An innovative gel that forms a layer over teeth and then recruits calcium and phosphate ions from saliva to build new enamel has the potential to change dental treatment. To date, we don't have any way to regenerate the tough outer layer of enamel on our teeth as it erodes with age.
My guess is that they can slowly regrow lost enamel under fillings, slowly build back up later by layer until a filling is no longer needed. What would be amazing is a cure for gum disease.