[Polymerization reaction of heat curing type thermo-setting resin for crown and bridge].

The purpose of this paper is to investigate the chemical composition, the polymerization ability and the abrasion resistance of two brands (Isosit, Plastique) of thermo-setting resin for crown and bridge. 1. Isosit (Is) contained approximately 55 per cent of MFR type filler and 45 per cent of a comonomer (urethane dimethacrylate, 1, 3 butane dimethacrylate and 1, 10 decamethylene dimethacrylate). 2. The extent of polymerization (Ep) of experimental comonomers (Is', Pl') and composites (Is-E and Pl-E) which corresponded to Is and Pl was as follows: Is', Pl'>ls-E, Pl-E>Is, Pl 3. There was no significant difference in Ep between Is group and Pl group. 4. The residual monomer was less than 4 per cent. 5. The efficiency of cross-linking (Ec) of two experimental comonomers was higher than those of the corresponding brands. 6. The Ep and Ec of the two brands cured by at the designated temperatures were slightly less than those cured by at 150•Ž. 7. The amount of abrasive wear of all materials cured by DSC decreased with increase the Ep and Ec. And the cured products of experimental comonomers showed lower abrasive wear values than those of the two brands cured by DSC. The abrasive wear values of the two brands cured by specified polymerization apparatus were intermediate between the two groups as above mentioned. 8. The surface roughness of Pl group was slightly larger than that of Is group through the