RETENTION CAPACITY OF THE BRACKET BASES OF NEW AESTHETIC ORTHODONTIC BRACKETS

Tensile bond strength and bond failure locations were evaluated in vitro for three types of direct bonding cements (self-cured diacrylate, dual-cured diacrylate, and dual-cured glass ionomer) with four types of brackets (stainless steel, polycarbonate, ceramic, and ceramic-polycarbonate) by using a plastic cylinder as the substrate. A highly filled, self-cured diacrylate cement gave the highest bond strength values with the polycarbonate, stainless steel, and ceramic-polycarbonate brackets. A dual-cured diacrylate cement gave the highest bond strength with a mechanically retained ceramic bracket. The dual-cured glass ionomer cement gave the highest bond strength values with a silanated ceramic bracket. All bond failures occurred at the bracket/cement interface with the stainless steel bracket, whereas failure locations were at the bracket/cement interface and within the cement with the polycarbonate bracket. Bond failures occurred between bracket and cement, within the cement, and within the bracket with the ceramic brackets.