Cephalometric parameters in obstructive sleep apnea
Alessandri-Bonetti G, Ippolito DR, Bartolucci ML, D’Antò V, Incerti-Parenti S. Cephalometric predictors of treatment outcome with mandibular advancement devices in adult patients with obstructive sleep apnea: a systematic review. Korean J Orthod 2015;45:308-21
Mandibular advancement devices (MADs) are used to hold the mandible forward with the aim of preventing collapse of the upper airway during sleep—an alternative to nasal continuous positive airway pressure. The efficiency of MADs in obstructive sleep apnea ranges from 42% to 65%. Selection of predictive factors for mandibular advancement treatment is still unclear. In a systematic review of 907 potential articles, 15 met the inclusion criteria based on polysomnographic diagnoses of obstructive sleep apnea (ie, 5 or more respiratory events per hour of sleep). The synergistic value of a 2-dimensional cephalometric analysis together with the construction of a MAD, is an attempt to validate its usage over other more expensive diagnostic tools, such as magnetic resonance imaging, computed tomography, and nasopharyngoscopy. Skeletal cephalometric measurement data showed conflicting values for cranial base angle and the distance between sella turcica for 2-piece MADs and the deepest point in the posterior cranial fossa for the 1-piece MAD. Sagittal jaw relationships such as SNA, SNB, Sn-Pg, ANB, Wits appraisal, and linear measurements related to vertical jaw dimensions such as AFH, LAFH, and LPFH were not conclusive. Soft tissue and dental cephalometric measurements such as overjet and overbite were also not predictive. There was a shorter distance between the epiglottis and ANS; this correlates to treatment success with 2-piece and 1-piece MADs. Study designs were case controls, and the samples were not randomly selected, leading to selection and attrition biases. No definitive clinical recommendations could be made, and cohort studies with larger samples are encouraged.
Reviewed by Elvin Bhaskar
Three-dimensional evaluation of the airway after LeFort I maxillary distraction osteogenesis
Gokce SM, Gorgulu S, Karacayli U, Gokce HS, Battal B. Three-dimensional evaluation of nasal and pharyngeal airway after Le Fort I maxillary distraction osteogenesis. Int J Oral Maxillofac Surg 2015;44:455-61
The use of distraction osteogenesis for treatment of craniomaxillofacial anomalies has become popular in the last decade. The aims of this study were to evaluate the volumetric changes in the nasal cavity and the pharyngeal airway spaces after LeFort I maxillary distraction osteogenesis (MDO) using a 3-dimensional simulation program and to determine the effects of MDO on respiratory function during sleep. Eleven male patients (18-33 years old) with severe skeletal Class III discrepancies caused by maxillary retrognathia were treated with LeFort I osteotomy and intraoral MDO. Photographs, cephalograms, computed tomography images, 3-dimensional stereolithographic models, and polysomnography evaluations were obtained presurgery and at least 6 months postsurgery for each patient. SimPlant-OMS software (Materialise, Leuven, Belgium) was used to build stereolithographic models for distractor harmonization, to plan the virtual surgery, and to evaluate nasal cavity and polysomnography volumetric changes. The polysomnography evaluation included the apnea-hypopnea index, sleep efficiency, sleep stages, and mean lowest arterial oxygen saturation. After the LeFort I osteotomy, distraction devices were fixated to the zygomatic buttresses and maxillary segments bilaterally. After a 7-day latency period, distraction was performed at a rate of 0.5 mm twice a day until the negative overjet was overcorrected by 1 mm (approximately 20 days). The distractors were removed after a 60-day consolidation period. The results showed that MDO was successful in all patients. The average forward movement of A-point was 10.2 mm, and increases in nasal cavity and polysomnography volumes were statistically significant at 14.1% and 7.3%, respectively. Additionally, the polysomnography parameters showed a significant improvement of sleep quality in all patients. The authors concluded that using stereolithographic models and virtual planning before surgery simplified the operation and ultimately increased success.
Reviewed by Matt Davis