title: Effects of long-term repeated topical fluoride applications and adhesion promoter on shear bond strengths of orthodontic brackets.
abstract: OBJECTIVE
  The purpose of this study was to assess the effects of long-term repeated topical application of fluoride before bonding and an adhesion promoter on the bond strength of orthodontic brackets.
  
  
  METHODS
  A total of 76 bovine incisors were collected and divided equally into four groups. In group 1, the brackets were bonded without topical fluoride application or adhesion promoter. In group 2, before bonding, the adhesion promoter was applied to nonfluoridated enamel. In group 3, the brackets were bonded without the application of the adhesion promoter to enamel, which had undergone long-term repeated topical fluoride treatments. Teeth in group 4 received the long-term repeated topical applications of fluoride, and the brackets were bonded using the adhesion promoter. All the brackets were bonded using BeautyOrtho Bond self-etching adhesive. The shear bond strength was measured and the bond failure modes were evaluated with the use of the adhesive remnant index (ARI) after debonding.
  
  
  RESULTS
  The mean shear bond strength was significantly lower in group 3 than in groups 1, 2, and 4, and there were no significant differences between the groups except for group 3. There were significant differences in the distribution of ARI scores between groups 2 and 3, and between groups 3 and 4.
  
  
  CONCLUSIONS
  The adhesion promoter can recover the bond strength reduced by the long-term repeated topical applications of fluoride to the prefluoridation level and had a significantly great amount of adhesives left on either fluoridated or nonfluoridated enamel.
authors.affiliation: Orthodontic Dentistry, The Nippon Dental University Niigata Hospital, Niigata, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
authors.affiliation: Orthodontic Dentistry, The Nippon Dental University Niigata Hospital, Niigata, Japan.
authors.forename: Rieko
authors.initials: R
authors.lastname: Ishida
authors.affiliation: Department of Preventive and Community Dentistry, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Komatsuzaki
authors.affiliation: Pediatric Dentistry, The Nippon Dental University Niigata Hospital, Niigata, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Sanpei
authors.affiliation: Department of Pediatric Dentistry, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Pediatric Dentistry, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Sekimoto
keywords: Adhesion promoter; fluoride; orthodontic bracket; shear bond strength