THE STABILITY OF SEGMENTALIZED LEFORT-I OSTEOTOMIES WITH MINIPLATE FIXATION IN PATIENTS WITH MAXILLARY HYPOPLASIA

Purpose: This study evaluates the postsurgical stability of segmentali zed Le Fort I osteotomies with miniplate fixation in patients with max illary hypoplasia. Materials and Methods: Eighteen adult patients who had undergone segmentalized Le Fort I osteotomy for anterior and infer ior repositioning of their hypoplastic maxilla were studied radiograph ically. The positional change of five maxillary landmarks (PNS, ANS, A , U1, and UM) were measured on serial cephalometric radiographs accord ing to a reference frame constructed by using the SN line for superimp osition, sella as the origin of the coordinates, and a line parallel t o Frankfort horizontal plane as the x-axis, The positional changes of all variables were measured twice, and the means were calculated for a nalysis, The paired t-test was used for statistical analysis. Results: Statistically significant mean vertical change (P < .01) was found in the anterior maxilla, with U1 having moved up by 27.8% (1.5 mm) of it s initial downward surgical movement by 1 year postoperatively. U1 and UM had moved forward 2.0 mm and 1.5 mm, respectively (P < .01) by 1 y ear postoperatively, but the bony landmarks had no statistically signi ficant change in their horizontal positions. Conclusion: Although stat istically significant postsurgical changes were found at 1 year postop eratively, overcorrection is not recommended because of the large indi vidual variation observed and the relatively small magnitude of the re lapse.