Tongue thrust is defined as a condition in which the tongue makes contact with any teeth anterior to the molars during swallowing.
Etiology of tongue thrust
Fletcher has proposed the following factors as being the cause for tongue thrusting.
Genetic factors: They are specific anatomic or neuromuscular variations in the oro-facial region that can precipitate tongue thrust. For example, Hypertonic orbicularis oris activity.
Learned behavior (habit): Tongue thrust can be acquired as a habit. The following are some of the predisposing factors that can lead to tongue thrusting:
a. Improper bottle feeding
b. Prolonged thumb sucking
c. Prolonged tonsillar and upper respiratory tract infections
d. Prolonged duration of tenderness of gum or teeth can result in a change in swallowing pattern to avoid pressure on the tender zone
Maturational: Tongue thrust can present as part of a normal childhood behavior that is gradually modified as the age advances. The infantile swallow changes to a mature swallow once the posterior deciduous teeth start erupting. Sometimes the maturation is delayed and thus infantile swallow persists for a longer duration of time.
Mechanical restrictions: The presence of certain conditions such as macroglossia, constricted dental arches and enlarged adenoids predispose to tongue thrust habit.
Neurological disturbance: Neurological disturbances affecting the oro-facial region such as hypo sensitive palate and moderate motor disability can cause tongue thrust habit
Psychogenic factors: Tongue thrust can sometimes occur as a result of forced discontinuation of other habits like thumb sucking.
Classification of tongue thrust
James s. Braner and Holt have classified tongue thrust as follows:
Type I: Non-deforming tongue thrust
Type II: Deforming anterior tongue thrust
- Sub-group 1: Anterior open bite
- Sub-group 2: Anterior proclination
- Sub-group 3: Posterior cross bite
Type III: Deforming lateral tongue thrust
- Sub-group 1: Posterior open bite
- Sub-group 2: Posterior cross bite
- Sub-group 3: Deep overbite
Type IV: Deforming anterior and lateral tongue thrust.
- Sub-group 1: Anterior and posterior open bite
- Sub-group 2: Proclination of anterior teeth
- Sub-group 3: Posterior cross bite.
The term non-deforming in this classification implies that the inter digitation of teeth and the profile are acceptable and within normal range. Deforming tongue thrust is associated with some dento alveolar defect. Tongue thrust can also be classified as simple tongue thrust and complex tongue thrust.
Simple tongue thrust
The following features can be observed:
a. The simple tongue thrust is characterized by a normal tooth contact during the swallowing act.
b. Presence of an anterior open bite.
c. They ehibit good intercuspation of teeth.
d. The tongue is thrust forward during swallowing to help establish an anterior lip seal.
e. Abnormal mentalis muscle activity is seen.
Complex tongue thrust
The following features are seen:
a. This kind of tongue thrust is characterized by a teeth apart swallow.
b. The anterior open bite can be diffuse or absent.
c. Absence of temporal muscle constriction during swallowing.
d. Contraction of the circum-oral muscles during swallowing.
e. The occlusion of teeth may be poor.
The tongue thrust habit can be associated with the following features:
a. Proclination of anterior teeth
h Anterior open bite
c. Bimaxillary protrusion
d. Posterior open bite in case of lateral tongue thrust
e. Posterior cross bite
Management of tongue thrust
The management of tongue thrust involves interception of the habit followed by treatment to correct the malocclusion.
1. The tongue thrust can be intercepted by use of habit breakers as described for thumb sucking. Both fixed and removable cribs or rakes are valuable aids in breaking the habits.
2. The child is taught the correct method of swallowing.
3. Various muscle exercise of the tongue can help in training it to adapt to the new swallowing pattern.
Treatment of malocclusion:
Once the habit is intercepted the malocclusion associated with the tongue thrust is treated using removable or fixed orthodontic appliances.