After 1918, orthodontist Alfred R. Rogers proposed that an imbalance in orofacial muscles was a result of malocclusion and recommended targeted exercises to improve muscle tonicity and function.¹ Rogers introduced oral myofunctional therapy (OMT) by incorporating isometric and isotonic exercises that target the oral and oropharyngeal muscles to increase muscle tone, endurance, and coordinated movements. The function of OMT is usually to normalize tongue and lip posture at rest, establishing nasal breathing, correcting chewing and swallowing patterns, and ceasing harmful oral habits.²

Given its primary functions, OMT has been shown to be an alternative treatment for patients diagnosed with obstructive sleep apnea (OSA). The effectiveness of OMT to treat OSA in adults has been studied by comparing multiple factors, including the apnea-hypopnea index (AHI) score.

Apnea-hypopnea index

The AHI has been utilized by health-care providers to help diagnose sleeping disorders, such as OSA, aid in determining the severity of the disorder, and select the appropriate treatment. AHI is measured and calculated through a polysomnography, or a sleep study, which is an overnight test that monitors key body functions throughout sleep.³ These functions include breathing pattern, oxygen and blood oxygen levels, heart rate, brain waves, body movements, snoring, and sleeping positions through the use of sensors. These sensors or electrodes are placed on the scalp, chest, legs, and near the nose and mouth to monitor brain activity, breathing, heart rate, movement, and oxygen levels throughout sleep.

Sleep studies can be conducted overnight in a hospital or an accredited sleep center, where a trained sleep technologist will assist in attaching sensors and remain available all night, or at home utilizing portable equipment. The results are then analyzed by a sleep specialist to determine whether any sleep disorders are present.⁴ Based on the results, the specialist can determine the AHI by adding the number of apneas and hypopneas, then dividing by the total number of hours of sleep received.⁵

In 1978, several doctors conducted research that introduced the concept of sleep apnea syndromes and defined apnea as a cessation of airflow lasting for at least 10 seconds throughout a night of sleep. Patients suffering from at least 30 apneas during the night should be diagnosed with sleep apnea syndrome.

Additional reading: Early detection and intervention for sleep apnea through dental screenings

This formal evidence for respiratory problems during sleep later led to the proposal of a new metric—the AHI—a diagnostic tool that measured the number of apneic events a patient suffered per hour of sleep.⁶ An AHI score below five events per hour indicates healthy and normal breathing during sleep, with no indication of OSA. while a score between five and 15 indicates mild OSA, 15 and 30 indicates moderate OSA, and 30 or higher indicates severe OSA.⁵

This index was later revised with the addition of hypopneas, the blockage of airflow affecting the quality of breathing during sleep, to what we know today as the AHI. The inclusion of hypopneas gave the index a more comprehensive look to assess the severity of OSA.

Despite the addition of the hypopneas, there has been long-standing criticism of AHI for having significant limitations as it only captures breathing frequency and not additional relevant clinical characteristics such as heterogeneity of sleep-disordered breathing, the true severity of OSA, and differences between gender and age in apneic events. AHI also does not identify the potential extent or risk of systemic effects on the body, or the potential benefits patients may receive from treatment. Even with the limited research and criticisms, AHI has become the standard for assessing sleep-disordered breathing. It has also been embedded in laws and regulations as a method for assessments, including fitness for driving and medical reimbursements.⁶

How myofunctional therapy fits in

Myofunctional therapy and sleep apnea are directly related. Myofunctional therapy works with the orofacial muscles that help target the muscles that can help keep the airway open when sleeping. In 2015, multiple studies measured the before-and-after sleep outcomes of those who endured myofunctional therapy. It was found that exercises can reduce the AHI, improve muscle tone, tongue posture, and nasal breathing, which led to fewer interruptions when breathing. For the adult participants, there was an average reduction from 24.5 events to 12.3 events per hour, a 50% decrease throughout the studies, indicating that myofunctional therapy could show improvement in adults and could serve as an adjunct to other OSA treatments.⁶

The role of dental hygienists

As dental hygienists, we play a critical role in preventive care and continue to expand into performative roles. Using the AHI, we may be able to assess the scores with patients and identify issues, educate, and be knowledgeable about the patient's conditions and how to manage them. Myofunctional therapy can assist dental hygienists in identifying a potential need by assessing our patients’ body language, a common one being patients sleeping in dental chairs.

Another factor to consider alongside the AHI is how the use of an oral appliance, such as a nightguard, can influence the score. Changes in AHI with the appliance in place may help indicate whether myofunctional therapy could be effective for the patient.

Although additional research is needed on the effects of myofunctional therapy for helping treat OSA, implementing OMT and AHI scores can be used as a resource to further educate not only the patient but also greatly expand the future of managing further care for conditions that are closely linked to airway dysfunction, sleep-disordered breathing, and overall systemic health.

Additional reading: New treatment for sleep apnea may replace bulky CPAPs for patients

References

1. Mills CS. International Association of Orofacial Myology history: origin—background—contributors. Int J Orofac Myol Myofunct Ther. 2011;37(1):5-25. doi:52010/ijom.2011.37.1.1
2. Stefani CM, de Almeida de Lima A, Stefani FM, Kung JY, Flores-Mir C, Compton SM. Effectiveness of orofacial myofunctional therapy in improving orofacialfunction and oral habits: a scoping review. Can J Dent Hyg. 2025;59(1):59-72.
3. Sarver A. Sleep study (polysomnography). SleepApnea.org. Updated March 31, 2026. https://www.sleepapnea.org/diagnosis/sleep-studies/
4. Sarver A. Apnea-hypopnea index (AHI). SleepApnea.org. Updated April 29, 2026. https://www.sleepapnea.org/diagnosis/ahi-apnea-hypopnea-index/#h-what-is-ahi
5. Beyond the stereotypes: obstructive sleep apnea in women. Sleep Institute. Resmed. July 14, 2025. https://www.resmedsleepinstitute.com/sleep-apnea/history-of-apnea-hypopnea-index-ahi
6. Camacho M, Certal V, Abdullatif J, et al. Myofunctional therapy to treat obstructive sleep apnea: a systematic review and meta-analysis. Sleep. 2015;38(5):669-675. doi:10.5665/sleep.4652