RESUMO
Surgical repositioning of the downward displaced premaxilla in bilateral cleft lip and palate patients remains a controversial and perplexing issue because of its detrimental effects on the growth of the premaxilla. The purpose of this prospective clinical study was to introduce and evaluate the treatment results of an innovative technique for nonsurgically intruding the downward displaced premaxilla. Eight consecutive cases of bilateral cleft lip and palate at the age of mixed dentition were included for the correction of their premaxillary deformities. A pair of intraoral tooth-borne distraction devices was used for the orthopedic intrusion. Serial lateral and posteroanterior cephalometric radiographs were taken periodically for evaluating the growth of the premaxilla 1 year before the intrusion, changes during the intrusion, and growth/relapse up to 1 year after the intrusion. There was no overgrowth of the premaxilla or overeruption of the maxillary incisors during the 1-year observing period before the orthopedic intrusion. The treatment results revealed that the downward displaced premaxillae were all corrected within 1 month. Cephalometrically, 46 percent of the correction resulted from a true orthopedic intrusion and another 54 percent from a dentoalveolar effect in which the maxillary incisors were intruded and the premaxillary dentoalveolus was shortened. The cephalometric evaluations also implied that what occurred during the orthopedic intrusion was mostly the sutural contraction osteogenesis/osteolysis in the vomeropremaxillary suture combined with slightly mechanical upward displacement of the vomeronasal septum complex and nasal bones. The orthopedic intrusion of the premaxilla with distraction devices is an effective nonsurgical method for correcting the downward displaced premaxilla before alveolar bone grafting in patients with bilateral cleft lip and palate, and the results remained stable after 1 year.