title: Efficacy of quercetin flavonoid in recovering the postbleaching bond strength of orthodontic brackets: A preliminary study.
abstract: OBJECTIVE
  To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI).
  
  
  METHODS
  Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3-8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9-10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05).
  
  
  RESULTS
  Bleaching reduced the SBS below 10 Megapascal (MPa) level (P< 0.05) while all the postbleaching treatments (except the application of the solvent of quercetin) recovered the SBS back to values greater than 10 MPa (P< 0.05) and also back to nonbleached SBS levels (P> 0.01). All eight postbleaching treatments had rather similar efficacies (P= 0.1396). The concentration of quercetin (beta = 0.259,P= 0.042) but not its duration (beta = 0.213,P= 0.093) significantly improved its efficacy.
  
  
  CONCLUSIONS
  Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS.
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Mana
authors.initials: M
authors.lastname: Shamsedin
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Valiollah
authors.initials: V
authors.lastname: Arash
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Masoud Babaei
authors.initials: MB
authors.lastname: Jahromi
authors.affiliation: Department of Pharmacology, University of Medical Sciences, Babol, Iran.
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Moghadamnia
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Manouchehr Rahmati
authors.initials: MR
authors.lastname: Kamel
authors.affiliation: Department of Restorative Dentistry, University of Medical Sciences, Babol, Iran.
authors.forename: Fariba
authors.initials: F
authors.lastname: Ezoji
authors.affiliation: Social Determinants of Health Research Center, University of Medical Sciences, Babol, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Bijani
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Kavoli
authors.affiliation: Department of Orthodontics, University of Medical Sciences, Babol, Iran.
authors.forename: Tania
authors.initials: T
authors.lastname: Ghasemi
authors.affiliation: Department of Pediatric Dentistry, Dental Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Gholamhossein
authors.initials: G
authors.lastname: Ramezani
keywords: Antioxidants; ascorbic acid; delayed bonding; orthodontic brackets; quercetin; shear bond strength; tooth bleaching