15 September 2020

---

Orthodontically induced external apical root resorption: a clinical practice guidline

Davide Elsido

---

In the latest issue of European Journal of Orthodontics (April 2020) a clinical practice guideline on orthodontically induced external apical root resorption (EARR) was published, with consensus-based recommendations concerning diagnosis, risk factors, management during treatment, and after-treatment care. Orthodontically induced external apical root resorption (EARR) is an unwanted side effect of orthodontic treatment. In the available literature, a distinction is made between histologically and radiologically determined EARR. Over 90 per cent of all orthodontically moved teeth are associated with histologically noticeable EARR . Lower percentages have been reported for radiologically detected EARR.

Between 48 and 66 per cent of orthodontically treated teeth show mild to moderate EARR (less than 2.5 mm), and only 1–5 per cent of all moved teeth end up with severe apical root resorption, defined as a loss of 4 mm of the original root length or more than one-third of the root. Despite the prevalence and severity of EARR, little is known about the pathology and aetiology. Previously, it was assumed that EARR was caused by complex multifactorial interactions between patient-related factors and treatment-related factors . Additionally, there is much uncertainty about how to prevent EARR and how to manage it when it occurs during orthodontic treatments.

To identify an EARR, a radiologic examination is necessary. However, there is no consensus about the type or timing of radiographs needed for identifying initial EARR during orthodontic treatments. Furthermore, little is known about the long-term stability and prognosis of affected teeth, including their mobility, vitality, and periodontal status, their suitability for prosthetic abutments, or their resistance to masticatory function. It was calculated that 3 mm of EARR was equivalent to a loss of 1 mm of periodontal attachment. When periodontal attachment is lost due to root resorption, it is important to avoid additional alveolar bone destruction that can occur with periodontal disease. There is much uncertainty among orthodontists on how to reduce the risk of EARR as much as possible, how to manage EARR when it occurs during an orthodontic treatment, and what type of after-treatment care is required.

This is why the authors decide to produce clinical practice guideline.
To sum up, the clinical recommendations are:
 1.1 Consider taking an OPT at 12 months after starting fixed appliances in a patient with any extraction treatment.
 1.2 Consider taking additional periapical radiographs when the available radiographs do not provide adequate information about the shape and size of the roots.
 2.1 Inform the patient prior to orthodontic treatment about the risk of EARR.
 2.2 When an extraction treatment is planned, inform the patient of the possibility that it is associated with increased risk of severe EARR.
 3.1 Re-evaluate the treatment goals and treatment plan when EARR is detected (≥2 mm) during an orthodontic treatment. Inform the patient and discuss the consequences, the patient’s preferences, and the treatment goals.
3.2 Consider stopping orthodontic treatment when generalized severe EARR occurs.
3.3 Consider avoiding further loading on teeth that exhibit severe EARR.
 3.4 When deciding to continue active orthodontic treatment, consider discontinuing treatment for 3 months. Make sure that the appliance is passive during that time to avoid loading the affected teeth.
 3.5 When deciding to continue orthodontic treatment, attempt to avoid displacement of the affected teeth.
 3.6 When deciding to continue active orthodontic treatment after treatment interruption of 3 months, consider taking a new radiograph at 6 months after the restart.
 4.1 Follow the patient according to your normal retention protocol.
 4.2 Patient information about the long-term prognosis must include at least the following:

                • EARR will stop after the appliances are removed.
                • EARR will not lead to pain or discomfort (sensibility).
                • The affected tooth may be mobile, and mobility might increase over time (for root lengths less than 10 mm).
                • Affected teeth might be lost earlier, if periodontal bone destruction (periodontitis) occurs.

 4.3 Take care of a good communication with the dentist at the end of treatment to inform the dentist about affected teeth and advice:
                 • periodical screening for periodontal diseases, especially around the affected teeth.
                 • assurance that retention devices remain passive after the regular retention check-ups with the orthodontist have ended. 

For additional information:  Development of a clinical practice guideline for orthodontically induced external apical root resorption.