Comparison of bonding strengths of metal brackets after home and office bleaching application

The aim of this study was to evaluate the effects of hydrogen peroxide and carbamide peroxide, which are frequently used agents in whitening treatments that are increasingly demanded by patients, on the bond strength of metal brackets. 66 bovine lower incisor teeth were divided into three equal groups. These groups were; the teeth group that was bleached with 20% carbamide peroxide used in home bleaching treatment, the teeth group that was bleached with 40% hydrogen peroxide used in office bleaching treatment and the control group. The 0.18 slot metal brackets (3M Unitek Gemini, Unitek, Monrovia, Calif) used in all three groups were polymerized by irradiating them for 4 seconds with a high intensity LED light source (Valo, Opal Orthodontics by Ultradent, USA) using the Transbond XT (3M Unitek, USA) adhesive system. Bond strength tests were performed on the Universal testing machine (LLOYD İnstron, Foreham Hampshire, England) where the force was loaded at a speed of 0.5 mm/min until the brackets were separated from the tooth surface. Whether there was a significant difference between the maximum compressive loads according to the groups was tested with the Kruskal Wallis test. After the bond strength test, the amount of residual adhesive on the enamel surface was evaluated with the naked eye. The average bond strength values were found to be 31.72 MPa in the group that underwent home bleaching with carbamide peroxide, 18.55 MPa in the group that underwent office bleaching with hydrogen peroxide, and 37.25 MPa in the control group. According to the bond strength test results, it was determined that the average bond strength values of the group that underwent office-type bleaching with hydrogen peroxide were statistically significantly lower than the group that underwent home-type bleaching with carbamide peroxide and the control group. No statistically significant relationship was observed between these groups in the distribution of ARI scores. The results of the study showed that carbamide peroxide used in home whitening treatment did not adversely affect the bond strength of metal brackets, while high concentration hydrogen peroxide used in office whitening treatment adversely affected the bond strength of metal brackets. Keywords: Metal bracket, Bond strength, Home type whitening treatment, Office type whitening treatment