Chris M Jolley DDS

EVER SEEN A DOUBLE TOOTH?

Many parents wait with great excitement and anticipation for the eruption of their baby's first tooth. Once in a while baby teeth don't quite look right. This can cause extreme worry among parents. Pictured to the left is one such scenario of a baby's two upper teeth. The tooth on the left is a "double tooth" while the one on the right is normal.

Double teeth are two teeth that are joined together by dentin or even by the pulp. If you're not sure what dentin and pulp are, take a look at the layers of a tooth.

In 20 years of dental practice, Dr. Jolley has only seen one case of ‘Fusion’ and that happens to be our own son! He has one giant front bottom tooth with two roots. (The front teeth normally only have one root.)  It was quite exciting and fun for Dr. Jolley to finally see an x-ray of the tooth when our son became old enough. Now that our son has arrived to the age for his permanent teeth erupt, we have been watching this tooth with a lot of curiosity.

There are two scientific terms for teeth that appear to be two teeth stuck together as one tooth: gemination and fusion.

Teeth Stuck Together: What is Gemination?

Gemination is when one developing tooth has split off into two distinct teeth that remain attached to each other and develop together. Gemination comes from the latin word geminus which means twin. You can think of gemination as two "twins" that are permanently attached.

When you count the geminated tooth as one tooth, there are a normal number of teeth in the mouth. The picture of the baby is shown to have gemination because he has all of his other teeth when you count the "double-tooth" as one tooth.

The same boy pictured above, a year or so later. He has all four upper incisors including the double tooth. If he only had three upper incisors including the double tooth, it would be fusion.

Teeth Stuck Together: What is Fusion?

Fusion is when two different developing teeth have joined together to create one tooth. You can think of it as two teeth fusing together. Gemination and fusion look very similar. Sometimes the only way to tell them apart is to count the number of teeth.

When you count the fused teeth as one tooth, the person will appear to be missing one tooth. (See the picture of our son’s teeth shown on the right.) Notice there are only three teeth where there would normally be four, but the one on the left is extra wide.

How Common Are Double Teeth?

Gemination and fusion have been reported to occur in the baby teeth in anywhere from 0.5% to 2.5% of Caucasian children. It is more common in Asian children, where it has been reported to occur sometimes in excess of 5% of Asian kids.

Gemination and fusion occur most commonly in the upper front teeth. However, it can also occur on the lower teeth as well. As a general rule, if a double tooth is located in the upper teeth, it is probably gemination and if the double tooth is found in the lower teeth, then it is probably fusion.

Interestingly enough that is exactly what we have in our two scenarios. The baby boy pictured 1^st above and to the left, has an upper ‘double tooth’ which is Gemination. Our son, the toddler pictured 2^nd, has a lower ‘double tooth’ which is Fusion.

Can Gemination and Fusion Happen with Permanent Teeth, Too?

Gemination and fusion do occur in permanent teeth, although it is not nearly as common as in baby teeth. It reportedly occurs in one out of every 250 people.

Can Gemination and Fusion Cause Any Problems?

Gemination and fusion in the baby teeth can cause crowding, atypical spacing between the teeth, and can cause problems with or delay the eruption of the permanent teeth underneath.

Because of this, when a double tooth is found, you should have your dentist monitor the permanent teeth underneath it to ensure that they come in normal. (Which means Dr. Jolley can check it during each of your regular 6 month check-ups.) Sometimes, your dentist will have to remove the double tooth in order to allow the permanent tooth to erupt normally. Dr. Jolley's 1st recommendation though is to not pull it until seen as necessary.

Rarely, there are no permanent teeth located under fused double teeth. Your dentist will be able to provide more information about the permanent teeth through a simple x-ray.

One thing to watch out for is the propensity for fused and geminated teeth to have deep grooves between the "two" teeth. This groove can be very susceptible to developing cavities as it is hard to get a toothbrush all the way down in the crevice to clean it properly. You may want Dr. Jolley to put a sealant in this groove to help prevent a cavity. (See our previous blog post or website on sealants.)

How Are Gemination and Fusion Treated?

Dr. Jolley’s recommendation for his own son is to let the tooth run its own course. In other words, we treat the tooth as a normal tooth. There aren’t any deep grooves to worry about, and there is no reason to split the tooth, because his mouth appears to be allowing for ample space for both permanent teeth to come in.

Sometimes, your dentist will be able to shave down and smooth the double tooth so that it doesn't appear very obvious to the casual observer. (Cosmetics shouldn’t be an issue yet.) I say sometimes because the anatomy of twinned teeth can be complex. If the pulp (click here to learn about the different layers of the tooth) is too close to the surface, then the dentist won't be able to shave down very much of the surface.

Very rarely, the dentist may be able to surgically divide the teeth but usually this is not necessary. This often works best with fusion because both teeth usually have their own separate pulp chambers and root systems. In any case, when surgically dividing the teeth, both teeth will need to have root canal treatment performed on them, which can end up being quite costly. Again, not a recommendation by Dr. Jolley.

In case you're curious - no one really notices it at all. Only a few family members asked about the tooth when our son was a baby. When he was pre-school age to present, no one can even tell. Now that his permanent teeth are erupting there is a little bit of crowding and crooked teeth, but Dr. Jolley has learned through his education and experience that the tongue, to some degree, is a natural aid in pushing permanent teeth into place. We are keeping an eye on it and hoping not to have to pull the fused tooth. If we do, even that is minimal in treating it.

Since kids will most likely lose all of their front teeth by the time they're 9, you may elect to do nothing about the double tooth ~ unless it's a huge orthodontic concern. I noticed some pictures on the web show an open bite caused by it, but this is even rarer than the tooth itself. One lady commenting on a blog discussing a geminated tooth said to just "enjoy its cuteness"...and that may very well be sound advice!

Conclusion & Further Reading

Do you have any questions or comments about double teeth? Do you or your child have double teeth? If so, what did you do, if anything, to treat it?

Please share your experiences in the comments section below, so we can all learn from them. Thanks for reading!

Portions of this article were written and edited by Debie Jolley. (Dr. Jolley’s wife) My resource of expertise comes from the answers I get from Dr. Jolley himself. 

Article source:Tom @ http://www.oralanswers.com/2010/09/double-teeth-gemination-and-fusion/

Tom is a 4^th year dental student who has a lot of really interesting articles on his blog! Thanks Tom!

For the record, (Tom, a blogger and dental student) got his facts (the statistics) about gemination and fusion from this book: Oral and Maxillofacial Pathology by Neville. If you want to read more on double teeth, Tom highly recommends that book.