Influence of Multiple Peak Light-emitting-diode Curing Unit Beam Homogenization Tips on Microhardness of Resin Composites

2020 ◽  
Vol 45 (3) ◽  
pp. 327-338 ◽  
Author(s):  
J Soto-Montero ◽  
G Nima ◽  
FA Rueggeberg ◽  
CTS Dias ◽  
M Giannini
Keyword(s):  
Light Guide ◽  
Profile Analysis ◽  
Light Emitting Diode ◽  
Beam Profile ◽  
Composite Resins ◽  
Bottom Surface ◽  
Light Emitting ◽  
Blue Led ◽  
Significant Difference ◽  
Light Guides

SUMMARY This study evaluated the effect of light curing unit (LCU) guide type (regular or homogenizing) on top and bottom microhardness of conventional and bulk-fill resin-based composites (RBCs). A polywave light-emitting-diode (LED) LCU (Bluephase Style, Ivoclar Vivadent AG) was used with two different light guides: a regular tip (RT, 935 mW/cm2 emittance) and a homogenizer tip (HT, 851 mW/cm2 emittance). Two conventional RBCs (Herculite Ultra [HER], Kerr Corp; Tetric EvoCeram [TEC], Ivoclar Vivadent AG) and two bulk-fill RBCs (SonicFill [SOF], Kerr Corp; Tetric EvoCeram Bulk Fill [TBF], Ivoclar Vivadent AG) were tested. Disc-shaped samples (10 mm Ø), 2-mm thick for conventional composites and 4-mm thick for bulk-fill composites were prepared. Samples were light cured according to manufacturer-recommended times. Knoop microhardness values (KHN) were obtained on the top and bottom surfaces of each specimen at locations correlated with the output of the three LED chips emitting blue (456 nm) or violet light (409 nm). Beam profile analysis using both light guides was also performed. Microhardness of each composite was analyzed using three-way analysis of variance and Tukey honestly significant difference post hoc test (α=0.05). Beam profile images showed better light distribution across the surface of the HT light guide. Use of the HT decreased KHN of HER at the locations of the blue LED chips at bottom of the sample but had no effect on the top surface. For TEC, use of HT increased KHN of all three LED locations at the top surface. Use of the HT increased KHN of SOF at locations corresponding to one of the blue and the violet LED chips at the bottom surface. For TBF, HT increased KHN at all top surface locations. All RBCs showed higher mean KHN at the top compared with the bottom surfaces. In general, all composites presented a higher KHN at the blue LED areas regardless of the surface or the tip used. Results suggest that the homogenizer light guide resulted in significantly increased microhardness at the top, in composite resins containing alternative photoinitiators; however, that effect was not observed at the bottom surfaces.

scholarly journals Microhardness of resin-based materials polymerized with LED and halogen curing units

2005 ◽  
Vol 16 (2) ◽  
pp. 98-102 ◽  
Author(s):  
Daniela Francisca Gigo Cefaly ◽  
Giovano Augusto de Oliveira Ferrarezi ◽  
Celiane Mary Carneiro Tapety ◽  
José Roberto Pereira Lauris ◽  
Maria Fidela de Lima Navarro
Keyword(s):  
Statistical Analysis ◽  
Light Emitting Diode ◽  
Surface Hardness ◽  
Bottom Surface ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Led Light ◽  
Significant Difference ◽  
Light Curing ◽  
Curing Light

The purpose of this study was to evaluate the microhardness of resin-based materials polymerized with a LED (light-emitting diode) light-curing unit (LCU) and a halogen LCU. Twenty cylindrical specimens (3.0 mm in diameter and 2.0 mm high) were prepared for each tested material (Z100, Definite and Dyract). Specimens were light-cured with two LCUs (Ultraled and Curing Light 2500) for either 40 or 60 s on their top surfaces. Hardness was measured on top and bottom surfaces of each specimen. Statistical analysis was done by ANOVA and Tukey's test (p<0.05). There was no significant difference in hardness between LED LCU and halogen LCU for Z100 and Dyract on top surface. Conversely, lower hardness was recorded when Definite was light-cured with the LED LCU than with the halogen lamp. On bottom surface, hardness was significantly lower for all materials light-cured with LED LCU. Z100 was harder than Dyract and Definite regardless of the light curing unit. There was no significant difference in hardness between the exposure times on top surface. Higher hardness was obtained when the materials were light-cured for 60 s on bottom surface. The tested LED was not able to produce the same microhardness of resin-based materials as the halogen LCU.

scholarly journals A Light Guide Plate That Uses Asymmetric Intensity Distribution of Mini-LEDs for the Planar Illuminator

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 141 ◽  
Author(s):  
Zhi-Ting Ye ◽  
Yung-Min Pai ◽  
Cheng-Huan Chen ◽  
Hao-Chung Kuo ◽  
Lung-Chien Chen
Keyword(s):  
Intensity Distribution ◽  
Light Guide ◽  
Light Emitting Diode ◽  
Bottom Surface ◽  
Total Efficiency ◽  
Considerable Time ◽  
Light Emitting ◽  
Light Guide Plate ◽  
Guide Plate ◽  
Diffusion Reflection

Traditional backlights are designed with new dot patterns, and then injection molding, laser beam fabrication, or UV (Ultraviolet) roll-to-plate imprinting is used to apply dot patterns to a light guide plate—the process consumes considerable time and resources. Therefore, we propose a novel light guide design that does not use a dot pattern. We designed an asymmetric intensity distribution of mini-LEDs (Light Emitting Diode) and a light guide plate with a fully printed diffusion reflection on the bottom surface for a planar illuminator. The design rules for the proposed architecture are described in this paper. The archetype design with a 152.4 mm circular down-light has a diameter of 143 mm for the planar light source module. The experiment achieved a total efficiency of 85% and uniformity of 92.6%.

scholarly journals Effect of the light-emitting diode units on the depth of polymerization of a composite

2013 ◽  
Vol 1 (3) ◽  
pp. 240
Author(s):  
Anderson Catelan ◽  
Bruno De Castro Ferreira Barreto ◽  
Thaís Yumi Umeda Suzuki ◽  
Giselle Maria Marchi ◽  
Débora Alves Nunes Leite Lima ◽  
...  
Keyword(s):  
Second Generation ◽  
Composite Resin ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Composite Resins ◽  
Bottom Surface ◽  
Third Generation ◽  
Percentage Reduction ◽  
Absolute Alcohol ◽  
Light Emitting

The physical characteristics of composite resins strongly influence their clinical durability. The purpose of this study was to evaluate the influence of different light-emitting diode units on the Knoop hardness (KHN) and plasticization (P) of a composite resin. Disc-shaped specimens (5 x 2 mm) of the Filtek Supreme (3M ESPE) methacrylate-based nanofilled composite were light-cured using second-generation light-emitting diode (LED2) Bluephase 16i (Vivadent) or third-generation (LED3) Ultralume LED 5 (Ultradent) curing units at 1390 and 800 mW/cm2 of irradiance, respectively. After 24 h, KHN was measured with 50-g load for 15 s, and was evaluated by percentage reduction of the hardness after 24 h immersed in absolute alcohol at top and bottom surfaces. Data were subjected ANOVA and Tukey’s test at a pre-set alpha of 0.05. LED2 device showed higher KHN than LED3 (p < 0.05), top surface of composite cured with LED 2 showed higher softening resistance after alcohol storage than bottom surface (p < 0.05), but there was difference on the plasticization values between curing devices and between the top and bottom surface of composite cured with LED3 (p > 0.05). The highest irradiance promoted higher KHN, but overall not affected the plasticization.

scholarly journals Analysis of Energy and Cost Performance of Retrofitting Fluorescent Tubes with Compact Fluorescent and Light Emitting Diode Lamps

2020 ◽  
pp. 34-46 ◽  
Author(s):  
J. S. Adeleke ◽  
A. B. Wahab ◽  
E. A. Olanipekun
Keyword(s):  
Light Emitting Diode ◽  
Electricity Consumption ◽  
Poor Performance ◽  
Payback Period ◽  
Optimal Performance ◽  
Light Emitting ◽  
Tertiary Institutions ◽  
Fluorescent Lamps ◽  
Significant Difference ◽  
Compact Fluorescent Lamp

Over the years, visual comfort has been described as a major requirement needed to enhance optimal performance of occupants in any learning environment in tertiary institutions. This is reflected in the poor performance of the commonly used Fluorescent Lamps (FL) occasioned by its constant burn-off, high failure rate and reduced durability. Hence, there is a shift to the adoption of Compact Fluorescent Lamp (CFL) and Light Emitting Diode (LED). This study therefore examined the pattern of electricity consumption involving the adoption of FL, CFL and LED in the purposively selected lecture theatres of Obafemi Awolowo University, Ile-Ife, Nigeria. The study was carried out using energy monitor to obtain the consumption data of the lamps for periodic logging at intervals of 1 hr, 3 hrs, 6 hrs, 12 hrs, 1 day, 7 days, 1 month and 3 months respectively; and also to determine the payback period of each of the lamps. From the data collected, patterns of electricity used, electricity savings were calculated and compared to establish performance potentials of each of the lamps. The study found that there was a significant difference in the pattern of electricity consumption of FLs compared with that of CFLs and LEDs, but a reduced margin existed between CFLs and LED lamps. It showed that the FLs consumed 681.576 kWh, 1619.466 kWh and 5652.432 kWh, CFLs consumed 387.302 kWh, 692.479 kWh and 1936.600 kWh, while LED consumed 294.188 kWh, 426.608 kWh and 1499.015 kWh. There were significant differences in consumption with 43, 47 and 65% reduction in electricity consumption using CFLs while 57, 73 and 73% using LED fittings were obtained. The CFLs performed better in terms of return on investments by having a lower payback period when compared to LED. The study concluded that replacing FL with CFL and LED would be desirable option in order to enhance optimal performance of lecture theatres, but in terms of payback period, it would be beneficial to retrofit FLs with CFLs.

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.

scholarly journals Monomer Release from Resin Based Dental Materials Cured With LED and Halogen Lights

2010 ◽  
Vol 04 (01) ◽  
pp. 034-040 ◽  
Author(s):  
Asli Topaloglu Ak ◽  
A. Riza Alpoz ◽  
Oguz Bayraktar ◽  
Fahinur Ertugrul
Keyword(s):  
High Performance ◽  
Light Emitting Diode ◽  
Dental Materials ◽  
Composite Resins ◽  
Time Intervals ◽  
Significance Level ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Bonferroni Test ◽  
One Way Anova

ABSTRACTObjectives: To measure the release of TEGDMA and BisGMA from two commercially available composite resins; Filtek Z 250 (3M ESPE, Germany), Leaddent (Leaddent, Germany) and two fissure sealants; Helioseal F (3M ESPE, Germany) Enamel Loc (Premiere Rev, USA) over 1, 3 and 7 days after polymerization with standard quartz-tungsten halogen Coltolux II (QHL) (Coltene Switzerland) and a standard blue light emitting diode Elipar Freelight 2 (3M ESPE, Germany).Methods: 9 samples of each material were placed in disc shaped specimens in 1 mm of thickness and 10 mm in diameter (n=36). Each material was polymerized using LED for 20 s (n=12), 40 s (n=12) and halogen for 40 s (n=12), respectively. High Performance Liquid Chromatography (HPLC) was used to measure the amount of monomers released over 1, 3 and 7 days. Data was analyzed using one way ANOVA and Bonferroni test for multiple comparisons with a significance level of .05.Results: LED 20 sec group showed the highest release of monomers at 1, 3 and 7 days in sealant groups. Halogen 40 sec group resulted highest release of monomers for Leaddent at all time intervals (P<.05)Conclusions: Efficiency of the curing unit and applying the recommended curing time of the light activated resin based dental materials is very important to protect the patient from potential hazards of residual monomers. (Eur J Dent 2010;4:34-40)

Discomfort glare caused by white LEDs having different spectral power distributions

2017 ◽  
Vol 50 (6) ◽  
pp. 921-936 ◽  
Author(s):  
WJ Huang ◽  
Y Yang ◽  
M Ronnier Luo
Keyword(s):  
White Light ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
White Leds ◽  
Significant Difference ◽  
Discomfort Glare ◽  
Led Lights ◽  
Green Leds

This paper describes an experiment to investigate discomfort glare caused by white light-emitting diode (LED) lights having different spectral power distributions. It included two groups: a ‘Metamerism’ group and a ‘correlated colour temperatures (CCT)’ group. In the former group, it was found that white lights at 7000 K constructed from different blue LEDs and the same red and green LEDs gave about the same glare perception. In the latter group, there was a significant difference in glare perception between white lights having different CCTs. Finally, glare models, including unified glare rating (UGR) and the newly derived QUGRspd, and mUGRspd models, were tested using the data from the experiment. All of them gave quite accurate predictions of the data.

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 5-ALA Mediated Fluorescence Detection of Gastrointestinal Tumors

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Ekaterina Borisova ◽  
Borislav Vladimirov ◽  
Latchezar Avramov
Keyword(s):  
Light Guide ◽  
Aminolevulinic Acid ◽  
Light Emitting Diode ◽  
Protoporphyrin Ix ◽  
Normal Mucosa ◽  
Effective Algorithm ◽  
Mechanical Device ◽  
Light Emitting ◽  
Clinical Applicability ◽  
Dimensionless Ratio

Delta-aminolevulinic acid/protoporphyrin IX is applied for fluorescent tumor detection in the upper part of gastrointestinal tract. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built to use the light guide of standard video-endoscopic system. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. In such way, 1D detection and 2D visualization of the lesions' fluorescence are received, and both advantages and limitations of these methodologies are discussed in relation to their clinical applicability. Comparison of the spectra received from normal mucosa, inflammatory, and tumor areas is applied to evaluate the feasibility for development of simple but effective algorithm based on dimensionless ratio of the fluorescence signals at 560 and 635 nm, for differentiation of normal/abnormal gastrointestinal tissues.

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