Delayed Tooth Eruption in Children: When to Wait and When to Check

Delayed tooth eruption in children is usually normal variation, and the simple rule is to have it checked if no baby teeth have appeared by 18 months, if no adult teeth have appeared by around age 7, or if a gap where a baby tooth fell out has stayed empty for six months. Outside those thresholds, most children who look late are simply running on their own schedule.

Parents notice teeth. It is one of the first visible milestones, so a child whose front teeth arrive months after everyone else's in the playgroup causes real worry. In practice most of the children seen for this need nothing more than a note in the file and a look again in six months.

What follows is what is typical, what the thresholds are, what an x-ray answers that looking cannot, and what is done when something genuinely is blocking a tooth.

Key takeaways

• Baby teeth typically start erupting between 6 and 12 months, and an assessment is generally advised if none have appeared by 18 months.
• Permanent teeth typically start appearing around age 6, and a delay is generally considered if none have erupted by around age 7.
• If a baby tooth was lost six months or more ago and nothing is showing through, it is worth having looked at.
• Common causes include crowding, an over-retained or ankylosed baby tooth, an extra tooth blocking the path, an ectopically positioned tooth, past trauma, and a missing successor.
• Assessment usually involves a clinical examination plus an x-ray to confirm the tooth exists and to see where it is heading.
• Most children assessed for delayed eruption need monitoring only, and the delay is very rarely caused by anything a parent did.

What the typical timing looks like

Baby teeth generally begin to erupt between 6 and 12 months, usually starting with the lower front teeth, and the full set of twenty is normally complete somewhere around two and a half to three years of age. The order tends to be more consistent than the timing, which is why an unusual order is often more informative than a late start. If you want to see the usual sequence, our baby teeth eruption order chart sets it out.

Permanent teeth generally begin arriving around age 6, often with the first molars appearing behind the baby teeth without anything falling out first, and the lower front teeth loosening at a similar time. The changeover then continues in stages until around age 12 or 13.

The spread around those averages is wide. A range of six to twelve months either side of a typical age is common and is not a problem in itself.

A simple decision rule for parents

The last two rows are the most useful in practice. Comparing left with right in your own child's mouth is far more reliable than comparing your child with anyone else's.

What is not a reliable sign

Comparing a child to their classmates tells you very little. Eruption timing varies enormously between children of the same age, and a class photo is not a clinical dataset. Comparing to an older sibling is not much better, since timing varies within families too, and a first child who was early does not set the standard for the second.

A family history of late eruption, on the other hand, does mean something. It makes late eruption more likely in the child and is usually entirely benign. If one parent remembers being a late starter, that is worth mentioning at the appointment.

What actually causes a tooth to be late

The causes fall into two groups: local reasons, which are far more common, and general reasons, which are rare.

Local causes

• Lack of space or crowding. The permanent teeth are larger than the baby teeth they replace, and if the space has closed there may be nowhere for the tooth to come through.
• An over-retained or ankylosed baby tooth. A baby tooth that has fused to the bone will not loosen normally and can hold up its successor. These teeth often sit lower than their neighbours.
• A supernumerary tooth. An extra tooth sitting in the path of a permanent tooth is one of the classic reasons an upper front tooth does not arrive.
• An ectopically positioned tooth. The tooth is present but pointing the wrong way and heading somewhere other than its proper position. This is a common story with upper canines and is covered further in ectopic eruption of first molars.
• Previous trauma to the baby tooth. A knock in the toddler years can affect the developing permanent tooth sitting above it.
• Congenital absence of the successor. Sometimes the adult tooth simply never formed, which is more common than most parents expect and is explained in congenitally missing teeth.

General causes, which are uncommon

Less often, delayed eruption across the whole mouth rather than in one spot can relate to a general medical cause. These include hypothyroidism, hypopituitarism and hypoparathyroidism, nutritional deficiency including calcium and vitamin D, and syndromes such as Down syndrome, Apert syndrome and Ellis-van Creveld syndrome. The distinguishing feature is that these tend to affect eruption generally and are usually accompanied by other findings that a GP or paediatrician would already be following. A single late tooth is a local problem, not a systemic one.

What an x-ray answers that looking cannot

Looking in the mouth tells you a tooth has not arrived. It does not tell you why. An x-ray answers three questions that change what happens next.

First, is the tooth actually there? A tooth that never formed needs a completely different plan from one that is present but stuck. Second, where is it, and which way is it pointing? A tooth heading in the wrong direction may need space made or may need to be guided. Third, is anything in the way, such as an extra tooth, a cyst or a root that has not resorbed?

Radiographs in children are taken only when the answer will change the management, and modern equipment uses low doses with protective settings. How often they are appropriate is covered in dental x-rays for kids.

What is usually done about it

Treatment is chosen to be as light as the situation allows, and in most cases the answer is the lightest option of all.

• Monitor. Where the tooth is present, correctly positioned and simply slow, the plan is a review in six to twelve months with no intervention.
• Remove an over-retained baby tooth. If a stubborn baby tooth is physically blocking the path, taking it out often lets the permanent tooth come through on its own.
• Remove a supernumerary tooth. Extra teeth in the path are removed to clear the way, sometimes combined with orthodontic help.
• Maintain or regain space. A small appliance can hold space open so the arriving tooth has somewhere to go.
• Expose and guide the tooth. For a deeply positioned tooth, the surface can be uncovered surgically and an orthodontic attachment used to guide it into place over months.

The cost of waiting too long

Delay is usually harmless, but not always, and the risk is mostly about space. When a tooth does not arrive, the neighbouring teeth drift into the gap. What began as a tooth that needed a clear path becomes a tooth with no room at all, and a problem that could have been solved by removing one baby tooth turns into an orthodontic case with appliances and a longer timeline. That is the reason for the thresholds rather than open ended waiting.

Common questions

At what age is delayed tooth eruption a concern?

For baby teeth, an assessment is reasonable if nothing has appeared by the first birthday and is generally advised by 18 months. For permanent teeth, a delay is generally considered if none have begun erupting by around age 7. A gap that has stayed empty for six months after a baby tooth was lost is also worth checking.

Is late teething a sign of a problem?

Usually not. Late teething on its own, in a child who is otherwise growing and developing normally, is one of the more common normal variations. It becomes more relevant if it is combined with other developmental findings, which is a conversation for your GP as well as the dentist.

Could something I did cause this?

Almost certainly not. Eruption timing is largely determined by genetics and by local factors inside the jaw, none of which are influenced by feeding choices, dummies or how a child is cared for. Where a family history of late eruption exists, that is inherited rather than caused.

Does a missing baby tooth mean the adult tooth is missing too?

Not necessarily, though the two are linked more often than by chance. An x-ray settles it quickly by showing whether the permanent tooth is developing in the bone. If a permanent tooth is genuinely absent, there are several options and no rush to decide at a young age.

My child's adult tooth is coming through behind the baby tooth. Is that normal?

It is very common with the lower front teeth and is often called shark teeth. In most cases the baby tooth loosens and comes out on its own within a few weeks, and the new tooth moves forward into place. If the baby tooth stays firm after a couple of months, have it looked at.

Do we need an x-ray straight away?

Not always. If the clinical picture is clear and the child is only slightly behind, monitoring is often the first step. An x-ray is taken when the answer would change what happens next, such as when one side is well behind the other or when a baby tooth is not budging.

Book a check-up if a milestone has passed

If your child has passed one of the thresholds above, a routine check-up is the right first step, and it is usually a short, straightforward appointment. The team at Lumi Dental in Melrose Park sees children for exactly this kind of assessment and will explain clearly whether the answer is to monitor or to act.

Eligible children may be covered under the Child Dental Benefits Schedule, which is explained in our guide to the CDBS. You can read more about the practice on our general dentistry page, and see what is available for new families on our current deals page.