Dental ankylosis is a condition where a tooth directly fuses to the surrounding jawbone. This fusion prevents the tooth from erupting or moving. Unlike healthy teeth, which are connected to the bone by a flexible periodontal ligament, an ankylosed tooth becomes rigidly attached. This can occur in both primary and permanent teeth.
Understanding Dental Ankylosis
Normally, teeth are held in their sockets by the periodontal ligament, which allows for slight movement and eruption. In dental ankylosis, this ligament is lost, leading to a direct bone-to-root fusion. This means the tooth cannot erupt or respond to orthodontic forces.
An ankylosed tooth often appears shorter or “submerged” compared to adjacent teeth. This happens because the ankylosed tooth remains static while surrounding bone and other teeth continue to grow and erupt. The tooth will also lack normal mobility and may produce a dull, high-pitched sound when gently tapped.
Why Dental Ankylosis Occurs
The exact reasons for dental ankylosis are not fully understood, but several factors contribute to its development. One cause is dental trauma, such as a severe blow or injuries like luxation (dislocation) or avulsion (tooth knocked out). Such injuries can damage the periodontal ligament, allowing bone cells to invade and fuse with the tooth root.
Genetic predisposition also plays a role, with some individuals inheriting a tendency for their periodontal ligament to malfunction or for bone to fuse with the tooth. Infections or chronic inflammation can also contribute by damaging the periodontal ligament and promoting abnormal bone growth. Developmental anomalies during tooth formation or disturbed local metabolism have also been implicated.
Recognizing and Confirming Dental Ankylosis
Ankylosis is diagnosed through clinical examination and imaging. Visually, infraocclusion may be observed, where the affected tooth appears lower than its neighbors. The tooth will also feel immobile when tested, unlike healthy teeth that have a slight give.
Percussion testing, involving tapping the tooth, can reveal a characteristic dull or metallic sound, differing from a healthy tooth’s clear sound. Dental X-rays confirm the diagnosis. Radiographs show absence or partial loss of the periodontal ligament space around the tooth root, indicating direct bone-to-root fusion. They may also reveal signs of replacement resorption, where the tooth root is gradually replaced by bone.
Managing Dental Ankylosis
Management of dental ankylosis depends on factors like the patient’s age, whether the tooth is primary or permanent, and condition severity. In mild cases, especially with primary teeth not causing significant issues, observation may be recommended. However, if the ankylosed primary tooth interferes with permanent tooth eruption, extraction is often necessary.
For permanent teeth, treatment options vary. Decoronation, surgically removing the crown while leaving the root submerged, can preserve alveolar bone and allow for future prosthetic solutions like implants. This is useful in growing patients to maintain jawbone height. Orthodontic treatment alone is ineffective for moving ankylosed teeth due to their fusion with the bone, but it may be used to align surrounding teeth or create space.
If the ankylosed tooth causes significant functional or aesthetic problems, or if decoronation is not suitable, extraction may be required. Following extraction, prosthetic solutions like dental implants or bridges can restore the missing tooth and maintain oral function. Long-term management often involves a multidisciplinary approach with ongoing monitoring and tailored interventions.