Weltman B, Vig KW, Fields HW Root resorption associated with orthodontic tooth movement: a systematic review. Am J Orthod Dentofacial Orthop. 2010; 137:462-476 https://doi.org/10.1016/j.ajodo.2009.06.021
Ottolengui R. The physiological and pathological resorption of tooth roots. Dent Items Interes. 1914; 36
Brezniak N, Wasserstein A. Orthodontically induced inflammatory root resorption. Part I: The basic science aspects. Angle Orthod. 2002; 72:175-179
Currell SD, Liaw A, Blackmore Grant PD Orthodontic mechanotherapies and their influence on external root resorption: a systematic review. Am J Orthod Dentofacial Orthop. 2019; 155:313-329 https://doi.org/10.1016/j.ajodo.2018.10.015
Walker SL, Tieu LD, Flores-Mir C. Radiographic comparison of the extent of orthodontically induced external apical root resorption in vital and root-filled teeth: a systematic review. Eur J Orthod. 2013; 35:796-802 https://doi.org/10.1093/ejo/cjs101
Sondeijker CFW, Lamberts AA, Beckmann SH Development of a clinical practice guideline for orthodontically induced external apical root resorption. Eur J Orthod. 2020; 42:115-124 https://doi.org/10.1093/ejo/cjz034
Samandara A, Papageorgiou SN, Ioannidou-Marathiotou I Evaluation of orthodontically induced external root resorption following orthodontic treatment using cone beam computed tomography (CBCT): a systematic review and meta-analysis. Eur J Orthod. 2019; 41:67-79 https://doi.org/10.1093/ejo/cjy027
Gandhi V, Mehta S, Gauthier M Comparison of external apical root resorption with clear aligners and pre-adjusted edgewise appliances in non-extraction cases: a systematic review and meta-analysis. Eur J Orthod. 2021; 43:15-24 https://doi.org/10.1093/ejo/cjaa013
Yazid F, Teh Y, Ashari A Detection methods of orthodontically induced inflammatory root resorption (OIIRR): a review. Australas Orthod J. 2020; 36:101-107
Ahangari Z, Nasser M, Mahdian M Interventions for the management of external root resorption. Cochrane Database Syst Rev. 2015; 2015:(11) https://doi.org/10.1002/14651858.CD008003.pub3
El-Bialy T, Farouk K, Carlyle TD Effect of low intensity pulsed ultrasound (LIPUS) on tooth movement and root resorption: a prospective multi-center randomized controlled trial. J Clin Med. 2020; 9 https://doi.org/10.3390/jcm9030804
Michelogiannakis D, Al-Shammery D, Akram Z Influence of low-level laser therapy on orthodontically-induced inflammatory root resorption. A systematic review. Arch Oral Biol. 2019; 100:1-13 https://doi.org/10.1016/j.archoralbio.2019.01.017
Kaklamanos EG, Makrygiannakis MA, Athanasiou AE. Does medication administration affect the rate of orthodontic tooth movement and root resorption development in humans? A systematic review. Eur J Orthod. 2020; 42:407-414
Haugland L, Kristensen KD, Lie SA, Vandevska-Radunovic V. The effect of biologic factors and adjunctive therapies on orthodontically induced inflammatory root resorption: a systematic review and meta-analysis. Eur J Orthod. 2018; 40:326-336 https://doi.org/10.1093/ejo/cjy003
Zymperdikas VF, Yavropoulou MP, Kaklamanos EG, Papadopoulos MA. Effects of systematic bisphosphonate use in patients under orthodontic treatment: a systematic review. Eur J Orthod. 2020; 42:60-71 https://doi.org/10.1093/ejo/cjz021
Standards for the Dental Team. 2013;
Jiang RP, McDonald JP, Fu MK. Root resorption before and after orthodontic treatment: a clinical study of contributory factors. Eur J Orthod. 2010; 32:693-697 https://doi.org/10.1093/ejo/cjp165
El-Angbawi AM, Yassir YA, McIntyre GT, Revie GF, Bearn DR. A randomized clinical trial of the effectiveness of 0.018-inch and 0.022-inch slot orthodontic bracket systems: part 3 – biological side-effects of treatment. Eur J Orthod. 2019; 41:154-164 https://doi.org/10.1093/ejo/cjy039
Severe root resorption is a rare, but serious, complication of orthodontic treatment, which can affect the long-term prognosis of the teeth affected. This case presents a young, healthy patient with severe root resorption affecting nearly all of her dentition. It was an incidental finding by her GDP 8 months after completion of her orthodontic treatment. The article aims to raise awareness about the importance of obtaining a valid consent at the start of each orthodontic treatment, and highlight the possible risk factors associated with severe root resorption, diagnostic methods, and interventions to prevent or manage it when it occurs.
CPD/Clinical Relevance: Although developing severe root resorption as a result of orthodontic treatment is relatively uncommon, the consequences are serious. This article highlights the importance of identifying high-risk orthodontic patients, where possible, and obtaining valid, informed consent prior to every course of orthodontic treatment.
Article
Orthodontically induced inflammatory root resorption (OIIRR) is a term used to describe the iatrogenic damage caused to the roots of teeth as a result of orthodontic treatment, leading to root shortening. It is also known as external apical root resorption (EARR).1,2 Root resorption (RR) was first attributed to orthodontics by Ottolengui in 1914.3 Orthodontics uses the body's own natural inflammatory process to allow movement of the dentition into the desired position. OIIRR occurs when osteoclastic activity exceeds the reparative capacity of the root cementum.4,5 Orthodontically induced EARR (OIEARR)6,7 is associated with both patient-related factors, such as gender, age, genetics, medical history, abnormal root morphology, previously root-filled or traumatized teeth, and also several treatment-related risk factors, such as magnitude, direction and duration of orthodontic forces and types of appliances used.2,5,8,9
Radiographic and histological findings claim 73% and 90% of patients, respectively, experience OIEARR following orthodontic treatment.2 In order for OIEARR to be classified as severe, more than 4 mm or one-third of the entire root length has to be resorbed, which in one study has been shown to affect nearly 15% of orthodontic patients.5 Other studies suggest only 1–5% of orthodontically moved teeth are severely affected.2,7 Maxillary followed by mandibular incisors are the most commonly affected teeth,2 with maxillary incisors having a mean resorption of 0.49 mm,9 which, from a clinical point of view, is insignificant.
Emphasis is placed on assessing the potential for root resorption and, where possible, preventing this irreversible and destructive process because of its serious threat to the longevity of the teeth involved and to the treatment outcomes.2,9 Despite the high prevalence of OIEARR, there is no high-quality evidence to create definitive guidelines to manage this problem, or to advise best methods for prevention or indicate the prognosis of the resorbed teeth with regards to their periodontal status, mobility and viability.7
Diagnosis of OIEARR is predominantly carried out through radiographic imaging, since patients often have no clinical signs, except in very severe cases where mobility is present. Two-dimensional imaging, such as peri-apical and panoramic radiographs, is the most commonly used method of detecting OIEARR. Three-dimensional methods, such as cone beam computed tomography (CBCT) are, however, becoming an increasingly popular method of assessing RR.8,9
Case report
A 12-year-old female presented in May 2016, in the permanent dentition, with a Class 3 skeletal pattern due to a mild maxillary hypoplasia, and a Class 3 incisor relationship and a retained upper right deciduous canine (Figure 1).
The pre-treatment OPT, with the benefit of hindsight, perhaps showed some slight root shortening of the lower first molars and the upper left first molar; however, a quick scan of the radiograph would have probably concluded that there were reasonable root lengths and good bone levels, wisdom teeth present, and little else of note. The pre-treatment cephalogram confirmed a slight maxillary hypoplasia, but again nothing else of note.
The patient underwent a routine course of orthodontic treatment involving extraction of lower second premolars to facilitate camouflage of the Class 3 malocclusion, expansion of the maxillary dentition with a quadhelix, upper and lower fixed appliances and intra-oral elastics. The treatment time was slightly longer than average, at 36 months. Despite this, there was no indication to take further radiographs, as spaces had largely been closed, the teeth were aligned well and the patient and her parents were all delighted with the result achieved (Figure 2).
Figure 2.
(a–g) Post-treatment extra- and intra-oral photographs.
At 8 months following debond, the patient's general dental practitioner (GDP) saw her as an emergency. The patient reported that she had been fighting with her brother 3 weeks previously, and was now complaining of a painful, slightly loose upper left central incisor. She also felt that several of her lower teeth were mobile after the collision. Although the patient had been provided with removable retainers, she admitted to her dentist she had not been wearing them.
Radiographs taken by the GDP indicated significant root resorption of her upper left central incisor and affecting several of her upper and lower front teeth. She was then referred to the Charles Clifford Dental Hospital for specialist endodontic advice.
While awaiting this appointment, the specialist practitioner who had provided the treatment reviewed the patient, discussed root resorption and its long-term management, and fitted both upper and lower bonded retainers, and also remade the vacuum-formed retainers.
The specialist restorative opinion from the dental hospital noted that while the UL1 had grade 1–2 mobility, the other incisors had grade 1 mobility, and none of the teeth was tender to percussion. All of the teeth gave a positive response to electric pulp testing, with the exception of the UL1; however, this tooth was responding to cold stimuli. Radiographs taken at the Charles Clifford dental hospital were suggestive of external surface resorption involving all incisors (Figure 3).
Figure 3.
(a–d) Peri-apical films from the dental hospital.
It was decided that no further investigations or treatment were required for any of the teeth. The UL1 did not require endodontic treatment at this stage,, but needed to be monitored in the future.
When the patient was seen at their local hospital, a CBCT scan was taken so the exact extent of the root resorption was fully documented (Figure 4). The consultant orthodontist explained to the patient and parents that this was an extreme presentation of root resorption, which they had been warned about at the start of treatment. It was explained that it was unusual to see this extent of root damage, but that everything possible had been done to maintain the health of the teeth in the short to medium term by placing bonded retainers as well as providing removable retainers. The retention protocol was discussed in detail to ensure that the parents and the patient understood the importance of regular monitoring. She was reassured that the hospital, together with the restorative department of the local dental hospital, would do their utmost to maximize dental health in the long term.
Figure 4.
(a–c) CBCT images to fully document the extent of the root resorption.
Another set of detailed images, involving a repeat CBCT, would be required 2 or 3 years later to determine whether the root resorption had progressed. The findings could then be discussed with the patient and her parents.
Discussion
2D imaging exposes patients to a lower dose of radiation and is more widely available, while 3D methods produce more specific, less magnified and distorted images that allow assessment of all aspects of the roots.8,9 This is, however, at a cost of 15–140 times higher radiation exposure dose to the patient.8 Although controversy exists around whether CBCT under-9 or overestimates8 the amount of OIIRR compared to 2D methods, the difference is probably not clinically significant. The risk-to-benefit ratio must be weighed by the clinician on a patient-to-patient basis.8 Biological markers, such as inflammatory, bone remodelling and dentine matrix protein markers in saliva or gingival crevicular fluid, are potentially the diagnostic tools of the future that could be used for early and safer diagnosis of OIIRR; however, further research is required prior to their widespread clinical use.10
Early detection, wherever possible, is important in the management of severe OIIRR because discontinuation of the orthodontic force on the teeth may cease the resorptive process of the roots.5,11 In very severe cases where the teeth have become mobile, splinting might also be indicated12 to enhance their long-term prognosis.
According to a Cochrane review, there is little evidence to recommend particular interventions for the management of OIIRR.12 However, a more recent randomized controlled trial concluded that daily application of low-intensity pulsed ultrasound during orthodontic treatment decreased OIIRR while also enhancing tooth movement.13 There is no conclusive data to show that interventions, such as ultrasound or low-level laser therapy, actually improve OIIRR.14
British Orthodontic Society guidelines for the use of radiographs in clinical orthodontics indicate that obtaining intra-oral radiographs during orthodontic treatment to assess OIEARR is only justified when there is clinical evidence of excessive mobility, loss of vitality, abnormal delay in tooth movement, extended treatment periods or repeated treatments. Routine end-of-treatment radiographs to check for RR are, therefore, not recommended.15
In order to minimize the effects of OIEARR, the risk level of patients should be individually assessed, as part of obtaining the valid consent. It is important to identify the patient-related risk factors prior to commencing orthodontic treatment; therefore, thorough history-taking is essential. Age and gender are two factors that are suggested to influence OIEARR, although one systematic review suggested that resorption occurs irrespective of the patient's age and gender.7 Other risk factors have been suggested to impact how different individuals experience OIEARR; however, there is a low level of evidence to support these findings.7 This list includes patients with pre-treatment trauma to their teeth, endodontically treated teeth, abnormal root length/shape (pointed, pipette, dilacerated), agenesis, previous orthodontic treatment, increased overjet/overbite and corrected impacted canines.2,7 Systemic illnesses (asthma) and some medications (steroids, NSAIDs, thyroxine and systemic fluoride) can also impact the development of OIEARR.16,17 Patients taking bisphosphonates have shown milder root resorption and a slower rate of orthodontic tooth movement.18
It is therefore important that patients with these risk factors are identified early, by obtaining a thorough medical history and performing a careful examination following which, if deemed vulnerable, are informed of their higher risk of developing OIEARR prior to the treatment. This might also be an indication for them to have more frequent follow-up appointments focusing on the signs of increased tooth mobility, and mid-treatment and possibly post-treatment radiographs could be justified to monitor their condition.
According to the General Dental Council standards, valid consent must incorporate all the consequences and risks involved with a proposed treatment.19 It is therefore important to know the risk level of each treatment prescribed to relay this information to the patient, so that they can then make an informed decision.
Specific orthodontic mechano-therapies have been suggested to have variable effects on the development or prevention of OIEARR; however, there is only a low level of evidence to support them.5 It has been clearly established that there is a positive correlation between the application of orthodontic forces and the incidence, as well as the extent, of EARR.5 The probability of developing OIEARR also increases with continuous, rather than intermittent, application of forces, in addition to longer treatment durations.2,5,20 The former believed to be due to a lack of recovery time, preventing the dental tissues from healing following the inflammatory process.5 It is generally accepted that resorption of the roots will cease, and the reparative process will begin once the orthodontic forces have been discontinued. The use of both intrusive and heavy forces have been linked to an increased incidence of OIEARR. Compression on periodontal ligaments, rather than tension, appears to contribute to EARR, which is why intrusion of dentition, especially the incisors, imposes a greater risk than extrusion.2,5 A Cochrane review concluded that there is insufficient evidence to suggest a favoured archwire type in terms of preventing OIEARR.21 The sequence of archwires used, the bracket slot size22 and the choice of ligation system have also been shown to have no significant effect on the amount of OIEARR.2,5,7 When teeth are extracted as part of an orthodontic treatment plan, the risk of OIEARR has been shown to increase, which is probably linked to longer treatment times.7,8,20 Comparing clear aligners and pre-adjusted edgewise appliances, research shows that neither cause a clinically significant EARR in the maxillary incisors.9
The uncertainty around the efficacy of preventive measures or relative importance of exacerbating factors in relation to OIIRR, brings into question the validity of the consent taken at the beginning of each orthodontic episode. It also highlights the need for further research in this area to increase the quality of the guidance for the clinicians to follow.
The patient information leaflet outlining orthodontic treatment risks by the British Orthodontic Society (Figure 5) notes that any brace work can lead to root-related changes in the teeth. These root changes are commonly seen, and are usually minor and clinically insignificant, although these changes can occasionally be severe. It is, of course, essential that these discussions have been had with each and every potential orthodontic patient, and that written information is given to them to peruse in their own time before committing to a course of treatment.
Figure 5. Patient information leaflet from the BOS
Conclusions
The orthodontist should be able to identify some patients at high risk for resorption, and this is why a thorough history and clinical examination is essential in obtaining valid informed consent.
A thorough review of the literature, however, shows that there is no clear line separating high-risk from low-risk patients.
If resorption risk is thought to be high, measures should be taken to minimize the damage to the teeth.
All patients should be warned of the risks, and should sign to confirm they have understood the warnings.
If extensive root resorption occurs, all measures should be taken to minimize further damage and maximize the prognosis for the teeth.
In the event of root resorption, the patients and their parents should be fully informed of the situation and should be told the prognosis for the dentition in the medium and long term.
