Tongue thrust, also known as reverse swallow or immature swallow, describes an oral motor pattern where the tongue presses forward during swallowing. This forward movement places pressure against the lips or teeth, distinguishing it from the mature swallowing pattern seen in older children and adults. Understanding this pattern helps determine when a natural infant reflex becomes an ongoing concern requiring professional attention.
Defining the Reflex and Movement
Tongue thrust is the functional term for the movement where the tongue protrudes forward or pushes against the front teeth during swallowing. In a typical mature swallow, the tip of the tongue elevates and rests against the palate, specifically the alveolar ridge (the firm area just behind the upper front teeth). This action creates suction that helps move food or liquid toward the throat.
The immature swallow, by contrast, is characterized by a piston-like action of the tongue, pushing forward to form a seal with the lower lip. This mechanism is necessary for an infant to effectively draw milk from a breast or bottle nipple. During this reverse swallow, the tongue exerts a significant outward force, estimated at approximately 1.8 kilograms of pressure with each swallow.
The crucial difference lies in the direction of the force and the point of contact. The mature pattern directs force upward and backward against the roof of the mouth, while the immature pattern directs force forward and outward against the front oral structures. This forward positioning is an orofacial myofunctional pattern observed during swallowing, speaking, or when the mouth is at rest.
Distinguishing Normal Infant Reflex from Persistent Thrust
All babies are born with the tongue thrust, or extrusion, reflex, which is a protective and functional mechanism. This reflex causes the tongue to push outward when the front of the mouth is touched. This action is necessary for extracting milk and simultaneously helps prevent choking on foreign objects. This reflex is a normal and expected part of infant development during the first several months of life.
The reflex usually begins to fade and transition to a more mature swallowing pattern between four and seven months of age. This developmental shift coincides with the introduction of solid foods, as the baby develops the coordination to move food from the front of the mouth to the back for swallowing. When the forward tongue movement continues past this natural period, it becomes known as a persistent tongue thrust, or an orofacial myofunctional disorder.
Persistence of the pattern may stem from several underlying factors that interfere with the development of a mature swallow. One common cause is a chronic open-mouth posture, often due to impaired nasal breathing from conditions like chronic allergies or enlarged tonsils or adenoids. When a child breathes through their mouth, the tongue is often positioned low and forward to maintain an open airway, reinforcing the forward-thrusting habit. Other contributing factors include prolonged non-nutritive sucking habits, such as extended pacifier or thumb use, and structural issues like a short lingual frenulum (tongue-tie).
Identifying Signs and Impact on Feeding
When tongue thrust persists beyond the typical infant stage, observable signs become apparent during functional activities like eating and speaking. During the introduction of solids, a persistent thrust may manifest as difficulty keeping food in the mouth, with the tongue pushing purees or small pieces of food back out. This often results in messy eating and a struggle to transition from a bottle or breast to a cup and spoon.
The persistent outward pressure of the tongue can have a direct physical impact on developing dentition and facial structures. Over time, the force exerted can push the teeth out of alignment, leading to a dental condition called malocclusion. A common result is an anterior open bite, where the upper and lower front teeth do not meet when the jaw is closed.
The pattern also significantly affects speech development, particularly the production of certain sounds. The tongue’s forward placement interferes with the precise movements required for sibilants, such as the “s” and “z” sounds. This interference often results in a lisp, where the tongue is visible between the front teeth during speech. Additionally, a child with a persistent thrust may exhibit excessive drooling or an open-mouth rest posture where the tongue rests visibly between the lips or teeth.
Therapeutic Approaches for Correction
Once a persistent tongue thrust is identified, professional intervention is typically recommended to correct the swallowing pattern and mitigate long-term issues. The primary professional addressing this condition is a speech-language pathologist (SLP) or a specialized oral myofunctional therapist. These professionals assess the underlying causes and develop a targeted treatment plan.
The most common approach to correction is orofacial myofunctional therapy (OMT), which involves a series of exercises designed to re-educate the oral and facial muscles. The therapy focuses on strengthening the tongue and teaching it the proper resting position (high against the palate) and the correct swallowing motion. These exercises are typically performed daily and aim to establish a mature swallowing pattern.
Early consultation is important because the habit can become more entrenched the longer it persists. Treatment may involve a multidisciplinary team, including an orthodontist. Orthodontists may use dental appliances to correct tooth alignment or create a physical reminder for the tongue to stay in the correct position. The goal of therapy is to establish correct muscle memory, supporting proper dental development and clear speech production.