Treatment results with light wires studied by panoramic radiography.

The purpose of this investigation is to evaluate "parallelism" and the incidence of root resorption in fifty-three extraction cases treated with light continuous wire therapy, following the principles of minimum force application, minimum tooth movement, avoiding the outward displacement of the roots from the apical bases, and a minimum time of active treatment. Differential tooth movement was performed and active displacement of the full complement of teeth was avoided when possible, according to the needs of the particular case. Panoramic radiographs were taken before and after active treatment and 1 year out of retention. The long axes of upper and lower canines and second premolars were traced and the angulation between them was measured to appraise root "parallelism." Only 1.8 percent root resorption was estimated for those teeth measured. A possible explanation for this low figure may be the mesiodistal movement of the teeth along the apical bone base, without deviations toward the labiobuccal or lingual sides.