Properties of prosthetic resin-veneer materials processed in commercial laboratories

Seventeen dental technicians heat-cured microfilled resins, and light-cured hybrid and microfilled resins were used. Marginal adaptation, porosity, hardness, and indentation creep were determined. The results demonstrated considerable variations in all properties studied. The most pronounced variations within the individual brands were found for the properties of porosity and marginal adaptation. When the different products studied were compared, in general the most substantial variations were found for the light-cured specimens. The extremes of number of pores per mm2 were 1.52 and 10.46 for one light-cured product. A moderate scattering of the results of hardness and creep was found. The highly-filled light-cured brands obtained the highest hardness numbers (VHN) and the lowest creep values compared with those of the heat-cured resins. The uneven technical quality found may in part explain the clinical failures of resin facings which are occasionally observed.