More than 18 million Americans have sleep apnea, a condition that affects their breathing while they are asleep. Not only does sleep apnea impact their sleep quality, but it can also increase the risk of strokes, heart attacks, congestive heart failure, and hypertension.
To treat the condition without surgery, patients use continuous positive airway pressure (CPAP) machines or oral appliances that resemble retainers. Many oral appliances, however, are bulky and can cause pain in the temporomandibular joints below the ears.
When Seungkyu Lee, a Seoul-based dentist, realized how much sleep apnea decimated the quality of life for his patients, he began working on an alternative oral appliance called the QT33 and then spent the next 10 years tinkering with it until its hardware was as small as possible. Now Lee’s startup domobio, which recently completed SparkLabs’ accelerator program, is seeking Food and Drug Administration approval and distributors in the U.S. for the device. QT33 is already available at 200 clinics in Canada under the name SNR.X.
The QT33, which holds patents in South Korea, China, and the U.S., is molded from orthodontic resin and has a small metal fastener made from titanium alloy just behind the front teeth. Patients can “unlock” it by opening their mouths or sliding their jaws side-to-side, but when the fastener is engaged, it holds the lower jaw in the best position for proper breathing during sleep.
Before creating QT33, Lee used SomnoMed, one of the leading sleep apnea oral appliances, on his patients. Some complained that it caused joint pain in their jaws, however, and so Lee decided to develop a slimmer alternative that would also be faster to prepare and make. He says that it only takes two ten-minute sessions with a patient to prepare the QT33: one to make an impression for the device of the patient’s teeth and then another to make sure it fits properly. Lab technicians can make up to three QT33 a day, compared to one for other devices.
The current version of Lee’s QT33 device, which costs about $2,000, has already been used by 1,500 patients in Korea.
Before working with sleep apnea patients and creating QT33, Lee says he saw being a dentist as just a job, because his father and grandfather had both been in the profession before him.
Disrupt 2026: The tech ecosystem, all in one room
Your next round. Your next hire. Your next breakout opportunity. Find it at TechCrunch Disrupt 2026, where 10,000+ founders, investors, and tech leaders gather for three days of 250+ tactical sessions, powerful introductions, and market-defining innovation. Register now to save up to $400.
Save up to $300 or 30% to TechCrunch Founder Summit
1,000+ founders and investors come together at TechCrunch Founder Summit 2026 for a full day focused on growth, execution, and real-world scaling. Learn from founders and investors who have shaped the industry. Connect with peers navigating similar growth stages. Walk away with tactics you can apply immediately
Offer ends March 13.
“We’ve been in the dental field for the last 90 years. Being a dentist was just how I earned my living, but after I started treating sleep apnea patients, I changed my mind because they really, really appreciate it,” Lee says.
“There are things that most people take for granted, like being able to sleep lying down, that some sleep apnea patients can’t do,” he adds. “Sleep apnea patients really suffer a lot. This is related directly to their quality of life.”
For more information about QT33, contact Lee at sk.lee@domobio.co.kr
