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Adult Permanent Teeth Coming In Behind Baby Teeth: Shark Teeth

Many parents become alarmed when they look in their child's mouth and see the permanent teeth growing behind the baby teeth.  What went wrong?  Aren't the permanent teeth supposed to grow under the baby teeth and push them out?

Rest assured, permanent teeth coming in behind baby teeth is not an emergency!

Ordinarily, as the permanent teeth push up, the roots of the baby teeth dissolve and the baby tooth eventually falls out, allowing the permanent teeth to come in.  Sometimes, the baby teeth don't want to leave the mouth, and the permanent teeth come in right behind them.  This condition is technically known as lingually erupting mandibular incisors and more commonly known as shark teeth or simply permanent teeth coming in behind baby teeth.

In this article, I'll talk about why shark teeth happen, how common shark teeth are, whether or not they're serious, and what your dentist or pediatric dentist can do to treat shark teeth.  I'll even sprinkle in a couple of pictures so you can check to see if this is what is happening with your child.

Here's a close-view of the lower jaw of a child with his permanent lower incisors coming in behind his baby incisors.  The child's parent commented that hours after this picture was taken, one of the baby teeth fell out.  So sometimes the body can even correct the problem on its own!

Shark Teeth - Permanent Teeth Coming In Behind Baby Teeth

Why Permanent Teeth Grow In Behind The Baby Teeth

The book Pediatric Dentistry by Jimmy Pinkham states that "the cause of ectopic and lingually erupting incisors is not well established."

There are a few guesses as to why shark teeth occur.  Some dentists believe that this occurs because the roots of the baby teeth don't get dissolved like they normally should and the permanent teeth have nowhere else to go, so they just come into the mouth where there is the least amount of resistance.

Other dentists say that the permanent teeth start growing in behind the baby teeth because there is too much crowding in the lower jaw.

Another theory says that because the permanent teeth develop behind the baby teeth, this is simply a slight deviation from normal and they just didn't make it as far forward as they should have.

I think that all of these are good explanations as to why this phenomenon occurs.  I personally think that all three are possible explanations and any of them might be true for a specific individual.

How Common/Serious Is It to Have Permanent Teeth Grow In Behind The Baby Teeth?

This study by Gellin states that permanent teeth growing in behind baby teeth is a fairly common condition, occurring in about 10% of all children.

Luckily, many times shark teeth will resolve on their own with the baby teeth eventually falling out.  Sometimes, they don't resolve on their own.  So far, in less than a year of actually working in the clinics at dental school , I've seen two patients who are close to 20 years old that still had baby teeth in front of some of their permanent teeth.

One young woman has decided she will probably get braces because the baby tooth that hung around in her mouth caused a bit of crowding and now her teeth aren't aligned very well.  Sadly, she never had this corrected when her permanent tooth first came in.  Most of the time, your dentist will be able to correct shark teeth before it becomes a problem.

Here's a picture of a little boy named Evan.  If you look closely, you'll see that he has two permanent teeth coming in on the bottom with two baby teeth still hanging around.  His mom stated that the day after this picture was taken, Evan lost one of the teeth.

Shark Teeth: Permanent Teeth Coming In Behind Baby Teeth

The two photos in this article show that many times, shark teeth can resolve on their own.  However, if they don't, there are certain things a dentist can do to resolve the problem.

How a Dentist Can Help Manage Permanent Teeth Coming In Behind Baby Teeth

If your child's shark teeth don't resolve on their own within a couple of weeks, it would be a good idea to have your dentist take a look at what's going on.  Your child's dentist will be able to remove the baby teeth from your child's mouth if needed, and this usually resolves the problem.

If the dentist has removed the baby teeth and there is still not enough room for the permanent teeth to move forward and assume their permanent position in the mouth, then your dentist may perform a procedure known as disking where the dentist slims down some of the remaining baby teeth by removing a bit of enamel from them.  This procedure should allow enough room for the permanent teeth to move into their final position.

In another article on this same topic, a pediatric dentist, Dr. Dean Brandon states "Often teeth come in pairs, so if one tooth is not coming in correctly its partner on the other side won't either."

It's important to make sure that all of the teeth have enough room to come into the mouth and line up just right so that your child can have a straight smile that allows for efficient chewing.


Keep in mind that shark teeth really aren't abnormal.  It happens to approximately 1 in 10 children.  Most of the time, shark teeth will resolve without intervention (i.e. the baby tooth will fall out and the permanent tooth will assume its proper position).  If they don't, your dentist can assess the situation and remove the lingering baby tooth if it is necessary.

If you have any questions or comments, feel free to leave them in the comments section below and I'll respond.  Thanks for reading!

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352 Comments |  Leave A Comment

  1. My daughter who is 6 had shark teeth on the bottom.(bottom 2)When I brought her to the dentist he told me that all front 4 baby teeth need to be removed to make room for the 2 adult teeth that are coming in.
    So I listened to the dentist. My daughter's teeth are growing and shifting into correct position. However, now she has spaces next to them. Was wondering how long until side ones grow in? Did I make the right decision?

  2. How long after the permanent tooth coming in should the baby tooth fall out? My son has one permanent tooth behind his baby tooth. His baby tooth is not loose at all.

  3. My son is 5, will be 6 in July. He has autism. Just this week I noticed he has a shark tooth coming in behind one of his bottom front teeth. I've had people tell me I should take him to the dentist ASAP and others say I'd be fine waiting to see if it fixes itself. My biggest issue is with him having autism even going to the Dr is a huge ordeal so the dentist would be like torture for him. I'd really like to hold off if I don't absolutely need to take him ASAP. Am I ok with waiting? I'm so back and forth after hearing both sides of the situation.

    • This is EXACTLY what we are going through!!! My son is also 5 (6 in July), has autism, and has two shark teeth coming through on the bottom front. He has never been to the dentist due to his dislike of doctors and I'm worried this won't correct itself. However I did feel the two baby teeth in question and they seem loose... so I'm hoping they will fall out soon. Hang in there! and let us know what happens!

      Tanya & Myles.

      • We are still holding off on the dentist. I've been checking his baby tooth daily since I noticed the shark tooth and it is finally feeling a little loose! Its not really loose yet but I'm hopeful it'll fix itself. I was worried at first but after speaking with our pediatrician she assured me it was ok to wait it out for a little while. Hoping both of our boys don't have to make the dreaded trip to the dentist over this! Keep me informed too!! Glad I'm not alone here!!

        • It is really wild I found this tonight... My son is almost 7 (end of the month) and Autistic... he has his first loose tooth.. he has had it for 2 months... and 2 weeks after it became loose i saw he had two coming in behind the front bottom teeth... we took him to the dentist today as the loose tooth still won't come out and the tooth next to it is firmly in there... the dentist said eh just leave it.. it will fall out on it's own..

          So I thought i would pass it along seeing as we are kind of in the same boat! Good Luck!

          • I just noticed my son who is 5 and autistic too has these teeth, that's why I'm here trying to find out about them. I was very shocked to see the extra teeth and had concerns as going to the dentist is an ordeal, general anaesthetic for simple procedures. I wish everyone well with their children :)

      • I originally posted and was concerned about my sons shark teeth and him having autism worried me about taking him to the dentist. As of today both of his baby teeth have come out on their own and one of the adult teeth has already moved into the correct place and the other is on its way. I'm very glad we decided to wait for the time being and didn't stress him out and/or traumatize him with going to the dentist. Especially now that the baby teeth fell out on their own and everything looks as it should!

    • My son has some behavior issue. He's very smart but really has troubles in social situations at times. He has been seen by a neurologist at Childrens Hospital and diagnosed with tourettes syndrome . His teeth are coming in like this too. He also has hazy eye. His mom and sister both have ADHD. Both of his grandfathers have lazy eye as well. I have had similar issue as a child and adult. Genetics, ay!

  4. My Six Years daughter has damaged baby teeth means that teeth are broken. now two adult teeth have started to grow from the right and left upside of the upper jaw. what should i do to solve the issue and what the dentist will do. is it abnormal or painful to remove the roots or anyother solution.

  5. My daughter has been developing shark teeth forabout 6 weeks. Is it time to go to the dentist?

    • Yes. As Tom said in the article, if it does not resolve after a couple weeks, have him checked out.

      "If your child's shark teeth don't resolve on their own within a couple of weeks, it would be a good idea to have your dentist take a look at what's going on. Your child's dentist will be able to remove the baby teeth from your child's mouth if needed, and this usually resolves the problem."

  6. My 8 years old daughter, is having shark teeth. in the last 1 and 1/ 2 months. One of her baby teeth resolved on its own, another 1 is still developing behind baby teeth. I went to my dentist, he suggested to pull out the teeth. Should I wait or go as per dentist said?

  7. My daughter will be 7 in two weeks, she to has shark teeth on the bottom behind the front. She is worried that she will have teeth like mine and I am too. I am 32 and still have baby teeth and severe crowding with adult teeth behind adult teeth? As a child when my mother took me to the dentist he said my teeth were fine and that they should adjust themselves and over 25 years later as an adult that had the shark teeth issue with, that dentist was very wrong.
    I now as an adult have social anxiety, I love to laugh and smile, but I embarrass my daughter, so I try to maintain my smile to a minimum. My daughter is outspoken and says what she thinks and I love that about her, but she does hurt my feelings a lot. All because my teeth are not straight like everyone else's.
    So my advice to you as an adult with dental imperfections, I do advise you to take your children to the dentist and beg them to pull out those baby teeth and their adult teeth will have nowhere to go, but the designated areas.

  8. Hi I am a 34 year adult woman and I have shark teeth.....yep my parents never took me to get this sorted when I was younger.....I still have three milk teeth at the bottom and my top canines are milk teeth...no perants have come behind thoughs though. The problem is now the bottom milk teeth are starting come loose, Im worried now, what if they fall out, can this be fixed at my age?

  9. My daughter will be 5 in October and has her second "shark tooth" . The first adult tooth came in fine and the baby tooth fell out. I am just concerned why it is happening at such a young age. Is this anything to worry about? Or do different children get their teeth earlier?

    • I Holly, I am not a dentist but I am a parent and, No there is nothing to worry about. my daughter is 5 and her teeth are starting to get loose and she also has a shark tooth growing in. I'm pretty sure it depends on how early the child got their baby teeth in. My baby had all 4 of her front teeth(top and bottom) by the time she was 4months old. When I asked her dentist he did state that she may loose her teeth earlier. She is my only child so I too was worried about this, Everything is fine don't worry.

  10. Hello, When I came home from work today my 5 year old daughter was so excited about the fact that her tooth is coming in. The problem is that it is coming in behind the loose tooth (exactly what I saw in the first picture in this article). I noticed the loose tooth a few months ago, though it is more loose than before, it still is not about to fall out and the tip of the permanent tooth is showing through the gum. I am so worried about my baby's teeth being crooked. my question is should I make an appointment at the dentist or should I wait and see what happens?

  11. OK, so my 12 year old daughter still has several of her baby teeth and they are not loose at all, and her grown up teeth are all crowded in her mouth. We are having 2 removed next month, hoping that there will be enough room for the grown up teeth to settle in. As they are now, she can barely get the floss in there to clean (which is troubling). We were told orthodontic work can't begin until all those baby teeth come out.
    Her 12 year molars came in VERY early and there seems to be a lot of room at the very back of her gums....maybe those molars locked up the space and caused the crowing? Her grown up teeth are at least twice the size of the baby ones....poor kid!!

  12. When I was about 12 years old, I noticed that my last adult tooth (2nd from the right of my middle teeth) started to grow before my last baby tooth had fallen out, I didn't really think anything of it so I let it fall out in it's own time, not long after it did, but now at 19 years old, I now have a "shark tooth" because by the time my baby tooth had fallen out, there wasn't enough room for my adult tooth to adjust itself into the right spot (I can see a small gap in my gums between the tooth and the one next to it where it was supposed to grow into, but it grew a little crooked instead)

    I was wondering if there was any sort of procedure to fix this tooth, that doesn't involve braces? Some days I get self concious about it because it can be really noticeable when I smile or laugh. For the most part I'm used to it and I can live with it, but I wouldn't mind it being aligned normally like the rest of my teeth if there was a procedure other than braces. Thanks.

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About Me

Tom, Creator of Oral AnswersHi, I'm Tom. I recently graduated from dental school and am now a dentist in Bridgewater, Virginia. I started this blog to help people take better care of their teeth. You can learn more about me or ask me a question.

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