title: Blood contamination effect on shear bond strength of an orthodontic hydrophilic resin.
abstract: OBJECTIVE
  The aim of this study was to assess the impact of blood contamination on shear bond strength (SBS) and bond failure pattern of metallic brackets bonded using a new hydrophilic resin.
  
  
  METHODS
  Eighty human premolars were randomly allocated into 4 groups (n=20) according to the bonding material and contamination pattern. GI: brackets bonded with the Transbond XT conventional system without contamination; GII: brackets bonded with the Transbond XT conventional system with blood contamination; GIII: brackets bonded with the Transbond Self Etching Primer and Transbond Plus Color without contamination; GIV: brackets bonded with the Transbond Self Etching Primer and Transbond Plus Color with blood contamination. The specimens were stored in distilled water at 37°C for 24 h and then submitted to SBS test at a crosshead speed of 0.5 mm/min. After bond failure, the enamel surfaces were observed under an optical microscope at 40x magnification.
  
  
  RESULTS
  Blood contamination decreased (P<0.05) shear bond strength when both the hydrophobic (GII) and the hydrophilic resin (GIV) were used. However, the bond strength of Transbond Color Change group was significantly higher (P<0.05) than that of the Transbond XT conventional system group under blood contamination condition. Under dry conditions no difference was observed between the hydrophobic and hydrophilic resin groups. Regarding the bond failure pattern, when blood contaminated the enamel, the adhesive remnant index (ARI) showed predominance of scores 0 and 1, which indicates low adhesion to enamel.
  
  
  CONCLUSIONS
  Although there was a significant decrease in the shear bond strength for both adhesive systems under blood contamination, the hydrophilic system showed significantly higher bond strength than the hydrophobic resin adhesive. Therefore, it is advisable to use the hydrophilic resin under risk of blood contamination.
authors.affiliation: Dental School, Pontifical Catholic University of Paraná, Curitiba, PR, Brazil.
authors.forename: Taís de Morais Alves da
authors.initials: Tde M
authors.lastname: Cunha
authors.forename: Bruna Ariela
authors.initials: BA
authors.lastname: Behrens
authors.forename: Denise
authors.initials: D
authors.lastname: Nascimento
authors.forename: Luciana Borges
authors.initials: LB
authors.lastname: Retamoso
authors.forename: Luís Filipe Siu
authors.initials: LF
authors.lastname: Lon
authors.forename: Orlando
authors.initials: O
authors.lastname: Tanaka
authors.forename: Odilon
authors.initials: O
authors.lastname: Guariza Filho
mesh_terms: D000704:Analysis of Variance; D001769:Blood; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D004866:Equipment Contamination; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C477790:Transbond XT