The use of laser beams for measuring tooth mobility and tooth movements

The laser reflexion method, a direct contactless measuring technique with a high accuracy, has been applied for clinical purposes. A prototype has been tested using a laser beam to illuminate a patient's tooth fixed to the equipment by an impression plate. The reflected patterns were thrown onto a screen with a coordinate system and photographically recorded, and the movement of the tooth has been geometrically calculated. The relapse tendency after orthodontic treatment of a patient with periodontal disease and parafunctions was studied by repeated measurements of the left medial upper incisor. By use of the method, it was possible to observe that the velocity of the studied tooth was highest during the 1st day and, besides the horizontal movement, a rotation of the tooth began at the end of the measuring period.