ABSTRACT
INTRODUCTION: Distraction osteogenesis has gained popularity because of the hypothesized concurrent soft-tissue expansion, which is believed to reduce postoperative relapse. Although many articles describe the immediate success of mandibular distraction, little research has been done on its long-term stability. Our goal was to examine the long-term craniofacial changes after distraction. METHODS: Four hemifacial microsomic patients treated with unilateral mandibular distraction were recalled. Changes in maxillary width and height, occlusal height, ramus height, mandibular length, and chin position were quantified by using the posteroanterior and 45 degrees lateral oblique cephalographs. Predistraction and postdistraction measurements were taken over a 5-year period. The data were analyzed by using paired t tests and ANOVA. RESULTS: Maxillary height, ramus height, mandibular length, and chin point deviation all experienced moderate improvement after distraction. Although the growth patterns between the control side and the treated side were comparable until 2 years after removal of the device, the normal side outgrew the affected side thereafter until 5 years after distraction. CONCLUSIONS: Because of the greater inherent growth potential of the unaffected side, more overcorrection than originally believed is needed to offset the persistent asymmetry in growing hemifacial microsomia patients who undergo unilateral distraction osteogenesis.
Subject(s)
Cephalometry , Facial Bones/pathology , Mandible/surgery , Osteogenesis, Distraction/methods , Child , Chin/growth & development , Chin/pathology , Dental Arch/growth & development , Dental Arch/pathology , Dental Occlusion , Facial Asymmetry/surgery , Female , Follow-Up Studies , Humans , Longitudinal Studies , Male , Mandible/growth & development , Mandible/pathology , Maxilla/growth & development , Maxilla/pathology , Radiography, Panoramic , Tomography, X-Ray , Vertical DimensionABSTRACT
The purpose of this pilot study was to evaluate cephalometrically the efficacy of an intraoral distraction osteogenesis device in treating patients with unilateral mandibular hypoplasia. Six patients with hemifacial microsomia underwent unilateral mandibular distraction. Posteroanterior and 45 degrees lateral oblique cephalograms were measured, and changes in maxillary width and height, occlusal height, ramus height, mandibular length, and chin position were quantified. Measurements were taken preoperatively and postoperatively at 7 time points (T1-T7) over 2 years. Calculations for statistical significance were done to T6 for all patients and through T7 for 4 patients. The means and variances were calculated for the 6 cephalometric variables for each time point. The mean differences between treatment and control were calculated as well as analysis of variance. Mean differences between specific time periods were measured by pairwise comparison with significance determined at the 0.05 level of confidence. Statistical analysis was used for descriptive purposes only. The cephalometric data suggest that the intraoral distractor is as capable of lengthening hypoplastic mandibles as the initial extroral appliances. The bone lengthening appears stable, with the distracted side of the mandible maintaining a growth rate similar to the normal side. Immediately after distraction, transient improvements were noted in maxillary height, ramal height, and maxillary width. All patients demonstrated an immediate improvement in chin position toward the skeletal midline; however, after T4, menton appeared to be moving away from the midline over time.
