BlueRose
I'm assuming that by your usage of "whilst" that you are not in the US? The reason I ask is that different countries have different policies when treating war vets. For example, here in the US if it is a war-related injury, then what ever care a vet needs gets fully covered. That said, I don't know how other countries handle it.
Do you have any idea as to why he hasn't fully correct his problem? Is it because the government won't cover his dental care? Or does he dislike going to dentists?
From what you wrote about him having had bridges in the past, I'm guessing that if he doesn't have them now, they weren't a good fit for him and he gave up on them. Perhaps, he thinks that he will never find a good fit.
You say he cannot smile, laugh or kiss? Is that injury related or is it because he is self-conscious? If it is the latter, perhaps you can reassure him that you don't care how he looks when he smiles, laughs or kisses.
I was born with an inherited condition that caused me to have very bad teeth. For a long time, the inside of my mouth was in terrible condition. For me, it was for 2 reasons --- 1) I just didn't have the funds at the time to properly take care of it and didn't have decent dental insurance; and 2) When I had insurance and sought out a dentist, far too many looked into my mouth and saw dollar signs. I knew my condition well enough to know that what they wanted to do would never work for me.
So, after you reassure him that you don't care how he looks when he smiles, laughs or kisses, bring up the prospect of getting good work done. Find out if the government will cover his expenses. If not, then offer to help him look for ways to help with his dental treatments. Let him know that once his teeth and mouth are properly fixed, he will be a lot happier, more comfortable and all without pain.
Best wishes to you both.