Dental decay, also known as dental caries, begins first inside the tooth. A white spot appears on the enamel where the tooth has started to weaken inside. At this stage, the tooth can repair the weakened area with the help of fluoride and minerals in saliva.
Beijing, also Peking, is the capital of the People's Republic of China and one of the most populous cities in the world. Its population in 2013 was 21,150,000. The city proper is the 3rd largest in the world.
Paris's 2017 population is now estimated at 11,011,000. In 1950, the population of Paris was 6,283,000. Paris has grown by 168,000 in the last year, which represents a 1.50% change. These population estimates and projections come from the latest revision of the UN World Urbanization Prospects.