title: Shear bond strengths of plastic brackets with a mechanical base.
abstract: This study compares the shear bond strengths of plastic brackets with a mechanical base and metal brackets using two different adhesives, and examines the modes of failure using a scanning electron microscope (SEM). Forty extracted human premolars were selected for bonding. Two types of brackets: metal and plastic-Spirit MB, and two orthodontic adhesives: System 1 + and Enlight, were used. After bonding, all samples were put into a 37 degrees C distilled water bath for 24 hours before shear bond strengths were tested. The bond strengths of the plastic brackets were significantly lower than those of the metal brackets (P < .0001). There was a statistically significant difference in bond strengths between System 1 + and Enlight for plastic brackets (P < .05), but not for metal brackets. The modes of failure predominantly occurred at the enamel/adhesive interface in the metal bracket-System 1 + group, within the adhesive in the metal bracket-Enlight and plastic bracket-System 1 + groups, and at the bracket/adhesive interface in the plastic bracket-Enlight group.
authors: Department of Dentistry, College of Medicine, National Cheng Kung University, National Cheng Kung University Hospital, Tainan, Taiwan, ROC. jkliu@mail.ncku.edu.tw
authors: Jia-Kuang
authors: JK
authors: Liu
authors: Li-Tung
authors: LT
authors: Chang
authors: Shu-Fen
authors: SF
authors: Chuang
authors: Dar-Bin
authors: DB
authors: Shieh
mesh_terms: D001641:Bicuspid; D001840:Dental Bonding; D003799:Dental Stress Analysis; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D008670:Metals; D016910:Orthodontic Brackets; D010969:Plastics; D019279:Resin Cements; D013718:Tensile Strength
chemical_list: C418867:Enlight; D008670:Metals; D010969:Plastics; D019279:Resin Cements; C045637:System 1 plus