In Vitro Bond Strengths of Resin Modified Glass Ionomer Cements and Composite Resin Self-cure Adhesives: Introduction of an Adhesive System with Increased Bond Strength and Inhibition of Decalcification

This study evaluated the shear bond strength and adhesive remnant index of 5 self-cure adhesives to comparatively evaluate a new adhesive system. Extracted human incisors were randomly divided into 7 test groups of 20 each. Incisor mesh-backed brackets were bonded to the tooth specimens in each group with their respective adhesive according to the manufacturer's instructions. The specimens were thermocycled for 2 weeks at temperatures from 5° to 55°C to simulate oral conditions and debonded using an Instron machine. Acceptable bond strength parameters were present with the Contacto No-Mix (composite resin containing glass ionomer 8.75 MPa) and Fuji Ortho SC with acid conditioning (6.98 MPa). Contacto No-Mix had a higher bond strength (11.2 MPa) when microetching and Megabond were employed than when these adjuncts were not employed. When FUJI Ortho SC specimens were conditioned with polyacrylic acid, they showed a higher bond strength (6.98 MPa) than when bonded to unetched teeth (5.41 MPa). In test 3, EXPT-fluoride adhesive (AF) demonstrated a higher bond strength (13.44 MPa) than both resin composite Contacto No-Mix (8.8 MPa, GAC 7.4 MPa) and FUJI Ortho SC (5.41 MPa). Expt AF (Test 3) and Concise had equal bond strengths, however, the former can potentially release fluoride from the glass ionomer. Although the Expt AF had the highest bond strength, its adhesive remnant index was the same as FUJI Ortho SC acid etched. This may be attributable to the layer of Megabond used with the Expt AF. No correlation was evident between bond strengths and adhesive remnant on tooth surfaces after debonding. It was noted that a self-cure resin modified glass ionomer adhesive system that releases fluoride and has high bond strength can be employed. Microetching and adhesion promoters increase the bond strength.