A submerged baby tooth is one that has fused to the surrounding bone and stopped erupting, so it appears to sink lower and lower as the teeth around it keep growing. The technical name for the fusion is ankylosis, and the result, a tooth sitting below the level of its neighbours, is called infraocclusion. It is a common finding in children, most often affecting the lower baby molars, and catching it early is what keeps management simple.
Key takeaways
- Ankylosis is a fusion of the tooth root to the bone, which stops the tooth erupting.
- As neighbouring teeth keep growing, the fused tooth appears to sink, which is called infraocclusion or submergence.
- The lower baby molars are most often affected, and the younger the child, the more marked it can become.
- Management ranges from monitoring a mild case to removing the tooth and holding the space.
What ankylosis is
A healthy tooth is held in its socket by the periodontal ligament, a thin cushion that separates the root from the bone and allows the tooth to erupt and adjust. In ankylosis, part of that ligament is lost and the root fuses directly to the bone. Because the fused tooth can no longer move, it stops erupting while the jaw and the neighbouring teeth continue to grow upward around it. Over time this makes the tooth look as if it is sinking into the gum, when in fact it is standing still while everything else rises. A dentist may first suspect it from a solid, higher-pitched note when the tooth is tapped, and confirm it on an X-ray.
Why it happens
The exact cause is not always clear. Recognised contributors include a family tendency, an earlier knock or injury to the tooth, a local disturbance in bone growth or metabolism, localised infection, and gaps in the periodontal ligament that let bone bridge across to the root. A missing permanent successor beneath the baby tooth also makes submergence more likely, because the adult tooth is not there to prompt the baby tooth to shed. This overlaps with the pattern behind a retained baby tooth in adults, where a missing successor lets the baby tooth linger and sometimes sink.
Why it matters
A mildly submerged baby tooth may cause no trouble at all, but a more marked case can create knock-on effects as the child grows. The table summarises the main ones.
| Consequence | What happens |
|---|---|
| Tipping of neighbours | Adjacent teeth lean into the space, causing crowding and lost arch length |
| Over-eruption opposite | The opposing tooth can grow down or up into the gap |
| Midline shift | The dental midline can drift, affecting symmetry |
| Successor problems | Any permanent tooth beneath can be deflected or blocked from erupting |
| Vertical bone defect | Bone height around the sunken tooth can fail to develop fully |
How it is managed
Because the effects build up over the growing years, early recognition and monitoring are the most important steps, so a dentist tracks a submerged tooth with regular reviews and X-rays and measures how far it sits below the bite. A mild, stable case in a child with a healthy successor beneath is often simply watched, as the tooth may still be shed naturally. A more severe case, a tooth with no successor, or one causing neighbouring teeth to tip is usually planned for removal, followed by a space maintainer to hold the gap for the adult tooth or for a later replacement. In some cases the biting surface can be built up to keep the tooth level while it is retained. The right plan depends on the child’s age, the severity, and whether an adult tooth is waiting below. Our guide on a baby tooth pushed into the gum covers a trauma-related situation that can precede ankylosis.
What parents should know
If a dentist mentions that your child has a submerged or ankylosed baby tooth, the key message is that it is common and manageable, and that regular monitoring is doing important work. Keeping up check-ups lets the dental team act at the right moment, neither too early nor too late, so the space is protected and the adult teeth have the best chance to come through in good position. Continue normal brushing and cleaning, since a submerged tooth can be harder to keep clean where it dips below the gumline. This is general information and not a substitute for an assessment of your child.
Frequently asked questions
What does a submerged baby tooth mean?
It has fused to the bone and stopped erupting, so it sits below the level of the neighbouring teeth as they keep growing. The fusion is called ankylosis.
Is an ankylosed baby tooth an emergency?
No. It is managed over time with monitoring and, where needed, planned treatment. The important thing is regular review so any knock-on effects are caught early.
Will it fall out on its own?
Sometimes, especially a mild case with a healthy adult tooth beneath. Others need removal, particularly if there is no successor or if neighbouring teeth are tipping.
What happens if it is left?
A significantly submerged tooth can let neighbouring teeth tip in, the opposing tooth over-erupt, the midline shift, and any successor be blocked, which is why it is monitored.
How is it treated?
Options range from monitoring a mild case to building up the biting surface, or removing the tooth and holding the space with a space maintainer for the adult tooth or a later replacement.
If your child has a baby tooth that seems to be sinking or sitting low, the team at Lumi Dental in Melrose Park can assess it and plan the right timing. Learn about our general dental care or see our current deals. We do not publish prices in our articles and are happy to provide a written estimate after an examination.
This article is general information only and is not a substitute for personalised dental advice. Please see a dentist about your child’s situation.
