Spinel/zirconia-glass dental composites were prepared by melt infiltration to investigate the effect of zirconia addition on mechanical, optical properties and infiltration rate of the composites. The glass infiltration rate decreased with raising the zirconia content having a parabolic dependence of infiltration distance on time described by the Washburn equation due to the reduction in pore size. Although the optimum strength (308 MPa) of the spinel/zirconia-glass dental composite was observed when 20 wt% of zirconia was added, transmittance decreased with further increase in the zirconia content. (C) 2004 Kluwer Academic Publishers.