To Evaluate the Effect of Primer and Two Different Curing Times of Primer on Shear Bond Strength of Orthodontic Brackets Bonded to Tooth Surface: An Invitro Study

The aim of the study isto evaluate the effect of primer and two different curing times of primer on shear bond strength of orthodontic brackets bonded to tooth surface Materials and methods : 33 extracted first Premolar teeth was embedded in auto-polymerizing acrylic resin till cervical region. They were randomly divided into three groups (each of 11 premolar). All teeth were etched in same manner using 37% orthophosphoric acid Etchant gel and after thatit was divided into 3 groups Group 1: Primer was not applied, Transbond XT Adhesive Light Cure Paste was applied and the bracket was light cured for 20 second with standard intensity curing light.Group 2:Transbond XT Primer was applied and cured with high intensity LED Light(2500mW/cm2 ) for 1 second.Transbond XT Adhesive Light Cure Paste was applied and the bracket was light cured for 20 second with standard intensity curing lightGroup 3: . Transbond XT Primer was applied and cured with normal intensity LED Light(1200mW/cm2 ) for 10 seconds.Transbond XT Adhesive Light Cure Paste was applied and the bracket was light cured for 20 second with standard intensity curing light.After bonding,each specimen was loaded into a Universal Testing Machine for testing. A computer connected with Universal Testing Machine recorded the results of each test. The readings were recorded in Newton(N). And it was converted into Mega Pascal Units for statistical analysis. Results : In the present study the mean SBS of no primer group was 12.20MPa, SBS when primer was cured for 1 sec with high intensity curing light was 15.54 MPa and SBS when primer was cured for 10 sec with normal intensity curing light was 16.60MPa, all the three value were more than the clinically acceptable values Conclusion: The result of our study showed that use of primer by curing for 1sec with high intensity LED light, curing for 10sec with normal intensity LED light and not using primer all three-condition produced SBS which was clinically acceptable, but by using primer and curing it for 1sec with high intensity LED light we can eliminate the disadvantages which are caused by not using primer and we can save our chair side time also by reducing the curing time. Further studies can be done considering the above aspects. Further research by doing a scanning electron microscopy (SEM) study of the debonded tooth surface to check for the enamel cracks and resin tag formation in the various groups can be conducted to evaluate the results bette