Bond strength of esthetic brackets to esthetic substrates

This study was carried out to compare the shear bond strength of esthetic brackets [composite and ceramic] to enamel surface and to two esthetic restorative materials [millable composite blocks [MZ 100] and machinable ceramic blocks [Vita Mark II] using the Bistite II DC adhesive luting agent. This study was classified into three groups, two test groups [millable composite blocks [MZ 100, machinable ceramics [Vita Mark II] and control group [natural teeth extracted upper first premolars] [n=16]. The control group [upper first premolars] was extracted during routine orthodontic treatment. The teeth were washed then stored in 0.1% thymol solution. Small area on the buccal surface was ground flat then, polished with wet 400 and 600-grit silicon carbide abrasive paper. The second group was formed of sixteen blocks of millable composite [MZ 100]]. In addition, the third group was formed of sixteen blocks of machinable ceramics [Vita Mark II]. Each group was divided into two subgroups [A and B] according to the brackets type [composite or ceramic brackets] [n=8]. Adhesive bonding agent [Bistite II DC] was used for bonding of brackets to different substrates of the main three groups. All specimens were stored in water bath at 37 C for 45 days followed by thermal cycling for 500 cycles. Results; There was significant difference between composite brackets bonded to ceramic substrate and composite brackets bonded to composite substrate and vice versa, ceramic brackets bonded to ceramic substrate showed significant higher shear bond strength compared with ceramic brackets bonded to composite substrate. The clinical implication of this study is that the Bistite II DC adhesive can be used clinically for bonding esthetic brackets to esthetic substrates. Moreover, it is preferable to use ceramic brackets in case of ceramic restorations and composite brackets in case of composite restorations to get the highest shear bond strength regardless to the other characteristics of their designs