The Lisp, The Tongue Thrust and their Subsequent Dental Problems

The lisp is a speech disorder known amongst, well, just about everybody. Everyone has heard someone with a lisp, and plenty have had a lisp of their own which diminished with age. What some people don't know is that their are two different types of lisps: "interdental" and "bilateral".

Interdental lisps are most commonly occurring. Sylvester suffers from an interdental lisp. While making an "S" sound, Sylvester pushes his tongue through his front teeth, create a "th" sound where a "s" sound should be.

Then, there's the bilateral lisp; a little less common. This occurs when air is pushed through the sides of the mouth because the tongue lies flat when it should be curling during pronunciation of the "s". Think about Sid the Sloth from Ice Age when you're picturing a bilateral lisp. Cartoon characters never catch a break. These two can't even get their names right. 

Oh Sid. You're the reason everyone suddenly loves sloths. But there you have it. There are actually two different types of lisps, in case you didn't already know. Both treatable at the Suffolk Center for Speech. 

The Tongue Thrust, also known as a "reverse swallow," is very common in young, school aged children. Babies use this "reverse swallow" at birth in order to protect their airway. But, as a child grows, they develop a better pattern, and the tongue thrust action should cease. For those whose tongue thrust does not cease, there can be a few well-regarded contributing factors. Developmental delays, hereditary factors, premature loss of teeth, thumb sucking, respiratory difficulties, and even prolonged bottle feeding are all possible causes of the tongue thrust problem. 

To help you visualize the tongue thrust, you can compare the normal swallow to the deviant swallow of a "tongue thruster". 

During a normal swallow:

• teeth and lips are sealed, relaxed and firm
• the tongue tip presses up against the top teeth
• the anterior of the tongue slopes downward to push food into the throat
• a negative inter-oral pressure forces the tongue into a wave like motion

During a deviant swallow:

• sides of the tongue press against the inside of the front teeth
• the front of the tongue pushes upward and the tip of the tongue thrusts forward, sometimes through the teeth and lips
• the lips are pursed, the jaw is open
• food is pushed back with a "positive pressure"

The Dental Problems

The continual thrusting movement against the front teeth causes a Class II Malocclusion: an overbite. Orthodontists give children with these overbites a set of braces with an anterior cage. Significant spacing between the front teeth is another problem often ensued by the tongue thrust. 

Why Speech Therapy?

Research into the tongue thrust problem suggests that it results in a lisp with secondary orthodontic features. Braces cannot cure the problem without "myofunctional therapy". The lisp also requires "myofunctional therapy" for remediation. 

Children who present these problems often see speech therapists in school, or privately. Therapy consists of a combination of strengthening the tongue, repositioning it, and practice with producing the correct "s" sound. An orthodontist and speech therapist paired will confer on an appropriate time to fit braces and start therapy. Children who still bare intrusion of the tooth fairy every so often may not be ready for this. But, some children who are still losing teeth get the therapy anyways because of poor speech intelligibility in the classroom.  Lisps and the tongue thrust problem should not be ignored based on the importance of applying good dental health (braces, a retainer, etc.). Most often, these treatments alone will not fix the underlying tongue thrust problem, and so myofunctional therapy is crucial for young tongue thrusters. If you suspect your child is a tongue thruster or is exhibiting a lisp, and likewise if you are a teacher and suspect this of a child, bring the child to a speech therapist or fill out a speech referral form.

Resources

Merket-Piccini, Robyn, M.A. CCC-SLP. Super Duper Handy Handouts (2001):  Tongue Thrust, Dental Problems and Lisps: A perfect combin