Preprosthetic molar uprighting using skeletal anchorage.

after extraction or loss of a first molar, the second molar may tip mesially into the edentulous space. Not only will the first-molar space contract mesiodistally, but eccentric occlusal loading will reduce the biomechanical loading capacity of the second molar. Such a situation requires preprosthetic up righting of the second molar using appropriate mechanics. Simply tipping the molar distally with a statically determined force system will lead to extrusion and likely cause occlusal interference. Therefore, a statically indeterminate system applying both an intrusive force and an uprighting mo ment of force would be preferable.1 Stable anchorage is critical, since simultaneous intrusion and up righting forces create a high moment load on the anchorage unit—a Class V geometry under the classification of Burstone and Koenig.2,3 Otherwise, unwanted mesial tipping and extrusion of the anchorage teeth may occur. The use of an orthodontic mini-implant for direct anchorage can help avoid such dental side effects. However, an uprighting spring applies an axial moment to a screw inserted in the buccal segment, thus increasing the likelihood of implant failure4 (Fig. 1). This article describes an alterna-