title: Factors affecting the shear bond strength of orthodontic brackets to porcelain.
abstract: The aim of this investigation was to establish a regime for orthodontic bonding to feldspathic porcelain, which ensures adequate bond strength (6-8 MPa) with minimal damage on debond and consisted of an ex vivo investigation measuring the effects of porcelain surface preparation and thermocycling on shear bond strength of orthodontic brackets. One-hundred-and-twenty feldspathic porcelain bonded crown surfaces were divided into 12 equally-sized groups to assess the effects of: (1) glaze removal, (2) application of hydrofluoric acid, phosphoric acid, or omission of acid treatment, and (3) silane priming upon the bond strength of premolar brackets bonded with Right-on (TM) composite resin adhesive. Specimens were subjected to thermocycling and then to shear debonding forces on an Instron machine. Removal of the porcelain glaze, or use of hydrofluoric acid, prior to bonding were found to be unnecessary to secure the target bond strength. Hydrofluoric acid application was associated with increased porcelain surface damage. Thermocycling caused a significant reduction in shear bond strength to porcelain (P < 0*001). The best regime for orthodontic bonding to feldspathic porcelain was to apply phosphoric acid for 60 seconds, and prime with silane prior to bonding. Usually the porcelain surfaces could be repolished. Refereed Paper
authors.affiliation: Department of Orthodontics, School of Dentistry, University of Birmingham, Birmingham, U.K.
authors.forename: B M
authors.initials: BM
authors.lastname: Bourke
authors.forename: W P
authors.initials: WP
authors.lastname: Rock
mesh_terms: D000134:Acid Etching, Dental; D000269:Adhesives / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D001840:Dental Bonding; D017005:Dental Debonding; D003775:Dental Polishing; D003776:Dental Porcelain / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D006858:Hydrofluoric Acid / Q000008:administration & dosage; D008422:Materials Testing; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000008:administration & dosage; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D000269:Adhesives; D000538:Aluminum Silicates; D017220:Dentin-Bonding Agents; D010756:Phosphoric Acids; D017680:Potassium Compounds; D019279:Resin Cements; D012821:Silanes; D003776:Dental Porcelain; C071164:Right-On cement; C016447:feldspar; D006858:Hydrofluoric Acid