You must first visit a dentist to find the reason of decalcification.. there are a few pastes to help you in the same also.. you can book an appointment with us via practo for the same

Hi mam... Remedies taken to treat decalcification: Serve real food:    Use quality food...Eliminate processed and packaged food...Eat fresh foods. Eat fat _soluble vitamins:vitamin: A,D,E,K Vit A:Butter,Fish,cord liver oil Vit D:cord liver oil,egg yolk from pasteurized chicken,shiitaki mushrooms Vit E:Butter,organ meats,nuts,seeds VitK:liver,egg yolk,green leafy vegetables,cabbage Reduce Phytic acid:   Avoid Bread,pasta,rice,Take vitamin c rich foods like gova,citrus fruits,cauliflower,oranges papayas,sweet potatoes Use reminaralization tooth paste.... Use of fluoridated tooth paste under 3 years of age ia not advicible....In this condition Use soft bristles tooth brush and washing with water

See an experienced pedodontist.