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.
Tallest residential building in the world: 23 Marina in Dubai  --- 395m (1,296 ft.), with 90 storeys.  Tallest hotel in the world: Makkah Royal Clock Tower Hotels ---  601m (1,972 ft.) with 95 storeys.  Tallest structure in the world: Burj Khalifa, Dubai ---  828m (2,717 ft.).  Tallest tower in the world: Tokyo Sky Tree, Japan ---  634m (2,080 ft.).  First Building to have more than 100 storeys: Empire State  Building (New York City, USA) --- 381m (1,250 ft.), 102 storeys.