Tooth Retention

Tooth retention (synonyms: Tooth entrapment; Impacted tooth; Retained tooth; Partially retained tooth; Displaced nucleus; Fully retained tooth; Tooth retention; ICD-10: Ko1,- Retained and impacted teeth) refers to the retention of teeth in the jawbone.

A tooth is always considered retained when it does not appear in the oral cavity at the approximate time of its physiological eruption.

Sometimes we also speak of impacted teeth. In the case of an impacted tooth, tooth eruption has not occurred due to obstruction by another tooth.

One speaks of retention only when the affected tooth has not yet erupted, but root growth is already complete. In the case of a retained tooth, no tooth eruption has occurred even though there was no obstruction by another tooth.

The following teeth are most commonly retained:

  • Wisdom teeth
  • Upper canine – girls twice as common, usually left-sided.
  • Upper central incisor
  • 2nd premolar (premolars are the smaller molars of the resident dentition located directly behind the canines) of the mandible.
  • Lower canine tooth

Symptoms – complaints

If a tooth is impacted, it is missing in the tooth row, which has both functional and visual consequences for the affected patient.

Often, the situation is that of a persistent deciduous tooth, meaning that a deciduous tooth is present that shows no loosening and should normally have already been replaced by a permanent tooth.

Sometimes retained teeth are palpable as protrusions on the palate or in the vestibule (vestibule of the mouth).

Pathogenesis (development of disease) – Etiology (causes)

In most cases, the wisdom teeth simply do not have enough space in the jaw. Furthermore, it often happens that the tooth germs do not straighten and the teeth lie obliquely or even transversely in the jaw, which makes their eruption impossible.

The upper canines are often affected by the tooth germ deviating from its regular eruption path.

Traumatic causes, space-occupying processes as well as syndromes (see under diseases) are also possible for the retention of teeth.

Diseases associated with multiple tooth retentions are dysostosis cleidocraniales and osteodystrophia hereditaria (Martin-Albright syndrome).

Consequential diseases

As a result of leaving impacted teeth in place, root resorption of adjacent teeth or their displacement may occur. If the upper canine is impacted, physiological canine guidance cannot take place, sometimes resulting in dysfunction.

In older age, the canine tooth represents the strongest prosthetic pillar, so retention can make prosthetic restoration difficult in old age.

Diagnostics

The dentist or orthodontist knows the eruption times of the teeth quite well. Unilateral deciduous tooth persistence is one of the most important signs of retention. In addition, there is a midline shift and radiographically completed root growth in teeth that have not erupted into the oral cavity.

In addition to panoramic radiography, the following radiographic procedures are used:

  • Dental films
  • Bite recordings
  • Cephalometric lateral radiographs
  • Computed tomography (CT)

Therapy

Depending on which tooth is affected by retention, there are different therapeutic approaches. Sometimes, when retention of an upper canine is foreseeable, it is reasonable to remove the deciduous canine early to encourage and facilitate eruption of the permanent canine.

Alternatively, impacted canines are surgically exposed and then orthodontically aligned. Retained incisors, usually as a result of trauma or supernumerary teeth, are also exposed and classified, usually around age seven to nine. The earlier the intervention, the less severe the consequences of retention.

Retained wisdom teeth are usually removed. Retained wisdom teeth are often associated with cyst formation. Similarly, abscesses occur in association with impacted teeth, which can bring threatening complications.