Examqo › Examqo library › Speech-language pathology and audiology › Speech sounds
Sibilant distortions (lisps), dental occlusion, tongue thrust and tongue-tie
An interdental lisp is a phonetic distortion that can be developmental at a young age, but a lateral lisp is never developmental and is treated at once; malocclusion, tongue thrust and tongue-tie are structural and functional factors that may affect articulation, and they are sometimes treated together with an orthodontist.
Why it matters in the exam
Questions present a child of a given age with a sibilant distortion and ask whether to treat: a 6-year-old with a lateral /s/ — start treatment right away; a 13-year-old with an interdental lisp — treatment is recommended, especially if the distortion affects daily life or dental occlusion. You are also asked what the main component of an interdental /s/ and /z/ is (phonetic, that is motor-articulatory), and what is not appropriate when assessing an interdental lisp — for example analysing complex sentences before checking the sound.
The second part concerns structure and function: in Class II occlusion the upper jaw protrudes over the lower, and in Class III the lower jaw protrudes, with possible articulation difficulty; tongue thrust is linked to nasal obstruction and mouth breathing, and shows as atypical tongue posture and movement at rest and in swallowing; and tongue-tie mainly affects sounds that need tongue-tip elevation, such as a lateral consonant (/l/).
Key points
- Interdental lisp — can be developmental; lateral — treat at once.
- Interdental = phonetic distortion.
- Class II: upper jaw protrudes; Class III: lower jaw protrudes.
- Tongue thrust: linked to mouth breathing and nasal obstruction.
- Tongue-tie: difficulty lifting the tongue tip, mainly on /l/.
Summary table
| Condition | What is seen | What is done |
|---|---|---|
| Interdental (frontal) lisp | The tongue comes between the teeth on /s/ and /z/; a phonetic distortion | Can be developmental in the preschool years; if it persists — treatment, especially when it affects function or occlusion |
| Lateral lisp | Air escapes over the sides of the tongue; a "wet" sound | Never developmental — treat at once, at any age |
| Class II occlusion | The upper jaw protrudes over the lower | Orthodontic assessment; articulation therapy as needed |
| Class III occlusion | The lower jaw protrudes | May cause articulation difficulty; work with an orthodontist |
| Tongue thrust | Atypical tongue posture and movement at rest and in swallowing; linked to mouth breathing | Assess the nasal airway; myofunctional therapy with an orthodontist |
| Tongue-tie | Limited tongue-tip elevation | Difficulty mainly with the lateral /l/; medical assessment by function |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- What matters for the exam
The full version is open to subscribers of: Speech and hearing (communication disorders).
Subscriber? Read the full topic Plans and prices 25 free questions
Sources
- ASHA Practice Portal, 2024 — Orofacial Myofunctional Disorders
- Bauman-Waengler, Articulation and Phonology in Speech Sound Disorders, 6th edition (2020) — Structural and functional factors: occlusion, tongue thrust and sibilant distortions
- Bleile, Manual of Speech Sound Disorders, 3rd edition (2015) — Lisps and their treatment
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.