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.
Completed in 2009, the Burj Khalifa, in Dubai (United Arab Emirates), is currently the tallest skyscraper in the world, with a height of 829.8 metres (2,722 ft). It shows a typical skyscraper feature: setbacks. A skyscraper is a tall, continuously habitable building having multiple floors. When the term was originally used in the 1880s it described a building of 10 to 20 floors but now describes one of at least 40â50 floors.