Impact of the Different Types of Le Fort I Maxillary Surgical Movement on Nasal Width Changes: A Photogrammetric Analysis.

BACKGROUND: Le Fort I maxillary movements affect nasal width, but nasal width changes with specific movement types have not been formally addressed to date. OBJECTIVES: The purpose of this study was to analyze and compare the changes in nasal width with different maxillary movements. METHODS: A retrospective study was performed among consecutive patients who underwent bimaxillary orthognathic surgery (n = 138) and who were grouped based on the type of maxillary movement (ie, maxillary advancement with intrusion [MAI], maxillary advancement with extrusion [MAE], and maxillary setback with intrusion [MSI]). Preoperative and 12-month postoperative nasal widths were analyzed photogrammetrically by 2 blinded evaluators. RESULTS: Maxillary advancement with intrusion and MAE presented a significantly (P < 0.05) higher alar base widening than MSI did, with no significant (P > 0.05) differences between MAI and MAE. Maxillary advancement movements (MAI and MAE) showed significantly (P < 0.05) higher alar base widening than maxillary setback movement (MSI). However, no significant (P > 0.05) difference was observed between maxillary intrusion (MAI and MSI) and maxillary extrusion (MAE) movements. CONCLUSIONS: This study shows that the nasal width varies distinctly depending on the type of Le Fort I maxillary surgical movement.

Development of the Customized Asymmetric Fixation Plate to Resist Postoperative Relapse of Hemifacial Microsomia Following BSSO: Topology Optimization and Biomechanical Testing.

Hemifacial microsomia (HFM), one of the most common congenital facial anomalies, was usually treated with the bilateral sagittal split osteotomy (BSSO) procedure to correct the asymmetric appearance and malocclusion of the mandible. However, the frequent post-operative relapse incidents would lead to the restoration of the mandibular segment to its preoperative position and failure of the BSSO procedure. In this study, a customized asymmetric fixed plate (CAF plate) was developed to resist relapse due to hemifacial microsomia occlusal forces and the different muscular traction forces on both sides of the mandible. For the actual HFM case in this study, the reconstructed mandibular segmental bone model was fixed using BSSO with a rectangular plate (the original CAF plate appearance) in the topology optimization analysis. With the topology optimization technique, the CAF plate was designed with a lightweight profile and excellent structural strength in consideration of the HFM asymmetrical muscle traction and occlusal force. Using biomechanical simulations, the von-Mises stress and CAF plate mandibular segment displacement and the miniplate were compared to evaluate which had superior relapse resistance. In the in-vitro biomechanical test, a fatigue force of 250,000 cycles and a constant muscle traction force were applied to the HFM mandibular model, which was fixed with the CAF plate fabricated using metal 3D printing (selective laser melting, SLM) to obtain the mandibular segment displacement as a relapse assessment. The topology optimization analysis showed that the CAF plate has the best characteristics, light weight and structural strength with 30% volume retention. The biomechanical analysis showed that the maximum von Mises stress of the mini-plate was 2.71 times higher than that of the CAF plate. The relapse displacement of the mandibular segment fixed with the mini-plate was 1.62 times higher than that fixed with the CAF plate. The CAF plate ability to resist relapse was confirmed by the biomechanical testing results so that only 0.29 mm of recurrence displacement was observed in the mandibular segment. The results indicated that the CAF plate structural strength and resistance to relapse was significantly better than that of the mini-plate. This study developed a customized asymmetric fixation plate for hemifacial microsomia, integrating topology optimization, metal 3D printing, and in vitro biomechanical testing to resist occlusal forces and differential muscle traction on both sides of the mandible to reduce relapse and improve fixation stability.

Objective and subjective long term outcome of maxillomandibular advancement in obstructive sleep apnea.

STUDY OBJECTIVES: To evaluate the objective and subjective long-term outcome of maxillomandibular advancement (MMA) in Far-East Asian patients with moderate to severe obstructive sleep apnea (OSA). METHODS: This is a long-term follow-up study to evaluate the treatment outcome of MMA in OSA patients by objective polysomnography (PSG) and subjective questionnaires (Pittsburgh Sleep Quality Index-PSQI, Insomnia Severity Index-ISI, Beck Anxiety Inventory-BAI, Beck Depression Inventory-BDI, Epworth Sleepiness scale-ESS, and Short Form-36 Quality of Life-SF-36). Evaluation was done before surgery and we followed these patients one and two years after surgery. We also assessed the neurocognitive function by Continuous performance test (CPT) and Wisconsin Card Sorting Test (WCST) before and after MMA. RESULTS: A total of 82 patients with OSA (female = 19) were enrolled and 53 participants (75.7% men, age 35.66 ± 11.66 years [mean ± SD], BMI = 24.80 ± 3.29) completed the two-year follow-up. The apnea-hypopnea index (AHI) decreased from a mean of 34.78 ± 26.01 to 3.61 ± 2.79 and 7.43 ± 6.70 events/hour (p = 0.007) at the first and second year evaluation. There was significant improvement in PSG (especially respiratory profile), questionnaires (PSQI and ISI total score), and neurocognitive testing (attention and executive function) after MMA. Meanwhile, no major complication such as avascular necrosis of bonny segments, facial nerve injury, blindness or compromise of airway was found after surgery. CONCLUSIONS: MMA is a clinically effective treatment for patients with moderate-to-severe OSA as demonstrated by significant long-term decrease in AHI and improvement in neurocognitive testing.

Maxillomandibular Rotational Advancement: Airway, Aesthetics, and Angle's Considerations.

Obstructive sleep apnea is a medical syndrome with multifactorial pathophysiology. Surgery can be the primary treatment option when anatomic factors are identified with narrowing at specific or general levels of pharyngeal airway. The surgeries are directed to the etiologic anatomic structure to achieve greatest effectiveness. Body weight, Mallampati scale, and tonsil grade are key evaluations to select effective surgical procedures. Surgical weight reduction, maxillomandibular advancement, and pharyngeal soft tissue surgeries are considered for the patient with obesity, maxillomandibular retrognathism, and tonsillar hypertrophy, respectively. Tailored surgical planning can meet the patients needs for airway, esthetics, and normal Angle's occlusion.

Experience with the transparotid approach via a mini-preauricular incision for surgical management of condylar neck fractures.

INTRODUCTION: The aim of this study was to describe our experiences of a mini-preauricular transparotid approach for direct reduction and plating of condylar neck fractures. MATERIALS AND METHODS: A retrospective study was conducted on 58 patients from 2009 to 2011 with 69 condylar neck fractures in Chang Gung Memorial Hospital. The fractures were treated surgically either with a 2-cm mini-preauricular and transparotid approach in 29 patients with 36 fractures, or via endoscope-assisted intraoral, or facelift or retromandibular approaches in a control group of 29 patients with 32 fractures. The postoperative hospital stay, occlusion status, mouth opening and facial nerve and parotid gland related complications were compared between the two groups. RESULTS: In both groups around 90% of patients had good restoration of preinjury occlusion. Postoperative mouth opening was 39.8 mm and 39.9 mm in the mini-preauricular approach and the other approaches group, respectively. Facial symmetry was achieved in all of the patients. There was no incidence of facial nerve palsy, infection or hemorrhage in the mini-preauricular group. One patient in the control group had a persistent weakness due to frontal nerve palsy. CONCLUSION: Based on the results, the mini-preauricular approach can be an alternative, safe and effective method in the management of condylar neck and high subcondylar fractures.