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.
1 Large Urban Population. 2  China has the largest urban population of any country in the world even though most Chinese live in rural areas. 3  More than 311,000,000 Chinese live in cities compared to 194,700,000 in the United States.4  26% of China's population is urban while 75% of the population of the United States is urban. More than 311,000,000 Chinese live in cities compared to 194,700,000 in the United States. 2  26% of China's population is urban while 75% of the population of the United States is urban.