Physical and mechanical properties of PMMA resins containing γ-methacryloxypropyltrimethoxysilane

The polymethylmethacrylate (PMMA) resins containing gamma-methacryloxypropyltrimethoxysilane (gamma -MPS) of 0, 2, 4, 6, 10, 15, 20 and 30 mo1%, added to methylmethacrylate, were prepared using a monomer-polymer technique and stored in air or water at 37 +/- 0.5 degreesC for 28 days. The flexural strength and flexural modulus of the PMMA resins containing gamma -MPS of 20 and 30 mo1% were significantly smaller than those containing 2-6 mo1% and the same statements were true for the adhesive strength to porcelain tooth. However, its value of adhesive strength to Co-Cr alloy was remarkably less than to porcelain tooth. By contrast, there was no significant difference among the Knoop hardness of the PMMA resins examined. On the other hand, the thermal expansion had an increasing tendency with an increase of a gamma -MPS content. The dynamic shear modulus within a temperature measured (20-140 degreesC) decreased s1ightly as the gamma -MPS content of the PMMA resins increased, and the peak temperature of mechanical loss tangent also tended to decrease. These results indicated that the PMMA resin containing gamma -MPS of 6 mol% was the best composition from the standpoint of an excellent adhesive strength against porcelain, although its water absorption was 1.9 times that of PMMA.