The best things I've found are the pieces of stag horn that you can buy. Some of the pet shops sell them here so think they're probably easily available in other countries.
They last my Yorkies forever, though the non edible Nylabones ( there are different types, some are edible) do too.
Now I just need someone to recommend something my Skyes can't eat
They eat The black Kongs, the very largest Nylabones, you name it, they've eaten it.
Someone did suggest I begged a length of sewer pipe next time I pass a construction site
