Evaluation of the effects of two different indirect bonding methods on strength of the brackets in mandibular model of severe anterior crowding

AbstractAn indirect bonding method was developed to solve the problems likely to be encountered during proper positioning of the brackets. The aim of this study is to compare two different indirect bonding methods on the bond strength of the brackets. A 160 extracted human lower incisors were assigned into two groups. Transparent silicone material and bioplast material were used in transfer tray preparation in groups 1 and 2, respectively. Transbond XT adhesive system was used to bond brackets to teeth in both groups. A high intensity LED light source was used for 3 s for adhesive polymerization. Brackets were subjected to shear forces with universal test machine under 0.5 mm/min crosshead speed until failure. Adhesive Remnant Index was used to assess the amount of adhesive remnant on enamel surface after shear test under 10× magnification. Two subjects from both groups were evaluated for enamel surface characteristics with scanning electron microscope (SEM). Mean shear bond strengths were found to be 5.13 ± 1.8 MPa and 5.93 ± 2.19 MPa for silicone and bioplast groups, respectively. Bioplast group showed significantly greater shear bond strength than that of the silicone group. Maximum ARI score, assessed under ×10 magnification was 3 in both groups. A score of 3 was significantly more frequent in bioplast group. Differences were seen between the groups in terms of enamel surface characteristics under SEM evaluation. It was determined that bioplast material, which is considered to be the gold standard for the indirect bonding method, has greater shear bond strength than silicone material.