Orthodontic appliance providing for mesial rotation of molars

摘要

An orthodontic bracket, preferably in the form of a buccal tube, is provided for connecting an orthodontic archwire to each mandibular first molar of a patient. The bracket has an archwire groove oriented to maintain the archwire at a positive rotation angle relative to the point on the surface of the molar at which the bracket is connected. The rotation angle is preferably approximately 2° for Caucasian patients and approximately 4° for Asian patients. The groove, while inclined to a positive (distal) rotation angle of greater than zero, may additionally be inclined mesially relative to the wire to account for smaller cross-sectional dimensions of the wire relative to the groove. In making a custom orthodontic appliance, a computer designs such buccal tubes with the grooves rotated to an angle optimally calculated for the patient. In the custom method, based on digitized tooth shape date for the patient, the embrasure of the upper first molars are placed perpendicular to an archform to occupy the least space on the arch, and the mesial buccal cusp and disto lingual cusp of each lower first molar is placed on a line coinciding with a line through the mesial marginal ridge and disto lingual groove of the upper first molar.