In order to practice, all orthodontists must be licensed by their state. To receive a dental license, candidates must graduate from an accredited dental school, successfully complete the written National Board Dental Examinations and pass state clinical tests.
The world's tallest artificial structure is the 829.8 m (2,722 ft) tall Burj Khalifa in Dubai . The building gained the official title of Tallest Building in the World and the tallest self supported structure at its opening on January 9, 2010. The second tallest self-supporting structure and the tallest tower is the Tokyo Skytree. The tallest guyed structure is the KVLY-TV mast.
Taipei 101 in Taipei, Taiwan, set records in three of the four skyscraper categories at the time it opened in 2004; at the time the Burj Khalifa opened in 2010 it remained the world's tallest inhabited building 509.2 m (1,671 ft) as measured to its architectural height (spire).