ABSTRACT
In this in vitro study, fourteen used and seven new mesh-pad base bonded brackets were used and divided into three groups. Seven used brackets which were cleaned only by burning procedure, separated as first group; seven used brackets which were cleaned by burning and ultrasonic cleaning procedures, separated as second group; seven new brackets separated as third (control) group. Furthermore, separate sample brackets were prepared for each of the groups and examined under the SEM. The brackets were bonded directly to maxillary first premolars. The bond strengths of the brackets were calculated and then evaluated bioistatistically. The bond strength of the first group brackets was statistically different from the bond strengths of the other groups. The bond strenght of the second group brackets was not found statistically different from the new brackets' bond strength. From the SEM observations of the sample brackets, the rest resin material was observed in the base of bracket which was cleaned by burning procedure; there weren't differences between the new bracket's base and the bracket's base which was cleaned by burning and ultrasonic cleaning procedures.