I have healed caries by eating a high animal fat diet of traditional foods. My enamel thinned after a few pgs, but it rebuilt during my fourth pg with lots of organic meat and loads of fat, gelatinous bone broth, fermented veggies and Concentrace. We were eating sprouted grain and whole-fat dairy then. I had absorption issues, too, but this still worked.
Dec. 1st 2010, my family quit all forms of grain (I ate about two servings/day max., previously, so not much to begin with) and two days later, we quit all dairy. Since doing this, my partner, who has teeth that are missing pieces from cracking off, has had them heal over with thick, shiny enamel. My teeth, and my children's teeth (deciduous and permanent) have also become thickly enameled and shiny. We no longer have any trace of tartar. My teeth are so strong now that I've been smashed in the mouth with a big metal spoon, and on teeth that used to throb from a cool breeze, the pain of impact lasted a few minutes, and they remained firm in my gums, where previously, being hit in the teeth caused days or weeks of pain and looseness. The healing has been dramatic, and it's happened to all of my bones.
This past winter, my seven yr old son had a fast slip on wet tile at the hardware store. He went from standing to a face plant- straight down, and smacked his two front teeth onto the bare tile (they are permanent teeth). I expected broken teeth; he hit so hard. Instead, he had a sore jaw for about a week, minor abrasion to his lip, and absolutely not a mark on his teeth. He weighs 63lbs and is 4'4" tall, so there was a lot behind those teeth slamming into the floor.
We drink water from a spring-fed, mineral-rich creek for the past year, and we've reduced our Concentrace to about once or twice/week since then.
You absolutely can rebuild enamel, and also, if your teeth bones are weak, then the rest of your bones are, too, so dental care won't address the underlying issue anyway. You have to remineralize your whole body. Use oil-based preparations to bypass your gut, for things you can absorb through your skin, like magnesium. Also, take D3 in oil (olive oil gelcaps or droplets in medium-chain-triglycerides or mct's) to speed up the process of replenishing. You can rub the D3 oil into your skin, too.
eta: I just noticed that you are in MN. You really need to take D3; you just cannot get enough UVB to make enough D3 in your body at that latitude. Without adequate D3, calcium cannot enter the bones. If you are eating grains, your are flushing out minerals at a faster rate than you can acquire them, as well. Here's a link to the Vitamin D Council if you want to read up on it. :)