This in silico kinematic study was performed to evaluate the best attainable outcomes of maxillary distraction osteogenesis given the constraints of linear and helical motion. The study sample included the retrospective records of 30 patients with maxillary retrusion who had been treated with distraction or had been recommended this treatment. The primary outcomes were the errors of linear and helical distraction. The study measured two types of error: misalignment of key upper jaw landmarks and misalignment of the occlusion. Concerning the misalignment of key landmarks, the median misalignments resulting from helical distraction were minimal; the interquartile ranges were also minimal. The median misalignments and interquartile ranges that resulted from linear distraction were significantly larger. Regarding the occlusal misalignments, helical distraction produced minor occlusal misalignments, while linear distraction produced significantly larger errors. The results of this study confirmed that helical motion is the ideal motion for LeFort I distraction.

Distraction osteogenesis (DO) is a highly effective technique for correction of severe maxillary hypoplasia, especially in patients with orofacial clefts and craniofacial syndromes. The purpose of this retrospective, longitudinal study was to assess long-term airway alterations after maxillary advancement using a rigid external distraction system (RED) in non growing cleft patients. Fifteen cleft patients (8 males and 7 females) aged from 14 to 25 years were included in this study. All of them were treated with a rigid external distraction system for maxillary advancement after a high Le Fort I osteotomy. To analyse airway changes lateral cephalograms were obteined before distraction (T0), immediately after distraction (T1) and 1 to 3 years and 3 months after distraction (T2). All the measurements were describled by means of median, minimum and maximum. In order to evaluate differences between each time interval, a Wilcoxon test associated to a Delta Cliff test was used to evaluate the effect size (level of significance adopted was 5%). A significant maxillary advancement and increased upper airway antero-posterior dimensions were observed after the distraction osteogeness process, as demonstrated by the difference between T1 and T0. No significant relapse at T2 was found. Lower airway and the airway at tip of uvula region did not display significant alterations. A significant maxillary advancement and increased antero-posterior upper airway dimension was measured immediately after maxillary distraction with rigid external distraction in non growing cleft patients. The findings were stable three years after distraction.