A surgical procedure to eliminate rotational relapse.

M any orthodontists evaluate the retention phase of orthodontic treatment as the most difficult problem of therapy. In fact, the more conscientious the orthodontist, the more he might regard retention as the problem in treatment. Angle1 summarized orthodontic retention as follows : “After malposed teeth have been moved into the desired position they must be mechanically supported until all the tissues involved in their support and maintenance in their new positions shall have become thoroughly modified, both in structure and in function, to meet the new requirements.” As every clinical orthodontist realizes, however, it is far easier to summarize the ideals of a successful retention program than to accomplish them during actual treatment. The type and duration of the varying retentive measures are clinically determined by a myriad of factors-the number of teeth moved, the extent of orthodontic movement, the previous occlusion and age of the patient, the alleged cause of the particular malocclusion, habits related to the mouth, the actual cuspal anatomy of the teeth involved, the health of the periodontium, muscular pressures in the oral region, problems of apical base limitations, facial growth changes, and perhaps even atmospheric pressure.5l I31 14, 22 In any event, very few practitioners underrate the significance of retention in successful orthodontic therapy. Additional knowledge of facial growth and development, greatly improved techniques of orthodontic mechanics, and recent advances in diagnosis of the various factors related to dentofacial deformities have all enabled the orthodontist to obtain better treatment results-results which would seem less likely to cause problems in the retention phases of treatment. Nevertheless, relapse tendencies still exist in a fairly high percentage of treated malocclusions, especially in the cases studied over a period of years following active correction. Volumes have been written on the causes and prevention of retention failures, but to date there still exists great validity to HellmanP complaint: “We are in almost complete ignorance of the specific factors causing relapses and failure.” Although an orthodontist today has the capabilities to achieve dramatic