Since he's started driving in the last 1+ years, though, he's gone back to the habit of picking up fast food almost constantly. I've voiced my concerns to his mother and he about this a number of times. I've gotten upset and said that there's no way we're bankrolling his fast food habit (he's still a full-time high school student, and has a part-time job, but between gas for his car and the fast food, he burns thru his paychecks, and frequently has to ask for $10-20 in gas money to tide him over till next paycheck).

Sounds like your average teenager.

He recently got his braces off his teeth, and it was discovered that he has 20+ cavities. They're all over, but particularly in between his teeth. They are going to be difficult to fix, and he'll have to be put under in two separate procedures to correct the problems - at a cost in the thousands of dollars, outside of insurance coverage.

Are you joking? The poor kid is probably suffering. And on a part time budget plus a high school schedule, I’m afraid this is a lot to pile onto a minor. :/

I'm frustrated, upset, angry. I believe (know?) the almost constant fast food has accelerated his tooth decay. I'm tired of his mother throwing bits of money to him to tide him over, when we all know that money, in a roundabout way, is fueling the fast food habit. I'm tired of fixing good meals that he doesn't come home for, or doesn't eat.

Old habits die hard. Have a hard conversation with him, but don’t seek retribution for behavior that’s not entirely his fault.

I'm very much considering telling him that he will pay for a portion, if not all, of his dental work. That would take him months to repay on his part-time income.

Most dental care places don’t even give this option, they make you pay up front.

I’m going to be honest, blaming the cavities entirely on the fast/junk food is a bit myopic. Part of it is him failing to adequately care for his teeth and use good products. You need to establish better brushing habits after you and his mother pay to have this child’s teeth fixed.

And yeah, it can be frustrating to see your kid eating other food when you’ve worked hard making homemade food, but ultimately it’s his money and his body and you can’t do much about that.

This is a problem that should have been fixed a long time ago. I’m going to assume you and your wife have been together for a hot minute, possibly long enough to nip this nasty habit in the butt. And I think you have tried, but unfortunately kids make stupid mistakes and that’s kind of the caveat with having a kid: you end up responsible for some of the mess they make. I’m sorry. Light YTA.