Root Resorption

In root resorption (synonyms: dental resorption; inflammatory root resorption; inflammatory resorption; replacement resorption; external root resorption; external tooth resorption; internal inflammatory root resorption; internal granuloma of the pulp; internal root resorption; invasive cervical resorption (ECIR); surface resorption; pathologic tooth resorption; physiologic root resorption; physiologic tooth resorption; tooth resorption; Engl. infection related root resorption; orthodontically induced inflammatory root resorption (OIIRR); ICD-10 K03.3: pathological tooth resorption; internal granuloma of the pulp) is the physiological or pathological (pathological) degradation of root cementum or cementum and dentin in the area of one or more tooth roots, which is not caused by caries. Forms of the disease

Physiological/pathological root resorption

Root resorption on teeth of the first dentition (deciduous teeth) is considered physiological in the context of tooth change. If resorption of a deciduous tooth root is initiated by an adjacent tooth rather than the actual successor, this is referred to as undermining resorption. If teeth of the second dentition (permanent teeth) are affected, a pathological event must be assumed. Differentiation according to localization

  • Internal resorptions originate in the endodont (pulp/tooth pulp):
    • Metaplastic – root canal replacement resorption; dentin replacement (dental bone replacement) by bone or cementum.
    • Internal root resorption (internal granuloma/inflammatory nodular tissue neoplasm) – chronic inflammatory; up to root perforation, without replacement with hard tissue
  • External resorptions show defects on the outer root surface:
    • Surface resorption
    • Apical (“around the root tip”)
    • Cervical – supraalveolar (“above the tooth socket”), in the cervical region.
    • Lateral – subalveolar (“below the tooth compartment”).

Differentiation by cause

  • Trauma-induced resorption
    • Transient resorption/surface resorption: in cases of small, spatially limited root cementum damage (<20% of surface area).
    • Replacement resorption / ankylosis (“fusion of the teeth with the jawbone“): from massive root cementum damage (> 20% of the surface) results in remodeling in the form of an external bony replacement resorption (English : osseous replacement), thereby dentoalveolar ankylosis.
  • Infection-related resorption
    • External resorption due to continuation of a root canal infection into the periodontium (periodontium) associated with root cementum damage.
    • Internal resorption in the presence of a root canal infection with vital tissue in the resorption area.
  • Invasive cervical resorption (ECIR; Hyperplastic invasive resorption – Resorption processes originating from the neck of the tooth, depending on the extent (classes I to IV) small to beyond the coronal (“towards the crown”) third of the root to apical (“around the root apex”).

Differentiation according to course

  • Transient (temporary)
    • External – surface resorption, e.g., after trauma (injury); self-limiting.
    • Internal – e.g. after trauma, after orthodontic or periodontal treatment.
  • Progressive (progressive)
    • Replacement resorption – root replacement by bone formation in the desmodont (tooth root membrane) and on the root surface; due to ankylosis of the tooth.
    • Internal resorption in infection of vital pulp tissue with increasing spread without replacement by hard tissue.
    • Invasive cervical resorption (ECIR).

The prevalence (disease frequency) of internal resorption (internal granuloma) is reported between 0.01% and 1.64%. Anterior teeth are most commonly affected, followed by molars (permanent, large, multicuspid posterior teeth) and premolars (anterior molars). Course and prognosis: recurrences (recurrence of the disease) cannot be ruled out.

  • Transient (temporary) external resorption: self-limiting (resorption period two to three weeks), reversible (capable of regression).
  • Replacement resorption: the more severe the periodontal damage caused by trauma, the worse the prognosis. The older a patient is at the time of trauma, the slower the progression in the form of root replacement by bone to tooth loss.
  • Resorption due to infection: complete dissolution of the root is possible within months.
  • Internal resorption: circular resorption up to spontaneous fracture (“spontaneous tooth fracture”); progression (progressive) as long as vital (“living”) resorptive tissue is given in the root canal.
  • Invasive cervical resorption: aggressive progression.

Comorbidities (concomitant diseases): replacement resorption/ankylosis may result in infraposition (malposition of teeth or groups of teeth) of the affected tooth in growing patients.