You could try a stiffer putty. It might help some. Either way,.. I'd say to roll out a tapered cone to whatever diameter you need, cut the tip off,.. then bend/shape if necessary to achieve any curvature the fang/claw might have. Then sculpt any imperfections in the tooth (cracks, chips, worn or rotten spots,.. whatever might give them some character). Let dry/harden. Then paint and/or glue into place.