Tooth Pushed Into the Gum After a Fall: Why Intrusion Is the Most Serious Luxation

Of all the ways a tooth can be displaced without coming out altogether, being driven upwards into the bone is the one with the least favourable outlook. It looks less dramatic than a tooth knocked sideways or hanging loose, which is part of the problem — it is easy to underestimate.

Understanding why it is serious also explains why the single most important instruction is to leave it alone.

A tooth is not fixed to bone. It is suspended in its socket by the periodontal ligament, a layer of collagen fibres less than half a millimetre thick running between the root surface and the socket wall. Within that layer are the cells that maintain the root surface and the bone, and it is these cells that allow a displaced tooth to reattach and heal.

An intrusive force compresses that layer between two hard surfaces — root and bone — and crushes it. Three things happen at once:

The ligament cells over the compressed areas die. This is the critical damage, and it is what distinguishes intrusion from a sideways displacement, where the ligament is stretched and torn but large areas survive.

The socket wall fractures. The tooth is essentially being driven into bone that has to give way, so the thin plate of bone lining the socket splits.

The blood vessels at the root tip are severed or crushed. They enter through a small opening at the apex, and driving the root deeper shears them.

Where the ligament cells are destroyed over a wide area, the bone remodelling process that continuously turns over the jaw does not recognise a boundary any more. Bone cells make direct contact with the root surface, and the root becomes incorporated into the normal bone turnover cycle.

The result is ankylosis — the tooth fuses directly to bone — followed by replacement resorption, in which root substance is gradually replaced by bone over years. The tooth becomes rigidly immobile and produces a distinctive high-pitched note when tapped, quite different from the dull sound of a normal tooth.

In a growing child this has a further consequence: an ankylosed tooth cannot move with the developing jaw, so as the surrounding teeth and bone grow downwards, it is left behind and appears progressively submerged.

This is the main reason intrusion is graded as the most severe of the luxation injuries, and it is also the reason why forcing the tooth back manually makes things worse — additional uncontrolled force damages whatever ligament cells have survived.

This is the distinction that governs management, and it is worth knowing because it explains why two people with apparently identical injuries are treated completely differently.

An immature tooth with an open apex — typically in a child, where the root is still forming — has a wide opening at the root tip. Blood vessels can re-enter, so the pulp has a genuine chance of surviving. These teeth also have a strong tendency to re-erupt spontaneously. For mild and moderate intrusion the usual approach is therefore to wait and monitor, often for several weeks, intervening only if no movement occurs.

A mature tooth with a closed apex has a narrow opening and effectively no prospect of revascularisation. The pulp will become necrotic in the great majority of cases. These teeth are repositioned actively — either surgically or by orthodontic traction pulling the tooth down gradually — and, critically, root canal treatment is usually started within a couple of weeks, before the necrotic pulp can trigger inflammatory root resorption.

That timing matters. Inflammatory external resorption after intrusion can destroy a root remarkably quickly, and removing the necrotic pulp early is what prevents it. A placement of calcium hydroxide within the canal is commonly used during this phase.

• The surviving ligament cells are the tooth's only route to normal healing, and they are fragile

• Force applied by hand is uncontrolled in both direction and magnitude, and the socket wall is already fractured

• The root may already be fractured below the gum where it cannot be seen

• Bacteria from fingers enter traumatised tissue

• Any residual blood supply is put at further risk

Professional repositioning uses measured force in a planned direction, guided by radiographs, and is often done gradually with orthodontic traction precisely to avoid a second crushing injury.

• Stay calm and look at the whole picture, not only the tooth. A fall hard enough to intrude a tooth can cause concussion, a jaw fracture or a cut needing closure

• Do not touch, wiggle, push or pull the tooth

• Rinse gently with lukewarm water or saline

• Cold compress to the outside of the face

• Control bleeding from the gum with gentle pressure on clean gauze — our article on bleeding after a dental injury covers this

• Soft diet, nothing requiring biting with the front teeth

• Contact a dentist the same day, and an emergency service if out of hours

• Note the time and circumstances of the injury, which affects treatment decisions

• Check tetanus status if the injury involved soil or a dirty surface

Go to A&E rather than a dental practice if there was loss of consciousness, vomiting, confusion, persistent headache, clear fluid from the nose or ear, an inability to bring the teeth together, or a deformity of the jaw.

Our article on what counts as a true dental emergency covers the thresholds, and our article on urgent care for a broken tooth after an accident covers the associated injuries. Where a tooth has come out entirely, the priorities are completely different — our article on handling a knocked-out adult tooth covers that.

Intrusion is common in toddlers, whose front teeth sit in thin, soft bone. The concern is not the baby tooth but the permanent tooth developing directly behind and above it.

The direction of displacement determines management, and it can only be established radiographically. If the root has been driven away from the permanent tooth bud, the baby tooth is usually left to re-erupt, which frequently happens over weeks to months. If it has been driven towards the bud, extraction is generally advised to avoid damage to the developing permanent tooth.

Parents should be aware that an injury at this age can leave a permanent mark on the successor tooth — a white or brown patch, or an irregularity in the enamel — which may only become apparent years later when it erupts. Our article on dental trauma in children covers this.

An intruded tooth is monitored at intervals over several years. Reviews look for loss of vitality, discolouration, ankylosis, inflammatory resorption, loss of surrounding bone and, in children, whether the tooth is keeping pace with jaw growth.

The realistic outlook depends heavily on the depth of intrusion and the maturity of the root. Deeper intrusion and a closed apex both worsen it. This is not a reason for pessimism, but it is a reason for attending reviews even when everything feels normal — resorption usually produces no symptoms and is detected on radiographs long before it is felt. Our article on apical periodontitis covers one of the complications, and our article on root canal treatment after trauma covers the endodontic side.

Where a tooth is eventually lost, planning the replacement early matters, particularly in a growing patient where implants are not appropriate until growth has finished. Our article on preserving the ridge after extraction covers the bone considerations.

Prevention, for what it is worth afterwards: a properly fitted mouthguard for contact and wheeled sports. Our article on sports dental trauma and mouthguards covers this.

• Intrusion crushes the periodontal ligament between root and bone, killing the cells needed for normal healing.

• Loss of those cells can lead to ankylosis and gradual replacement of root by bone.

• The blood supply at the root tip is usually severed, so a mature tooth almost always loses vitality.

• An open root apex allows revascularisation and spontaneous re-eruption; a closed apex does not.

• Root canal treatment in a mature intruded tooth is usually started within about two weeks to prevent inflammatory resorption.

• Never attempt to reposition the tooth yourself.

An intruded tooth needs same-day assessment. You can contact our team or use our emergency dentist service, and treatment may involve root canal treatment at a later stage.

This article is provided for general information only and does not constitute dental or medical advice. Dental trauma requires prompt clinical assessment and radiographs, and outcomes vary considerably with the depth of intrusion and the maturity of the root. If there was loss of consciousness, vomiting, confusion or a suspected jaw fracture, attend an accident and emergency department.

Next review due: 13 August 2027