title: Shear bond strength after multiple bracket bonding with or without repeated etching.
abstract: The purpose of the study was to measure the in vitro shear bond strength (SBS) of metal brackets after multiple bonding and debonding with and without repeated etching. One hundred and twenty extracted premolars were divided into three equal groups. In group 1, the brackets were bonded and debonded three times with repeated enamel etching and in groups 2 and 3 without repeated etching. In group 2, all composite remnants were removed before bonding, while in group 3, the remnants were levelled. Analysis of variance was used to determine significant differences in SBS with Bonferroni adjustment for the multiple testing procedures. The results showed that in group 1, the mean SBS was 11.69 MPa (SD 2.65) at the first, 14.30 MPa (SD 2.69) at the second, and 12.19 MPa (SD 2.26) at the third debonding. In group 2, SBS decreased from 12.57 MPa (SD 2.54) to below 8.0 MPa. In group 3, SBS remained constant from the first (11.93 MPa; SD 2.14) to the second (12.06 MPa; SD 1.65) debonding and only decreased significantly to 9.74 MPa (SD 1.80) at the third debonding. Less composite remained on the teeth after each debonding sequence. This was characterized by a shift from adhesive remnant index (ARI) scores 2 and 3 after the first debonding to ARI scores 1 and 2 after the second debonding to predominantly scores 0 and 1 after the third debonding. After bracket loss and levelling of composite remnants, the SBS is sufficient for application of orthodontic forces. Repeated etching may involve a higher risk of enamel tear-outs during debonding.
authors.affiliation: Department of Orthodontics, Technical University of Dresden, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rüger
authors.forename: Winfried
authors.initials: W
authors.lastname: Harzer
authors.forename: Zane
authors.initials: Z
authors.lastname: Krisjane
authors.forename: Eve
authors.initials: E
authors.lastname: Tausche
mesh_terms: D003188:Composite Resins / Q000009:adverse effects; D001840:Dental Bonding / Q000379:methods*; D003738:Dental Cements / Q000009:adverse effects; D017005:Dental Debonding / Q000009:adverse effects; D003743:Dental Enamel / Q000293:injuries / Q000648:ultrastructure*; D045662:Dental Etching / Q000009:adverse effects* / Q000379:methods; D003799:Dental Stress Analysis; D006801:Humans; D016910:Orthodontic Brackets; D019233:Retreatment; D033081:Shear Strength
chemical_list: D003188:Composite Resins; D003738:Dental Cements