Lisp vs. Tongue Thrust: What’s the Difference?
The terms "lisp" and "tongue thrust" are often used to describe the same thing, but they are actually different conditions. Understanding the distinction between them—and knowing when professional help is needed—can make all the difference in your child’s speech and dental development.
What is a Lisp?
A lisp is a speech disorder in which a person mispronounces the letters "s" and "z," generally replacing them with a "th" sound. Instead of saying "please," a person with a lisp would pronounce it as "pleathe."
Many children have a lisp up to around age 4½ as they develop their vocabulary and learn how to speak properly. There are four different types of lisps:
Frontal/Interdental Lisp
The tongue pushes through the teeth, creating the "th" sound when trying to pronounce words with "s" and "z."
Dentalized Lisp
The tongue doesn’t push through the teeth, but it touches or pushes against the back of the front teeth.
Bilateral Lisp
When pronouncing the letter "s," both sides of the tongue should curl up. In this type, both sides remain flat, allowing air to escape from the corners of the mouth, producing a slurred or slushy sound.
Palatal Lisp
The mid-section of the tongue pushes against the roof of the mouth, towards the back.
What is Tongue Thrust?
A tongue thrust, also called a reverse swallow, occurs when a person pushes food toward their gums or front teeth when swallowing.
All babies are born with a tongue thrust—it’s how infants eat. However, children generally learn to swallow with their lips closed and learn to use their tongues to move food back toward their throats by age 7. If this pattern persists past age 4, it’s considered a parafunctional habit.
Causes of Lisps
Several factors can cause lisps:
- Overbites or underbites
- Missing front teeth
- Wearing dental appliances
- Thumb or finger sucking
- Tongue thrusts
Another common cause of interdental or dentalized lisps is tongue thrust. If your child has a lisp, they may also have a tongue thrust.
How to Know if Your Child Has a Tongue Thrust
In normal swallowing, the teeth and lips are sealed, and the tip of the tongue presses against the top teeth. The tongue moves food toward the throat in a wave-like motion.
When a tongue thrust is present, the sides of the tongue push against the front teeth. The jaw is typically open, even if the lips aren’t. The front part of the tongue moves forward in a thrusting motion against or through the teeth, sometimes even through the lips, pushing food back toward the front of the mouth.
Treatment Options
While lisps can generally be treated with speech therapy, tongue thrusts require both dental treatment and speech therapy.
Braces are a common part of the treatment, especially if the lisp or tongue thrust is a result of an over- or underbite. An orthodontist can evaluate your child’s specific situation and recommend the best approach.
When to Seek Help
If you believe your child has a lisp or tongue thrust, talk with an expert dentist to help choose the best treatment. Early intervention can prevent more serious dental and speech issues from developing.
At Greenspoint Dental, we’re dedicated to helping your children achieve healthy, properly aligned smiles. If you have concerns about your child’s speech or dental development, schedule a consultation with us today.