How can I get my dog to eat hard food?

When I got him he had a broken jaw and was almost starved so I had to feed him soft food. Now his jaw is fine but he refuses to eat hard food. I have tried countless brands and sizes, searched the internet for ideas, and tried to starve him out but nothing works. All he thinks about is food. The soft food is getting old and expensive and messy and makes his breath reek and I am sure it can’t be that good for his teeth.