Lisp With Braces, Aligners or a Retainer: What Research Shows

✓ Reviewed against ASHA Practice Portal: Orofacial Myofunctional Disorders, European Journal of Orthodontics systematic reviews (2018, 2023), The Angle Orthodontist clinical studiesEvidence level BLast reviewed October 23, 2026Published October 23, 2026

A lisp with braces is common and usually temporary. Braces, clear aligners, retainers and expanders can all change S and Z. Most aligner wearers adjust in 7–14 days, and most people with outside braces adjust within 2 months. S can take longer, especially with lingual braces. The evidence is limited.

The short answer: common, and usually temporary

Yes, a lisp with braces is common. A systematic review of 13 studies with 297 patients found that fixed braces, retainers and palatal expanders could all change how clearly people speak. S and Z were among the sounds affected, along with L, T, D, R, SH and some vowels.³

Clear aligners are no exception. A separate review of 7 studies with 332 patients found aligners affected S, Z, SH, ZH, TH and CH, and some of those studies reported lisping.¹

For most people, the change fades as the tongue gets used to the appliance. In the aligner review, most patients were back to normal within 7–14 days. In a study of outside (labial) braces, 44% of patients had no speech change at all, and most of the rest adapted within 2 months.^1,4

The exception is S, which often takes the longest. The appliance review found most speech changes resolved within weeks, but S distortion could last more than 3 months. Both reviews rated the evidence as low quality, pointing to weaknesses in how the studies were designed and big differences between them. Treat every timeline on this page as a rough range, not a promise.^3,1

What research shows for each type of appliance

Not all appliances affect speech equally. The appliance review named three with the clearest effect: lingual braces, palatal expanders and Hawley (wire-and-acrylic) retainers. The sounds most often affected were S, T, D and the “ee” vowel.³

Speech changes by appliance type, from small studies with low-quality evidence overall.
Appliance	What studies found	Typical settling-in time	Strength of evidence
Clear aligners (e.g., Invisalign)	S, Z, SH, ZH, TH and CH affected; with trays in, Z was affected most, then S	Most people 7–14 days; a few 30–60 days	Low (review of 7 studies)
Outside (labial) fixed braces	44% unaffected; 39% adapted within 2 months; 17% still had errors at 2 months; S affected most often	Most within 2 months; all errors resolved by 8 months after removal	One small study (23 patients)
Lingual (behind-the-teeth) braces	Among the clearest effects; S measurably worse	Up to 1 month with one bracket type; still affected at the 3-month check with the other	One randomized trial (46 adults)
Retainers (Hawley and clear)	Both types distorted S; larger changes with Hawley	Most sounds within about a week; S lasted a month or more for a few Hawley wearers	One small trial (20 adults) plus review
Palatal expander	Speech acceptability dropped when it was fitted	Improved over time; back to baseline after removal	One prospective study (22 patients aged 9–19)

Speech changes by appliance type, from small studies with low-quality evidence overall.^{1,7,4,8,3,5,9}

Clear aligners and Invisalign

In a study of 30 people in Invisalign treatment, each person read a standard passage twice: once with the trays in and once with them out. A speech-language pathologist rated the recordings. Consonant errors were significantly linked to having the trays in. Z was affected most, then S, while SH was not significantly affected.⁷

The authors also noted that speech changes might affect how consistently people wear their trays. Questions about taking trays out to talk belong with your orthodontist.⁷

Lingual braces

Lingual braces are attached to the inside of the teeth. In a randomized trial, 46 adults received one of two lingual bracket types. With one type, S was measurably worse for up to 1 month. With the other, it was still significantly worse at 3 months.⁸

A commentary on the aligner evidence also reported that lingual braces caused more speech difficulty than either outside braces or aligners.²

Retainers and palatal expanders

A randomized trial followed 20 adults who had just finished braces. Both Hawley and clear vacuum-formed retainers distorted S, with larger changes from Hawley retainers, so a clear retainer is no guarantee that your speech won’t change. A small study of 12 adolescents also found speech changes after they started wearing Hawley retainers.^5,6

With a palatal expander, speech acceptability dropped when it was fitted, improved over time, and returned to baseline once it was removed.⁹

How long does a lisp from braces last?

It depends on the appliance and on you. The studies give these rough ranges. Aligners: most people adjust in 7–14 days, and a few take 30–60 days. Outside braces: most people are unaffected or adapt within 2 months. Lingual braces: in one trial, S was affected for up to 1 month with one bracket type and was still affected at the 3-month check with the other. S is often the slowest sound to recover and can sometimes take more than 3 months.^1,4,8,3

After braces come off

If your braces are off and your S still sounds different, one study gives a reference point. In that outside-braces study, all the speech errors that appeared during treatment had resolved by 8 months after removal. People who had more trouble adapting tended to have more severe bite problems, so wearing braces wasn’t the only factor.⁴

Are aligners better than braces for speech?

The research doesn’t agree yet. The aligner review concluded that aligners affect speech in much the same way as fixed braces. A commentary on that evidence noted that lingual braces caused more difficulty than both outside braces and aligners. A short 2026 report found fewer articulation errors with aligners than with braces: 1.2 versus 3.5 errors per 50 words. That report is weak evidence because its methods weren’t fully described. Which appliance to choose is a decision for you and your orthodontist.^1,2,10

No study we found compared teens with adults, so it isn’t known whether either group adapts faster. The retainer and lingual-braces trials were in adults, one Hawley retainer study was in 12 adolescents aged about 12 to 18, and the expander study included patients aged 9 to 19.^5,8,6,9

Practice that may help your tongue adapt

Researchers describe the tongue changing its target position when an appliance goes in, then adapting to it over time. In aligner studies, people slowed down when reading aloud so they could pronounce words more clearly.^6,2

No trial we found has tested specific exercises for adapting to braces, aligners or retainers. The research in this area is limited and low in quality. The ideas below are low-risk and reasonable, but they are not proven.^1,3

Read aloud for a few minutes a day, wearing your appliance as your orthodontist has told you to.
Speak a little more slowly than usual while your tongue adjusts.
Practice words and sentences full of S and Z, such as “sixty-six sunny seats” and “zebras zigzag.”
Record yourself once a week and listen back, so you can hear progress you might not notice day to day.
Keep sessions short and relaxed. Straining doesn’t help.

If you’d like a starting point before you begin practicing, try the quick listening check below.

Free Lisp Test

A quick listening check of your S sound that can help you decide whether to talk to a speech-language pathologist. It is a preliminary screen, not a diagnosis, and it can’t tell whether a change comes from braces.

Try it free →

A lisp you had before braces is a different thing

If your S sounded like “th” long before you got braces, the appliance didn’t cause it, and we found no research showing that braces alone fix it. ASHA describes a distorted S and Z, often an interdental (tongue-between-the-teeth) lisp, as one possible sign of an orofacial myofunctional disorder. These disorders involve how the tongue and mouth muscles work. ASHA also links them with bite differences such as open bite, a large overjet and underbite.¹¹

Bite matters for appliance-related changes too. In the outside-braces study, lasting difficulty was linked to how severe the bite problem was.⁴

A long-standing lisp is worth having assessed by a licensed speech-language pathologist, who can look at speech and tongue habits together. Your orthodontist looks after your teeth and bite.¹¹

When to ask your orthodontist, and when to see an SLP

Ask your orthodontist about the appliance

The appliance feels like it’s in the way of your tongue.
Something rubs, feels loose or doesn’t seem to fit.
You have questions about wear time, or about taking trays or a retainer out to talk.
You have questions about which appliance or retainer is right for you.

See a speech-language pathologist about your speech

The S change lasts longer than the usual range for your appliance.
It continues after your braces, aligners or retainer come off.
You had a lisp before treatment started.
Your S sounds wet or slushy, or seems to come from far back in your mouth.
It bothers you at school, at work or with friends, at any point.

🩺

If any of the speech points above apply to you, the next step is a licensed speech-language pathologist (SLP). An SLP can assess your speech and help you work out whether the change is linked to your appliance. You can start at /find-support. No app, including SpeechStep, can tell you whether a lisp comes from braces.

Start daily practice at home — free

Guided practice runs in your browser with a free parent account. SpeechStep is practice, not therapy: if your child may need a therapist, your country’s register of licensed professionals is the place to start.

Start free practice →Where to find a licensed therapist

Frequently asked questions

Is it normal to get a lisp with braces?＋

Yes, it’s common. Studies show that fixed braces, clear aligners, retainers and palatal expanders can all change how S and Z sound. It doesn’t happen to everyone: in one study of outside braces, 44% of patients had no speech change at all.

How long does a lisp from braces last?＋

It depends on the appliance. Most aligner wearers adjust within 7–14 days, and most people with outside braces are unaffected or adapt within 2 months. In one trial of lingual braces, S was affected for up to 1 month with one bracket type and was still affected at the 3-month check with the other. These figures come from small, low-quality studies, so they are rough ranges, not promises.

Does Invisalign cause a lisp?＋

It can. In one study, consonant errors were linked to having the trays in, and Z and S were the most affected sounds. A review found most aligner wearers were back to normal within 7–14 days, while a few took 30–60 days.

Do retainers cause a lisp?＋

Both Hawley (wire-and-acrylic) and clear vacuum-formed retainers can change S. In one trial, the changes were larger with Hawley retainers. Which retainer you wear, and how long you wear it each day, is a question for your orthodontist.

Are lingual braces worse for speech?＋

On the limited evidence available, they seem to be. A commentary on the research found lingual braces caused more speech difficulty than outside braces or aligners. In one randomized trial, S was still affected at the 3-month check with one type of lingual bracket.

My braces are off but my S still sounds off. Is that normal?＋

In one study of outside braces, all speech errors that appeared during treatment had resolved by 8 months after the braces came off. If the change lasts longer than that, or it’s getting in the way of school, work or social life, see a licensed speech-language pathologist.

I had a lisp before braces. Will braces fix it?＋

We found no research showing that braces alone fix a lisp that was already there. ASHA links an interdental lisp with how the tongue and mouth muscles work, not just with the bite. A licensed speech-language pathologist is the right person to assess it.

Can an app tell me if my lisp is from braces?＋

No. SpeechStep’s listening check is a preliminary screen only. It doesn’t diagnose, it doesn’t name a lisp type, and it can’t tell whether a change comes from an appliance. A licensed speech-language pathologist can assess what’s going on.