Evaluating Once a Week Maxillary Advancements Using a Distraction Device

Abstract

Introduction: Maxillary distraction is often used to correct significant molar Class III malocclusion. We have introduced a modification of the traditional distraction schedule utilizing larger interval distractions once a week under sedation. We hypothesize that this new schedule still allows for successful advancement with limited relapse of the LeFort segment. The underlying principle is that the greatest benefit of maxillary advancement is utilizing the LeFort I segment to expand the soft tissues of the palate and midface. Methods: The modified advancement schedule consisted of the placement of internal distraction devices following a LeFort I osteotomy with an initial advancement of 5 to 8 mm. Thereafter, the patient underwent weekly “interval” advancements under sedation in the operating room. Cephalograms were taken preoperatively, perioperatively, and 6 months after distraction device removal. The cephalometric landmarks were analyzed including SNA and ANB angles as an indicator of maxillary positioning. Results: From June 2021 to September 2023, 13 consecutive patients underwent maxillary advancement with the new interval advancement schedule. Nine patients were found to have all 3 data points required for inclusion in this study. The total distance of advancement averaged 17.2 (±2.9) mm. Patients had an average of 2.7 (±0.7) advancement events. Advancement on the day of surgery averaged 6.7 (±0.8) mm and during each interval advancement event averaged 6.1 (±1.0), 5.2 (±1.6), and 0.5 (±0.5) mm. Conclusion: Modifying the schedule of maxillary distraction from twice daily advancements during the activation phase to weekly advancements with larger interval movements grants acceptable advancement with limited relapse. This new approach to maxillary advancement utilizes both the principles of distraction osteogenesis and soft tissue expansion.