It's only a screw

Abstract

Temporary anchorage devices have revolutionized our ability to move teeth. No longer are we concerned about retracting or protracting teeth without moving the anchor teeth. We can completely avoid using the support of posterior teeth to retract incisors or the support of anterior teeth to protract molars. In some cases, we can even avoid the use of extraoral appliances, which have always been objectionable to patients and therefore less dependable for providing absolute anchorage. After all, miniscrews and miniplates are relatively stable in the long term. But even long-term stability is not necessary for anchorage plates or screws because they not needed for more than 6 to 9 months. So is this miracle tool the best orthodontic adjunct developed in many years? Maybe not. Certain biologic and esthetic principles exist in orthodontics and dentistry that previous research has shown are inviolate, no matter what magic device we use. As clinicians, we must remember that these principles cannot be overcome, even with an immobile screw or plate. I have attended meetings at which temporary anchorage devices were extolled for their ability to accomplish unbelievable types of tooth movement. But were these movements appropriate or stable? In some cases, their use might be inappropriate. Let me give you 2 examples. I read a case report in another orthodontic journal that described the treatment of a girl in late adolescence with a deep anterior overbite and a gummy smile. The treatment plan was to intrude her maxillary incisors to eliminate her gummy smile and correct the deep overbite at the same time. To make certain that the maxillary incisors would intrude, a miniscrew was placed in the labial midline of the anterior maxilla above the roots of the central incisors. An elastomeric chain was used to intrude the maxillary incisors by 3 mm. As a result, the deep overbite was reduced, and the gummy smile disappeared. Sounds like a wonderful result. Wrong. Here is the problem. Before any orthodontic treatment, the distance from this patient's upper lip to her maxillary central incisal edge at rest was 4 mm. This is nearly normal for an adolescent. After intruding the