Implants of biologically active glass or glass ceramic containing titania

Claim 1

An improved implant comprising a biocompatible metal core coated with a layer of a biologically active glass or glass-ceramic having a composition consisting essentially of by mol%: ______________________________________ SiO.sub.2 40-60 B.sub.2 O.sub.3 8-15 Na.sub.2 O 15-30 CaO 8-30 P.sub.2 O.sub.5 0-8 K.sub.2 O 0-20 Li.sub.2 O 0-10 MgO 0-5 Al.sub.2 O.sub.3 + ZrO.sub.2 + Nb.sub.2 O.sub.5 0-8 La.sub.2 O.sub.3 + Ta.sub.2 O.sub.5 + Y.sub.2 O.sub.3 0-8 and F.sub.2 0-15 ______________________________________ the glass or glass-ceramic having substantially the same thermal expansion coefficient as that of the metal core, wherein the improvement comprises adding TiO 2 in an amount from 0.5 to 3 mole% to make up a total of 100 mol% glass composition to regulate the degree of biological activity of the glass or glass-ceramic represented by a saturated pH-value at the time when the glass or glass-ceramic is immersed in a simulated physiolgical solution, with no substantial change of the thermal expansion coefficient of the glass or glass-ceramic.