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.
Some experts believe that in 2050 there will be more than 50 million people living in Beijing. Is Beijing the largest city in China? Although Beijing is the capital city of China, there are larger cities in the country. Shanghai is home to over 24 million people in 2016, and is considered to be China's largest city. Others, however, argue that Chongqing, a municipality of 28,846,200 in the center of China is technically China's largest city.