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Article
Microleakage of two resin composites by using different light curing systems *

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Abstract

This study was conducted to evaluate marginal microleakage of two resineomposite (Glacier resin composite and Filtek P 60 resin composite) either cured witheonventional light cure unit ( Astralis 5) or light emitting diodes (LED) light cure unit»Radii). Forty class V cavities were prepared in 20 extracted second premolars, onebuccaly and one palataly in each tooth. Each cavity was located lmm coronal toeementoenamel junction and lmm apical to it. The teeth were randomly divided into 4groups, each group of five teeth (I0 cavities): Group I was filled with Glacier resincomposite and cured with LED curing unit. Group ll filled with Glacier and curedin ith Astralis 5 curing unit. Group lll filled with Filtek P60 resin composite and curedv- ith LED curing unit. Group IV filled with Filtek P 60 and cured with Astralis curingxnit. The teeth were stored in distilled water for seven days. Then the apices of theteeth were sealed with sticky wax and the teeth were covered with two layers of nailvamish except lmm around the restoration. The teeth were immersed in 0.5% basicfaehsin dye for 24 hours at 37°C in the incubator and then were longitudinallyxctioned in a buccolingual direction and the extent of dye penetration was recorded.The statistical analysis of the result revealed that the use of LED light cure unit,results in highly significant reduction in the microleakage occlusally and gingivally


Article
Evaluation of brackets shear bond strengths using two different light–emitting diode curing units

Author: Ahmad A Abdul–Mawjood
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2006 Volume: 6 Issue: 2 Pages: 171-175
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the efficiency of two types of light–emitting diode (LED) curing units in bonding orthodontics brackets. Materials and Methods: Three groups, ten teeth each, of newly extracted premolars were used in the study. In the control, the brackets were bonded using a halogen bulb light curing unit, while in the other two groups the brackets were bonded using a high and a low intensityLED curing unit, respectively. The brackets were bonded to the teeth using Transbond® light–cured orthodontic adhesive. The bonded brackets were tested for their shear bond strength using a universal compression machine. Results: The mean bond strength of brackets bonded with the high intensity LED curing unit was above the clinically accepted value and it was comparable to that of the halogenbulb light curing unit group. Meanwhile, the mean bond strength of brackets bonded with the lowintensity LED curing unit significantly differed from the other two groups and was below the clinicalacceptance level. Conclusion: The high intensity LED curing units can be used successfully in bonding orthodontic brackets. The bond strength was sufficient to consider these units as good substitutes for the halogen bulb–based units. The low intensity LED curing units are not recommended to be used inorthodontics.


Article
Effectiveness of Four Different Light-activated Composites Cure with Different Light Energy Densities

Author: Dr. Ali A. Al- Shekhli B.D.S., M.Sc., Ph.D.* د. علي الشيخلي
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2006 Volume: 3 Issue: 3 Pages: 224-229
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Background: This study investigated the influence of light energy density (intensityx time) on the effectiveness of composite cure in view of the curing profiles of lightpolymerizationunits with different light- activated composites to determine theenergy density that satisfies adequate polymerization of all light-activatedcomposites types used in this study.Materials and methods: This study investigated the hardness of the top/bottomsurfaces and hardness ratio of 2-mm thick composite specimens after exposure todifferent light energy densities. Parameters included five light intensities (200, 300,400, 500 and 600 mW/cm2) and seven curing times (20, 40, 60, 90, 120, 150 and180 seconds) for each of the four different light-activated composite materials(Tetric Ceram, Heliomolar, Herculite XRV and Degufill Mineral).Results: Statistical analysis of the data by using the one-way analysis of variancerevealed that, most of the hardness ratios exhibited a very highly significantdifference according to intensity, composite type and curing time. The resultsindicated that, Heliomolar and Degufill Mineral light-activated composites requiredapproximately (36 J/cm²) energy density for adequate polymerization for a 2-mmthick specimen while, Herculite XRV and Tertric Ceram light-activated compositesrequired approximately (12 J/cm²) energy density for adequate polymerization for a2-mm thick specimen.Conclusion: This study indicated that, final curing should not be done with energydensity less than (300 mW/cm2 for 120 seconds, 400 mW/cm2 for 90 seconds and600 mW/cm2 for 60 seconds) for Heliomolar and Degufill Mineral light-activatedcomposites.


Article
The Effect of LED Light on Depth of Cure and Microhardness of Three Types of Bulkfill Composite

Authors: Mohannad R. A --- Luma M.S. Baban لمى بابان
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 1 Pages: 36-40
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: To evaluate the ISO depth of cure of bulkfill composites and depth of cure which determined byVickers microhardness test.Materials and Methods: Bulkfill resin composite specimens (n=150) were prepared of three bulkfill compositematerials (TetricEvo Ceram, Quixfil and SDR) and light cured by Flash max p3 for 3, 10, 20 seconds and by woodpecker for 10, 20 seconds respectively, a mold was filled with one of the three bulkfill composites and light cured.The specimens removed from the mold and scraped by plastic spatula and the remaining length (absolute length)was measured which represent the ISO depth of cure. After that the specimens were returned into the mold and amicrohardness indentation device applied on the specimen and hardness measurements (Vickers hardness, VHN)were made at defined distance, beginning at the resin composite that had been closest to the light curing unit (i.e.at the top) and proceeding toward the uncured resin composite (i.e. toward the bottom) on the basis of the VHNmeasurement, Vickers hardness test generated for each group.Results and Conclusion: ISO depth of cure of bulkfill composite materials is time and type of light curing protocoldependent rather than type of material of bulkfill composite while the depth of cure determined by Vickershardness number is material dependent in addition to the light curing protocol


Article
The Effect of Light Curing Tip Distance on Curing Depth of Resin Composite: A Comparative Study

Author: Ashraf S Qasim
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 3 Pages: S78-S83
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To determine the correlation between intensity (I) of light–emitting diode (LED) and tungsten–halogen light sources, and depth of cure of a resin composite at different distances. Materials and Methods: LED curing light (Ultra Lite 200E plus) and tungsten halogen light (Astralis 5 Vivadent) were evaluated. Intensity was measured at distances of 0, 2, 4, 6, 8, and 10mm between the light tip and detector. A blackened aluminum plate, 0.5mm thick, with a 4mm–diameter aperture was placed over the detector. The use of this aperture limited the amount of light reaching the detector to a uniform area for both curing lights and also corresponded to the area of the mould for the depth of cure studies. Both light tips were centered on this aperture to reduce any influence of varying I across the light tip. Depth of cure (DOC) of light–curing universal micro hybrid composite shade A2 was also measured. A metallic mould was used to measure the depth of cure at distances of 0, 2, 4, 6, 8, and 10mm between light tip and mould. The degree of divergence of the light of both light curing units was also determined by tracing the illuminated area at a 10mm distance for each of the curing lights. Results: For both lights, intensity decreased as distance increased. While, both I and DOC decrease with increasing distance, the relationship between these factors and distance may not be similar for both lights and may depend on the characteristics of individual lights. Conclusions: Both I and DOC decreased with increasing distances. DOC usually decreases with decreasing I, the rate of decline varies between various light brands.


Article
A comparative study evaluating the microleakage of different types of restorative materials used in restoration of pulpotomized primary molars

Authors: Zainab A. Al-Dahan زينب الدهان --- Aseel I. Al- Attar اسيل العطار --- Huda E.A. Al-Rubaee هدى الربيعي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 2 Pages: 150-154
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Possibly the greatest deterrent to the development of an ideal restorative material is the leakage thatoccurs along the restoration, tooth interface. There is yet no truly adhesive dental material that exactly duplicatesphysical properties of the tooth structure. This in vitro study was carried out to compare the microleakage of twotypes of restorative materials used in pediatric dentistry Colored light curing compomer(Twinky star) and nanoceramic restorative material (Ceram.x)) with that of amalgam by measuring their ability to prevent dye penetration.Materials and Methods: Standardized Proximo-occlusal cavity preparations were prepared in 30 extracted soundprimary first lower molars. Pulpotomy was performed, and pulpotomy paste filled the pulp chamber with hard settingcement over it all have same occlusal depth. The teeth were then randomly divided into three groups: Group A:filled with Amalgam. Group B: filled with compomer (Twinky star). Group C: filled with nano ceramic (Ceram.x).After that the teeth were stored in distilled water for 30 days at 37 °C in an incubator and during the period of storagethe teeth were subjected to 300 thermal cycles (10 cycles each day), then sectioned to be examined under thestereo microscope.Results: Data was analyzed using ANOVA test with help of spss soft ware, even though nano ceramic (Ceram. X)showed higher resistance to dye penetration, when compared to compomer (Twinky star and amalgam), therewere no significant differences between the three studied groups in their resistance to dye penetration.Conclusion: Depending on the ability to prevent marginal leakage, nano ceramic (ceram.x) and compomer (Twinkystar) restorative materials can be used as an alternative to amalgam in restoring pulpotomized primary teeth


Article
Flexural strength of dual cured composite resin cements polymerized with different light sources

Authors: Sabah.A. Ismail --- Eman M. Yahya --- Ali M. Rasheed
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2011 Volume: 11 Issue: 3 Pages: 310-316
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: To determine the flexural strength of dual cured composite resin cements polymerized with LED light and Quartz-tungsten halogen light and to determine the effect of curing and storage time on the flexural strength. Materials and Methods: feldspathic porcelain (IPS InLine) used to produce uniform disc-shaped specimens (10mm diameter and 1.5mm thickness ). An electronic caliper was used to confirm precise specimen dimensions. Vita shade 2A was selected. One commercial dual-polymerizing composite resin cement was used (Variolink II; Ivoclar Vivadent ). The resin cement was placed in brass molds 8 ×6× 2 mm in size that lined with a teflon used to prepared the specimens to determine flexural strength. After insertion of the resin cements a glass slab was pressed over the mold and removed any expressed materials around the margins of the mold. A mylar strip (0.07 mm) was used to prevent adhesion of the resin cement to ceramic disk. Two types of light source were used: Quartz-tungsten halogen light and LED. The specimens divided into 8 groups (10 specimens for each). For each light source the curing time done for 20 and 60 sec. and the specimens either tested 15min. after curing or after 24hrs. Measurements for the 3-point flexural strength test were performed at a constant crosshead speed of 1 mm/min. Statistical data analysis was performed by three-way ANOVA and Duncan Multiple Range Tests to determine the significant group. Results: three- way ANOVA indicated there is no statistical significant differences between the two light sources (p>0.05), were as there is statistically significance between the flexural strength of specimen cured for 60 sec. and tested after 24hrs more than other groups (p<0.05). Conclusions: adequate curing time with 60sec. and instruction for the patient not to use of the restoration until at least 24hrs after the insertion of the restoration is advocated

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