Prevention of external apical root resorption during orthodontic treatment

  • Roberto Justus
Part of the following topical collections:
  1. Orthodontics


The issue of orthodontic-induced external apical root resorption (EARR) has attracted the interest of clinicians and investigators because of the alarming clinical and legal implications associated with its occurrence in a severe form. The January/February 2005 issue of the American Association of Orthodontist’s Bulletin reported that medical malpractice is a significant problem in the USA today and that patients are filing claims and lawsuits against medical and dental practitioners, including orthodontists, in record numbers. EARR is a common iatrogenic consequence of orthodontic treatment. Cross-sectional as well as longitudinal studies show that EARR is a small problem for the average orthodontic patient, with radiographic mean resorption of less than 2.5 mm. This magnitude of resorption has no adverse clinical consequences. However, 1–5% of orthodontic patients experience a severe form of EARR, defined as exceeding 4 mm or one-third of the original root length. Severe root resorption mainly occurs in maxillary incisors. It compromises crown–root ratios and can result in tooth mobility. The main etiologic risk factor for the severe form of EARR is genetic predisposition. Emphasis is thus given on the root-sparing treatment procedures to minimize the risk for development of the severe form of EARR. Orthodontists are highly trained dental caregivers obligated to abide by the Hippocratic Oath of doing no harm. It is the author’s hope that this article will create awareness among clinicians that there are orthodontic and orthopedic treatment regimes designed precisely to minimize or even avoid the development of EARR. Successful treatment should begin at a young age so that the clinician can take advantage of eruption guidance and of growth modification when a Class II skeletal problem exists. Suggested treatment regimes outlined in this paper minimize the distance that teeth/root apices need to be moved.


External apical root resorption Orthodontic treatment Genetic predisposition Risk management Root-sparing treatment procedures Eruption guidance Growth modification 

Quick reference/description

External apical root resorption (EARR) is the loss of root structure involving the apical region (Fig. 1). In severe cases, patients may experience a loss of more than 4 mm or one-third of the original root length. To successfully treat EARR, an adequate patient education and proper risk management is essential.
Fig. 1

Maxillary incisor periapical radiograph. Note severe EARR

Different types of root resorption include:


Causative factor

Infection root resorption

Microbial pathogens

Ankylotic root resorption


Pressure root resorption

Orthodontic forces

Pressure of impacted teeth

Tumors against adjacent roots


Root resorption


Arch wires

Fixed appliances

Intracoronal stabilizer

Palatal tongue spur appliance


External apical root resorption caused due to orthodontic pressure can be assessed by:
  • Pathology

  • Epidemiology

  • Risk factors

  • Etiology

  • Prognosis

  • Clinical recommendations to protect patients from developing EARR

  • Recommendations to minimize or avoid complaints

  • Pathology

Undermining resorption occurs as a result of compression of periodontal ligament which causes EARR. A sustained orthodontic force results in compression of the periodontal ligament that causes total occlusion of the blood vessels resulting in discontinuation of the blood supply to PDL area.

  • Epidemiology

Development of EARR is related to degree of applied orthodontic force, treatment duration, amount of apical displacement and patient’s individual genetic predisposition or susceptibility.

  • Risk factors

Following are the orthodontic treatment-related and the patient-related risk factors:

Treatment-related risk factors are

Patient-related risk factors

Treatment duration

Previous history of EARR

Magnitude of applied force

Tooth-root morphology, length, and roots with developmental abnormalities

Direction of tooth movement

Genetic influences

Amount of apical displacement

Systemic factors including drugs (nabumetone)

Method of force application (continuous vs. intermittent)

Hormone deficiency, hypothyroidism, and hypopituitarism

Type of appliance

 Treatment technique


Root proximity to cortical bone

Alveolar bone density

Chronic alcoholism

Previous trauma

Endodontic treatment

Severity and type of malocclusion and patient age

Patient gender

Patient habits

  • Etiology
    • Genetic predisposition

    • Inhibition of bone resorption in the direction of tooth movement

    • Idiopathic root resorption

  • Prognosis

Prognosis of EARR can be divided as:
  1. (a)

    Pretreatment prognosis–pretreatment risk assessment can be done by considering patient’s genetic background and patients with dental history of macro trauma.

  2. (b)

    Active treatment prognosis-If EARR progresses during the treatment, either the treatment can be stopped or it can be continued.

    While continuing the orthodontic treatment following points should be considered:

    • Radiographic monitoring

    • Application of lighter forces

    • Alternate upper and lower arch wire activations

    • Building rest periods during treatment

  3. (c)

    Posttreatment prognosis-occlusal equilibration for eliminating interferences is important for improvement of post-orthodontic treatment

  • Clinical recommendations to protect patients from developing EARR

To minimize EARR:
  • Use light forces for moving teeth

  • Monitor radiographs periodically

  • Move teeth for least distance possible

Root-sparing orthodontic treatment regimes that can be used for minimizing EARR include:
  • Growth Modification to Correct Severe Skeletal Class II Malocclusions (Early Treatment)

  • Early interception of maxillary canines with mesial eruption paths

  • Serial extraction to modify eruption paths

  • Correction of anterior open bite with a palatal tongue spur appliance

  • Orthognathic surgery to avoid moving teeth large distances and against cortical plates

  • Recommendations to minimize or avoid complaints

To minimize the risk for development of the severe form of EARR and also to avoid complaints:
  • Obtain quality initial patient records

  • Obtain signed informed consent forms specifically outlining EARR

  • Look at siblings and parents’ post-orthodontic periapical radiographs if available

  • Use treatment strategies that spare the root apices

  • Use light and well-distributed forces

  • Obtain periapical radiographs 6 months after fixed appliance placement of every patient

When EARR is detected during orthodontic treatment:
  • Inform the patient and/or parents

  • Change treatment plans if necessary

  • Interrupt treatment for approximately 3 months using passive archwires.

  • Alternatively reactivate maxillary and mandibular archwires every other month

  • Avoid tooth movement against cortical plates.

  • Obtain final patient records

Pitfalls and complications

  • Large defects created at the apex during orthodontic treatment can result in separation of the defect from the root surface.

  • In case of patients having crestal alveolar bone height loss and teeth with short roots there is increased risk of tooth mobility and/or loss.

  • The mandibular and maxillary growth is different in individual patients. Therefore, patients will not always grow in a favorable direction and magnitude, resulting in unpredictable results.

  • Good patient compliance is needed.

Further reading

  1. 1.
    Justus R (2015) Iatrogenic effects of orthodontic treatment: decision-making in prevention, diagnosis, and treatment. Prev Extern Apical Root Resorption. CrossRefGoogle Scholar
  2. 2.
    Proffit WR, Fields HW, Sarver DM (2007) Contemporary Orthodontics, 4th edn. Mosby Inc., Saint Louis, pp 279–283Google Scholar
  3. 3.
    Weltman BJ (2011) External root resorption and orthodontic treatment—assessment of the evidence. In: Huang GJ, Richmond S, Vig KWL (eds) Evidence-based orthodontics. Wiley, Chichester, pp 63–87Google Scholar
  4. 4.
    Weltman B, Vig KWL, Fields HW et al (2010) Root resorption associated with orthodontic tooth movement: a systematic review. Am J Orthod Dentofacial Orthop 137:462–476CrossRefPubMedGoogle Scholar
  5. 5.
    Chan E, Darendeliler MA (2006) Physical properties of root cementum: part 7. Extent of root resorption under areas of compression and tension. Am J Orthod Dentofacial Orthop 129:504–510CrossRefPubMedGoogle Scholar
  6. 6.
    Levander E, Malmgren O, Eliasson S (1994) Evaluation of root resorption in relation to two orthodontic treatment regimes. A clinical experimental study. Eur J Orthod 16:223–228CrossRefPubMedGoogle Scholar
  7. 7.
    Årtun J, Smale I, Behbehani F et al (2005) Apical root resorption six and 12 months after initiation of fixed orthodontic appliance therapy. Angle Orthod 75:919–926PubMedGoogle Scholar
  8. 8.
    Al-Qawasmi RA, Hartsfield JK Jr, Everett ET et al (2003) Genetic predisposition to external apical root resorption. Am J Orthod Dentofacial Orthop 123:242–252CrossRefPubMedGoogle Scholar
  9. 9.
    Brin I, Tulloch JFC, Koroluk L et al (2003) External apical root resorption in Class II malocclusion: a retrospective review of 1-versus 2-phase treatment. Am J Orthod Dentofacial Orthop 124:151–156CrossRefPubMedGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.Universidad Intercontinental, Facultad de OdontologiaMexico CityMexico

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