title: Can brackets be bonded with a composite resin after expiration date?
abstract: BACKGROUND
  The aim of the study was to compare shear bond strengths of brackets bonded with a composite resin before and after expiration dates.
  
  
  METHODS
  Forty-five freshly extracted premolar teeth were randomly divided into 3 groups of 15. Ormco Mini 2000 (Ormco Corp, Glendora, Calif) bicuspid metal brackets were used in the study. Group I: the brackets were bonded with Blugloo (Ormco Corp, Glendora, Calif) adhesive paste before the expiration date. Groups II and III: the brackets were bonded with same light cure composite resin 1 and 2 years after the expiration date. All of the groups were cured with a LED light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. One-way ANOVA with post-hoc Tukey tests were used to compare shear bond strengths of the groups. The chi-square test was used to determine significant differences in the adhesive remnant index (ARI) scores between the groups. Significance for all statistical tests was predetermined at p&lt;0.05.
  
  
  RESULTS
  No statistically significant difference was found in shear bond strengths and ARI scores between three groups (p&lt;0.05). There was a greater frequency of ARI scores of 2 and 3 and 4 in all groups.
  
  
  CONCLUSIONS
  Expiration dates do not have a significant effect on the shear bond strength of the composite material. Further studies are needed to investigate in other ways such as cytotoxicity of the composite resins after expiration date.
authors.affiliation: Department of Orthodontics, Akdeniz University Faculty of Dentistry, Antalya - Turkey.
authors.forename: Ahmet Yalcin
authors.initials: AY
authors.lastname: Gungor
authors.affiliation: Department of Orthodontics, Suleyman Demirel University Faculty of Dentistry, Isparta - Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Alkis
authors.affiliation: Department of Orthodontics, Suleyman Demirel University Faculty of Dentistry, Isparta - Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Turkkahraman
mesh_terms: D003188:Composite Resins / Q000627:therapeutic use*; D001840:Dental Bonding / Q000379:methods*; D006801:Humans; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000627:therapeutic use; D033081:Shear Strength; D013997:Time Factors
chemical_list: C522883:Blugloo; D003188:Composite Resins; D019279:Resin Cements