TL;DR: Here’s how it works…
The new treatment, called Electrically Accelerated and Enhanced Remineralisation (EAER), accelerates the natural movement of calcium and phosphate minerals into the damaged tooth.A two-step process first prepares the damaged area of enamel, then uses a tiny electric current to push minerals into the repair site.
Source: No more fillings as dentists reveal new tooth decay treatment | Society | The Guardian