[Bonding of MMA-BPO. DMPT resin to bovine tooth coated by poly (methyl methacrylate-co-p-styrene sulfonic acid)].

The objective of this study was to prepare a new type water-soluble bonding agent, methyl methacrylate (MMA)-p-styrene sulfonic acid copolymer (MS), and to investigate the effect of MS on bonding between resins and tooth substrates. MS is cross-linked with Ca2+ released from ground enamel and dentin and could be immobilized on their surface. A sample was prepared by bonding an acrylic rod with a BPO-amine catalyzed self-curing resin to ground enamel and dentin coated with an aqueous mixture of FeCl3 and 10 wt% MS. After immersion in water for 24 hrs, the tensile bond strength was measured. The bond strength to both enamel and dentin was only 2 MPa and adhesive failure occurred at the interface between cured MS and self-curing resin. This suggested that cured MS could adversely effect the polymerization of self-curing resins. A second treatment of cured MS on the tooth surface with metallic cations was carried out to minimize the amount of free sulfonic acids in the MS disturbing radical formation in self-curing resin. The second treatment improved the bond strength to 6 MPa.