Your child has been working on the /s/ sound for months, but the lisp persists. They can sometimes make the sound correctly during practice, yet their tongue slips forward again during conversation.
Perhaps a dentist has also mentioned tongue thrust. Or you’ve noticed that your child rests with their mouth open, pushes their tongue against their teeth when swallowing, or seems to have difficulty coordinating certain tongue movements.
Could these patterns be connected?
Tongue thrust and certain speech sound errors can occur together, particularly interdental lisps affecting /s/ and /z/. But tongue thrust does not cause every lisp, and not every child with tongue thrust needs myofunctional therapy.
The important question is whether the child’s speech production, oral resting posture, swallowing patterns, and other functional findings are related in a clinically meaningful way.
At BreatheWorks, our approach begins with listening to the patient and family, understanding what has already been tried, and evaluating the relevant functions before recommending treatment.
What Is Tongue Thrust?
Tongue thrust commonly describes a swallowing pattern in which the tongue moves forward against or between the teeth.
It may occur alongside a forward or interdental tongue resting position, although resting posture and swallowing are separate functions that should be assessed individually.
During an orofacial myofunctional evaluation, a clinician may also investigate:
- Habitual lips-apart or mouth-open resting posture
- Low or forward tongue resting position
- Tongue and jaw movement coordination
- Oral habits
- Chewing and swallowing patterns
- Relevant dental or orthodontic findings
- Breathing patterns and possible airway-related symptoms
These observations help establish the broader functional picture.
A tongue thrust pattern is not automatically abnormal at every age. Its significance depends on development, persistence, and associated functional findings.
What Is a Lisp?
A lisp is a common term for certain distortions of speech sounds, especially /s/ and /z/.
The term describes how a sound is produced. It does not identify the underlying cause.
Interdental or frontal lisp
An interdental lisp occurs when the tongue protrudes between the teeth during production of sounds such as /s/ or /z/.
For example, the word “sun” may have a sound quality resembling “thun.”
This type of distortion can coexist with forward tongue resting posture or tongue thrust swallowing.
Lateral lisp
A lateral lisp occurs when airflow escapes along the sides of the tongue rather than being directed appropriately through the center.
It may create a wet, slushy, or imprecise sound.
A lateral lisp is not the same as a frontal lisp and should not automatically be attributed to tongue thrust.
Other speech sound errors
Some patients with orofacial myofunctional disorders also demonstrate atypical tongue placement during sounds such as /t/, /d/, /n/, /l/, “sh,” or “ch.”
However, many speech sound disorders are unrelated to tongue thrust.
A comprehensive speech assessment is needed to determine the actual error pattern.
Can Tongue Thrust Cause a Lisp?
Tongue thrust and a frontal lisp may be associated, but association does not establish causation.
Both involve tongue movement, yet swallowing and speaking are different motor tasks.
A child may push the tongue forward while swallowing but produce clear speech.
Another child may have an interdental lisp without demonstrating a clinically significant tongue thrust.
A third child may show both patterns.
The clinician’s task is to determine what is actually happening rather than assuming that one symptom explains the other.
Why oral resting posture may matter
Speech movements begin from the position of the oral structures immediately before speaking.
In some patients, persistent forward tongue or mouth-open resting patterns may be relevant to how speech sounds are produced.
For example, a child who habitually rests the tongue between the teeth may also use an anterior tongue placement for /s/.
But changing resting posture alone does not guarantee that speech production will improve.
Speech sound learning requires direct assessment and, when indicated, specific speech treatment.
Why Might a Lisp Persist Despite Speech Therapy?
There are several possible explanations.
The child has not fully learned the target sound
Some children can produce a sound with substantial cueing but have difficulty using it independently.
Therapy may need to address sound production, practice, generalization, and carryover into conversation.
The error pattern has not been fully characterized
A frontal lisp, lateral lisp, phonological error, and motor-planning difficulty require different clinical reasoning.
Accurate identification matters.
The child has difficulty coordinating relevant movements
Some patients demonstrate difficulty separating tongue movement from jaw movement or coordinating the articulators during speech.
This may warrant additional functional assessment.
Oral resting posture or swallowing patterns may also be relevant
If an atypical oral resting posture or tongue thrust pattern coexists with the speech difficulty, a clinician may investigate whether addressing both is appropriate.
This does not mean myofunctional therapy should automatically be added.
Structural or dental factors may influence production
Dental relationships, palatal anatomy, or other structural features may affect how a patient produces particular sounds.
An SLP may coordinate with a dentist, orthodontist, or medical professional when indicated.
Practice and generalization may be the primary issue
Sometimes the child has the necessary movement ability but needs a different practice structure, cueing strategy, or approach to transferring the sound into everyday speech.
A persistent lisp is a reason to reassess the treatment approach—not proof that the child has an undiagnosed OMD.
How Does BreatheWorks Evaluate a Persistent Lisp and Possible Tongue Thrust?
At BreatheWorks, a comprehensive evaluation is designed to understand the patient’s functional difficulties and determine which findings are clinically meaningful.
Our clinicians do not begin by assuming that a lisp requires tongue exercises.
They begin by asking questions, listening carefully, and examining the relevant speech and oral-function patterns.
1. Understanding the patient’s history and goals
A detailed case history helps clarify the concern.
For a child, the clinician may ask:
- When did you first notice the speech sound error?
- Which sounds are difficult?
- Has the child received speech therapy previously?
- What techniques have been tried?
- Can the child produce the sound correctly during structured practice?
- Does the error return during conversation?
- Has a dentist or orthodontist identified tongue thrust or a dental concern?
- Does the child habitually rest with the mouth open?
- Are there concerns about chewing, swallowing, or breathing?
- Does the child snore or experience persistent nasal congestion?
- How does the speech difficulty affect communication, confidence, or participation?
- What are the family’s priorities?
These questions help the clinician understand both the speech difficulty and the broader functional context.
For example, a child who has never established an accurate /s/ sound may need a different approach from a child who can produce /s/ correctly in words but not during spontaneous conversation.
2. Analyzing the actual speech sound errors
The clinician examines how speech sounds are produced.
Depending on the patient’s age and presentation, assessment may include structured speech tasks, connected speech samples, standardized testing, and analysis of error patterns.
The clinician considers:
Sound placement: Where the tongue is positioned during the target sound.
Airflow: Whether airflow is appropriately directed or escapes laterally.
Consistency: Whether the error occurs in isolation, words, sentences, or conversation.
Developmental expectations: Whether the pattern is appropriate for the child’s age and speech development.
Intelligibility and functional impact: How the error affects the child’s communication.
Error classification: Whether the findings suggest an articulation distortion, phonological pattern, motor-planning concern, or another type of speech disorder.
This distinction is essential because different problems require different treatment approaches.
3. Testing stimulability
Stimulability testing investigates whether the patient can produce a target sound more accurately with appropriate cues.
The clinician may provide verbal instructions, visual feedback, or other clinically appropriate support.
For example, a child who produces an interdental /s/ may be guided to change tongue placement and airflow.
The clinician observes whether the sound improves and what level of assistance is needed.
Stimulability provides useful information about treatment planning.
It does not, by itself, establish whether tongue thrust caused the speech error.
4. Observing oral resting posture
When an OMD is suspected, the clinician may observe the natural resting positions of the tongue, lips, and jaw.
Questions include:
- Does the tongue habitually rest forward or between the teeth?
- Are the lips usually together or apart?
- Is comfortable lip closure possible?
- Are there compensatory jaw or facial movements?
- Are the findings developmentally appropriate?
The clinician also considers whether breathing difficulties or structural factors may be influencing the resting pattern.
A child who cannot breathe comfortably through the nose should not simply be instructed to maintain closed-mouth posture.
5. Examining tongue, lip, and jaw movement
When clinically indicated, the clinician evaluates relevant oral movements and coordination.
For example, the examination may investigate whether the child can move the tongue independently of the jaw or whether compensatory movements occur during selected tasks.
The purpose is not to label every unusual movement as weakness.
It is to understand whether the observed pattern is relevant to the child’s speech or other functional concerns.
6. Evaluating swallowing when tongue thrust is suspected
If the history suggests tongue thrust swallowing, the clinician may observe relevant swallowing behaviors.
Depending on the patient’s needs, this may include saliva, liquid, or food swallowing tasks.
The clinician considers tongue placement, lip and jaw participation, compensatory movements, and the consistency of the pattern.
Swallowing observations are interpreted according to age and functional context.
If the patient demonstrates signs of a broader swallowing disorder, a separate comprehensive evaluation may be indicated.
7. Screening breathing and airway-related concerns
A child with persistent mouth-open posture may also have nasal congestion, allergies, enlarged adenoids, or other airway-related concerns.
The clinician may ask about nasal breathing, snoring, restless sleep, and previous medical evaluations.
An SLP can recognize concerning symptoms and make appropriate referrals but cannot diagnose obstructive sleep apnea or structural nasal obstruction through an oral-function assessment.
If medical airway concerns are present, evaluation by a pediatrician, ENT, or sleep specialist may be appropriate.
8. Integrating the findings
The most important step is determining what the findings mean together.
For example:
Scenario A: A lisp without a clinically significant OMD
The child has an interdental /s/ distortion but otherwise demonstrates functional oral resting and swallowing patterns.
Direct speech sound treatment may be the appropriate approach.
Scenario B: A lisp with a persistent orofacial functional pattern
The child demonstrates a speech distortion alongside clinically significant resting-posture or swallowing differences.
An integrated plan addressing the specific speech and orofacial functional goals may be appropriate.
Scenario C: A lisp with suspected airway obstruction
The child demonstrates mouth-open posture and chronic congestion alongside speech errors.
Medical airway assessment may be necessary, while the SLP separately evaluates the speech concern.
Scenario D: A persistent error influenced by dental relationships
The child has a speech distortion alongside an open bite or another relevant dental finding.
Coordination with the orthodontic or dental team may help clarify treatment priorities.
These examples illustrate why an evaluation should not end with a checklist of symptoms.
The clinician must determine which findings are related, which are independent, and which require additional expertise.
Speech Therapy vs. Myofunctional Therapy: What’s the Difference?
Speech therapy for a lisp directly targets accurate speech sound production and the ability to use those sounds in everyday communication.
Orofacial myofunctional therapy addresses selected functional patterns involving oral resting posture, swallowing, and related movements.
The approaches can overlap, but they are not interchangeable.
| Clinical concern | Possible treatment focus |
| Inaccurate /s/ or /z/ production | Direct articulation treatment |
| Difficulty carrying correct sounds into conversation | Speech practice and generalization |
| Clinically significant tongue thrust swallowing | Individualized swallowing-pattern intervention |
| Persistent atypical oral resting posture | Functional assessment and, when indicated, retraining |
| Both speech and relevant OMD findings | Coordinated speech and myofunctional treatment |
| Suspected nasal obstruction | Medical assessment and appropriate treatment |
A child may need speech therapy alone, myofunctional therapy for a separate functional concern, or a coordinated plan addressing both.
The evaluation determines the appropriate approach.
Can Myofunctional Therapy Help Correct a Lisp?
It may have a role for selected patients whose speech sound errors coexist with clinically significant orofacial functional patterns.
However, evidence does not establish that myofunctional exercises alone reliably correct speech sound disorders.
Direct articulation treatment remains important when the clinical goal is accurate speech production.
An appropriately trained SLP may integrate functional work with speech treatment when the findings support that approach.
Progress should be measured using actual speech outcomes—not simply whether the patient can complete an oral exercise.
For example, relevant outcomes may include:
- More accurate /s/ or /z/ production
- Improved production across words and sentences
- Greater accuracy during spontaneous conversation
- Reduced need for clinician cues
- Improved communication participation
- Changes in a separately identified swallowing or resting-posture concern
Each goal should correspond to an identified clinical need.
Why Choose an SLP With Specialized OMD Training?
A speech-language pathologist is trained to evaluate speech sound disorders and differentiate among types of speech production difficulties.
With additional specialized OMD training, an SLP can also assess relevant oral resting-posture and swallowing patterns.
This combination is particularly useful when a child has both a speech sound concern and possible orofacial functional differences.
Instead of assuming that tongue thrust explains a lisp, the clinician can evaluate the speech error directly, investigate related oral functions, and determine whether an integrated approach is justified.
The clinician can also identify when dental, orthodontic, ENT, or other medical collaboration is needed.
Not all SLPs have specialized OMD training, and other appropriately trained professionals may contribute to interdisciplinary care.
The priority is relevant clinical expertise, careful assessment, and treatment based on the patient’s actual needs.
What Can Parents Do if Their Child Has a Persistent Lisp?
Ask what type of speech error is present
Understanding whether the child has a frontal lisp, lateral lisp, or another speech sound disorder can clarify treatment planning.
Ask how progress is being measured
A useful treatment plan should identify specific speech targets and track whether skills are transferring into everyday communication.
Mention other functional concerns
If you’ve noticed tongue thrust swallowing, persistent mouth-open posture, chewing difficulties, or chronic nasal congestion, share those observations.
They may or may not be related to the speech error, but they are worth considering.
Ask whether additional evaluation is appropriate
An SLP can determine whether an OMD assessment, medical referral, or orthodontic collaboration would add useful information.
Avoid assuming exercises are the answer
Tongue strengthening, posture exercises, or nonspeech oral movements are not substitutes for evidence-based articulation treatment.
The appropriate intervention depends on the diagnosis and functional findings.
Frequently Asked Questions
Can tongue thrust cause a lisp?
Tongue thrust and certain lisps can coexist, particularly interdental distortions of /s/ and /z/. Whether the patterns are functionally related requires individualized evaluation.
Will correcting tongue thrust automatically fix a lisp?
No. Speech sound production is a learned motor skill that often requires direct articulation treatment. Changing swallowing or resting posture alone does not guarantee speech improvement.
What sounds are most commonly affected?
Interdental distortions of /s/ and /z/ are commonly discussed in relation to OMDs. Other sounds may be affected by atypical placement, but each error must be evaluated directly.
Can a child have tongue thrust without speech problems?
Yes. Some children demonstrate tongue thrust swallowing or forward resting posture while producing clear speech.
Can a child have a lisp without tongue thrust?
Yes. A lisp can occur without a clinically significant orofacial myofunctional disorder.
Is a lateral lisp caused by tongue thrust?
Not necessarily. Lateral airflow errors and forward tongue thrust are different patterns. An SLP can determine the type of speech distortion and appropriate treatment.
Does my child need both speech therapy and myofunctional therapy?
Not automatically. The need for either or both depends on the speech assessment, oral-function findings, developmental readiness, and treatment goals.
Can tongue-tie cause speech sound errors?
A restrictive lingual frenulum may coexist with speech concerns, but the evidence concerning tongue-tie and speech outcomes is mixed. Functional evaluation is important, and surgery is not automatically indicated.
What if my child has already received speech therapy?
Previous treatment is valuable information. A comprehensive reevaluation can examine the exact error pattern, progress, stimulability, functional carryover, and whether any additional factors warrant assessment.
Understanding the Whole Pattern Leads to Better Treatment Decisions
When a child has a persistent lisp, the answer is not always more of the same therapy—or a completely different therapy.
The answer begins with understanding the speech error and the child who is producing it.
At BreatheWorks, we listen to the family’s concerns, investigate relevant speech and oral-function patterns, interpret the findings together, and recommend an individualized plan.
If your child has a persistent lisp, suspected tongue thrust, or related oral-function concerns, contact BreatheWorks to discuss whether a comprehensive speech and orofacial myofunctional evaluation may be appropriate.
This article is educational and does not replace individualized assessment, diagnosis, or treatment.
