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
1st above and to the left, has an upper ‘double tooth’ which is Gemination. Our son, the toddler
pictured 2nd, 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.
Tom
is a 4th 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.
