scholarly journals INVESTIGATION OF LIGHT INTENSITY OF LIGHT CURING UNITS AFTER DIFFERENT PERIODS OF USE

2021 ◽  
Vol 27 (4) ◽  
pp. 4164-4169
Author(s):  
Georgi Georgiev ◽  
◽  
Tsanka Dikova ◽  
Vladimir Panov ◽  
◽  
...  
Keyword(s):  
Light Intensity ◽  
20Th Century ◽  
Direct Relationship ◽  
Maximum Light ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Intensive Use ◽  
Operation Period ◽  
Light Curing

Quartz-tungsten halogen light curing units (LCUs) have been the main source of light for the polymerization of resin based composites (RBCs) for several decades. Since the beginning of the 20th century, however, their use has been reduced due to the invention and improvement of LED LCUs. Various factors can cause a decrease in the light intensity of LED LCUs, one of which is diode aging. The aim of the present paper is to study the change in light intensity of LCUs after different periods of intensive use. For this purpose, the light intensity of 94 regularly used LED LCUs aged between 1 and 10 years was measured with a digital radiometer. The devices were used in conventional mode with maximum light intensity. It was found that regardless of the type and model of LCU, there is a direct relationship between the time of use and light intensity - the longer the operation period of a device is and the more used it is, the lower its intensity is. The decrease in light intensity as devices age is different for different models, as well as for different devices of the same model. In the studied LCUs with a 10-year period of use, 77.5% have light intensity lower than the required minimum of 400 mW/cm2, which makes them unusable. It can be concluded that dentists should regularly monitor and measure the light intensity of their LCUs, especially as they age, to ensure the longevity of their restorative procedures.

scholarly journals Surface Hardness of Nanohybrid and Microhybrid Resin Composites Cured by Light Emitting Diode and Quartz Tungsten Halogen Light Curing Systems: An Invitro Study

2020 ◽  
Author(s):  
Anuradha Vitthal Wankhade ◽  
Sharad Basavraj Kamat ◽  
Santosh Irappa Hugar ◽  
Girish Shankar Nanjannawar ◽  
Sumit Balasaheb Vhate
Keyword(s):  
Light Emitting Diode ◽  
Surface Hardness ◽  
Composite Resins ◽  
Resin Composites ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Intergroup Comparison ◽  
Light Curing ◽  
Curing Systems

Introduction: New generation composite resin materials have revolutionized the art of aesthetic dentistry. The clinical success is dependent on effective polymerisation and surface hardness which in turn are dependent on the performance of Light Curing Units (LCU). This study utilises surface hardness as a measure of degree of polymerisation of composite resins achieved by LCUs. Aim: To evaluate the difference in surface hardness of nanohybrid and microhybrid resin composites cured by light curing systems, Light Emitting Diode (LED) and Quartz Tungsten Halogen (QTH). Materials and Methods: In this invitro experimental study, two types of hybrid composites (Nanohybrid and Microhybrid) were tested for surface hardness by using two different light curing systems (LED and QTH). All the Nanohybrid and Microhybrid specimens were cured using LED and QTH LCUs, thus giving four combinations. A total of 60 specimens (6 mm diameter and 2 mm depth) were prepared using Teflon mould with 15 samples for each combination. Surface hardness was measured on upper and lower surface after 24 hours and hardness ratio was calculated. Data was analysed using independent t-test for intergroup comparison. Level of significance was kept at 5%. Results: Surface hardness of resin composites cured by LED LCU was greater than those cured by QTH LCU. Additionally, the hardness value was greater for the upper surface. Nanohybrids showed better surface hardness than Microhybrids for both the LCUs. Conclusion: Nanohybrid composite resins and LED system were found to be more effective in terms of surface hardness as compared to their counterparts.

Intensity of quartz-tungsten-halogen light-curing units used in private practice in Toronto

2005 ◽  
Vol 136 (6) ◽  
pp. 766-773 ◽  
Author(s):  
OMAR EL-MOWAFY ◽  
WAFA EL-BADRAWY ◽  
DONALD W. LEWIS ◽  
BABAK SHOKATI ◽  
JAFFER KERMALLI ◽  
...  
Keyword(s):  
Private Practice ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Light Curing

scholarly journals The Effect of Irradiation Distance on Microhardness of Resin Composites Cured with Different Light Curing Units

2010 ◽  
Vol 04 (04) ◽  
pp. 440-446 ◽  
Author(s):  
Isil Cekic-Nagas ◽  
Ferhan Egilmez ◽  
Gulfem Ergun
Keyword(s):  
Light Emitting Diode ◽  
Resin Composite ◽  
Composite Layer ◽  
Hardness Test ◽  
Resin Composites ◽  
Plasma Arc ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Light Curing

Objectives: The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc).Methods: A total of 210 disc-shaped samples (2 mm height and 6 mm diameter) were prepared from different resin composites (Simile, Aelite Aesthetic Enamel, Clearfil AP-X, Grandio caps and Filtek Z250). Photoactivation was performed by using quartz tungsten halogen, light emitting diode and plasma arc curing units at two irradiation distances (2 mm and 9 mm). Then the samples (n=7/ per group) were stored dry in dark at 37°C for 24 h. The Vickers hardness test was performed on the resin composite layer with a microhardness tester (Shimadzu HMV). Data were statistically analyzed using nonparametric Kruskal Wallis and Mann-Whitney U tests.Results: Statistical analysis revealed that the resin composite groups, the type of the light curing units and the irradiation distances have significant effects on the microhardness values (P<.05).Conclusions: Light curing unit and irradiation distance are important factors to be considered for obtaining adequate microhardness of different resin composite groups. (Eur J Dent 2010;4:440-446)

Effect of Energy Density on Low-Shrinkage Composite Resins: Diode-Pumped Solid State Laser Versus Quartz-Tungsten-Halogen Light-Curing Unit

2013 ◽  
Vol 31 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Young-Joon Heo ◽  
Geun-Ho Lee ◽  
Jeong-Kil Park ◽  
Jung-Hoon Ro ◽  
Franklin García-Godoy ◽  
...  
Keyword(s):  
Solid State ◽  
Energy Density ◽  
Solid State Laser ◽  
Composite Resins ◽  
State Laser ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Light Curing ◽  
Diode Pumped

scholarly journals Compressive strength of esthetic restorative materials polymerized with quartz-tungsten-halogen light and blue LED

2009 ◽  
Vol 20 (1) ◽  
pp. 54-57 ◽  
Author(s):  
Cecy Martins Silva ◽  
Katia Regina Hostilio Cervantes Dias
Keyword(s):  
Compressive Strength ◽  
Light Source ◽  
Composite Resin ◽  
Light Emitting Diode ◽  
Testing Machine ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Significant Difference ◽  
Restorative Materials ◽  
Light Curing

This study compared the compressive strength of a composite resin and compomer photoactivated with a conventional quartz-tungsten halogen-light (XL 3000, 3M/SPE) and a blue light-emitting diode (LED) (SmartLite PS; Dentsply/De Trey). Forty disc-shaped specimens were prepared using a split polytetrafluoroethylene matrix (4.0 mm diameter x 8.0 mm hight) in which the materials were inserted incrementally. The curing time of each increment was of 40 s with the QTH and 10 s with the LED. The specimens were randomly assigned to 4 groups (n=10), according to the light source and the restorative material. After storage in distilled water at 37oC ± 2oC for 24 h, the specimens was tested in compressive strength in a universal testing machine with load cell of 500 kgf running at a crosshead speed of 0.5 mm/min. Data (in MPa) were analyzed statistically by ANOVA and Student-Newman-Keuls test (p<0.05). For the composite resin, light curing with the QTH source did not produce statistically significant difference (p>0.05) in the compressive strength when compared to light curing with the LED source. However, light curing of the compomer with the QTH source resulted in significantly higher compressive strength than the use of the LED unit (p>0.05). The composite resin presented significantly higher (p>0.05) compressive strength than the compomer, regardless of the light source. In conclusion, the compressive strength of the tested materials photoactivated with a QTH and a LED light source was influenced by the energy density employed and the chemical composition of the esthetic restorative materials.

Effect of Preheating Resin Composite and Light-curing Units on the Microleakage of Class II Restorations Submitted to Thermocycling

2011 ◽  
Vol 36 (1) ◽  
pp. 60-65 ◽  
Author(s):  
R. E. Agostinho dos Santos ◽  
A. F. Lima ◽  
G. P. Soares ◽  
G. M. B. Ambrosano ◽  
G. M. Marchi ◽  
...  
Keyword(s):  
Clinical Relevance ◽  
Resin Composite ◽  
Class Ii ◽  
Light Irradiance ◽  
Quartz Tungsten Halogen ◽  
Halogen Light ◽  
Light Curing ◽  
Dispersion Of Light

Clinical Relevance Deficient polymerization can occur in deeper cavities due to the dispersion of light irradiance, and it may affect microleakage of the tooth-restoration interface. When using a quartz-tungsten-halogen light-curing unit with relatively low irradiance (420 mW/cm2) to restore a Class II restoration, microleakage can be reduced if the resin-composite is heated prior to use.

Parameter Optimization for Vibration Flow Field of Polystyrene Melts via RBF Neural Networks Combined with SALS

2012 ◽  
Vol 602-604 ◽  
pp. 757-761
Author(s):  
Guang Ming Xian ◽  
Jing Ping Qu ◽  
Bi Qing Zeng
Keyword(s):  
Light Intensity ◽  
Flow Field ◽  
Polymer Melts ◽  
Scattered Light ◽  
Projection Area ◽  
Rbf Neural Networks ◽  
Maximum Light ◽  
Before And After ◽  
Small Angle Light Scattering ◽  
Slit Die

This work aims at developing an accurate measurement of characterization flow field of polymer melts by small-angle light scattering (SALS). In this article we propose a new method, based on radial basis function neural network (RBFNN) for predicting the optimum vibration field parameters. A laser light passes through polymer melts in the visual slit die. The results reported in this study were obtained with polystyrene (PS) with rotation speed at 20 rpm. In order to capture the scattered light, a polarizer and an analyzer are placed before and after the polymer melts. RBFNN inputs consist of frequency and amplitude, which are used as input parameters to predict the maximum light intensity projection area. RBFNN predicts that the optimum value of frequency, amplitude are 15.86 Hz and 0.20mm, respectively. And the maximum light intensity projection area is predicted to be 9260 pixels.

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