Light-emitting diode vs halogen light curing of orthodontic brackets: A 15-month clinical study of bond failures

2007 ◽  
Vol 132 (4) ◽  
pp. 518-523 ◽  
Author(s):  
N. Rengarajan Krishnaswamy ◽  
Chakravarthi Sunitha
2009 ◽  
Vol 79 (1) ◽  
pp. 144-149 ◽  
Author(s):  
Mustafa Ulker ◽  
Tancan Uysal ◽  
Sabri Ilhan Ramoglu ◽  
Huseyin Ertas

Abstract Objective: To compare the microleakage of the enamel-adhesive-bracket complex at the occlusal and gingival margins of brackets bonded with high-intensity light curing lights and conventional halogen lights. Materials and Methods: Forty-five freshly extracted human maxillary premolar teeth were randomly separated into three groups of 15 teeth each. Stainless steel brackets were bonded in all groups according to the manufacturer's recommendations. Specimens (15 per group) were cured for 40 seconds with a conventional halogen light, 20 seconds with light-emitting diode (LED), and 6 seconds with plasma arc curing light (PAC). After curing, the specimens were further sealed with nail varnish, stained with 0.5% basic-fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage for the enamel-adhesive and bracket-adhesive interfaces from both the occlusal and gingival margins. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests with a Bonferroni correction. Results: The type of light curing unit did not significantly affect the amount of microleakage at the gingival or occlusal margins of investigated interfaces (P >.05). The gingival sides in the LED and PAC groups exhibited higher microleakage scores compared with those observed on occlusal sides for the enamel-adhesive and adhesive-bracket interfaces. The halogen light source showed similar microleakage at the gingival and occlusal sides between both adhesive interfaces. Conclusions: High-intensity curing units did not cause more microleakage than conventional halogen lights. This supports the use of all these curing units in routine orthodontic practice.


Author(s):  
Anuradha Vitthal Wankhade ◽  
Sharad Basavraj Kamat ◽  
Santosh Irappa Hugar ◽  
Girish Shankar Nanjannawar ◽  
Sumit Balasaheb Vhate

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.


2004 ◽  
Vol 125 (3) ◽  
pp. 342-347 ◽  
Author(s):  
Maria Francesca Sfondrini ◽  
Vittorio Cacciafesta ◽  
Andrea Scribante ◽  
Catherine Klersy

2008 ◽  
Vol 02 (04) ◽  
pp. 240-246 ◽  
Author(s):  
A. Ruya Yazici ◽  
Cigdem Celik ◽  
Berrin Dayangac ◽  
Gul Ozgunaltay

Objectives: The aim of this in vitro study was to evaluate the influence of different light curing units and modes on microleakage of flowable composite resins.Methods: Eighty Class V cavities were prepared in buccal and lingual surfaces of 40 extracted human premolars with cervical wall located in dentin and the occlusal wall in enamel. These teeth were randomly assigned into two groups (n=20) and restored with different flowable composites; Group I: Esthet-X Flow, Group II: Grandio Flow. Each group was randomly divided into four subgroups; while the samples of the first subgroup were polymerized with conventional Halogen light, the rest of them were polymerized with different curing modes of Light Emitting Diode (LED). The second subgroup was polymerized with fast-curing; the third subgroup with pulse-curing and those of the fourth subgroup with step-curing modes of LED. After the samples were thermocycled and immersed in dye, they were longitudinally sectioned. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests.Results: None of the restorations showed leakage on enamel margins. On dentin margins no significant differences were observed between flowable composite resins polymerized with halogen light (P>.05). While step curing mode of LED presented significant differences between the resins, the difference was insignificant when fast-curing and pulse-curing mode of LED were used. No statistically significant differences were observed between curing units for Esthet-X Flow samples. For Grandio Flow samples, only step-curing mode of LED caused statistically higher leakage scores than halogen and other curing modes of LED (P<.05).Conclusions: The effect of curing units� type and curing mode on flowable composite resin leakage might be material-dependent. (Eur J Dent 2008;2:240-246)


2004 ◽  
Vol 18 (3) ◽  
pp. 266-270 ◽  
Author(s):  
Bianca Micali ◽  
Roberta Tarkany Basting

The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED) with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental). The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting systems: light-emitting diode Ultraled (Dabi Atlante) or halogen light Degulux (Degussa Hüls) curing units. Immediately after polymerization, each specimen was individually immersed in 1 ml of 2% methylene blue solution at 37°C ± 2°C. After 24 hours, the specimens were rinsed under running distilled water for 1 minute and stored at 37°C ± 2°C at relative humidity for 24 hours. The composite resins were removed from the moulds and individually triturated before being immersed in new test tubes containing 1 ml of absolute alcohol for 24 hours. The solutions were filtered and centrifuged for 3 minutes at 4,000 rpm and the supernatant was used to determine absorbance in a spectrophotometer at 590 nm. To verify the differences between groups polymerized by LED or halogen light t-test was applied. No significant differences were found between composite resins light-cured by LED or halogen light-curing unit (p > 0.05). The commercially LED-based light-curing unit is as effective to polymerize hybrid composite resins as the halogen-based unit.


2010 ◽  
Vol 04 (04) ◽  
pp. 440-446 ◽  
Author(s):  
Isil Cekic-Nagas ◽  
Ferhan Egilmez ◽  
Gulfem Ergun

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)


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