The demands on nasal breathing differs between wakefulness and sleep.

Anatomic causes of nasal obstruction often include structures of the internal nasal valve - the septum, the inferior turbinates, and the upper lateral cartilages. Often times, we are successful in treating nasal obstruction surgically with focus in these structures.

What happens when patients do not respond as well after “intra-nasal” procedures such as septoplasty and inferior turbinate reduction?

The cross-sectional area of the internal nasal valve is significantly influenced by the width of the nasal floor. The nasal floor is also the roof of the maxilla (upper jaw).

For patients with sleep-disordered breathing (including upper airway resistance syndrome and obstructive sleep apnea), a narrow nasal floor means

1) More resistance to nasal breathing during sleep

2) Less room for the tongue, leading to posterior tongue displacement (obstructs airway). Posterior displacement of the tongue can also push against the soft palate during sleep, which further exacerbates the problem.

In that situation, expansion of the nasal floor via the maxillary floor/palatal roof becomes an option.

This slows airflow through the nasal passages, which lessens the negative pressure that collapses the pharyngeal airway.

Expansion of the nasal passages means more nasal mucosa, which is responsible for the benefits to nasal breathing.

In 2015, when we first started addressing this anatomic phenotype at Stanford with Dr. Christian Guilleminault and Dr. Audrey Yoon, I found myself explaining to patients that we aim to transform the “narrow, high-arch” palate to a “dome” shaped palate.

Over time, we decided to describe the process as “DOME - Distraction Osteogenesis with Maxillary Expansion.” It is easy to understand, as we create a dome-shaped palatal roof. Furthermore, we aim to grow bone via distraction (hence distraction osteogenesis), at the nasal floor, during transverse maxillary expansion.

DOME has since evolved significantly in all areas.

1. More specific patient phenotyping

2. Custom expander designs

3. Less invasive, or elimination, of osteotomies

4. Improved esthetic and periodontal processes

Many orthodontists and surgeons have since developed their own approaches to naso-maxillary expansion, for the treatment of patients with sleep-disordered breathing and transverse maxillary hypoplasia (narrow upper jaw).

I envision that we will all continue to improve patient-specific methods to creating the “dome” shaped palate, to promote nasal breathing during sleep. Our common goals are to alleviate severity of sleep-disordered breathing, nasal obstruction, and daytime sleepiness.