Tooth Eruption: What Happens When? A Dentist’s Guide to How a Smile Develops

Most parents remember the first tooth.

Then, almost before they realize it, they are watching that same child wiggle a loose baby tooth, grow permanent front teeth that suddenly seem enormous, develop new molars seemingly overnight, and eventually wonder whether wisdom teeth will have enough room to erupt.

Tooth eruption is often presented as a simple calendar: this tooth appears at this age, that tooth falls out at that age.

Clinically, I think that misses the more interesting and more important story.

Tooth eruption is part of a carefully coordinated developmental process involving the teeth, jawbones, gums, roots, bite, facial growth, and available space within the dental arches. The timing matters, but so does the sequence, symmetry, position, and overall pattern.

The American Academy of Pediatric Dentistry describes dental development as progressing from primary dentition into mixed dentition—when baby and permanent teeth coexist and eventually into adolescent and adult dentition. The mixed-dentition period generally occurs from approximately ages 6 through 13.

As a dentist, I am therefore rarely interested in one number on an eruption chart by itself. I am looking at the entire developing smile.

“An eruption chart tells me what usually happens. Examining the individual child tells me whether what is happening is healthy for that child.”
— Marielaina Perrone, DDS

What Does “Tooth Eruption” Actually Mean?

Tooth eruption is the process through which a developing tooth moves into the mouth and ultimately assumes its functional position.

Long before you see a tooth break through the gum, development has been occurring beneath the surface.

This is why eruption is not simply a tooth suddenly “popping out.”

The visible tooth is only one part of a much larger developmental process.

Humans normally develop two dentitions:

Primary dentition — the 20 baby or deciduous teeth.

Permanent dentition — generally 32 teeth when all four third molars, or wisdom teeth, are present.

And there is an important period between them when both are present simultaneously: mixed dentition.

That transition is one of the most dynamic periods in dental development.

 

When Do Baby Teeth Begin to Erupt?

The first primary tooth commonly appears at approximately 6 months of age, although there is considerable normal variation. The lower central incisors are usually among the first teeth to arrive.

According to the American Dental Association’s eruption ranges, the typical pattern is approximately:

Notice something important about those ranges.

There isn’t a single “correct” eruption date.

One child’s first tooth may emerge earlier than another’s without anything being wrong.

By About Age 3: The Primary Smile Is Usually Complete

By approximately age 3, most children have their full complement of 20 primary teeth.

At this stage, those little teeth have a surprisingly big job.

Baby teeth help children:

• Bite and chew food
• Develop speech
• Maintain space for permanent teeth
• Support developing facial structures
• Establish early bite relationships
• Learn lifelong oral-hygiene habits

This is why I strongly disagree with the idea that cavities in baby teeth don’t matter because “they’re going to fall out anyway.”

They matter very much.

“Baby teeth are temporary teeth, but they are not unimportant teeth. They are part of the architecture that guides a child’s developing smile.”
— Marielaina Perrone, DDS

What Happens When Baby Teeth Begin Falling Out?

At approximately age 6, another major transition begins.

The roots of primary teeth gradually resorb as the permanent dentition develops. Eventually, there is not enough root structure remaining to hold a baby tooth firmly in place.

That’s when the famous wiggle begins.

Eventually, the primary tooth exfoliates (falls out) and the permanent successor can emerge.

Primary central incisors commonly shed around ages 6–7, while many of the remaining primary teeth are lost progressively through approximately ages 10–12.

But something else is happening at the same time that parents sometimes miss.

The Six-Year Molars: Permanent Teeth That Don’t Replace Anything

One of the most important moments in dental development can occur without a baby tooth falling out at all.

At approximately age 6–7, the first permanent molars commonly erupt behind the last primary molars.

These are permanent teeth from day one. They are sometimes mistaken for baby teeth because nothing fell out before they appeared.

That misunderstanding matters.

A parent may see a cavity developing in a six-year molar and assume:

We’ll just wait. That tooth will eventually fall out.

It won’t.

The first permanent molars can become some of the most important teeth in the adult bite.

“One of the messages I want parents to remember is simple: the molars appearing behind the baby teeth at around age six are usually permanent teeth. Protect them as permanent teeth from the beginning.”
— Marielaina Perrone, DDS

Their deep grooves can retain plaque and food debris, which is one reason good brushing, fluoride exposure, professional preventive care, and in appropriate patients dental sealants can be important.

Ages 6–8: The Smile Starts Looking Very Different

Around the same period, the lower permanent central incisors commonly emerge, followed by additional permanent incisors.

Typical ADA ranges for permanent incisors are:

Lower central incisors: 6–7 years
Upper central incisors: 7–8 years
Lower lateral incisors: 7–8 years
Upper lateral incisors: 8–9 years

This stage can alarm parents because permanent front teeth often look surprisingly large compared with the tiny baby teeth they replaced.

That’s frequently normal.

A child’s face and jaws are still growing. The permanent incisors are adult-sized teeth entering a developing face.

Color can look different as well. Permanent teeth may appear slightly more yellow than primary teeth because of differences in tooth structure and dentin.

So bigger or slightly warmer-colored permanent teeth do not automatically mean something is wrong.

Why Are My Child’s New Teeth Crooked?

This is another question I hear frequently.

New permanent teeth do not always erupt into a perfectly straight row.

They may appear:

• Slightly rotated
• Angled
• Crowded
• Separated
• Behind another tooth
• In front of the dental arch

Sometimes the developing jaw and surrounding tissues accommodate the teeth as growth continues.

Other times, the eruption pattern reveals a genuine space or alignment problem.

The distinction is exactly why eruption should be observed clinically rather than judged only by appearance at home.

Ages 9–12: The Busy Years of Tooth Eruption

This is where dental development becomes particularly interesting.

Canines and premolars begin replacing primary canines and molars.

According to ADA eruption ranges:

These ages overlap considerably.

That’s one reason sequence can sometimes tell us as much as chronological age.

There must be enough space for permanent teeth to move into useful positions while the jaws continue developing.

A tooth that seems delayed may simply be following an individual’s developmental pattern—or there may be something interfering with eruption.

The Canines Deserve Special Attention

Permanent canines are particularly important teeth.

They contribute significantly to:

• Smile aesthetics
• Dental arch form
• Bite guidance
• Facial appearance
• Functional tooth relationships

Upper permanent canines usually erupt around ages 11–12.

But occasionally, an upper canine does not follow its expected eruption path.

It may become impacted or develop in an unfavorable position.

This is one reason dentists monitor developing permanent teeth before every baby tooth has disappeared.

If the eruption pattern suggests a developing problem, appropriate imaging and evaluation may reveal where the tooth actually is and whether intervention should be considered.

“The best time to discover an eruption problem is usually before it becomes an obvious eruption problem.”
— Marielaina Perrone, DDS

That philosophy applies to more than canines.

Ages 11–13: The Second Permanent Molars Arrive

The second permanent molars generally erupt at approximately 11–13 years, depending on location and individual development.

You may hear these called the 12-year molars.

Like the six-year molars, they don’t replace baby teeth. They erupt farther back in the mouth.

By this stage, most children are approaching a predominantly or completely permanent dentition, excluding wisdom teeth.

This is also an important time to reassess:

• Oral hygiene
• Cavity risk
• Gum health
• Bite development
• Crowding
• Tooth position
• Orthodontic considerations

Adolescence introduces another challenge: patients increasingly take responsibility for their own brushing, dietary choices, and dental habits.

The biology may be progressing beautifully while the hygiene occasionally does not.

What About Wisdom Teeth?

Third molars, better known as wisdom teeth, are the final permanent teeth in the conventional eruption sequence.

The ADA lists a typical eruption range of approximately 17–21 years, although there is considerable individual variation.

And some wisdom teeth never erupt normally.

They may be:

• Completely absent
• Partially erupted
• Fully erupted
• Angled
• Impacted beneath gum or bone
• Positioned against neighboring teeth

Having wisdom teeth does not automatically mean they must be removed.

Likewise, the absence of pain doesn’t automatically mean they should never be evaluated.

The decision depends upon anatomy, eruption position, cleansability, surrounding tissues, pathology, neighboring teeth, and the patient’s individual circumstances.

Tooth Eruption Is a Range, Not a Deadline

This may be the most important concept in this entire article. Eruption charts describe population averages and expected ranges. They do not provide a deadline for an individual child.

A tooth erupting several months earlier or later than another child’s corresponding tooth isn’t automatically abnormal.

I am generally more interested in questions such as:

Is development progressing?

Are corresponding teeth appearing in a reasonably symmetrical pattern?

Is there enough space?

Is something physically blocking eruption?

Did a baby tooth remain much longer than expected?

Was a baby tooth lost unusually early?

Is the permanent tooth developing and positioned appropriately?

How does this fit with the rest of the child’s dental and facial development?

The eruption chart gives us context. The clinical examination gives that context meaning.

Why Might a Tooth Erupt Late?

Delayed eruption can have many explanations. Some are simply variations of normal development.

Others may involve local factors such as:

• Lack of space
• Retained primary teeth
• An impacted permanent tooth
• An abnormal eruption path
• Previous trauma
• Supernumerary (extra) teeth
• Developmental differences
• Certain cysts or other obstructions

Systemic and genetic factors can also influence dental development in some individuals.

This is why diagnosing “delayed eruption” from an age chart alone is inappropriate.

When a pattern concerns me, the next step may include examination and appropriate dental imaging to determine what is happening beneath the gum, rather than simply waiting indefinitely.

What If a Baby Tooth Falls Out Too Early?

Early loss deserves attention too.

A primary tooth can be lost prematurely because of:

• Tooth decay
• Infection
• Trauma
• Extraction
• Other dental conditions

One function of primary teeth is maintaining space within the developing arch.

When a primary tooth disappears significantly before its permanent successor is ready to erupt, neighboring teeth may sometimes move into the available space.

Depending upon the tooth, child’s age, developing permanent dentition, bite, and available space, a dentist may recommend simply monitoring the area or may consider whether space management is appropriate.

There is no universal answer.

What If the Permanent Tooth Comes in Before the Baby Tooth Falls Out?

Parents sometimes describe this as a “shark tooth.”

It commonly occurs when a permanent tooth, often a lower incisor, erupts behind a retained primary tooth.

It can look alarming.

But it does not automatically represent an emergency.

The important questions are whether the primary tooth is becoming mobile, whether the permanent tooth has room to move toward a better position, and whether intervention is actually necessary.

This is another situation where an examination is more useful than panic.

Eruption and Orthodontic Development

Tooth eruption and orthodontics are closely connected because eruption changes the dental arch continuously throughout childhood.

During the mixed-dentition years, we can evaluate:

• Crowding
• Spacing
• Crossbites
• Overbite
• Overjet
• Eruption asymmetry
• Missing teeth
• Extra teeth
• Developing canine position
• Jaw relationships
• Available space

The AAPD notes that evaluation and treatment of occlusal and skeletal disharmonies can begin at different stages of dental development depending on the particular problem and the risks and benefits of intervening or waiting.

That doesn’t mean every child needs early orthodontic treatment.

It means development should be observed intelligently.

“Monitoring growth is not the same as looking for something to treat. Sometimes the most appropriate treatment is simply knowing that development is progressing normally.”
— Marielaina Perrone, DDS

When Should Parents Ask Their Dentist About Eruption?

There is no need to compare your child’s mouth tooth-for-tooth with every classmate.

However, I would want parents to mention concerns such as:

• A significant difference between corresponding teeth on opposite sides
• A permanent tooth appearing while the primary tooth remains firmly in place
• A baby tooth lost unusually early
• Significant crowding
• A tooth erupting far outside the dental arch
• Persistent discomfort or swelling
• A tooth that appears substantially delayed compared with the child’s overall dental development
• Trauma to a primary tooth that could potentially affect the developing permanent tooth
• A permanent tooth that seems to stop erupting

These findings do not necessarily mean something is wrong.

They mean the situation deserves evaluation.

A Simple Tooth Eruption Timeline

For parents who want the big picture, I think this is more useful than trying to memorize 32 individual eruption dates:

Around 6 Months

The first primary teeth often begin appearing.

By About Age 3

Most children have all 20 primary teeth.

Around Age 6

Primary incisors begin loosening, while the first permanent molars and lower permanent incisors often start appearing.

Ages 7–9

More permanent incisors erupt.

Ages 9–12

Canines and premolars increasingly replace primary teeth.

Ages 11–13

Second permanent molars generally erupt and the transition toward a full permanent dentition continues.

Approximately Ages 17–21

Wisdom teeth may erupt—although some never do.

That is the developmental story in broad strokes.

Individual variation is expected.

How Parents Can Protect Newly Erupted Permanent Teeth

A newly erupted permanent tooth needs to last a lifetime.

I recommend focusing on fundamentals:

Brush thoroughly twice daily with fluoride toothpaste.

Young children may still need help reaching posterior teeth effectively.

Pay special attention to newly erupted molars.

Their grooves and location can make them easy to miss.

Discuss dental sealants when appropriate.

Sealants can help protect susceptible chewing surfaces of permanent molars.

Limit frequent exposure to sugary drinks and snacks.

Frequency matters because repeated carbohydrate exposure repeatedly challenges the teeth.

Maintain regular dental examinations.

We aren’t simply looking for cavities. We’re monitoring development.

Don’t ignore a developing bite problem because “the baby teeth will fall out.”

Sometimes they will. Sometimes what we’re seeing involves the permanent dentition or jaw development.

Frequently Asked Questions About Tooth Eruption

What age does the first baby tooth usually appear?

Often around six months, with the lower central incisors commonly among the first teeth to erupt. Normal variation is considerable.

How many baby teeth are there?

A complete primary dentition normally contains 20 teeth.

How many permanent teeth are there?

The complete permanent dentition generally contains 32 teeth, including four wisdom teeth. Some people do not develop all four third molars.

When do children begin losing baby teeth?

Commonly around age 6, often beginning with the central incisors.

What are six-year molars?

They are the first permanent molars, which typically erupt at approximately ages 6–7 behind the primary teeth. They do not replace baby teeth.

When do permanent front teeth come in?

The lower central incisors commonly erupt around ages 6–7, upper central incisors around 7–8, and lateral incisors generally follow.

When do permanent canines erupt?

Lower canines commonly erupt around ages 9–10 and upper canines around 11–12.

When do wisdom teeth come in?

The typical ADA eruption range is approximately 17–21 years, although development and eruption vary considerably.

Should I worry if my child’s teeth erupt later than another child’s?

Not necessarily. Eruption charts represent typical ranges, not rigid deadlines. The overall sequence, symmetry, available space and underlying development are often more informative than comparing one child with another.

Why are my child’s new permanent teeth so big?

Permanent teeth are adult-sized teeth erupting into a face and jaws that are still developing. They can therefore appear disproportionately large at first.

Do all eruption problems require treatment?

No. Some situations only need monitoring. The purpose of evaluation is to distinguish normal variation from a developing problem that could benefit from intervention.

Tooth Eruption Is Really a Story About Growth

Parents naturally focus on the tooth they can see.

As a dentist, I’m also thinking about everything around and underneath it.

I’m watching the developing permanent teeth. I’m looking at available space. I’m evaluating the bite. I’m watching how the right and left sides compare. I’m considering facial and jaw development. And I’m thinking several years ahead.

That’s why tooth eruption is much more than memorizing when a particular tooth is “supposed” to appear.

It is one of the most visible signs of a child’s ongoing growth.

“A developing smile doesn’t need to follow a calendar perfectly. What I want to see is a healthy, coordinated progression from one stage to the next—and to recognize early when something is interfering with that process.”
— Marielaina Perrone, DDS

For families in Henderson, Green Valley, Las Vegas, and surrounding Southern Nevada communities, regular dental examinations provide an opportunity to monitor that development while also protecting newly erupted teeth from decay and establishing healthy habits that can continue into adulthood.

The goal isn’t simply to count teeth as they arrive.

It’s to help those teeth arrive into a healthy environment and give the developing smile the best opportunity to function well for a lifetime.

About Marielaina Perrone

Dr. Marielaina Perrone, DDS, is a trusted cosmetic and family dentist in Henderson, NV, known for helping patients achieve healthy, beautiful smiles through personalized, compassionate care. With more than 20 years of clinical experience, she combines advanced dental expertise with an artistic eye to deliver exceptional results in porcelain veneers, dental implants, smile makeovers, periodontal therapy, Botox, dermal fillers, and facial aesthetic treatments.

A graduate with honors from Stony Brook University School of Dental Medicine, Dr. Perrone remains committed to lifelong learning and regularly pursues advanced continuing education in cosmetic dentistry, implant dentistry, and facial aesthetics. Her comprehensive approach focuses on enhancing oral health, facial harmony, and overall confidence through customized treatment plans tailored to each patient’s unique goals.

Dr. Perrone is passionate about patient education, preventive care, and building lasting relationships founded on trust, communication, and comfort. She believes every patient deserves individualized attention and treatment that supports both long-term health and a confident smile.

Proudly serving Henderson, Green Valley, Las Vegas, Summerlin, and surrounding communities, Dr. Perrone is dedicated to providing modern, patient-centered dentistry in a welcoming environment. Outside the office, she enjoys cooking, staying active, spending time with family, and participating in community activities throughout the Las Vegas Valley.

Reviewed for Clinical Accuracy

This article has been written and clinically reviewed by Marielaina Perrone, DDS, to ensure it reflects current evidence-based dentistry and the personalized philosophy of care practiced at her Henderson, Nevada office.

Last Reviewed: August 2026