Repair of glass ionomer cements — methods for conditioning the surface of the cement to achieve bonding

Two chemically different glass ionomer cements (Ketac Fil® and ChemFil II® Caps) and three different methods of conditioning the surface for repair were evaluated. Specimens of each material were prepared, aged and sectioned. The cut surfaces were treated with either phosphoric acid, polyacrylic acid or a combination of phosphoric acid followed by polyacrylic acid. Freshly mixed glass ionomer cement was injected against the treated surface and allowed to set under simulated intra-oral conditions. The specimens were then tested to failure in flexion after 7 days storage. The flexural strength of the repaired specimens was compared with that of control specimens of the same materials. The flexural strength of the repaired specimens was less than that of the controls. Treatment of the fractured surface with polyacrylic acid produced the weakest repair, and the use of phosphoric acid as the conditioning agent produced repaired specimens approximately 80% of the strength of the controls.