The Use of Segmental Corticotomy to Enhance Molar Distalization

maxillary molars requires a reduction of molar resistance to tooth movement, avoidance of distal crown tipping, good vertical control, and maintenance of anterior anchorage. Because molar distalization is a distolateral movement, however, it tends to dislodge the teeth from the alveolus. Corticotomy may be a useful adjunct procedure in such cases, since it has long been used to accelerate tooth movement and to minimize root resorption, loss of vitality, and relapse of orthodontic corrections.1-7 Suya suggested that most surgical and orthodontic procedures be performed in the first three to four months after corticotomy, before fusion of the toothbone units.8 In a report of two cases of crowding, Wilcko and colleagues described the combination of corticotomy with the grafting of resorbable, alloplastic freeze-dried bone implants to increase the volume of alveolar bone, regenerate bone affected by dehiscence and fenestration, and avoid gingival recession resulting from expansion of the arches.9 They argued that orthodontic movement results not from simple repositioning of single tooth-bone units, but from a cascade of physiological events leading to bone healing, which Frost has termed the “regional accelerated phenomenon”.10-13 An increase in bone metabolism in the periodontal tissues after surgical intervention has been demonstrated in beagle dogs14 and in Wistar rats.15,16 These phenomena are responsible for the rapid dental movement observed when orthodontic forces are introduced after corticotomy. The present article describes the implantation of freeze-dried bovine bone in the buccal alveolus after selective buccal and palatal decortication of the maxillary molars. This approach has the following advantages: • Corticotomy stimulates bleeding and capillary proliferation in the bone marrow, creating the perfect bed for a bone implant. • Corticotomy allows the identification and resolution of any areas of transitory secondary osteoporosis. • Dehiscence, fenestration, and