  
Halogen Light ◽  
Light Curing ◽  
Group B

ABSTRACT Purpose To evaluate the curing depth and compressive strength of dental composite using halogen light curing unit and light emitting diode light curing unit. Materials and methods Eighty cylindrical composite specimens were prepared using posterior composite P60(3M). Forty specimens, out of which 20 samples (group A) cured with halogen light and 20 samples (group B) cured using light emitting diode (LED) light were checked for curing depth according to ISO 4049. Remaining 40 samples out of which 20 samples (group I) cured using halogen light and 20 samples (group II) cured using LED light were checked for compressive strength using Instron universal testing machine. Results Twenty samples (group A) cured with halogen light showed better curing depth than 20 samples (group B) cured with LED light. Twenty samples (group I) cured with halogen light showed almost similar results as 20 samples (group II) cured with LED light for compressive strength. Conclusion Halogen light commonly used to cure composite resin have greater depth of cure, when compared to LED light, while both the lights produced compressive strength which is almost similar. Clinical significance Lower depth of cure with the LED unit, compared to the QTH unit, is associated with different light scattering due to differences in spectral emission. LED technology differs from QTH by the spectral emission that favorably matches the absorption spectrum of camphorquinone. How to cite this article Kumar CNV, Gururaj M, Paul J, Krishnaprasada L, Divyashree R. A Comparative Evaluation of Curing Depth and Compressive Strength of Dental Composite cured with Halogen Light Curing Unit and Blue Light Emitting Diode: An in vitro Study. J Contemp Dent Pract 2012;13(6):834-837.

Effects of Preheating and Precooling on the Hardness and Shrinkage of a Composite Resin Cured with QTH and LED

2013 ◽  
Vol 38 (3) ◽  
pp. E50-E57 ◽  
Author(s):  
FH Osternack ◽  
DBM Caldas ◽  
JB Almeida ◽  
EM Souza ◽  
RF Mazur
Keyword(s):  
Composite Resin ◽  
Light Emitting Diode ◽  
Resin Composite ◽  
Hardness Test ◽  
Optical Microscope ◽  
Knoop Hardness ◽  
Halogen Light ◽  
Different Temperatures ◽  
Composite Hardness

SUMMARY The aim of this study was to evaluate in vitro the hardness and shrinkage of a pre-cooled or preheated hybrid composite resin cured by a quartz-tungsten-halogen light (QTH) and light-emitting diode (LED) curing units. The temperature on the tip of the devices was also investigated. Specimens of Charisma resin composite were produced with a metal mold kept under 37°C. The syringes were submitted to 4°C, 23°C, and 60°C (n=20) before light-curing, which was carried out with the Optilux 501 VCL and Elipar FreeLight 2 units for 20 seconds. The specimens were kept under 37°C in a high humidity condition and darkness for 48 hours. The Knoop hardness test was carried out with a 50 gram-force (gf) load for 10 seconds, and the measurement of the shrinkage gap was carried out using an optical microscope. The data were subjected to analysis of variance and the Games-Howell test (α=0.05). The mean hardness of the groups were similar, irrespective of the temperatures (p&gt;0.05). For 4°C and 60°C, the top surface light-cured by LED presented significantly reduced shrinkage when compared with the bottom and to both surfaces cured by QTH (p&lt;0.05). It was concluded that the hardness was not affected by pre-cooling or preheating. However, polymerization shrinkage was slightly affected by different pre-polymerization temperatures. The QTH-curing generated greater shrinkage than LED-curing only when the composite was preheated. Different temperatures did not affect the composite hardness and shrinkage when cured by a LED curing unit.

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.

scholarly journals Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations

2005 ◽  
Vol 13 (2) ◽  
pp. 193-197 ◽  
Author(s):  
Maria Jacinta M. Coelho Santos ◽  
Mário Honorato da Silva e Souza Júnior ◽  
Gildo Coelho Santos Júnior ◽  
Omar El-Mowafy ◽  
Ana Paula Chedid Cavalcanti ◽  
...  
Keyword(s):  
Composite Resin ◽  
Step Cycle ◽  
Class V ◽  
Dye Penetration ◽  
Group I ◽  
Light Curing ◽  
Composite Resin Restorations ◽  
Qth Light ◽  
Curing Cycle ◽  
Resin Restorations

The aim of this study was to determine the effect of a softstart polymerization method from Quartz-Tungsten-Halogen (QTH) and Plasma Arc (PAC) curing units on microleakage of Class V composite resin restorations with dentin cavosurface margins. Seventy-five bovine incisors received standardized class V cavities in all dentin margins. Teeth were divided into 5 equal groups according to the curing cycle. The cavities were incrementally restored with a composite resin (Single Bond/Z-100, 3M). Light curing was applied as follows: Group I: PAC light continuous-cycle curing at 1600 mW/cm² for 3s; Group II: PAC light step-cycle curing (2s at 800 mW/cm² then 4s at 1600 mW/cm²); Group III: QTH light continuous-cycle curing at 400 mW/cm² for 40s; Group IV: QTH light ramp-cycle curing (from 100 to 600 mW/cm² in 15s followed by 25s at 600 mW/cm²); Group V: QTH light pulse-delay curing (200 mW/cm² for 3s followed by 3 min delay then 600 mW/cm² for 30s). Teeth were stored in distilled water at 37ºC for 30 days and then subjected to thermocycling for 500 cycles at 5 and 55ºC. Root apices were sealed and teeth coated with nail varnish before they were immersed in 0.5% fuchsine red dye solution. Teeth were then sectioned and slices were scanned with a computer scanner to determine the area of dye leakage using a computer program (Image Tools). Images of tooth slices were also visually examined under magnification and dye penetration along the tooth/restoration interface was scored. Significant differences in the degree of dye penetration and leakage were detected between groups (p<.05). Groups I and II had significantly higher values of dye penetration and leakage than groups III, IV and V. In conclusion, the use of PAC light curing in a continuous or step cycle modes resulted in increased microleakage of Class V resin composite restorations compared with medium intensity QTH light curing. Pulse, ramp and continuous-cycle curing modes with QTH light resulted in similar degrees of microleakage.

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