Studies have linked geographical variations in dental health and tooth loss to sunlight exposure. Dental caries were shown to be inversely related to mean hours of sunlight per year – people living in the sunny west proved to have half as many carious lesions as those in the much less sunny northeast.
Vitamin D, which is produced in your body in response to sunlight exposure, induces cathelicidin, which attacks oral bacteria. Cathelicidin also fights other infections such as pneumonia, sepsis, and tuberculosis.
According to the Vitamin D Council:
“Use of vitamin D appears to be a better option for reducing dental caries than fluoridation of community water supplies, as there are many additional health benefits of vitamin D and a number of adverse effects of water fluoridation such as fluorosis (mottling) of teeth and bones.”
Sources:
http://blogs.mercola.com/sites/vitalvotes/archive/2011/10/07/the-vitamin-that-is-better-than-fluoride-in-reducing-cavities.aspx