Shear Bond Strength of Orthodontic Brackets Cured with Different Light Sources, LED and QTH

Aim:The aim of this study was to compare the shear bond strength [SBS] of two different light sources, light-emitting diode and quartz-tungsten halogen, under thermal cycle frequencies.
Method and materials:Sixty human premolar teeth were divided into two groups, on which composite (Transbond XT™ adhesive paste) cured with light-emitting diode in group I, and with quartz-tungsten halogen in group II. Samples thermocycled 500 cycles, the exposure to each bath was 10 seconds and the transfer time between the two baths was 10 seconds. 500 cycles between 5°C and 55°C were performed. An Instron testing machine [Dartec Hc.10, England] was used for the shear bond test at a crosshead speed of 1mm/min. Force was applied directly to the bracket–tooth interface. The load at failure was recorded by a personal computer connected to the test machine. SBS values were expressed in mega Pascal [MPa]. T-test was used to compare the shear bond strength between two groups.
The comparison of both groups indicated that the quartz-tungsten halogen groups demonstrated higher mean shear bond strength [p=19.947Mpa] than light-emitting diode groups [19.878Mpa]. There was no statistical difference in the shear bond strength values between the two light sources. [P value =0.918]
Both light sources showed favorable shear bond strength performance and there was no statistical difference in the shear bond strength values between these two light sources.