The European Journal of Orthodontics Advance Access published online on May 19, 2007
The European Journal of Orthodontics, doi:10.1093/ejo/cjm017
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The effect of a light-emitting diode on shear bond strength of ceramic brackets bonded to feldspathic porcelain with different curing times
* Departments of Orthodontics
** Departments of Prosthodontics, Faculty of Dentistry, University of Ondokuz Mayis, Samsun, Turkey
Address for correspondence, Dr Selma Elekdag-Turk, University of Ondokuz Mayis, Faculty of Dentistry, Department of Orthodontics, 55139 Kurupelit, Samsun, Turkey, E-mail: turkset{at}superonline.com
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Abstract |
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The aim of this study was to evaluate different curing times of a light-emitting diode (LED) unit on shear bond strength (SBS) of ceramic brackets bonded to feldspathic porcelain.
Ceramic brackets were bonded with a light-cured adhesive to 96 feldspathic porcelain facets. Air-borne particle abrasion was performed using 25 µm aluminium trioxide (Al2O3) with an air abrasion device from a distance of approximately 10 mm at a pressure of 2.5 bars for 4 seconds, then the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid for 2 minutes. After surface preparation of the porcelain specimens, silane was applied. In groups 1 and 2, the adhesive was cured with a quartz–tungsten–halogen (QTH) unit for 10 and 20 seconds, respectively. The LED was used in the standard mode for 3, 5, and 10 seconds for groups 3, 4, and 5, respectively. For the other three groups, the LED was used in the fast mode for 3, 5, and 10 seconds, respectively. The SBS of the brackets was measured on a universal testing machine. The adhesive remnant index (ARI) scores, damage to the porcelain, and fracture of the ceramic bracket bases were determined.
No significant differences were observed for SBS between the eight groups (P = 0.087). There was no significant difference between the groups' ARI scores, porcelain damage, and bracket base fracture (P = 0.340, P = 0.985, and P = 0.340, respectively). There was a greater frequency of ARI scores of 0 for all groups. Fifty per cent of the porcelain facets displayed damage. Nineteen ceramic bracket base fractures were observed.
No significant difference was found for the SBS of the groups with QTH and LED units and curing times. It is reliable to use LED with a 3-second curing time since it provided adequate bond strength for ceramic brackets bonded to porcelain surfaces.