Adult Tooth Growing Behind a Baby Tooth? Here's What Parents Should Know

Noticing a second row of teeth in your child's mouth can be alarming, but it is usually harmless. Known as "shark teeth," this happens when an adult tooth grows in behind a baby tooth that has not yet fallen out.

Most cases sort themselves out, but a baby tooth that refuses to budge should not be ignored. Over time, it can trap plaque, cause crowding, and even lead to a root canal. Here is exactly what you should do next.

What Are Shark Teeth?

"Shark teeth" is a common nickname for a double row of teeth in kids. It happens when a permanent tooth erupts behind a baby tooth that has not fallen out.

Normally, the adult tooth presses on the baby tooth's root and dissolves it with physiological resorption, so the tooth loosens and falls out. With shark teeth, that important step is often missed entirely.

Although it looks unusual, this is common, especially around age six or seven with the lower front teeth. Most children have no pain, and many cases are simple to manage.

Why Do Adult Teeth Grow Behind Baby Teeth?

Adult teeth usually push baby teeth out of the way, but sometimes the natural pathway changes. Several factors can send a permanent tooth behind its baby predecessor. Here is why.

The Normal Process Gets Interrupted

Baby teeth fall out because the adult tooth presses on their roots and dissolves them. When something disrupts the permanent tooth eruption process, the baby tooth stays firmly in place. Common disruptions include:

• Missed Root Contact: The adult tooth erupts beside the baby tooth's root, not beneath it, so the root never dissolves properly on time.

• Slow Root Breakdown: Sometimes the baby root dissolves too slowly, so the adult tooth erupts behind it instead of waiting for its turn.

• Firm Baby Tooth: Without a dissolved root, the baby tooth feels solid when wiggled, often the first clue that something is not right.

Limited Space in the Jaw

Crowding is one of the most common reasons for shark teeth. Adult teeth are larger than baby teeth, and a small jaw may not have enough room for them all.

When space is tight, the new tooth takes the path of least resistance and emerges behind the baby tooth. Once the baby tooth is out, the tongue guides it forward.

Off-Track Tooth Development

Permanent teeth begin forming deep in the gums long before they appear. If a tooth develops slightly off course, it may erupt in an unexpected position. Some common examples include:

• Tongue-Side Eruption: The adult tooth usually emerges toward the tongue, which is the most common pattern in a child's lower front teeth.

• Cheek-Side Eruption: Less often, the tooth grows toward the lips or cheek, so it appears in front of the baby tooth instead.

• Tilted Position: A slight tilt in the tooth's angle can push it off its path, leaving the baby tooth in place longer.

Family Tendency

Genetics play a role in how and when teeth erupt. If a parent or sibling had shark teeth or late tooth loss, your child may be more prone to it.

Jaw size, tooth size, and eruption timing are often inherited. Mentioning any family history to your dentist can help them decide whether to monitor the tooth or step in early.

Early Eruption of the Adult Tooth

Sometimes the permanent tooth erupts before the baby tooth root has fully dissolved. Dentists call this ectopic eruption, meaning the tooth appears in a position other than the expected one.

It is most often seen between ages six and seven, and again around ten to twelve. A dentist can confirm the cause with an exam and, when needed, dental X-rays.

Adult teeth grow behind baby teeth for several reasons, from crowding to genetics. Knowing the cause helps you decide whether to wait patiently or to book a dental visit sooner.

When Does This Usually Happen?

This issue most often appears around age six or seven, when the lower front teeth, called incisors, begin to erupt. Since this is the first stage of losing baby teeth, it is the most common time for parents to notice.

A second common window occurs between ages ten and twelve, when premolars replace the baby molars at the back of the mouth. These teeth are harder to see, so a routine dental checkup often catches the problem before parents do.

That said, this can happen at any age and may affect neighbouring teeth. If one adult tooth grows in behind its baby tooth, the tooth beside it may follow, so watch the area closely and mention changes to your dentist.

Signs an Adult Tooth Is Growing Behind a Baby Tooth

Spotting the problem early makes it much easier to manage. Watch for these common signs in your child's mouth, especially during brushing, mealtimes, and ages when front teeth are changing.

Two Rows of Teeth

The clearest sign is a double row of teeth. The adult tooth sits behind the baby tooth, usually at the bottom front, and shows when your child smiles or talks.

Some parents only notice it while brushing or checking a wobbly tooth. A quick look with a flashlight can help you see the second row clearly, even in dim lighting.

Baby Tooth Does Not Feel Loose

Normally, a baby tooth loosens as the adult tooth pushes upward. If the tooth feels solid even though the new one is showing, the root has likely not dissolved yet.

Ask your child to gently wiggle it with a clean finger. Little or no movement after a few weeks is a good reason to book a dental visit for advice.

Red or Swollen Gums

The gum tissue around the new tooth may look slightly red, puffy, or tender. This mild irritation happens because the adult tooth is pushing through while the baby tooth remains.

Mild redness is usually harmless and settles once the baby tooth is out. Persistent swelling, bleeding, or pain can signal infection, so have a dentist take a look right away.

Food Getting Stuck Between Teeth

Two teeth sitting close together create tight spots where food easily gets stuck. Your child may often complain about something lodged between teeth after meals, especially chewy or sticky foods.

Trapped food feeds plaque and raises the risk of cavities. Help your child brush both sides of each tooth twice daily and floss gently around the crowded area each night.

Crowding or Crooked Position

The adult tooth may look tilted, twisted, or squeezed against its neighbours while the baby tooth remains. This crowding is often temporary and improves once the baby tooth is gone.

If the adult tooth stays crooked after the baby tooth falls out, or if crowding worsens, ask your dentist whether an early orthodontic assessment would help your child's growing smile.

Mild Pressure or Soreness

Some children feel gentle pressure or soreness where the adult tooth is coming in. It may be more noticeable when chewing crunchy foods or when brushing near the affected area.

This discomfort is usually mild and brief, fading within a few days. If your child complains of severe pain, has trouble eating, or develops a fever, contact a dentist promptly.

When to See a Dentist and What Treatment Looks Like

Most cases resolve without treatment, but some need a dentist's help. Book a visit if you notice these warning signs.

• Adult Tooth Keeps Growing: If the adult tooth keeps growing while the baby tooth stays put, crowding and crooked positioning become much more likely.

• Pain, Swelling, or Infection: Ongoing pain, swollen gums, bleeding, or a fever should not wait. Call a dentist promptly, since infection may need treatment.

• Dental Exam and X-Rays: The dentist checks how loose the tooth is and may take X-rays to see the root and the adult tooth.

• Simple Baby Tooth Removal: The dentist removes the baby tooth using local freezing if needed. It is quick, and adult teeth often move forward.

Trusted Children's Dental Care at Dentistry At Sullivan

Finding an adult tooth behind a baby tooth is common, and most children do well with timely care. If your child's baby tooth stays firm, our dental clinicians at Dentistry At Sullivan are ready to help. We offer thorough exams, clear answers, and comfortable treatment, so your child's smile grows in health.