He does not realize that his avoidance of medical and dental care will cost your family HUGE bucks sooner or later.
He is being exceptionally childish and selfish.
I would ask your dentist, first, to help you out here. Have the dentist do a simple list of the cost of two cleanings a year. Then have the dentist list the cost for each of these: Fillings. Root canal. Partial dentures. A full set of dentures. Show it all to your husband and explain: Two cleanings a year now, maybe a filling or a few, versus thousands upon thousands for root canals, dentures, gum work.
Now: Think about ALL that money going down hubby's mouth instead of going into your kids' college funds. That's the selfish part here: By not getting the most routine care, he is setting your family up for paying big-time for his dental and medical bills which means less money for your children's educations -- maybe even less money for THEIR medical bills if, heaven forbid, they (or you) get really ill.
Do the same with the doctor. Cost of routine annual physical (include costs of routine tests) versus costs of treatment for a host of things.
Did he have some horrid experience in the past? Probably he had pain with a dentist and/or with a doctor. I'm sorry if that's the case but frankly, he needs to "man up" and maintain himself or he will end up not being around to see your kids grow up, possibly, or he'll be so cranky from painful teeth or who knows what else that he wont' be able to enjoy his own kids. Seriously, he needs to grow up here. If he gets sick and does not get treated, he could end up spreading something to his own kids.
If he is not going to listen to you, have a male friend he trusts give him a verbal trip to the woodshed over this.
Oh, and he's also setting a truly poor example for his children. They will have every right to say eventually, "But daddy doesn't see the dentist, why should I have to?" Make HIM try to answer the kids on that one.
I'm sorry if it sounds harsh but it seems he might need a real wake-up call, hence the itemized bills and the talk with a guy he respects. It's sad when husbands don't listen to their wives on these things but unfortunately some men just will not listen to a woman tell them they need to do the right thing. Good luck.