The effect of light intensity and curing time of light emitting diode on shear bond strength using different types of bracket's materials

Abstract EN

Background : This study was intended to evaluate the effect of two LED devices which has different light intensity and curing time on the shear bond strength (SBS) using stainless steel and two other esthetic brackets. Materials and method : Sixty first premolar teeth were selected.

Three types of orthodontic brackets were used in this Study : stainless-steel brackets, the other two types are esthetic ceramic brackets.

Two high intensity LED units were used, the first one was of a lower intensity (HANGZHOU SIFANG, China), the output power 1200 mW / cm2, the second source had the higher intensity (FlashMax P3, Denmark) which has power intensity of 4000 mW / cm2.

The teeth were divided into two groups (A and B) of 30 teeth each.

Group A was used for testing HANGZHOU SIFANG device in standard cure time (20s) , while the group B was used for testing Flash Max P3 device in fast curing mode(6s).

A and B groups were further subdivided according to bracket type into three subgroups of 10 teeth each.

SBS of all subgroups were tested by using an Instron universal testing machine, ARI was assessed at (20X) magnification. Results : The clinically acceptable SBS were excelled in both the standard and fast curing mode groups for all bracket types, significant differences were found only when comparing the Pure with the other two types of brackets in the same group.

Comparing each bracket type between group A and group B reveals a significant difference only at stainless-steel type brackets. Conclusions : the new high intensity curing devise gave comparable SBS to the LED units previously available with shorter time.