If you have noticed a new tooth growing in behind your child's baby tooth — instead of pushing it out — you are seeing something that surprises most parents but is actually quite common. It is sometimes called "shark teeth" because it creates a double row. The clinical term is ectopic eruption of a permanent tooth.
Why does it happen?
Normally, the root of a baby tooth is gradually dissolved (resorbed) as the permanent tooth grows up from below. When resorption happens in the right place, the permanent tooth pushes the baby tooth out and erupts in its position.
Sometimes the permanent tooth begins erupting slightly behind or to the side of the baby tooth rather than directly below it. Because it is not pressing on the root from underneath, the baby tooth's root does not dissolve — and the baby tooth stays in place while the permanent tooth comes in regardless, creating the double row.
This is most common in the lower front teeth between ages 5 and 7, when the lower permanent incisors erupt.
Will it fix itself?
For the lower front teeth, often yes — if the baby tooth is already loose. Once the baby tooth is out (whether it falls out on its own or is removed), the tongue usually pushes the new permanent tooth forward into the correct position within a few weeks to a couple of months. The arch of the lower jaw is flexible and accommodating at this age.
If the baby tooth is already wobbly, encourage your child to wiggle it. Most cases in the lower front teeth resolve without any intervention once the baby tooth is gone.
When does it need attention?
Book an appointment if: the baby tooth is not loose at all and the permanent tooth is already fully or mostly through — if the baby tooth shows no sign of becoming loose on its own, it may need to be extracted to make room; the permanent tooth is erupting in the upper jaw behind a baby tooth — upper teeth have less room to self-correct; the new tooth is coming in very far out of line, or multiple teeth are involved; your child is over 7 and the baby tooth is still firmly in place with the permanent tooth already visible.
Dr. Bhuvanesswari and her team monitor eruption patterns from early childhood. If there is a concern about spacing or bite development, she will advise on the right time to act.
What the dentist will do
At the appointment, we will look at how mobile the baby tooth is, how far through the permanent tooth is, whether there is enough space for the permanent tooth to move into position, and whether the bite is affected.
If the baby tooth needs to come out, extraction of a baby front tooth is a simple, brief procedure. We use topical anaesthetic before the injection to minimise discomfort. Most children are surprised by how quick it is. In most cases, no further treatment is needed after the baby tooth is removed.
A note on eruption monitoring
Shark teeth in the lower front region are almost always a normal part of development and not a sign of a serious crowding problem. However, the timing and pattern of tooth eruption does give the dentist useful information about how the jaw and bite are developing — one reason regular dental visits from age 1 matter.
Sources: American Academy of Pediatric Dentistry Reference Manual 2022–2023; Gellin ME, "The distribution of ectopic eruptions of permanent first molars and permanent mandibular lateral incisors", ASDC Journal of Dentistry for Children, 1984.