A periodontist is a dentist who specializes in the prevention, diagnosis, and treatment of periodontal disease, and in the placement of dental implants. Periodontists are also experts in the treatment of oral inflammation.
Ground speed. Ground speed is the horizontal speed of an aircraft relative to the ground. An aircraft heading vertically would have a ground speed of zero. Information displayed to passengers through the entertainment system often gives the aircraft ground speed rather than airspeed.
To measure the difference between Economy and Premium Economy seats, âseat pitchâ is a key term. A seatâs pitch is the distance between one point on that seat and the same point on the seat in front of it. Comparing seat pitches between classes is the best way to judge legroom.