The breath behind the bite.

I didn’t think much about airway in residency.

We were taught the orthodontic catechism — Class II malocclusion, arch coordination, bracket positioning, bond failures, the Andrews Six Keys. It was a beautiful, contained curriculum. Nobody was teaching us to listen for snoring in a parent’s voice when they described their kid. Nobody mentioned that the narrow palate I was about to expand might also be the reason a child slept with their mouth open every night.

The shift happened slowly, over a few years in private practice. I started noticing patterns I hadn’t been trained to name. The mouth-breathing seven-year-olds with gummy smiles and dark circles under their eyes. The teenage Class II patients whose mothers, in passing, would mention they snored “like a small chainsaw.” The forty-year-old with a constricted upper arch who came in to fix his crowded front teeth and, mid-consultation, mentioned his wife had taken to recording his snoring and emailing it to him at work.

Once I started seeing it, I couldn’t stop. The bite was the visible symptom. Often, the airway was the upstream cause.

This was the thing nobody had told me in school: how a face develops, how someone breathes at night, and how their bite functions are not three separate stories. They’re the same story, told three different ways. A child who breathes through their mouth from age four onward grows a face that accommodates that — long lower third, narrow upper jaw, posterior tongue posture, an open bite that wasn’t there at birth. By the time they get to me at twelve, I’m not just straightening teeth. I’m trying to undo eight years of compensation.

That’s how I came to fit my first Mandibular Advancement Device. A patient in his early forties came in for crowding, left with a referral for a sleep study. He had moderate obstructive sleep apnoea. CPAP — the gold-standard machine that pushes air through a mask — is effective but, for some patients, intolerable. He couldn’t sleep with it. We discussed alternatives. A MAD became part of the plan.

A MAD is a custom dental appliance — a top tray and bottom tray fused together — that holds the lower jaw forward by five to eight millimetres during sleep. That bit of forward translation pulls the base of the tongue away from the back of the throat and opens the airway. It’s small, it’s quiet, and for the right patient it changes the night.

I fitted one on myself before I started prescribing them in earnest. I wanted to know what I was asking patients to wear for eight hours. The first night I slept terribly — the jaw position felt wrong, my teeth ached gently, I dreamed about teeth (orthodontists really do). The second night I slept badly. By the fourth night I had stopped noticing. By the second week it was just part of the bedtime routine. That experience changed how I described the device to patients. It’s awkward at first. By next month you won’t think about it.

The patient I mentioned earlier still wears his. His wife sleeps better too. The before-and-after wasn’t measured in tooth movement; it was measured in how rested he was at his daughter’s wedding.

This is the part of orthodontics I think most about now. Straight teeth are nice. They’re a good outcome. But a treatment plan that ignores how someone breathes at night is, in my view, doing half the job. How a jaw develops, how someone breathes, how a bite actually works — same picture, all of it. Once you start looking at it that way, you can’t unsee it.