title: Effect of etching and light-curing time on the shear bond strength of a resin-modified glass ionomer cement.
abstract: The aim of this study was to assess the influence of etching and light-curing time on the shear bond strength (SBS) and adhesive remnant index (ARI) of a resin-modified glass ionomer cement (RMGIC) upon debonding of orthodontic brackets. Sixty-eight bovine permanent incisors were obtained and embedded in acrylic resin. Edgewise metallic brackets were bonded to the teeth with Fuji Ortho LC RMGIC. The specimens were randomly assigned to 4 groups, using the following etching and light-curing times: G1: 10% polyacrylic acid and 40 s (control); G2: 37% phosphoric acid and 40 s; G3: 10% polyacrylic acid and 50 s; and G4: 37% phosphoric acid and 50 s. Shear test was performed at 0.5 mm/min and the ARI was assessed. G2 (3.6 ± 0.98 MPa) presented significantly higher (p<0.05) SBS than G1 (2.76 ± 0.86 MPa) and G4 (2.86 ± 0.68 MPa), and there was no statistically significant difference (p>0.05) between G2 and G3 (2.94 ± 0.67 MPa). ARI presented prevalence of scores 2 and 3 in all groups. RMGIC SBS enhanced with 37% phosphoric acid etching and 40 s light-curing time, but this did not occur when the light-curing time was increased, regardless of the acid used. RMGIC presented prevalence of failures at the adhesive/bracket interface.
authors.affiliation: Pontifical Catholic University of Paraná, Curitiba, PR, Brazil. ivan_maruo@yahoo.com.br
authors.forename: Ivan Toshio
authors.initials: IT
authors.lastname: Maruo
authors.forename: Juliana
authors.initials: J
authors.lastname: Godoy-Bezerra
authors.forename: Armando Yukio
authors.initials: AY
authors.lastname: Saga
authors.forename: Orlando Motohiro
authors.initials: OM
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maruo
authors.forename: Elisa Souza
authors.initials: ES
authors.lastname: Camargo
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000180:Acrylic Resins; D000538:Aluminum Silicates; D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D017005:Dental Debonding; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements / Q000737:chemistry; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D016910:Orthodontic Brackets; D033081:Shear Strength; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D000538:Aluminum Silicates; C095451:Fuji Ortho LC; D005899:Glass Ionomer Cements