The effect of bleaching on shear bond strength of resin bonded bridges

Abstract

Sixty intact upper central and lateral incisors were used in this study the teeth were divided into four groups, the first group was the control group the other groups were bleached with (10%)carbamide peroxide (Opalescence 10%) for two weeks the bleaching material was changed every (8) hours. Sixty discs shaped samples were cast from nickle chromium CB Blando 72 alloy the diameter of each sample was (5) mm and the thickness was (1) mm, the bonding surfaces were sandblasted. The discs were bonded to the teeth in the first and second groups one day after bleaching, the third group was bonded one week after bleaching while the fourth group was bonded two weeks after bleaching. The bonding material used for all groups was Super Bond Crown and Bridge Material. The shear bond strength of the samples was tested. The statistical analysis showed that the second group has the lowest bond strength while the fourth group showed the highest bond strength. This indicates that bleaching affects the bond strength of resin bonded bridges fabricated from CB Blando 72 nickel chromium alloy so that bridges must be fabricated at least two weeks after bleaching