When Should My Child’s Permanent Teeth Come In? A Parent’s Guide to Tooth Eruption

One of the questions I hear frequently from parents is some version of, “Shouldn’t that tooth have come in by now?”

Sometimes the answer is yes. More often, the answer is: maybe—but the age on the calendar is only part of what I look at.

There is a normal sequence in which permanent teeth tend to appear, and eruption charts can be very helpful. But there is also quite a bit of normal variation from one child to another. Some children simply get their permanent teeth earlier or later than their classmates.

When I evaluate a child’s developing teeth, I am usually paying attention to three things: sequence, symmetry, and whether each tooth appears to have a normal path into the mouth.

In many cases, those tell me more than the child’s exact age.

The First Permanent Teeth Usually Arrive Around Age Six

For most children, the transition to permanent teeth begins around age six.

The first permanent teeth to appear are usually the first permanent molars and the lower central incisors.

The first molars are particularly important because parents sometimes do not realize they are permanent teeth.

These are often called the “six-year molars.” They erupt all the way in the back of the mouth, behind the last baby molars. They do not push out or replace a baby tooth.

That means there is no loose tooth to announce their arrival.

A parent may see a new molar in the back and assume that it is another baby tooth. It isn't. That tooth is intended to remain for life and becomes an important part of the developing bite.

At about the same time, the lower front baby teeth usually begin loosening and are replaced by the lower permanent central incisors.

A healthy eight-year-old who is several months behind another healthy eight-year-old may have absolutely nothing wrong.

What gets my attention more often is when the normal pattern begins to break down.

Symmetry Can Be More Important Than Age

The right and left sides of the mouth usually develop at roughly similar rates.

They do not have to be perfectly synchronized. One tooth may appear before its partner on the other side, and that is very common.

But if one tooth has been in for quite a while and its matching tooth on the other side shows no sign of coming, I start asking why.

For example, imagine that both upper baby front teeth are lost. One permanent central incisor erupts normally, but months later there is still no sign of the other one.

That difference interests me much more than simply saying, “This child is eight years old and an eight-year-old should have this tooth.”

The first child may simply be a later developer. The second situation may indicate that something is interfering with the eruption of one particular tooth.

That is the difference between general delay and asymmetric delay.

What Can Cause a Permanent Tooth to Be Late?

There are several possibilities, and many of them are very manageable once we know what is happening.

A Baby Tooth May Be Staying Too Long

Sometimes a baby tooth remains firmly in place well beyond the time we would expect it to be lost.

That does not automatically mean there is a problem. But a retained baby tooth can occasionally be a clue.

The permanent tooth underneath may be developing slowly, positioned away from its normal eruption path, or unable to erupt normally. In other cases, there may simply not be a permanent replacement tooth underneath it.

Occasionally a baby tooth itself becomes ankylosed, meaning it is essentially fused to the surrounding bone and does not move normally as the other teeth erupt around it.

This is why I usually want to know why a baby tooth is hanging around rather than assuming that it will eventually fall out.

Sometimes the Permanent Tooth Is Missing

Not everyone develops all of the permanent teeth they are expected to have.

This is called congenitally missing teeth or dental agenesis.

Upper lateral incisors and some premolars are among the teeth we sometimes find are absent.

From the outside, this can look remarkably ordinary: a baby tooth simply stays in place much longer than expected because there is no permanent tooth underneath pushing it out.

An X-ray can answer that question very quickly.

Knowing that a tooth is missing early is valuable because it allows us to plan intelligently. Depending on the tooth, the bite, available space, and the child's facial structure, we may eventually choose to preserve the space, close the space orthodontically, or coordinate orthodontic treatment with future restorative dentistry.

There is usually no reason for a parent to try to make those decisions early. But it is helpful to know what we are working with.

There Can Also Be an Extra Tooth

Interestingly, the opposite problem can happen too.

Some children develop an extra permanent tooth, called a supernumerary tooth.

One of the more important places this can occur is between the upper front teeth. An extra tooth in this area is sometimes called a mesiodens.

It may never be visible in the mouth at all.

Instead, the first clue can be that one of the normal permanent front teeth does not erupt when expected.

That is one reason I pay particular attention when one upper central incisor erupts normally and the other does not. An X-ray can tell us whether the missing-looking tooth is actually there and whether something is blocking its path.

Sometimes There Simply Isn't Enough Room

Permanent teeth are considerably larger than the baby teeth they replace in some areas, and the developing mouth has to accommodate all of them.

If there is significant crowding, a permanent tooth may not be able to follow its ideal eruption path.

It might begin appearing toward the cheek, toward the tongue or palate, or in an unusual position. In other cases, it may remain higher in the jaw because another tooth is occupying the space it needs.

That does not necessarily mean orthodontic treatment has to begin immediately.

But it is information I want to have.

There is a big difference between intentionally watching a developing tooth whose position we understand and simply assuming that a tooth will eventually find its way into the right place.

Upper Permanent Canines Deserve Special Attention

The upper permanent canines are among the last front teeth to arrive, usually around ages 11 to 12.

They are also unusual because they develop relatively high in the upper jaw and travel a long distance before reaching their final position in the mouth.

Most make that journey normally.

But because of that long eruption path, an upper canine can sometimes begin moving in the wrong direction. It may drift toward the palate, become crowded out of the arch, or interfere with neighboring teeth.

This is one of the reasons orthodontists pay close attention to the developing canine well before it actually appears.

If I cannot clinically feel where I expect an upper canine to be developing, if there is significant crowding, or if the two sides are developing very differently, an X-ray can help determine where the tooth is and which direction it is traveling.

The goal is not to assume that every slow-erupting canine is a problem. It is simply much better to understand its position while the teeth are still developing than to discover much later that it has been traveling in the wrong direction.

When a Tooth Doesn't Seem to Be Coming

There are situations in which a permanent tooth does not erupt normally because its path has been blocked or it has become positioned in a way that prevents normal eruption.

That is an impacted tooth.

This article is not really about impacted teeth, because most variations in eruption do not mean that a tooth is impacted. But unusually delayed or asymmetric eruption is sometimes how we first discover one.

I discuss that subject in much more detail in our Journal article, The Tooth That Never Came In: Why Impacted Teeth Are Better Found Early.

The important point here is that waiting is appropriate when development looks normal; waiting without knowing what is happening is different.

X-Rays Can Tell Us What We Can't See

When there is a question about eruption, we do not have to guess.

An X-ray can show whether the permanent tooth exists, how far its root has developed, where it is positioned, whether there is enough space for it, and whether another tooth or structure is interfering with its eruption.

Sometimes a small targeted dental X-ray provides all the information we need. In other situations, a panoramic X-ray is useful because it allows us to look at the developing permanent dentition as a whole.

Not every child with a slightly late tooth needs additional imaging. The decision should be based on the examination and the child's individual development.

But when the eruption pattern does not make sense clinically, imaging can turn “I wonder where that tooth is” into a much more useful conversation.

What Parents Can Watch for at Home

You do not need to memorize an eruption chart. Instead, I would pay attention to patterns such as:

• One permanent tooth appearing while its matching tooth on the other side remains absent for a prolonged period.
• An upper front baby tooth being lost but the permanent tooth failing to appear while the neighboring teeth continue erupting normally.
• A baby tooth remaining much longer than the corresponding tooth on the opposite side.
• A permanent tooth beginning to erupt far toward the cheek, tongue, or palate rather than into the dental arch.
• Significant crowding that appears to leave no space for a developing permanent tooth.
• One side of the mouth progressing normally while the same teeth on the other side seem considerably behind.
• A tooth that seems to have stopped progressing after partially erupting.

None of these automatically means something is wrong.

They are simply good reasons to take a closer look.

When Should We Investigate Instead of Just Waiting?

There is a place for patience in orthodontics.

Children develop at different rates, and I do not want parents worrying because their child's teeth did not arrive during the exact month shown on an eruption chart.

At the same time, I do not like relying on age alone when something about the eruption pattern is unusual.

If both sides of the mouth are developing similarly, the teeth are following an appropriate sequence, and imaging or examination shows that the permanent teeth are positioned normally, waiting may be exactly the right thing to do.

But if a permanent tooth is substantially behind its counterpart, a baby tooth remains unexpectedly, there appears to be no room for the permanent tooth, or the eruption sequence simply does not make sense, I would rather find out why.

Very often the answer is reassuring.

And when there is something that needs attention, recognizing it while the permanent teeth are still developing usually gives us more options.

If you are in Charlottesville or the surrounding Central Virginia area and you are unsure whether your child's permanent teeth are developing normally, I am happy to evaluate them. Sometimes all a parent needs is reassurance that the teeth are on their way. Other times, a closer look at the eruption pattern or a simple X-ray can identify something worth addressing before it becomes a more complicated problem.

— Dr. Suzanne M. Dennis