Abstract
Aim: The aim of the study was to compare the bond strength of orthodontic brackets and mode of adhesive failure light-cured at various intensity and exposure duration. Material and methods: The sample of 63 extracted human molars randomly divided into three groups according to the light-curing conditions (I = 1200 mW/cm2, t= 10 s; I = 3200 mW/cm2, t =6 s; I = 3200 mW/cm2, t = 3 s).
After bonding of metal brackets Ultratrimm with adhesive system Transbond XT, the shear bond strength and adhesive remnant index were measured. Results: Mean values of the shear bond strength were in range from 10 to 12.6 MPa.
The mean values of all groups exceeded the limit of 6 MPa required for orthodontic bracket bonding. The lowest bond strength was found with the group polymerized at the shortest exposure time (3s) when as many as 10% of the brackets failed at the 6 MPa limit.
No significant difference was found between the characteristics of bond failure. Conclusion: Polymerization at the shortest exposure time is less reliable and leads to a greater number of bracket failures during orthodontic treatment.
The use of other modes of polymerization seemed reliable and sufficient.