LW-7 Backhoe teeth

I've seen most Chinese made backhoe bucket teeth are using two screws.

However our bucket has three, for some reasons? Maybe it's a newer design and a better distribution of the forces? Are these Chinese made teeth just a Chinese standard, so it is impossible to get spares in the western world?

If difficult to find spares, I might weld on a wear protection layer.

Any ideas whether it's an austenitic or mangan alloy in these teeth?