Sometimes. Not always, and not in the way people assume — but yes, where your teeth sit is one of the things your speech depends on, and certain bite problems make certain sounds harder to produce cleanly.
How teeth are involved in speech
Speech sounds are shaped by the tongue, lips, teeth and the roof of the mouth working together, quickly and precisely. A surprising number of English sounds depend on the teeth directly:
- S and Z — the tongue sits just behind the upper front teeth and pushes air through a narrow gap. Any change to that gap changes the sound.
- Th — the tongue tip rests against the edge of the upper front teeth.
- F and V — the lower lip meets the upper front teeth.
- T, D, N and L — the tongue tip touches the ridge just behind the upper front teeth.
When the teeth or jaws are somewhere other than where the tongue and lips expect them to be, the mouth compensates. Often that compensation is invisible. Sometimes it isn’t.
The bite problems most likely to affect speech
Not every crooked tooth matters here. Mild crowding of the lower front teeth, for instance, rarely changes how anyone speaks. The patterns that come up most often are these:
An open bite. If the front teeth don’t meet when the back teeth are together, air escapes through the gap during S and Z, and the tongue tends to push forward into it. A lisp is the classic result. Open bites and tongue-thrust habits often go together, each reinforcing the other.
A large overjet. When the upper front teeth sit well ahead of the lower ones, the lower lip has to travel further to reach them for F and V, and S can pick up a whistle.
Gaps between the front teeth. Spacing lets air escape sideways, which can make S sound slushy or whistly.
An underbite or crossbite. With the lower jaw or teeth sitting ahead of the upper, the tongue and lower lip have less room to meet the upper teeth cleanly, so F, V, S and Th can all be affected.
A narrow or very high palate. The tongue has less room to rest against the roof of the mouth, which can affect the sounds made there. This one is often paired with mouth breathing.
Each of these bites is described on our common orthodontic issues page, with real cases we’ve treated.
Will braces fix it?
This is the honest part. Orthodontic treatment corrects the structure: it closes the open bite, reduces the overjet, closes the gaps. If the structure was what got in the tongue’s way, speech often improves as the teeth move, sometimes noticeably.
But speech is also a habit. A child who has been making an S with the tongue pushed forward for years has learned that movement, and moving the teeth doesn’t automatically unlearn it. That is what speech-language pathologists do, and where a lisp or tongue thrust is part of the picture we’ll often suggest seeing one — before, during or after treatment, depending on what makes sense. The two work best together: the orthodontist gives the tongue somewhere to go, and the therapist teaches it to go there.
The reverse is also true. A tongue thrust that is never addressed can push an open bite back open after the braces come off. That is one reason we ask about it at the first visit.
A temporary lisp from the appliance itself
Braces, expanders and aligners all take up room in the mouth, and a lisp for the first few days is normal — a palatal expander in particular, because it sits exactly where the tongue makes S and T. Reading aloud speeds up the adjustment, and for most people it has faded within a week or two. It isn’t a sign that anything is wrong.
For parents: what to watch for
Some speech sounds arrive late in normal development, and a lisp in a four-year-old is not a reason to see an orthodontist. But by seven or eight most sounds should be in place, and if a lisp persists alongside an open bite, a thumb-sucking habit, or a tongue that shows between the teeth at rest, it is worth having both a speech evaluation and an orthodontic check-up. That is around the age we would want to see a child anyway — see when should my child first see an orthodontist — and it is the window in which early treatment can guide growth rather than correct it later.
For adults
Adults ask this too, often after years of steering around certain words. The structural side is just as treatable at any age, with braces or clear aligners. What differs is that the habit has had longer to settle in, so a speech therapist is more likely to be part of the plan. It is not too late for either.
If you or your child have a speech difficulty and a bite problem, an orthodontic evaluation is a sensible place to start. Call (212) 966-9628 or request an appointment. We speak English, Mandarin and Cantonese.