Dens Invaginatus

Types of Dens Invaginatus

Dens invaginatus is classified into three types using the Oehlers system, based on how deep the infolding goes. The deeper it extends, the higher the risk — and the more involved the treatment.

• Type I - Confined to the Crown

  The fold stays within the visible part of the tooth and does not extend into the root. It does not communicate with the surrounding gum and bone tissue — but the opening at the tooth surface is still accessible to bacteria, which is why sealing it early is recommended. This is the mildest form and, if caught early, can often be managed with a simple preventive seal.

• Type II - Extends Into the Root

  The fold reaches down into the root but remains a closed channel — it does not break through to the surrounding tissues. The nerve and blood supply inside the tooth (the pulp) may or may not be affected, depending on how deep the fold runs.

• Type III — Extends Through the Root

  The fold travels all the way through the root and opens either at the side of the root (Type IIIa) or at the root tip (Type IIIb). This creates a direct pathway between the inside of the tooth and the surrounding bone and tissue — which is why Type III carries the greatest risk of infection and requires the most complex care.

Which Teeth Are Affected

The upper lateral incisors — the permanent teeth sitting immediately next to your two front teeth — are the most commonly affected.

Dens invaginatus can also occur in upper central incisors, canines, and less commonly in premolars and molars. Any tooth in the mouth can theoretically be affected, though front teeth in the upper jaw are where it is found most often.

The condition can also affect the same tooth on both sides of the mouth at the same time. This means that if dens invaginatus is identified in one upper lateral incisor, the tooth on the opposite side should always be examined and X-rayed as well — even if it appears completely normal.

What Causes Dens Invaginatus

The exact cause of dens invaginatus is not fully understood. What is known is that the anomaly develops during tooth formation — before the tooth has even erupted — as a result of a disruption in the way the tooth folds and takes shape.

Several possible explanations have been proposed by researchers, including pressure on the developing tooth, localized infection or trauma affecting the tooth bud, and genetic factors. The fact that the condition sometimes affects the same tooth on both sides of the mouth, and that it has been observed across family members, points to a hereditary component in some cases.

The important thing to understand is that this is not caused by anything a patient did or did not do. The tooth erupts already carrying the structural anomaly — it is present from the moment the tooth forms.

Signs and Symptoms to Watch For

Dens invaginatus is often symptom-free in its early stages — the tooth can look and feel completely normal while the internal channel is already providing a pathway for bacteria. This is what makes routine dental X-rays so important for catching it before problems develop.

When symptoms do appear, they are usually a sign that infection has already taken hold inside the tooth:

• A tooth with an unusual shape — slightly more conical or pointed than expected, or smaller than the tooth on the opposite side
• A small pit or dimple on the inner surface of the tooth (the side facing the roof of the mouth)
• Pain or sensitivity to cold, heat, or biting pressure
• Swelling, tenderness, or a small lump in the gum near the affected tooth
• A small pimple-like opening on the gum that may weep or discharge — known as a sinus tract
• Darkening or discoloration of the tooth, which can be a later sign that the nerve inside has been affected

In children and teenagers, a recently erupted upper incisor that becomes painful or infected — with no obvious cavity or visible cause — should always be investigated for dens invaginatus.

Why Dens Invaginatus Should Not Be Left Untreated

The internal channel created by dens invaginatus is lined with defective or absent enamel — the hard protective layer that normally shields a tooth. It cannot be cleaned by brushing, and it gives bacteria a direct route to the nerve and blood supply at the center of the tooth (the pulp).

What makes this particularly concerning is the speed at which it can happen. The pulp can become infected and die in a tooth that has only recently erupted and shows no visible sign of decay on the surface. From the outside, the tooth looks fine. Inside, the damage is already underway.

Once the pulp is affected, infection does not stay contained:

• It can spread to the bone and tissue around the root tip, leading to a dental abscess or cyst
• In Type III cases, where the channel opens onto the root surface, infection can also spread along the root into the surrounding bone
• In severe or long-standing cases, the infection can extend further into the jaw

There is an additional concern for children and teenagers. In a developing permanent tooth, the root is still growing after the tooth erupts. If the pulp is lost before that process is complete, root development stops — leaving a shorter root with thinner walls that is more difficult to treat and less resilient long-term.

The earlier dens invaginatus is identified, the more options are available. When it is caught before infection has developed, a straightforward preventive seal may be all that is needed.

How Dens Invaginatus Is Treated

Treatment depends on the Oehlers type, whether infection is present, and — particularly in younger patients — how far the root has developed. The goal is always the same: eliminate the channel as a pathway for bacteria and, wherever possible, save the tooth.

• Preventive Sealing

  When dens invaginatus is caught before any infection has developed — ideally soon after the tooth erupts — the channel can be cleaned and sealed with a dental resin. This closes off the bacterial entry point entirely and, if done early enough, can keep the tooth healthy long-term with no further intervention needed.

  This is the best possible outcome, and it is only available when the condition is identified early.

• Root Canal Treatment

  When the nerve and blood supply inside the tooth have been affected, root canal treatment is required. In dens invaginatus cases, this is often more involved than a standard root canal — because the tooth may effectively have two separate internal systems to treat: the main canal of the tooth and the invagination channel itself.

  Before treatment begins, a CBCT scan — a specialist three-dimensional X-ray — is used to map the internal structure of the tooth in detail. This allows the endodontist to plan treatment precisely for that tooth's specific anatomy.

• Treatment for Teeth Still Developing

  In children and teenagers, a permanent tooth may still be forming its root at the time dens invaginatus is diagnosed. If the nerve has been lost before that process is complete, root development stops — which changes how treatment is approached.

  In these cases, the treating specialist may use procedures designed either to encourage the root to continue developing, or to create a stable seal at the root tip using a biocompatible material. Both approaches are well-established in specialist endodontic practice and are chosen based on the individual tooth and the patient's age.

• Surgical Treatment

  For the most severe cases — where the invagination channel opens onto the root surface or root tip — root canal treatment from inside the tooth may not be sufficient on its own. In these situations, a minor surgical procedure may be needed to access and seal the affected area from outside the tooth.

  Where a tooth cannot be saved and extraction is necessary, the options for managing that space — including tooth replacement — would be discussed with the treating specialist.

Who Carries Out Treatment

Because of the complexity of the internal anatomy involved, treatment is led by a Board-Certified Specialist Endodontist. Where surgical management is needed, the Oral & Maxillofacial Surgery team works in coordination. In cases where extraction creates a space that needs to be managed orthodontically, a Specialist Orthodontist may also be involved.