Repair of glass ionomer restorative materials: flexure strength of specimens repaired by two methods

This study evaluated the adhesion of newly mixed glass ionomer restorative materials to set materials. The flexure strength of specimens formed by the addition of new material to week-old material by using two different surface treatments was compared with the flexure strength of solid specimens that were 1 week old. All repaired specimens attained at least 44% of the average strength of unrepaired specimens of the same material. Repairs made with a combination of unlike materials were not significantly different from most repairs with like materials. For all materials collectively, repairs made with a 37% phosphoric acid pretreatment were significantly stronger than repairs made with a 40% polyacrylic acid pretreatment.