Osteodistraction of the Hypoplastic Maxilla using a Rigid External Distraction System: The Results of a One to Six-year Follow-up

Cho, Byung Chae; Kyung, Hee Mun

Abstract

A rigid external distraction device has been used for maxillary distraction osteogenesis and a number of papers have reported midface distraction after using this system. However, there is not enough information about long-term stability or further growth of the maxilla in adolescences after distraction. The purpose of this study was to evaluate the long-term stability of maxillary distraction osteogenesis by use of a rigid external distraction device. A total of 9 patients with severe cleft maxillary hypoplasia were treated between January 1998 and August 2003. The patients' ages at the time of surgery ranged between 13 and 19 years. The distraction started at five days after a Le Fort I osteotomy at a rate of 1mm per day for 10 to 15 days. All patients used the RED(rigid external distraction) I system. After distraction was completed, the device was left in place for another five to six weeks for bony consolidation. When this was completed, an orthodontic face mask was used with elastic traction for five to six weeks. The follow-up period ranged from one to six years. The mean distraction length was 13.6mm for an immediate postdistraction, 10.8mm at six months after distraction, and 10.4mm between the one year and six year follow-up period, resulting in relapse rate of 23.0%. Regarding three children with mixed dentition, the ANBangle ranged between 7.1 degrees to 8.5 degrees at immediate postdistraction, 2.8 degree to 4.0 degrees at the six- month postoperation period, and 0.4 degree to 1 degree at a five-year postoperation. Therefore, the growth rate of the distracted maxilla was lower than that of the mandible, respectively, in those three children. Our results suggested that greater anterior overcorrection of the hypoplastic maxilla is needed more in the growing child than in adults in order to compensate for a partial relapse and growth deficit.