Dana K. Hockenbury
Licensed Speech and Language Pathologist
Orofacial Myofunctional Disorders (OMD) describe abnormal resting postures and functioning of the oral and facial muscles. The prefix "myo" means muscle so our primary work begins with the muscles of the face, lip and tongue.
A tongue thrust is the most common Orofacial Myofunctional Disorder. In the general population, the prevalence is from 30-40% from childhood throughout adulthood (source: IAOM). It occurs when the tongue moves forward, between or against the sides of the teeth, rather than moving vertically against the roof of the mouth while swallowing saliva, liquids or solids.
An incorrect position of the tongue is another common Orofacial Myofunctional Disorder. When the tongue rests against the front, sides or in between the teeth, it no longer supports proper orofacial development. This light continuous pressure of the tongue against the teeth with lips parted and the jaw hinged open can cause the bite to open up, referred to as an open bite. If this occurs after braces are removed then this is referred to as 'ortho relapse'.
Specifically, the tongue acts as scaffolding to the hard palate, allowing the dental arches to form appropriately. Therefore the fundamental work of an Orofacial Myologist begins with teaching and habituating proper tongue and lip resting postures. This is the most important aspect of our work: it is addressed in the beginning and throughout the program.
A third common Orofacial Myofunctional Disorder is chronic non-nutritive sucking habits involving fingers, thumbs, blankets, clothes or pacifiers. During constant prolonged sucking, the tongue is positioned under the inserted object as well as forward against the front teeth. From this incorrect tongue resting posture, with lips opened, a tongue thrust swallowing pattern develops.
In addition, with the constant forward and upward pressure of the thumb, fingers or pacifier against the hard palate, the desired wide dental arch is reshaped into a high and narrow palatal vault. A cross bite might develop as well as an anterior open bite. If the sucking habit isn't extinguished then this distortion of the palate and dental arches can become permanent. A palatal expander is typically used to reshape and expand the width of the dental arches back toward a more normalized position. If the sucking habit is eliminated before 5 years of age, the bite is more inclined to close with the teeth drifting back to their neutral position.
Orofacial Myologists can design a program for the young child, teenager or adult to eliminate these non-nutritive sucking habits. If the elimination of these noxious oral habits are addressed early then potential problems may be avoided in the future.
Tongue-tie or ankyloglossia may also cause a tongue thrust. It occurs when the 'cord' or frenum restricts the range of motion of the tongue. This restriction causes the tongue to sit low in the bottom of the mouth. This vertical restriction interferes with the movements of the tongue in sucking, eating and clearing food off the teeth in preparation of the swallow. In addition, if the tongue's elevation is restricted it will not be able to assume the desired resting posture against the palate which helps to maintain a wide dental arch.
Many specialists agree that a restricted tongue (lingual) or lip (labial) frenum can be a precursor to dental, speech, skeletal (jaw growth) and myofunctional concerns. Malformation of the palate and dental arch may occur along with a negative influence on speech production.
If a restricted lingual or labial frenum is suspected, the Orofacial Myologist will refer to the patient to an oral surgeon or an ENT to have the frenum released. This will allow for better lip and tongue excursions. The Orofacial Myologist prescribes home-based exercises post-op to eliminate scaring, keeping the tongue or lip long and flexible.
Infected and enlarged tonsils and adenoids compete with the tongue for space in the back of the oral cavity and upper pharynx. Because of the lack of space with the competing soft tissue, the tongue is displaced forward, causing the lips to be parted and the mouth open. Obligatory mouth breathing can occur due to this restricted and compromised posterior airway space. Here again is another opportunity for a tongue thrust swallowing pattern to develop. Once the enlarged tonsils and/or adenoids are surgically removed or shrink on their own, the Orofacial Myologist can eliminate the tongue thrust and strengthen & tone the oral and facial muscles to recapture the appropriate lip and tongue resting posture. This ensures a normal dental freeway space in the oral cavity.
"The major primary factors in the dental equilibrium appear to be resting pressures of tongue and lips, and forces created within the periodontal membrane, analogous to the forces of eruption. Forces from occlusion probably also play a role in the vertical position of teeth by affecting eruption. Respiratory needs influence head, jaw and tongue posture and thereby alter the equilibrium. 'Deviate swallowing' is more likely to be an adaptation than a cause of tooth changes. Patients with failure of eruption have been recognized and alterations in the eruption mechanism may be more important clinically than has been recognized previously."
Equilibrium Theory Revisited: Factors Influencing Position of the Teeth
The Angle Orthodontist, 1978, Vol 48, No3, 175-186
Dr. William R. Proffit, D.D.S., Ph.D.
School of Dentistry
University of North Carolina
Chapel Hill, N.C.
This website is written and maintained by Dana Hockenbury, Certified Orofacial Myologist