Seeing a second row of teeth in a six-year-old's mouth worries many parents, but it rarely means the teeth are coming in wrong. The new adult tooth has simply arrived before the baby tooth in front of it has let go. Most of the time the baby tooth loosens and falls out by itself, and the tongue then guides the new tooth forward.
Why the lower front teeth are the usual culprits
The nickname "shark teeth" comes from the double row, and it shows up most often with the lower front teeth, usually around six to seven, when the lower front adult teeth tend to arrive. It can happen with upper teeth and back baby molars too, but less often.
The reason is mostly anatomy. The adult lower incisors develop just behind the roots of the baby incisors, on the tongue side. As they move up, they usually dissolve the baby roots and the baby tooth drops out on cue. When the adult tooth takes a path slightly further back, it may not dissolve enough of the baby root, so the baby tooth stays firm while the adult tooth comes through behind it. That is a difference in timing and angle, not a sign of a disease.
Lack of space can play a part. Adult incisors are wider than the baby teeth they replace, and a crowded jaw may push them further towards the tongue. Our chart of the order baby teeth come and go shows where this stage sits in the wider sequence.
A few weeks of waiting is normal
If the baby tooth is already wobbly, it will usually come out on its own, sometimes within weeks and sometimes after longer. Once it has gone, pressure from the tongue tends to move the adult tooth forward into the arch. The new tooth may still look a little crooked or crowded for a while, which is common at this age while the jaw grows and more adult teeth arrive.
A child can help things along by wiggling the loose tooth with the tongue or a clean finger and by eating normal textured food such as apple or raw carrot. Pulling hard, or tying string to a firm tooth, is not a good idea; it hurts, can tear the gum and may break the tooth, leaving a fragment behind.
Keep the crowded spot clean
Two rows of teeth create a small ledge where plaque and food sit. Angle the brush so the bristles reach behind the baby tooth and around the gum of the new tooth, and help younger children with brushing until they can do it thoroughly themselves. Gums around an erupting tooth can be a bit puffy and may bleed slightly when brushed; this usually settles once the area is kept clean.
Signs it is time for a check
A dental visit makes sense in any of these situations:
- the baby tooth is still firm after several weeks, even though the adult tooth is clearly through
- the double row has lasted a few months with little change
- there is pain, swelling, a gum boil or a bad taste near the area
- the adult tooth is coming in at a sharp angle or biting against the wrong teeth
- the same thing is happening at several teeth at once
At the appointment, the dentist checks how loose the baby tooth is, where the adult tooth sits and whether there is enough room. An X-ray is sometimes taken if the picture is unclear. Advice on how long to wait varies between dentists, because the evidence comes mostly from clinical experience rather than trials, and some lower front teeth straighten without any treatment. When a baby tooth is firmly holding on, removing it under local anaesthetic is a quick procedure and usually lets the adult tooth drift forward over the following months. If crowding is significant, the dentist may suggest keeping an eye on it as more teeth change, or talk about early orthodontic assessment.
Shark teeth are sometimes first spotted at a routine visit, which is one reason regular children's check-ups are useful through the mixed-teeth years.
What parents also ask
Will the adult tooth stay behind the others?
Usually not. Once the baby tooth is out, the tongue tends to push the adult tooth forward. If it stays out of line after the area has settled, the dentist can explain whether anything is worth doing and when.
Is it painful?
Most children feel little more than mild tenderness. Real pain or swelling is not typical and should be checked.
Did something we did cause it?
No. It reflects the angle and timing of the adult tooth, and sometimes the amount of room in the jaw. It is not caused by brushing habits or diet.
If a baby tooth is refusing to move in front of a new adult tooth, a dentist can tell you whether to wait or help it out. Read more in our guide to when baby teeth fall out, see the current family offers, or book a check-up.
