Which teeth become impacted, and why it varies
| Tooth | Frequency | Typical management |
|---|
| Lower third molar | Most common | Removal when findings warrant it |
| Upper canine | Second most common | Surgical exposure and traction into the arch |
| Upper second premolar | Uncommon | Depends on space and angle |
| Lower second molar | Uncommon | Uprighting, sometimes surgically assisted |
The upper canine deserves special attention. It is the cornerstone of the smile and of the bite, it has the longest eruption path of any tooth, and it is the one impaction where preserving rather than removing is almost always the goal. Age matters enormously: traction into position succeeds far more reliably in early adolescence than in adulthood.
Why an impacted tooth is not harmless just because it is quiet
The two consequences that concern dentists both develop without symptoms. The first is root resorption — an impacted canine or third molar pressing on a neighbouring root can dissolve it, and the neighbour, a perfectly healthy tooth, may be lost. The second is cyst formation in the follicle around the buried crown, which expands slowly, thins the bone, and in a minority of cases reaches a size requiring major reconstruction. Neither produces pain in its early stages. This is why periodic radiographs, not the absence of symptoms, are how impaction is monitored.
Signs that a tooth may be impacted
- A baby tooth still firmly in place well past the usual age of replacement — the classic sign of an impacted upper canine underneath.
- An obvious gap where a tooth should be, with the neighbouring teeth drifting.
- A firm bulge in the palate or the outer gum where the buried crown is sitting.
- Asymmetry — the same tooth erupted normally on the other side months ago.
- Intermittent swelling or a bad taste from a partially erupted molar.
Treatment routes
- Monitor. Reasonable for a deeply buried, asymptomatic tooth with no cyst and no effect on neighbours, especially in older adults, with periodic imaging.
- Surgical exposure and traction. The gum is opened, an attachment bonded to the crown, and light orthodontic force guides the tooth into the arch over months. This is the preferred route for upper canines and is part of a broader orthodontic plan.
- Uprighting. For a tilted lower second molar, moving it into an upright position rather than removing it.
- Removal. Indicated when the tooth is damaging a neighbour, has a cyst, is causing recurring infection, or cannot realistically be brought into function. Implant replacement is discussed when the lost tooth is functionally important.
Why CBCT imaging changed this diagnosis
A conventional two-dimensional radiograph flattens the picture, and the critical questions about an impacted tooth are three-dimensional: exactly where is the crown relative to the palate, is a neighbouring root already resorbing, and how close is the root to the nerve. Cone-beam CT answers these directly, which is why it has become standard before surgical exposure or difficult removal. Ask to see your own scan — the anatomy is usually easier to understand visually than verbally.
Notes for families based in Korea
If your child has a baby tooth that has not been replaced long after its counterpart on the other side, have it imaged rather than waiting further; an impacted canine treated in early adolescence has a substantially better outlook than the same tooth at twenty. For families near Camp Humphreys we are roughly 30 minutes away, consultations are conducted in English, and we provide written summaries and copies of all imaging so that treatment can be continued elsewhere if you relocate mid-course. Book a consultation to have it assessed.
Frequently asked questions
What does it mean if a baby tooth has not fallen out but the same tooth came in on the other side?
That asymmetry is one of the most reliable signs of an impacted permanent tooth underneath, most often an upper canine. The baby tooth stays because nothing is pushing it out. It should be imaged rather than watched further, since the success of guiding an impacted canine into position drops considerably with age.
Is an impacted tooth dangerous if it never hurts?
It can be, and the absence of pain is precisely why it is monitored radiographically rather than symptomatically. The two main risks are resorption of a neighbouring root, which can cost you a healthy tooth, and cyst formation around the buried crown, which expands and thins the bone. Both are silent in their early stages and both are visible on imaging long before they are felt.
Can an impacted tooth be brought into position instead of removed?
Often yes, particularly an upper canine. The gum is surgically opened, an attachment is bonded to the crown, and gentle orthodontic force guides it into the arch over several months. Success depends on the angle, depth, and above all the patient age. For a functionally important tooth like the canine, this is generally attempted before removal is considered.
Why does my dentist want a CBCT scan rather than a normal X-ray?
Because the decisions are three-dimensional. A flat radiograph cannot reliably show whether the crown lies toward the palate or the cheek, whether a neighbouring root is already resorbing, or how close a root sits to a nerve. CBCT answers all three, which improves both surgical planning and the accuracy of the risk discussion you are asked to consent to.
Is there an age at which it becomes too late to align an impacted canine?
There is no absolute cut-off, but the odds shift steadily. In early adolescence the bone remodels readily and traction is usually successful. In adulthood the tooth may be ankylosed, effectively fused to bone, in which case it will not move regardless of the force applied and removal with a replacement plan becomes the realistic option. Earlier assessment preserves choices.
What happens if an impacted tooth is simply left alone?
Sometimes nothing for decades, which is why monitoring is a legitimate option for a deeply buried asymptomatic tooth in an older adult. The problem is that the failure modes are silent, so leaving it alone must mean periodic imaging rather than ignoring it. Left genuinely unchecked, the possible outcomes are a resorbed neighbour or an expanding cyst discovered late.