1

Introduction

Maxillary morphology plays an important role in the pathophysiology of obstructive sleep apnea (OSA). Guilleminault et al. reported the presence of high and narrow hard palate differentiating OSA between relatives. Maxillary morphology studies have shown greater palatal heights in OSA subjects. Transverse maxillary hypoplasia with a high, arched palate in OSA is associated with increased nasal airflow resistance and inferior-posterior resting tongue position that results in retroglossal airway narrowing. Since 2014, Liu, Yoon, and Guilleminault at the Stanford Sleep Medicine and Surgery Center have applied minimally invasive maxillary osteotomies and distraction osteogenesis via mini-implants across the midpalatal suture for maxillary expansion (DOME) in adult OSA patients. This chapter highlights the surgical techniques and management principles.

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Indications

Pediatric OSA patients with maxillary hypoplasia and high, arched palate who failed tonsillectomy and adenoidectomy have been treated with rapid maxillary expansion (RME). RME achieves maxillary expansion via orthodontic devices that exert pressure on the dental arches bilaterally. This results in an expanded nasal floor and reduced nasal airflow resistance. It widens the distance between upper airway dilator muscles. The tongue also positions more superior-anteriorly, resulting in retroglossal airway increase. There are more studies that show efficacy of maxillary expansion, including 12-year follow-up data, in pediatric OSA. There have been limited data for adult OSA patients who have the same maxillary morphology and can benefit from expansion.

For adults with OSA and high, arched palate, previous expansion procedures showed unpredictable outcomes. Classic orthodontic expanders push the dental arches laterally, and although acceptable for correction of malocclusion, they are less effective for nasal obstruction and upper airway resistance, as there is limited expansion of the nasal floor in the palatal midline. The key difference compared with pediatric patients is midpalatal suture fusion in adults. Developmentally, fusion of the midpalatal suture occurs during the early teens, coinciding with a pubertal growth spurt. To effectively expand adults, surgical osteotomies were used to re-create suture lines and weaken the vertical pillars of the maxilla. The osteotomies tended to be more invasive, especially the blind osteotomy at the pterygomaxillary junction.

The advent of bone-anchored expanders with mini-implants has made less invasive surgery possible. Bone-anchored, as opposed to tooth-anchored, expanders are reliable for maxillary expansion without causing dental and periodontal damage. The implants anchored across the midpalatal suture line beneath the nasal floor allow physiologic suture expansion, reduce negative dentoalveolar effects, and achieve more nasal expansion than conventional RME.

The combination of minimally invasive surgery and bone-anchored expanders takes full advantage of the principles of distraction osteogenesis (DO) and reliably expands the maxilla in adults with OSA and narrow, high, arched palatal vaults ( Fig. 59.1 ).

Comparison of tooth- versus bone-anchored expanders.

(A) The tooth-anchored expander exerts most of its force at the dentoalveolar ridges (red arrow). The morphology of the palate even after expansion remains narrow and high-arched. (B) Intraoral view of the tooth-anchored expander. (C) Bone-anchored expander exerts most of its force across the midpalatal suture (red arrow). The dentoalveolar segments are expanded symmetrically. The nasal floor and palatal vault are widened. (D) Intraoral view of the bone-anchored expander. Note the four mini-implants.

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Contraindications

Relative contraindications include patients with significant hypopharyngeal collapse as seen on clinical examination, nasopharyngoscopy, or drug-induced sedation endoscopy, especially if DOME is performed as an isolate procedure. Other relative contradictions include existing periodontal bone loss or inability to follow up with postoperative ortho­dontic management.