Top rated dentist, such as Josey Lane Dentistry, agrees with the National Institute of Health when it calls tooth decay the most prevalent chronic disease.
Unlike, the tooth, the enamel is a nonliving tissue that cannot rejuvenate. Professor Janet Moradian-Oldak, at the Herman Ostrow school of Dentistry of USC, invested the last 20 years of her life looking for a way to recreate this nonliving hard tissue known as tooth enamel. According to the news release the solution may be in the form of a gel that is now waiting FDA approval.
Source: http://www.sciencedaily.com/releases/2015/11/151117091239.htm