Introduction

Dental trauma is a term to describe impact injuries to the teeth as well as hard and soft tissues in and around the mouth and oral cavity.1 This is often a distressing experience for the patient, with effects on their psychological and emotional wellbeing. Some of the adverse outcomes can be mitigated by instituting prompt and appropriate management. Factors such as timing of treatment, handling of the tooth, the severity of trauma, concommitant injuries to the supporting structures, the degree of contamination and tooth development maturity may influence outcomes.2,3

Appropriate management should take the form of a staged approach, commencing with correct acute or emergency treatment followed by a monitoring program to evaluate the patient's progress. This begins with a detailed history and examination followed by investigations. It should take into account general factors, such as the patient's desire for treatment, systemic factors (a severely immunocompromised individual may not be a suitable candidate for complex treatment), as well as any financial limitations that may preclude treatment. Treatment is provided based on the findings and prognosis of the affected teeth. The Dental trauma guide from the International Association of Dental Traumatology is a comprehensive evidence-based resource which provides detailed guidance on how to manage dental trauma.4,5 Prognosis for traumatised teeth can be determined by using the dental trauma ‘risk calculator' which is based on the Copenhagen Trauma Database.4 These should form part of every general dental practitioners' armamentarium as most dental trauma will first present itself to a general dental practice setting.

Various dental classifications for dental trauma have been developed but the most widely used include those given by Andreason, the World Health Organisation, Garcia-Godoy and Ellis.6,7,8,9

Good information is available on the immediate management of dental trauma; however, this paper will focus on providing an overview of fractured teeth, associated pulpal complications and resorption, followed by a discussion on the long-term complications and available treatment options in the adult patient. This two-part series aims to discuss the complications of dental trauma in the adult patient from a longer-term perspective, as categorised in Box 1. The first paper will focus on the management of fractured teeth, teeth with pulpal complications and resorption.

Fractured teeth

Fractures can be uncomplicated, involving only the enamel or enamel and dentine, and they can be complicated, involving enamel, dentine and pulp. They can be limited to the crown or involve the root or both. Isolated root fractures can also be present. This simplest of injuries is an enamel infarction, which involves cracking of the enamel without loss of tooth structure, best seen by transillumination10 (Fig. 1).

Fig. 1
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Transillumination. Image courtesy of Dr Keith V. Krell

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Uncomplicated crown fractures mainly involve the enamel rarely causing pulpal complication (0-1%) unless a luxation injury is also present (8.5%).11,12,13

Complicated crown fractures involve all three tooth layers, enamel, dentine and pulp. Pulp necrosis does not occur immediately in the absence of an associated luxation injury; however, if left untreated, it will inevitably lead to it.10

Crown-root fractures often involve enamel, dentine and the root surface. The pulp may or may not be exposed. Factors that will influence treatment planning include the extent of the fracture circumferentially, root maturity, severity of the fracture in the sub-gingival aspect and pulp exposure.10

Root fractures can be vertical or transverse in direction. They are usually divided into the apical, middle and coronal third. The prognosis of the tooth varies with the type and location of the root fracture, which can be seen by taking multiple radiographic images at different angles or a cone beam computed tomography (CBCT) scan. While detailed information on the management and treatment of fractured teeth is not in the remit of this paper, we will, however, very briefly touch upon the salient points below.

Treatment options

Management of all types of tooth fractures must begin with an assessment of prognosis of the involved tooth or teeth. This is done after completing an overall initial assessment comprising of a detailed history and clinical examination of the patient. Local factors need to be considered, which would include whole dentition prognosis, the amount of remaining coronal tooth structure (which can be assessed with a tooth restorability index to determine the restorability of the tooth),14 root length and aesthetics. Based on these factors, a choice can be made for the most suitable definitive treatment, which can be as simple as re-attaching the broken tooth fragment, or a bonded composite restoration, veneer, crown, post-core crown or burying the root with an overdenture.

Uncomplicated crown fractures are often treated with replacing the lost tooth structure with restorative materials15,16,17,18 or through re-attaching the broken fragment.15,17,19,20,21 Re-attaching the broken fragment is the simplest way to treat an uncomplicated crown fracture when the broken fragment is intact and in one piece (Fig. 2). Alternatively, the broken tooth can be repaired with a composite restoration (Fig. 3). This should be considered for immature as well as mature permanent teeth as the first line of treatment while the pulpal status is being monitored. However, this can suffer challenges such as poor aesthetics when compared to ceramic restorations, staining at the restoration margins and fracture of the restorations. It is always sensible to start with the least invasive option first as it will help retain as much of tooth structure as possible, for the long-term. In situations where there is evidence of pulp necrosis on pulp sensibility testing and radiographs, endodontic treatment should be undertaken as soon as possible and a definitive restoration provided thereafter.

Fig. 2
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a, b, c, d) Re-attaching a broken fragment for an uncomplicated crown fracture. The injury occurred when the patient accidentally hit his 11 with a glass bottle. Image courtesy of Dr Jagdip Kalsi

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Fig. 3
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a, b, c, d) Composite restorations for uncomplicated crown fractures following removal of an emergency splint that had been provided due to luxation injuries. The injuries occurred when the patient fell in her garden

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For complicated crown fractures involving the pulp, in teeth with open apices, the aim of treatment is closure of the root apex and promotion of root development. This can be achieved with partial pulpotomy procedures.22 Mature teeth with closed root apices are often candidates for root canal treatment (RCT) (Fig. 4); however, partial pulpotomy procedures can be useful for all traumatically fractured teeth, regardless of a patient's age and degree of apical closure of the teeth.23 A definitive restoration can be provided immediately after pulpotomy procedures thus avoiding problems with temporary restoration breakdown and re-inoculation of the exposure site with bacteria.10

Fig. 4
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a, b, c, d) RCT and composite restorations for non-vital upper anterior teeth with complicated crown fractures sustained when this pedestrian was hit by a person driving a motorised scooter

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Crown-root fractures can be challenging to treat and management depends upon the extent and severity of the fracture. A combination of techniques are available to choose from. These include re-attachment of the broken fragment; restorative management alone with extension of restoration margins equi- or sub-gingivally followed by a post-core and crown restoration (Fig. 5); periodontal surgery to expose crown margins; orthodontic extrusion; intentional replantation; surgical repositioning; auto-transplantation; root submergence; extraction and replacement; and orthodontic space closure.24 As mentioned earlier, in traumatised teeth with crown-root fractures and open apices, priority should be given to development of the root rather than restoring aesthetics and function.15 If a tooth is unrestorable, decoronation can be undertaken to maintain alveolar bone levels until such a time that an implant can be placed and restored (Fig. 6).

Fig. 5
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a, b, c, d, e, f) Patient with a fractured 22 managed via RCT and a post-core crown

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Fig. 6
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Complicated crown-root fractures of 11, 12, 13 and 21. All four teeth were planned for extractions and replacement with dental implants in the long-term; however, as the patient was young, it was decided to decoronate these teeth in order to preserve alveolar bone height until growth was complete. a) Fractured segment held in place with a composite restoration provided by an emergency dentist on 11 and 21. b) Two weeks post decoronation. c, d) Six weeks post de-coronation and fitting of an Essix retainer with prosthetic teeth to replace 11, 12, 13 and 21. e, f) Long cone periapical radiographs of 11, 12, 13 and 21

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Finally, with regards to the management of root fractures, treatment begins with an assessment of the affected tooth. All root-fractured teeth where the fracture is not communicating with the oral cavity require splinting, which should be non-rigid for up to four weeks, except for teeth with fracture in the cervical third, where the splitting may need to remain in place for up to four months.5,25 Pulp sensibility testing may not be reliable in the early stages but the tooth should be kept under a review and pulp status assessed at 3, 6 and 12 months.26 If later, there are signs of pulpal necrosis (PN), then a decision should be made whether to retain the tooth or extract. In most instances, RCT can be carried out up to the fracture line. This is because the pulp is often vital in the apical segment. RCT can be completed after a hard tissue barrier has formed with calcium hydroxide at the fracture site.27,28 A successful endodontic treatment can enable the tooth to be retained for a long time and keeps treatment options open for the patient. In many cases, the apical fragment will undergo pulp canal obliteration. In those instances where apical changes are visible along with symptoms, then a decision should be made whether to carry out RCT to full length or to remove the apical segment surgically. Figure 7 shows a flowchart outlining the management options for fractured teeth.

Fig. 7
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Flowchart of treatment options for fractured teeth

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Pulpal complications

Dental trauma can cause damage to the neurovascular tissues of the pulp. Often, this damage is reversible, as the pulp tissues heal themselves through re-vascularisation and re-innervation. However, when the damage exceeds the pulp's capacity to recover, sterile PN can ensue. In some cases, the pulp canal can be obliterated by the laying down of excessive tertiary dentine resulting in pulp canal obliteration (PCO). The literature reports a wide variation in the incidence of PN and PCO after the various types of traumatic dental injuries. These are summarised in Table 1. These figures can be used to inform patient discussion and diagnosis during long-term evaluations and follow-up, for example, we would have a high suspicion of PCO in avulsion cases.

Table 1 Incidence of pulp necrosis and pulp canal obliteration following dental trauma
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The tooth should be regularly monitored post-trauma for any signs of PN. Clinically, these can manifest as discolouration, tenderness to palpation or percussion of the tooth or vestibule, presence of a fistula and/or a negative pulp response to sensibility tests. Radiographically, a periapical radiolucency or infection-related external root resorption may be visible.35

Treatment options

For teeth that have been diagnosed with PN, orthograde endodontic treatment should be considered in the first instance (Fig. 8). This gives the tooth the best chance to be retained for a long time, as well as maintain alveolar bone level for dental implants, should it need to be extracted in the future. However, it is important that the endodontic prognosis of the tooth is established at the outset. Figure 9 provides a flowchart to summarise such an evaluation.

Fig. 8
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a, b) This patient lost vitality of her upper incisor teeth which were subsequently root canal-treated. The patient had an improvement of her symptoms but resolution was not achieved. A post-operative CBCT scan showed no abnormalities and working diagnosis of neuropathic pain was made. The patient was referred to oral medicine for further assessment

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Fig. 9
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Flowchart for assessing the endodontic prognosis of a tooth

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For cases of PCO, if the tooth is asymptomatic, no treatment is indicated, although, some of these teeth may show discolouration. In such cases, external bleaching can be considered, or a veneer restoration if the discolouration is significant. If the PCO is symptomatic, orthograde RCT may be attempted after explaining the risks and challenges to the patient. These can include the risk of perforation, separation of an instrument and weakening of the root structure. Figure 10 shows the 11 which suffered trauma decades earlier and had undergone partial PCO. It was successfully treated with orthograde endodontic treatment completed to the full working length. If the endodontic treatment cannot be completed, then the tooth may need to be extracted and replaced with a removable or fixed prosthesis.

Fig. 10
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a, b) This 49-year-old patient suffered trauma at eight years of age. A diagnosis of chronic apical periodontitis was made and the canal was found to be partially calcified. Orthograde endodontic treatment was carried out to the full working length

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There will be situations where teeth experiencing pulpal complications and undergoing subsequent RCT may experience failure of the treatment. A systematic review placed the proportion of teeth surviving after non-surgical RCT at 86-93% over a period of 2-10 years.36

As the epidemiology suggests that younger patients are more susceptible to trauma, we may find that these patients suffer complications associated with root canal treated-teeth later in life. When there is persistent periapical inflammation following RCT, consideration should be given to root canal retreatment, root-end surgery, extraction, or monitoring. The ideal option will vary depending on the circumstances of the individual case and patient preference. The authors' treatment planning principles involve maintaining tooth, bone and soft tissue structure as best as possible within the limits of predictability and keeping as many alternative treatment options open. The question to consider is ‘what are the options if the current planned treatment fails?'

Torabinejad et al. found that endodontic surgery had good initial success but non-surgical RCT had better long-term outcomes, with success rates for endodontic surgery at 2-4 years being 77.8% compared with non-surgical retreatment for the same follow-up period of 70.9%. At 4-6 years, however, this relationship was reversed, with non-surgical retreatment showing a higher success rate of 83.0% compared with 71.8% for endodontic surgery.37 Non-surgical retreatment enables thorough debridement of the entire root canal system and therefore should always be considered first, where feasible. Figure 11 shows the 11 which was endodontically treated in an orthograde manner first but due to persistence of symptoms, root-end surgery was carried out subsequently. Nevertheless, surgical techniques have improved greatly over the past few decades and success rates for endodontic micro-surgery have been found to be as high as 94% compared to 59% for traditional root-end surgery.38 Fig. 12 provides a flowchart outlining the treatment options for management of teeth with pulpal complications.

Fig. 11
figure 11

a, b, c, d, e, f, g, h) A patient who suffered dental trauma many years previously presented with internal resorption and apical periodontitis affecting her 11. This tooth underwent RCT and was obturated using a warm vertical compaction technique; however, the symptoms remained and an apicectomy procedure was undertaken

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Fig. 12
figure 12

Flowchart for treatment options of pulpally involved teeth

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Resorption

‘Dental resorption is a physiological or pathological process, which involves loss of dentine and/or cementum by hard tissue resorbing cells'.26 Trauma to the periodontal ligament, cementum and the subsequent loss of vitality are all intimately associated with the potential for resorption to follow.39 The nature of the resorptive process has been shown to be related to the size of the necrosed area of the periodontal membrane, with larger areas showing reduced healing and a greater predisposition to resorption.40,41 Traumatic dental injuries exert this kind of damage, with intrusion and avulsion injuries having the highest likelihood of resulting in resorption; however, all traumatic injuries should be considered as high-risk injuries.42 Resorption defects can be internal or external. Numerous classifications have been developed for resorption defects, with Andreasens' classification33 being the most widely used. A schematic classification is presented in Darcey and Qualtrough.43 This is based on Andreasen's classification but also incorporates external cervical resorption (ECR) which has been recognised as a pathological entity separate from other resorptive conditions.44,45

External surface resorption is often sub-clinical, with a localised area of inflammation sometimes seen as cavitation in the cementum and dentine on a radiograph.46 This type of resorption is often self-limiting and rarely needs intervention.

External inflammatory resorption (EIR) can be sterile or infective. Sterile EIR is usually associated with pressure which may come from orthodontics, impacted teeth and bony lesions. The defects are confirmed on radiographs, along with presence of impacted tooth or bony pathology. Teeth are often vital; however, pulpal involvement can occur at later stages, especially if there is history of trauma. Loss of pulpal vitality and subsequent periapical inflammation can lead to EIR of the infective type. It shows up on radiographs as a periapical lesion.

ECR appears in the cervical region of the tooth and while the aetiology is unclear, it has been linked to trauma,42,47,48 orthodontics,47,48 bleaching,48,49 periodontal treatment,42,48 dento-alveolar surgery,48 playing wind instruments,50 bisphosphonates51 and idiopathic causes. These lesions are often asymptomatic unless very advanced, at which stage pulpal involvement may occur. They are often picked up incidentally on radiographs but can be misdiagnosed as caries.52 Hithersay has given four classes of these lesions which aid in treatment planning.48 Class 1 and 2 lesions are fibro-vascular and the pulp is walled off by protective pre-dentine/dentinal barrier, whereas Class 3 and 4 lesions are infiltrative and fibro-osseous in character. These lesions have a poor prognosis and are often un-treatable.48

A modified classification of ECR (Table 2) has been proposed by Patel et al.53 which is based on the lesion height, circumferential spread and proximity to the root canal, thus classifying ECR in three dimensions. This information can be readily gleaned from using the combination of periapical radiography and CBCT scans.

Table 2 Three-dimensional classification of ECR. Reproduced with permission from Patel et al., ‘External cervical resorption: a three-dimensional classification', International Endodontic Journal, vol 51, 2018, Wiley53
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External replacement resorption (ERR) is often a result of traumatic injuries with avulsion and luxation injuries posing the highest risk. Here, the tooth structure is progressively replaced by alveolar bone. Clinically, the sound on percussing the tooth will be high-pitched or metallic, there will be a lack of mobility54,55 and the tooth will be infra-occluded.56 Radiographically, there will be a loss of lamina dura and a ‘moth-eaten appearance' of the tooth root.57 Progression is slow in older patients, may not necessitate treatment and the tooth may even last for years, but in younger patients, early treatment is indicated, as ankylosis may interfere with vertical development of the alveolar process.58 This can cause problems with aesthetics and function.51

Internal inflammatory resorption (IIR) can be due to trauma causing physical/chemical irritation or bacterial infection, whereas the aetiology of internal replacement resorption (IRR) is unknown. For active IIR lesions, pulp coronal to resorptive lesion is usually necrotic, while apically, it is vital and the main source of nutrients to the resorptive cells. Once the tooth becomes non-vital, resorption ceases.47 Teeth can be asymptomatic but may exhibit symptoms of pulpitis, or in advanced cases, periapical periodontitis.51 Radiographically, there will be an oval-shaped radiolucency visible within the canal, with sharp, well-defined margins, and the canal outline will not be visible in the lesion.59 A CBCT is often indicated to rule out the presence of a perforation. Clinically, IRR is indistinguishable from IIR and usually diagnosed in advanced lesions. Diagnosis is made based on the radiographic picture where the resorptive defect and adjacent root wall have a cloudy or mottled appearance, indicating radiopaque inclusions of hard tissue.51

Treatment options

Once a resorptive lesion is identified, a comprehensive clinical and radiographic examination should be carried out. This includes assessment and/or management to root resorption, which clinically appears to be potentially amenable to treatment. In some instances, plain film radiography is insufficient and CBCT will need to be performed to assess the type and extent of the lesion. European Society of Endodontology guidelines recommend the use of small field of view CBCT scans if the additional information is likely to aid diagnosis.60

In order to manage the lesion, the primary aim is to halt the activity of resorptive cells, either by removing source of stimulus or by stimulating repair or both.61 Management varies based on the type of resorptive lesion, its aetiology and the extent of the defect. This is discussed in greater detail under each section.

External inflammatory resorption

Management for this type of resorption is orthograde RCT which leads to resolution of the inflammation and a healing response in most of the cases (Fig. 13). A multi-visit approach is favoured, along with use of corticosteroids and antibiotic pastes, as they are associated with reduction of resorptive cells.62 However, calcium hydroxide remains the gold standard as it eradicates bacteria, stimulates repair, causes resorptive cells to necrotise and neutralises the acidic environment of the resorptive lacunae.63,64,65,66

Fig. 13
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a, b) A case of external inflammatory root resorption simply managed via conventional RCT

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External cervical resorption

Management should be according to its location, extent, severity, perforation and restorability of the tooth.52 Treatment options can vary and include external repair ± endodontic treatment, internal repair and endodontic treatment, intentional replantation, regular review (untreatable teeth) and extraction (untreatable teeth).67,68 ECR lesions diagnosed as Class 1 or 2 based on Hithersay's classification can be treated with simple curettage to cut off the vascular supply to the resorptive cells and restoration of the defect with a suitable restorative material. If there is pulpal involvement, then RCT needs to be performed.61 In cases where the defect may have perforated into the root canal, RCT should ideally be carried out accessing the canal via the resorption cavity, where possible, in order to retain as much tooth structure as possible.46 The resorptive defect can be restored with glass ionomer cement, mineral trioxide aggregate (MTA) or Biodentine (Fig. 14 and Fig. 15).

Fig. 14
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a, b, c, d, e, f, g, h) A case of external cervical resorption affecting the 21 subsequent to a traumatic injury sustained a decade earlier

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Fig. 15
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a, b, c, d, e, f, g, h) Another case of external cervical resorption associated with the 11 in response to dental trauma sustained 15 years ago. Image courtesy of Dr Jagdip Kalsi

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External replacement resorption

ERR in young adults means that the tooth will begin to show signs of infra-occlusion as the skeletal growth continues. In the short-term, the incisal edge can be restored with composite and the tooth kept under observation. For more definitive treatment, extraction of ankylosed teeth and replacement with fixed or removable prostheses is a suitable management option and may be the only one available for adult patients. Extractions of ankylosed teeth can often lead to significant bone loss and a bony defect is likely to be present,69,70 hence alveolar ridge preservation may be considered.71 The ensuing space can be restored with a fixed or a removable prosthetic option or in some cases, orthodontic closure may be an option, if feasible. Decoronation is an alternative to extraction and can be a suitable option in cases where implant placement is planned and if the infra-position of the ankylosed tooth becomes one-quarter or more of where it should be, in a young patient. Such a space can be restored with a removable prosthesis or a minimal preparation bridge until the bony growth is complete, at which stage implant-supported prosthesis can be considered. There is suggestion in the literature that decoronation should be carried out two years before implant placement considering the need for full remodelling of the root before implant insertion; however, other patient circumstances may dictate otherwise.72

Internal inflammatory resorption

IIR, like external and cervical inflammatory resorption, requires removal of the stimulus for halting the process of resorption. This means a thorough chemo-mechanical debridement must be carried out of the entire root canal system. These lesions are granulomatous and bleed profusely. Energised irrigation and inter-appointment medication have been recommended.73,74 Obturation should be performed using a thermoplasticised root filling to ensure optimal adaptation (Fig. 16). In cases of a perforation, a surgical approach may be indicated and the defect should be sealed with MTA or biodentine.73

Fig. 16
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a, b, c) A patient who suffered dental trauma 20 years previously presented with symptoms of periapical periodontitis and radiographic findings of internal inflammatory resorption. RCT was carried out with a warm vertical compaction technique used for obturation

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Internal replacement resorption

IRR also requires similar treatment to IIR; however, the procedural steps may be different and ultra-sonic tips may be required to navigate through the hard osteoid-like tissue.51 Decision to treat will be based on the degree of resorption, activity of lesion and its aetiology. Management can be with conventional endodontic treatment, surgical endodontic treatment, or through using a combined approach, for example, endodontics, periodontics, orthodontics and prosthodontics. Advanced lesions may not be amenable to treatment and extraction followed by appropriate prosthetic replacement may be indicated.

Conclusion

In the first paper of this two-part series, we have discussed the types of dental trauma and focused on the management of teeth fractured as a result of dental trauma, as well as teeth experiencing pulpal complications and resorption. Correct diagnosis and management can often lead to these teeth being retained for long periods. In the next paper of this two-part series, we will focus on the management of discoloured, displaced or missing teeth affected by dental trauma.