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.
The current population of China is 1,386,976,150 as of Saturday, April 15, 2017, based on the latest United Nations estimates. China population is equivalent to 18.47% of the total world population. China ranks number 1 in the list of countries (and dependencies) by population. The population density in China is 148 per Km2 (383 people per mi2). The total land area is 9,390,784 Km2 (3,625,800 sq. miles)