I would look into minerals as the cause; one thing our body does when it fights an infection is that it uses the bodies reserves such as fat, skin, hair, bones, etc. Magnesium chloride is a great supplement I use that purifies the blood, destroys uric acid deposits, and it kills all of the plaque within your blood. It also is great for promoting digestion.
Minerals strengthen teeth and bones within the body and if we have candida, we are likely deficient in many trace minerals. You can supplement yourself with calcium, magnesium, zinc, iodine, selenium, and many others and this should bring better dental health.
Also, fluoride in my opinion is a detriment to oral and general health and should not be consumed whatsoever. Dental fluorosis can occur if you consume too much. I would try a fluoride free toothpaste if you have not done so already.