Common Oral Habits That Can Affect a Child’s Development: What Parents Should Watch For

Estimated Reading Time: 8–10 minutes

Thumb sucking.

Pacifiers.

Chewing on shirt collars.

Biting fingernails.

Sleeping with the mouth open.

Parents notice all kinds of habits as their children grow—and inevitably wonder:

Is this something I should be worried about?

Usually, the answer isn't as simple as "good habit" or "bad habit."

Many oral habits are completely understandable during childhood. Some are developmentally normal. Some provide comfort or help a child regulate. Some disappear on their own.

What matters is often what the habit is, how frequently it happens, how intensely it occurs, and how long it continues.

Because when certain patterns persist, they can sometimes begin to influence how the muscles of the mouth and face function.

So rather than making parents feel guilty about every pacifier, thumb, or chewed-up pencil they see, let's talk about what is actually worth watching.

First: Habits Aren't Automatically Problems

This is important.

Babies suck.

Toddlers use pacifiers.

Children chew things.

People bite their nails.

And occasionally sleeping with an open mouth because of a cold is very different from chronically mouth breathing every day and night.

The presence of a habit alone doesn't tell us whether intervention is needed.

When I evaluate an oral habit, I'm interested in the bigger picture:

How often is it happening?

How long has it been happening?

How much force is involved?

What does the child's mouth look like at rest?

How are they breathing?

How are they swallowing?

Is the habit affecting function—or does it appear to be contributing to changes in the mouth or bite?

Context matters.

Let's look at some of the habits parents ask about most often.

1. Thumb and Finger Sucking

Thumb and finger sucking can be incredibly comforting to young children.

And in early childhood, that's not unusual.

The question becomes more important when the habit persists as a child gets older, particularly when sucking is frequent or prolonged.

Why?

Because the thumb or finger isn't just sitting in the mouth.

Repeated sucking can create pressure against the teeth and surrounding oral structures. Over time, persistent habits may contribute to changes in dental alignment or the bite.

It can also influence how the tongue learns to rest and function.

What parents can watch for

Notice whether your child:

• Sucks their thumb or fingers throughout the day

• Uses sucking to fall asleep every night

• Keeps the finger in the mouth for long periods

• Is beginning to show changes in tooth position

• Has difficulty stopping despite wanting to

• Also shows tongue-thrust or open-mouth resting patterns

The goal shouldn't be to shame a child.

These habits often have a strong soothing or emotional component.

Understanding why the habit is happening can be just as important as stopping the habit itself.

2. Pacifier Use

Pacifiers can be useful tools for babies and young children.

So this isn't an anti-pacifier article.

What matters is how long and how frequently they're being used.

Occasional use and prolonged daily sucking aren't necessarily the same thing.

As pacifier use continues, especially for extended periods as a child gets older, parents and dental providers may begin paying closer attention to dental development, bite relationships, tongue position, and oral function.

A practical question to ask

Instead of only asking:

"Does my child still use a pacifier?"

Ask:

"How much time each day is the pacifier actually in their mouth?"

A child who occasionally reaches for one at bedtime has a different pattern than a child who keeps one in their mouth throughout much of the day.

Frequency and duration matter.

3. Mouth Breathing

This one is different from many of the other habits on this list.

Why?

Because mouth breathing may not simply be a habit.

If your child can't comfortably breathe through their nose, telling them to close their mouth isn't the answer.

Persistent mouth breathing can occur for many reasons, including congestion, allergies, enlarged tonsils or adenoids, structural factors, and other airway concerns.

Sometimes, however, an open-mouth breathing pattern can continue even after the original obstruction or congestion has improved.

That's why we need to distinguish between:

"My child won't close their mouth."

and

"My child can't comfortably keep their mouth closed while breathing."

Those are very different situations.

Look beyond daytime breathing

Parents should also notice what happens during sleep.

Does your child:

• Sleep with their mouth open?

• Snore regularly?

• Drool?

• Sleep restlessly?

• Wake with a dry mouth?

• Seem congested frequently?

Persistent mouth breathing—especially when paired with sleep concerns—is something worth discussing with an appropriate healthcare provider.

4. Nail Biting

Nail biting is extremely common.

For many children—and plenty of adults—it happens during concentration, boredom, stress, or anxiety.

Occasional nail biting doesn't automatically mean there is a myofunctional problem.

But frequent or aggressive biting can place repeated stress on the teeth and jaw, irritate the skin around the nails, and become a deeply ingrained oral behavior.

I'm particularly interested when nail biting appears alongside other oral habits or functional patterns.

For example, a child may bite their nails, chew clothing, constantly put objects in their mouth, and show unusual oral resting posture.

At that point, we're no longer looking at one isolated behavior.

We're looking at a pattern.

5. Chewing on Clothing, Pencils, or Other Objects

Does your child constantly chew on:

• Shirt collars

• Sleeves

• Hoodie strings

• Pencils

• Toys

• Water bottle straws

• Other objects?

Parents sometimes feel embarrassed by this.

Don't.

The behavior can occur for many different reasons, including sensory seeking, self-regulation, concentration, or simply habit.

Chewing itself doesn't tell us the cause.

And Myofunctional Therapy isn't automatically the solution.

But persistent chewing can be useful information when we're evaluating the whole oral-function picture.

I want to know what else is happening.

How does the tongue rest?

Are the lips comfortably closed?

How does the child breathe?

How do they swallow?

Are there other repetitive oral behaviors?

The combination tells us much more than the chewing alone.

6. Lip Biting or Lip Sucking

Some children repeatedly pull a lip between their teeth, suck on it, or bite it.

Again, occasional behavior isn't usually the issue.

It's persistence that catches our attention.

Repeated pressure from the lips can interact with tooth position and oral muscle patterns, particularly when the behavior becomes a child's normal resting habit.

Parents may notice:

• A lower lip frequently tucked behind the upper teeth

• Dry or irritated lips

• Repetitive sucking

• Teeth marks on the lips

• The habit increasing when the child is concentrating or tired

Sometimes children don't even realize they're doing it.

7. Tongue Thrust

Tongue thrust is a little different because parents may not notice it as easily.

During a typical mature swallow, the tongue works in a coordinated pattern inside the mouth.

With a tongue-thrust pattern, the tongue may push forward or between the teeth during swallowing or other oral movements.

Parents sometimes notice the tongue appearing between the front teeth when their child swallows.

Other times, a dentist, orthodontist, speech-language pathologist, or Myofunctional Therapist is the first person to identify it.

A persistent tongue-thrust pattern may be relevant to:

• Swallowing function

• Dental alignment

• Orthodontic stability

• Oral resting posture

• Speech in some individuals

This is one reason Myofunctional Therapy and orthodontics often intersect.

Moving teeth is one thing.

Understanding the muscular patterns surrounding those teeth can be another important part of the picture.

The Habit Parents Rarely Think About: Where Is the Tongue at Rest?

Here's a quick experiment.

Stop reading for a second and notice your own tongue.

Where is it right now?

Most of us don't think about our tongue unless we're eating, speaking, or accidentally biting it.

But your tongue spends far more time resting than it spends doing any of those things.

Generally, when anatomy and the airway allow, we want to see a comfortable oral resting posture with the tongue resting appropriately toward the roof of the mouth, the lips relaxed together, and breathing occurring through the nose.

When the tongue habitually rests low or forward, that can be part of a larger myofunctional pattern.

And unlike thumb sucking or nail biting, parents may never realize it's happening.

There isn't anything obvious to take away.

No pacifier to find.

No fingernails to inspect.

It's simply the body's default position.

That's why resting posture matters.

Why Do Persistent Habits Matter?

Think about how children learn any physical skill.

They repeat it.

Again.

And again.

And again.

Eventually, the movement becomes automatic.

Oral patterns work the same way.

The muscles involved in breathing, chewing, swallowing, speaking, and maintaining oral posture perform thousands of movements every day.

When a particular pattern is repeated over a long period of time, the body becomes very good at performing that pattern.

That's why simply telling a child:

"Stop doing that."

isn't always enough.

Sometimes the behavior needs to be addressed.

Sometimes the underlying function needs to be addressed.

And sometimes both do.

Does Every Oral Habit Need Myofunctional Therapy?

No.

And that's an important distinction.

Some habits resolve naturally.

Some are better addressed through a pediatrician, dentist, orthodontist, ENT, occupational therapist, speech-language pathologist, mental-health professional, or another provider.

Some require no intervention at all.

Myofunctional Therapy becomes particularly relevant when a habit is associated with dysfunctional patterns involving things such as:

• Tongue resting posture

• Lip closure

• Swallowing

• Tongue thrust

• Oral muscle coordination

• Nasal-breathing habits when medically appropriate

The first goal of an evaluation isn't to find a reason to start therapy.

It's to understand what's actually happening.

Why "Just Stop" Often Doesn't Work

Parents hear this all the time.

"Just take the pacifier away."

"Tell them to stop sucking their thumb."

"Keep reminding them to close their mouth."

Sometimes a straightforward behavior change works beautifully.

Other times, it doesn't.

A child may rely on a habit for comfort or regulation.

They may perform it without realizing it.

Or there may be a functional reason behind what you're seeing.

Mouth breathing is the clearest example.

If a child is struggling to breathe comfortably through their nose, repeatedly reminding them to close their mouth isn't going to solve the underlying problem.

We need to understand the why before deciding on the what next.

A Simple Parent Observation Checklist

You don't need to diagnose anything.

Just observe.

Over the next week, notice whether your child regularly:

At Rest

• Keeps their mouth open

• Rests their tongue low or forward

• Has difficulty comfortably keeping their lips together

• Frequently puts objects in their mouth

During the Day

• Sucks a thumb or finger

• Uses a pacifier for extended periods

• Bites their nails

• Chews clothing, pencils, or other objects

• Sucks or bites their lips

• Mouth breathes

While Eating or Swallowing

• Pushes their tongue forward

• Frequently has food or liquid escape the mouth

• Appears to use excessive facial movement when swallowing

• Has chewing or swallowing concerns

At Night

• Sleeps with their mouth open

• Snores regularly

• Drools

• Grinds their teeth

• Sleeps restlessly

One checkmark doesn't mean your child needs therapy.

You're looking for persistent patterns and combinations of signs.

When Should I Ask Someone About It?

If you're concerned about an oral habit, your child's dentist or pediatrician can be a good starting point.

If you notice persistent mouth breathing, snoring, or difficulty breathing through the nose, medical evaluation may be appropriate to understand why.

And if you're seeing patterns involving tongue posture, tongue thrust, swallowing, lip closure, or other oral muscle functions, a Myofunctional evaluation can help determine whether therapy may be useful.

Sometimes the answer is:

"Let's work on this."

Sometimes it's:

"Let's watch it for now."

And sometimes it's:

"I'd like you to see another provider first."

All three are perfectly reasonable outcomes.

Frequently Asked Questions

At what age should thumb sucking stop?

There isn't one birthday when every child suddenly needs to stop. Duration, frequency, intensity, dental development, and the individual child all matter. Your child's dentist can help you determine whether the habit is beginning to affect their teeth or bite.

Are pacifiers bad for a child's teeth?

Not automatically. Pacifiers are commonly used in infancy and early childhood. Prolonged or frequent use as a child gets older can become more relevant to dental and oral development, which is why duration and frequency matter.

Should I make my child close their mouth if they mouth breathe?

Not until you know they can comfortably breathe through their nose. Persistent mouth breathing can have an underlying reason, and simply forcing the lips closed does not address nasal obstruction or another airway concern.

Will my child outgrow tongue thrust?

Some swallowing patterns change as children develop, but persistent tongue thrust should be evaluated in context. A dentist, orthodontist, speech-language pathologist, or Myofunctional Therapist may identify whether it is affecting function.

Is nail biting a myofunctional disorder?

Not by itself. Nail biting is common and can have many causes. It becomes more relevant to a myofunctional evaluation when it occurs alongside other oral-function concerns or is part of a broader pattern.

Can Myofunctional Therapy stop oral habits?

Myofunctional Therapy can help address certain oral habits and the functional patterns surrounding them when appropriate. The approach depends on the habit, the child's age and readiness, the underlying reason for the behavior, and whether other providers need to be involved.

Small Habits Can Tell Us Something Bigger

Parents are incredibly good observers.

You're the person who notices that your child always sleeps with their mouth open.

That the pacifier has become harder to give up than expected.

That every shirt collar ends up soaked.

That their thumb automatically goes into their mouth when they're tired.

That their tongue seems to push forward when they swallow.

Those observations matter.

They don't mean something is wrong.

And they certainly aren't reasons to blame yourself or your child.

They're simply clues about how your child is using the muscles of their mouth and face.

Sometimes a habit is just a habit.

Sometimes it deserves a closer look.

Knowing the difference starts with understanding the pattern.

About the Author

Reviewed and Written by

Emilee Hyland, RDH

Orofacial Myofunctional Therapist
Founder, Face Value Myofunctional Therapy

Emilee Hyland is a Registered Dental Hygienist and Orofacial Myofunctional Therapist at Face Value Myofunctional Therapy. She works with children, teens, and adults to address functional patterns involving breathing, tongue posture, swallowing, oral habits, and the muscles of the mouth and face. Her approach emphasizes education, individualized therapy, and collaboration with dental and medical professionals when appropriate.

Wondering Whether Your Child's Oral Habits Are Affecting Function?

If you're noticing persistent thumb or finger sucking, mouth breathing, tongue thrust, unusual tongue posture, lip habits, or other concerns involving oral function, Face Value can help you understand what you're seeing and whether a comprehensive Myofunctional evaluation may be appropriate.

Schedule a consultation with Face Value Myofunctional Therapy to learn more.