Two year-old has two pairs of joined teeth

I have noticed that my 2.5 year-old has 2 pairs of joined teeth, i.e. the 4 bottom center teeth do not appear separate, but as two joined teeth. Is this normal? Should I be concerned?

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Dear Sock-Cheng,

It sounds to me as if your child has 2 sets of primary teeth which have fused together. I do not have exact statistics on how often fusion of teeth occurs, but through reading and experience, it does not appear to occur often, especially with 2 sets. Not much information is known about the genetics of this occurrence, but recent evidence shows it is probably autosomal dominant with very low penetrance.

Basically, fusion is the union of two dental organs which form a single tooth. The size of the joined teeth usually depends upon the stage of development at which fusion occurred. If fusion occurred early in development of the primary teeth, the fused teeth may appear normal in size or only slightly larger than a normal-sized tooth. It fusion occurred late in development, the fused teeth can appear to be about twice the size of normal teeth. Fusion in primary teeth does not necessarily mean the permanent teeth will also develop in this manner.

From what you describe, it sounds as if the primary incisors (central and lateral) might have fused. If this is the case, there should not be much concern as the lower primary incisors are generally lost in close proximity to each other. Before your child reaches the average age of exfoliation of the primary teeth (about 6 years old), a radiograph of the area should be taken to determine development of the permanent teeth underneath the fused teeth. If the fused teeth are blocking one of the permanent teeth from eruption, extraction of the fused tooth (or teeth) may be necessary. The radiograph will also show the condition of the permanent teeth. At this point, there is no cause to worry or obtain special treatment of the fused teeth, except to have a dentist do an examination to determine that this is indeed the condition. Otherwise, continue to practice good oral hygiene, including flossing where possible.

Thank you for your interesting question!

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