this article provides explaination
long story short damage to the gut from celiac prevents absorption of the fat soluble vitamins that our teeth need
http://paleoleap.com/preventing-and-hea ... oth-decay/
The Importance of Fat-Soluble Vitamins
It’s impossible to write about Paleo and tooth decay without mentioning Weston A. Price. Weston A. Price was a dentist from Cleveland who traveled all around the world looking for the nutritional causes of tooth decay – he wrote a book about it called Nutrition and Physical Degeneration and there’s now an organization called the Weston A. Price foundation dedicated to advancing his discoveries.
So what did he discover that was so important? Mostly, his research pointed out the importance of fat-soluble vitamins: A, D, E, and K2, especially K2. Vitamin K2 is responsible for directing dietary calcium into the right place in your body, so that it ends up in your bones and teeth (where you want it) and not blocking your arteries (where you definitely don’t). Vitamin K2 is found in grass-fed (not grain-fed!) meat and butter. You can also make it yourself if you have a healthy gut, but that’s a pretty big if.
The other fat-soluble vitamins are also important. For example, if a mother has a high Vitamin D intake during pregnancy, her baby will be at a lower risk of developing cavities. Vitamin D is important for calcium absorption. There’s also some evidence that children with tooth decay have lower levels of Vitamin D, and that Vitamin D may be helpful for treating cavities, although not all studies show a relationship.
This study also found that Vitamin A intake was associated with lower tooth decay in children.
All of this research just confirms what Dr. Price found out back in the day: fat-soluble vitamins are important for building healthy bones and teeth. It’s not just calcium.
Evidence from Malabsorptive Diseases
Another important part of good dental health is making sure you absorb the nutrients from your diet. No matter how much calcium, K2, D, or other nutrients you eat, if you’re not absorbing them, there’s really no point. You can see this in action if you look at the way diseases that reduce absorption of vitamins and minerals from food increase rates of tooth decay.
For example, celiac disease is associated with an unusually high rate of tooth decay and an unusual amount of enamel problems. The problem might be malabsorption – celiac disease damages the gut, which prevents the absorption of important minerals like calcium, iron, and fat-soluble vitamins.
Other causes of malabsorption include Inflammatory Bowel Disease (Crohn’s Disease and Ulcerative Colitis), weight loss surgery, and abnormal intestinal permeability (aka “leaky gut”).