Management of Traumatic Dental Injuries in the Permanent Dentition

30 Management of Traumatic Dental Injuries in the Permanent Dentition

Gabriel Krastl, Roland Weiger, Andreas Filippi, Kurt A. Ebeleseder, and Kerstin M. Galler

Summary

In the permanent dentition, most traumatic dental injuries (TDI) result in crown fractures and minor luxation injuries. After crown fractures, reattachment of the coronal fragment is a conservative approach to re-establish function and aesthetics. As an alternative, resin composites can be used on a routine basis for a minimal invasive restoration of fractured teeth. When the pulp of a previously intact tooth is traumatically exposed, it can generally be assumed that the pulp is healthy and capable of regeneration. Vital pulp treatment is the treatment of choice and has high success rates. The treatment of crown-root fractures is challenging, requiring consideration of periodontal, endodontic, and, in particular, restorative factors. Teeth with crown-root fractures in proximity to the marginal bone level may be saved following surgical crown lengthening, orthodontic extrusion, or surgical extrusion.

30.1 Introduction and Epidemiological Data

Most teeth with intra-alveolar root fractures can be successfully treated by correct repositioning of the coronal fragment and subsequent splinting for 4 weeks. Likewise, teeth with luxation injuries require a flexible splint after repositioning in their original position in order to optimise healing outcomes for the periodontal ligament (PDL) and the pulp. The width of the apical foramen plays an important role in traumatic tooth dislocation. The smaller it is, the more likely the pulp is disrupted and the less likely it is repaired by revascularisation. In mature displaced teeth, pulp necrosis followed by root canal infection and apical periodontitis is expected. Additionally, in severe luxation injuries such as intrusions and avulsions with considerable mechanical damage to the cementoblast layer on the root surface, external infection-related root resorption may be an inevitable consequence. Thus, from an endodontic perspective, early initiation of root canal treatment is crucial to avoid infection-related root resorption.

A meta-analysis has suggested that almost one billion of the current world population have sustained traumatic dental injuries (TDI) to their permanent dentition [1]. Considering that a high proportion of minor cases are likely to be unreported, globally, the number of individuals who have suffered at least one TDI is likely to be even higher. The high prevalence, theoretically, ranks TDIs among the top five of the main chronic diseases and injuries, worldwide [1]. From an economic standpoint, TDIs and their consequences are associated with considerable costs for patients and health care systems [2]. Among injuries to the oral region, 92% include TDIs [3]. The teeth most frequently affected are the maxillary central incisors, followed by the laterals. More than 40% of all injuries to the permanent dentition occur before the age of 14 years, and nearly 25% of these occur before the age of 9 years, implying that the roots of the affected teeth are not fully developed [2].

30.2 Classification of Traumatic Dental Injuries

TDIs are classified as fractures and luxation injuries (Table 30.1). While tooth fractures are classified according to their location, the classification of luxation injuries is based on the extent and the direction of traumatic displacement of the tooth from its original position. Fractures of the crown are amongst the most common injuries to the permanent teeth, accounting for up to 40% of the injuries sustained (Figure 30.1). These fractures mainly affect the enamel and dentine with pulp exposure occurring in approximately 25% of all crown fractures. Crown-root fractures represent less than 5% of TDIs and are likely to expose the pulp [2].

Figure 30.1 Distribution of traumatic dental injuries. Adapted from Borum and Andreasen [2].

Table 30.1 Classification of traumatic dental injuries.

Fractures	Luxation injuries
Enamel crack/infraction Visible crack of enamel without loss of substance	Concussion Sensitivity to touch of the affected tooth. No signs of increased mobility. No signs of displacement. Oedema and bleeding in the periodontium and apex.
Crown fracture (with or without pulp exposure) Enamel or enamel-dentine fracture with possible exposure of the pulp.	Loosening/Subluxation Increased mobility. Sensitivity to percussion. Periodontal fibres are partially torn. Bleeding from the periodontal ligament (PDL) space. Irritation of the pulp at the apex.
Crown-root fracture (with or without pulp exposure) Crown fracture extending into the root. Mobile crown fragment is often still attached to the gingiva. Pulp exposure is frequently, but not necessarily, present.	Lateral luxation In maxillary incisors, lateral luxation generally leads to a palatal displacement of the crown and associated compression of the palatal socket wall. Fracture and displacement of the thin labial socket wall may be present. Tooth is often locked in this position or shows significantly increased horizontal mobility and enlargement of the bony socket. Apical periodontal ligament with palatal tearing and buccal compression. Presumably rupture of the neurovascular supply to the pulp in mature teeth with severe displacement.
Root fracture Horizontal or oblique root fracture. Increased mobility of the coronal fragment is common, and luxation may be present. Communication with the oral cavity via the sulcus is possible, depending on the location of the fracture line.	Extrusion Tooth appears elongated and is highly mobile. PDL fibres are largely torn. Bleeding from the periodontal ligament space. The pulp is stretched or detached.
	Intrusion Tooth appears shortened. (This effect can be masked by an accompanying crown fracture.) Increased buccolingual diameter of the socket. Tooth is wedged in the alveolar bone and has a metallic percussion sound. Severe PDL damage. Radiographic absence of periodontal ligament space; marginal bone covers enamel on the radiograph.
	Avulsion Complete displacement of the tooth from its socket.

Among luxation injuries, the majority of cases are minor such as concussion or subluxation [2]. One third of all TDIs are combinations of luxation injuries and fractures. In such cases, fractures are usually clearly visible and registered, but minor luxation injuries in particular are frequently overlooked [4].

30.3 Diagnosis of Traumatic Dental Injuries

Dental trauma is often associated with complex injury patterns, where correct diagnosis is of great importance because it forms the basis for developing the appropriate management strategy. Most injuries can be broken down into smaller components and related to the affected tissues, namely dental hard tissues, dental pulp, periodontium, alveolar bone, and gingiva [5, 6]. A traumatic dental injury should be considered an emergency and initially treated as such. Diagnostics involve detailed extra- and intraoral examinations, palpation, pulp testing, examination of tooth mobility or displacement, as well as radiographic assessment. In addition, informative photographs are necessary, not only for the initial diagnosis but also for forensic reasons in order to demonstrate that particular complications originate from the traumatic incident [7]. Crown fractures may reveal dentine or pulpal exposure upon inspection, if necessary, after removal of a coronal fragment.

The time that has elapsed between injury and therapy is of importance because it will influence the therapeutic approach as well as the prognosis [8]. Crown-root fractures with pulp exposure or root fractures may not be obvious but only become evident after careful radiographic examination. After dental trauma, radiographic images provide information not only on potential fracture lines but furthermore on the stage of root development, the size of pulp space and root canal (compared to the neighbouring teeth), resorptive processes, or periapical lesions. Furthermore, initial radiographic images (of same angulations and parameters) serve as a reference for the follow-up appointments.

Assessing the status of an injured pulp is particularly important in order to establish a reference point for later follow-up. However, this task may be difficult for several reasons. Patient compliance is required, which might not be granted due to young patient age or distress after the traumatic impact, leading to false results. Commonly used sensibility tests such as thermal or electric pulp testing elicit a response after stimulation of sensory receptors, which is physiologically dependent on a functional vascular supply. Therefore, reaction to sensibility testing is used as an indirect indicator (surrogate) of a vital pulp. This limitation in conventional pulp testing makes diagnostics after trauma challenging because temporary loss of sensibility occurs frequently due to pulpal oedema after luxation injuries. In such cases, it may take several weeks before a response to sensibility testing returns [9–11]. Thus, no reaction to sensibility testing of an initially vital pulp after trauma does not necessarily indicate pulp necrosis but rather indicates damage to the pulpal tissues with consequences regarding prognosis, as the vascular supply is responsible for pulp survival. Additional difficulties may occur after repeated injuries, which can influence sensibility testing and the healing/reparative capacity of the pulp. Furthermore, neural regeneration progresses at a slower rate compared to vascular regeneration or may even not occur [12, 13], which again conflicts with the nature of sensibility testing.

On the other hand, vitality tests (e.g. laser Doppler flowmetry, ultrasound Doppler flowmetry, pulse oximetry) assess the pulp’s blood supply, thus offering a more objective approach. Whereas vitality tests have been reported to have superior diagnostic accuracy compared to sensibility tests [14–16], there might be a high level of bias [17], and their complicated clinical application makes the benefit of these tests questionable [18]. Another factor that has to be considered when assessing pulpal status after dental trauma is the stage of root development. Immature teeth are associated with an increased excitation threshold [19], which may result in increased rates of false negative results [11].

Colour changes may be concomitant observations in traumatised teeth and may result from pulpal haemorrhage [20]. Pink colour changes that occur shortly after the accident can be reversible. However, if the crown of the tooth turns progressively grey, this may indicate pulp necrosis [21].

All these factors have to be borne in mind when performing sensibility testing of the pulp after dental trauma and obtaining the correct pulp diagnosis is only possible through combining and assimilating findings from the patients’ history, analysis of the injury pattern, further diagnostics, as well as radiographic assessment, which are all an integral part of the diagnostic process.

Despite the limitations of conventional two-dimensional radiography in visualising three-dimensional anatomical structures, periapical (PA) radiographic images combined with clinical examination remains the standard of care and should always be considered during the initial evaluation of the patient.

Cone-beam computed tomography (CBCT) can provide valuable additional information but its use should always be balanced against the potential risks. It should be noted that cases that appear straightforward on periapical radiographs might present a different and more complex situation when evaluated three‐dimensionally [22]. On the other hand, it should be taken into account that, particularly in children, the tissues are more sensitive to the effects of ionising radiation [23] with children below age 10 years having a threefold probability of radiation-induced stochastic effects compared to 30-year-old individuals [24]. Thus, CBCTs should be considered in situations in which further imaging is required to obtain an accurate diagnosis and develop a correct treatment plan. This applies particularly to cases of complex dentoalveolar trauma, root fractures where a communication of the fracture lines with the oral cavity appears likely, and complications such as root resorptions [25, 26].

30.4 Enamel Cracks and Crown Fractures

Enamel cracks are the most harmless injuries to teeth. They are described as incomplete fractures of a tooth that remains morphologically intact, but the crack line may extend into the dentine (Figure 30.2). An exact assessment of the depth of the crack and crack propagation prediction is not feasible [27]. Although a laboratory study identified enamel/dentine infractions as potential pathways for the invasion of microorganisms [28], an infection of a healthy pulp leading to necrosis is rather unlikely with a risk that has been reported to be less than 3.5% [29, 30]. However, the risk of pulp necrosis may increase in the presence of an undiagnosed concussion or subluxation of the affected tooth due to a compromised blood supply.

Figure 30.2 Multiple enamel cracks of the maxillary right central incisor and crown fracture of the maxillary left central incisor.

Adhesive sealing of enamel cracks has been reported to be effective in laboratory studies in order to prevent pulp infection [28]. However, there is no clinical evidence whether sealing a crack increases the fracture resistance of the crown or prevents pulp necrosis or discolouration of the crack lines.

Dentine Exposure: Most crown fractures expose dentine. In children, up to 70,000 tubules per mm2 with a diameter of 2–5 µm that lead to the pulp may be exposed [31, 32]. Due to an age-related smaller volume of peritubular dentine, a large percentage of the total cross-sectional area near the pulp consists of the lumina of the dentinal tubules resulting in the fractured dentine being highly permeable [33]. Defense mechanisms of the pulp such as the outward flow of dentinal fluid within the tubules and the ability of the pulp to elicit an immediate inflammatory response to external stimuli temporarily impede bacterial invasion and infection of the pulp tissue [34]. The risk of pulp necrosis is further increased in cases of concomitant luxation injuries [35]. A definitive adhesive restoration should be placed as soon as possible after the accident. If this is not feasible during the initial emergency treatment, placement of the restoration can be postponed if the dentinal wound is sealed properly to prevent pulp infection. Immediate dentine sealing can be carried out using a dentine bonding agent and a layer of flowable composite. Temporary dentine protection with a calcium hydroxide cement or a glass ionomer cement may be less effective but may be applied if subsequent treatment takes place within the next few days [36].

30.4.1 Vital Pulp Treatment

When the pulp of a previously intact tooth is traumatically exposed, it can generally be assumed that the pulp is healthy and capable of regeneration. This is particularly true in young patients without pre-existing pulpal damage caused by caries or by earlier dental trauma and without concomitant tooth luxation. Primate models studying the tissue reaction following experimental exposure of pulps to the oral environment demonstrated the presence of inflammatory cells in the pulp at the exposure site. However, during the first hours of exposure the tissue alterations rather reflect the damage resulting from the mechanical trauma with negligible superficial inflammatory changes [37, 38]. After 7 days of exposure, the inflammatory response has been reported to be more pronounced but does not extend more that 2 mm into the pulpal tissue at the site of exposure [39]. Thus, the conditions for vital pulp treatment (VPT) are favorable at least within the first days after trauma. Independent of the treatment strategy, it is essential that the tooth is isolated with rubber dam and disinfected prior to VPT [40]. Furthermore, the use of sterile instruments and magnification are highly recommended throughout the entire procedure.

Direct pulp capping aims to maintain the vitality of the entire pulp after application of a biomaterial directly onto the exposed tissue [40]. Animal studies suggest that direct pulp capping may be successful even if delayed for 24 hours [37, 41]. Nevertheless, direct pulp capping after trauma is usually preferred for small pulp exposures, which are treated shortly after the injury [42, 43]. Thus, partial pulpotomy is preferable for the majority of cases, particularly if a large area of the pulp is exposed and the treatment cannot be performed within the first few hours after the injury [36, 44] (Figure 30.3).

Figure 30.3 (a) Maxillary left lateral incisor with traumatically exposed pulp. (b) Incisal view under rubber dam. (c) Bleeding after removing the coronal 2 mm of the pulp (partial pulpotomy). (d) Sodium hypochlorite (3%) was used to assist haemostasis and bleeding stops after 5 minutes. (e) Application of the capping material, which was covered with a hard setting cement before restorative treatment with direct resin composite. (f) Clinical situation after 1 year with normal pulp test indicating pulp vitality.

Partial pulpotomy is preferably performed using a small cylindrical diamond bur in a high-speed handpiece under continuous irrigation and involves removing approximately 2 mm of the coronal pulp. Similar to direct capping, during partial pulpotomy rinsing the pulp wound with sodium hypochlorite (0.5–5%) or chlorhexidine (0.2–2%) is recommended to assist haemostasis and disinfection [44]. Cotton wool or sponge pellets soaked in sodium hypochlorite can be applied with gentle pressure. If the remaining pulp is reduced to a healthy level, any bleeding is expected to stop within 5 minutes. If haemostasis has not occurred within this time frame, the removal of the entire coronal pulp (full pulpotomy) can be considered as the last measure to maintain vitality of the radicular pulp. Before starting the capping procedure, the operator must make sure there is no blood clot on top of the exposed pulp [44].

30.4.2 Materials for Vital Pulp Treatment

The selection of the capping material for direct pulp capping and partial pulpotomy primarily depends on its bioactive properties, but the risk of discolouration should also be taken into account. Calcium hydroxide is still commonly used as a pulp capping material and has been reported to have high success rates [44] despite its mechanical instability and the dissolution of the material over time [45]. Hydraulic calcium silicate-based cements (HCSC) overcome this problem while at the same time offering excellent biological properties. The drawback of some of these materials is their discolouration potential caused by the radiopacifiers and by absorption of blood components within the material [46, 47]. Newer formulations of these materials that contain zirconium oxide or tantalum oxide appear more colour-stable [48–50].

A large variety of bioactive materials are available on the market, all of them largely sharing calcium-silicate chemistry with desirable biological effects. However, the use of light-curing liners and cements with calcium hydroxide or mineral trioxide aggregate (MTA) additives as pulp capping agents cannot be recommended at this time due to the paucity of reliable data regarding biocompatibility [44, 51, 52]. Likewise, dentine adhesives and resin composites are not biocompatible and therefore cannot be recommended as pulp capping materials [44, 53].

After application of a calcium hydroxide suspension or a nonstaining hydraulic calcium silicate-based cement on the exposed pulp, the pulp-capping material is covered with a thin layer of a hard-setting material to avoid unintentional removal during the restorative procedures that follow. Subsequently, the exposed dentine should be rinsed thoroughly and cleaned with water to minimise the negative impact of disinfecting solutions on the adhesive bond. The definitive adhesive restoration should ideally be applied in the same session.

A hard tissue bridge with histological evidence of tubular dentine may form over the healed pulp tissue [54]. However, in most cases, bridge formation after pulp capping is rather regarded as a repair process due to its unstructured mineralisation and lack of native tubular morphology [44, 55].

The capping material (calcium hydroxide versus HCSC) does not seem to be a decisive factor in the treatment of traumatically exposed pulps [43, 44]. One retrospective study demonstrated a significantly higher success rate when a new generation HSCS was used instead of calcium hydroxide; however, the latter still achieved a clinical success rate of 93% [56]. One randomised controlled trial demonstrated a similar pulp survival rate in traumatised immature teeth treated with partial pulpotomy regardless of whether calcium hydroxide or a new generation HSCS was used as a capping material [57].

Thus, calcium hydroxide can still be used but specific nonstaining HCSCs are the first choice [58–60], particularly if the colour stability of these materials can be confirmed in further clinical studies in anterior teeth.

Since discolouration is a clinically relevant issue in the anterior dentition, this is especially important in partial pulpotomies where a greater amount of capping material is used compared to direct pulp capping.

30.4.3 Success Rates of Vital Pulp Treatment in Traumatised Teeth

Survival of the pulp after complicated crown fractures can be achieved in 43–90% with direct pulp capping [61–64] and 86–100% with partial pulpotomy [42, 61, 62, 65–67]. Given the higher success rates of partial pulpotomy compared to direct pulp capping, the indication for direct pulp capping can be questioned.

Partial pulpotomy after trauma is associated with very high success rates in immature teeth (90–100%) and also high success rates ranging from 70 to 100% in mature teeth [42, 61, 62, 65–67]. With increasing age, alterations in terms of a reduced cell density and an increased amount of fibrous tissue may reduce the pulp tissue’s regenerative capacity [68, 69]. Nevertheless, vital pulp treatment after trauma should not be reserved for children and adolescents only. Even minor luxation injuries may compromise the nutritional supply to the pulp, particularly in teeth with completed root formation, and therefore substantially affect the success of vital pulp treatment [35, 70].

Teeth that have undergone pulp preservation procedures should be periodically monitored to assess a successful treatment outcome [71].

30.4.4 Reattachment Restoration

The adhesive reattachment of the coronal fragment is a conservative approach to re-establish function and aesthetics (Figure 30.4). If the fragment was stored under moist conditions after the accident, reattachment is ideally performed immediately during the emergency treatment. However, if the fragment is dehydrated due to dry storage for an extended time (>1 hour), both the aesthetic result and the bond strength may be compromised. Storage in saline or water for 1 day is recommended in such cases to allow rehydration of the fragment [72], while in the meantime the dentine is covered with a temporary material that is easy to remove (e.g. calcium hydroxide cements). Rehydration time may be shortened by wet storage of the fragment in a pressure vessel. According to our clinical experience, effective rehydration in terms of a resolved colour disharmony between fragment and tooth seems to occur within 30–60 minutes with this technique. However, evidence is lacking. Furthermore, the use of multi-mode adhesives may compensate for shorter rehydration times [73]. Rehydration of crown fragments in a special cell culture medium (tooth rescue box) is not necessary because no vital cells need to be kept alive. But if such a medium was chosen for storage at the place of the accident, no negative impact on bond strength is expected. Further alternative rewetting media such as milk, egg white, or hypertonic solutions have been proposed in the literature. However, there is only scarce and partly contradictory evidence on their benefit compared to saline or water [74–76].

Figure 30.4 (a) Crown fracture of the maxillary left lateral incisor. (b) The crown fragment is dehydrated and cannot be reattached immediately. (c) Adhesive reattachment of the crown fragment 1 day later. For rehydration, the fragment was kept in water. (d) Clinical situation 9 months after reattachment.

Before fragment bonding, both fragment and tooth should be cleaned thoroughly. Sandblasting might be a good option to remove any remnant of provisional material placed to seal dentine during the emergency treatment. However, careful consideration is necessary in areas with a reduced dentine thickness to avoid further damage to the pulp.

Additional preparation such as chamfering the enamel margins or placement of an internal groove lead to an improved bond strength but impede the exact repositioning of the fragment. Tooth surface and fragment are pretreated with an adhesive system, whereby previous enamel etching with phosphoric acid is highly recommended. Precuring the bonding agent would impair the fit and should therefore be avoided. A flowable resin composite is applied to the fracture surfaces of both parts and thoroughly spread over the surface. After repositioning of the fragment, excess material is removed and the fracture line is cured from the labial and the palatal side. High-power curing lights and/or longer irradiation time is recommended to ensure that enough energy is delivered through the tooth structure to the entire bonding surface. Cooling the tooth with compressed air helps to reduce temperature rise during photopolymerisation and may prevent heat-induced pulp damage [77].

Even though reattachment restorations only achieve about 50% of the cohesive strength of intact teeth in laboratory studies, the simplicity of the procedure and the optimal aesthetic result are strong arguments in favour of this approach. This is confirmed by a large number of case reports; nevertheless, the clinical evidence remains scarce. The only long-term clinical study was published 25 years ago and indicates a retention rate of reattached fragments of 40% after 5 years and only 25% after 7.5 years [78].

However, it should be noted that in more than half of the cases, no dentine adhesive was used, but adhesion was based solely on the enamel etching technique, resulting in a debonding rate of 50% within the first year. In comparison, using a then-current dentine adhesive, the 50% debonding rate was only achieved after 3 years. Furthermore, a second trauma was identified as the main cause of failure. Thus, the available data may not reflect the true clinical potential of adhesive fragment reattachment (AFR), which is more likely to be improved with modern dentine adhesives on perfectly cleaned dentine surfaces and optimal enamel margins. In case of debonding, renewed reattachment is possible. However, care must be taken to remove all adhesive or composite residues from both the fragment and the tooth. This may be achieved by sandblasting the surfaces with aluminum oxide.

A favourable aesthetic long-term result after AFR can be expected in half of the cases [78]. A visible fracture line and a discoloured fragment have been reported to be the main causes for an impaired aesthetic result. While discolouration of the fracture line no longer plays a major role today when using modern adhesive materials, gradual colour changes of the coronal fragment are occasionally observed. The sealed dentine surface may act as a diffusion barrier that prevents the exchange of moisture between the tooth and the coronal fragment. There are no current data on the frequency of this aesthetic limitation.

30.4.5 Direct Resin Composite Restoration

If repositioning of a coronal fragment is difficult or even impossible in cases of multiple or missing fragments, resin composites can be used on a routine basis for the restoration of fractured teeth. Especially smaller defects can be easily built up ‘freehand’ with a universal composite (Figure 30.5). If extended parts of the crown have to be restored, more sophisticated polychromatic, multiple-layer techniques using a esthetic resin composites provide excellent results [79, 80] (Figure 30.6). Whenever possible, isolation with a rubber dam should be attempted. However, in a mixed dentition with partially erupted teeth or in partly subgingivally located defects, the application of a rubber dam is not always feasible. In these cases, alternative methods of isolation utilising cotton rolls in combination with efficient saliva suction must be used.

Figure 30.5 (a) Enamel fracture of the maxillary right central incisor. Dentine is not exposed. (b) The tooth was restored with a universal resin composite.

Figure 30.6 (a) Seven-year-old patient with typical crown fracture of the maxillary right central incisor. (b) Direct mock-up with resin composite. (c) The artificial enamel frame is built first using a silicon key. Cotton rolls are used in combination with efficient saliva suction for isolation. (d) The dentine core is reconstructed leaving only limited space for the buccal enamel. (e) White tints are used for characterisation. (f) Completed restoration before finishing. (g) Restoration after finishing and polishing. (h) Smile of the patient. (i) Clinical situation after 18 months.

Although the aesthetic results initially achievable with resin composite are undisputed, the long-term prognosis of direct resin composite build-ups after tooth trauma is controversial. According to a meta-analysis, the prognosis of Class IV restorations after 10 years was approximately 90% [81]. However, a significantly higher failure rate was reported for restored crown fractures in children, with a second trauma being the main reason for failure [82].

30.4.6 Indirect Ceramic Restoration

All-ceramic restorations (veneers or crowns) are a feasible alternative to the direct resin composite technique. Tooth preparation, however, is more invasive and entails additional damage to the pulp, especially in immature teeth with large coronal pulps. Thus, the indication for indirect restorations should be restricted to extensive defects in adult patients [83].

30.5 Crown-root Fractures

In maxillary anterior permanent teeth, crown-root fractures have a typical fracture line: on the buccal side the fracture is localised paragingivally or supragingivally, whereas palatally the defect often extends far down the root. Although the coronal fragment may have increased mobility, it is still retained palatally by the intact periodontal fibre attachment. Usually, only one fracture line is visible on periapical radiographic images, which corresponds to the buccal fracture line. The palatally situated fracture is usually not visible because of an overlap with the alveolar bone and the absence of a space between the fragments in this region. The pulp is frequently, but not always, involved. To assess the extent of the fracture and identify additional fractures that are often located at the palatal side of the root, it is necessary to remove the mobile coronal fragment. A CBCT might help to detect additional fractures in the root.

The treatment of crown-root fractures is challenging, requiring consideration of periodontal, endodontic, and, in particular, restorative factors. Treatment options for various clinical situations are presented in Table 30.2.

Table 30.2  Treatment options for crown-root fractures [83] / with permission from John Wiley & Sons.

Clinical situation	Options for restorative treatment
Only slightly subgingival defect, with reasonable access after placement of retraction cords, gingivectomy, or surgical flap	Option 1: Restoration with reattachment of the coronal fragment, direct composite restoration, or indirect restoration
Inaccessible defect due to deep subgingival/subosseous extension	Option 2: Restorative treatment of the accessible regions (mostly supragingival) Option 3: Surgical crown lengthening + restoration Option 4: Orthodontic extrusion of the apical fragment (forced eruption) + restoration Option 5: Surgical extrusion (intra-alveolar transplantation) + restoration
Unrestorable tooth due to deep subosseous extension and/or additional fractures of the root	Option 6: Extraction

30.5.1 Adhesive Fragment Reattachment

Adhesive reattachment of the crown fragment is a very conservative but technique-sensitive approach for the restoration of crown-root fractures. For fragment reattachments performed meticulously after preparation of a mucoperiostal access flap, excellent results during the first 2 years have been reported [84]. A long-term study assessed the survival rate and periodontal health of deep crown-root-fractured teeth treated by AFR after a mean observation period of 8.6 (±4.6) years [85]. Overall, treatment success without any need for reintervention was only achieved in 22% (11 of 51) of the cases, whereas 30% (15 of 51) of cases ended in tooth extraction. Fragment reattachment was generally associated with mild gingival inflammation. However, in case of initially undetected additional root fractures, the periodontal health of the affected teeth was severely compromised. Despite the frequent need for reintervention and the potential impact on periodontal health, the functional survival of AFR treated teeth was high, suggesting that AFR might be suitable as a long-term temporary treatment approach, particularly in young patients for which other options are not feasible.

30.5.2 Two-step Direct Composite Restoration

If the coronal fragment is missing and adequate moisture management can be achieved, a composite restoration can be the treatment of choice. A two-step procedure with elevation of the margin in the first step can combine good marginal adaptation and an optimal anatomic reconstruction of the crown [86]. Astringent haemostatic agents with or without retraction cords may be used to control sulcus bleeding and reduce the flow of sulcular exudates during the first step. However, the clinician should be aware that bond strength to astringent-contaminated dentine is considerably reduced, particularly when self-etch adhesives are used [87]. Clinical evidence on the impact of margin elevation procedures on periodontal health of the affected teeth is scarce and contradictory [88–90].

30.5.3 Restorative Treatment of the Accessible Regions

If the defect margin is very difficult to access and the fractured surface has a steep inclination, a supragingival restoration that covers only the accessible regions may be a reasonable compromise over more invasive methods [83]. However, some fractured subgingival dentine areas remain unsealed. Evidence supporting this approach is missing; however, it can be a reasonable option compared to extraction of the tooth.

30.5.4 Surgical Crown Lengthening

Surgical crown lengthening represents an alternative treatment approach for teeth with subgingival caries or fractures. Resective osseous surgery makes the defect accessible for restorative treatment and re-establishes the biological width [27]. However, the disadvantages of this method include loss of alveolar bone and compromised aesthetics that limit its use [91].

Surgical crown lengthening results in significant increase of the crown length (6-month average: 1.4– 3.3 mm) but tissue rebound with a significant reduction of the crown length increase is likely to occur, particularly during the first three postoperative months [92–96]. None of the studies reported long-term data (>6 months) [97]. Furthermore, a systematic review demonstrated that adjacent and nonadjacent sites are affected by crown lengthening surgery and can lead to undesirable clinical and aesthetic alterations, which must be considered [98]. In general, the benefits of surgical crown lengthening should be balanced against the drawbacks, particularly the bone loss associated with this approach, which may result in a more unfavourable situation for any implant placement in the future if the treatment fails.

30.5.5 Extrusion

Extrusion of the remaining root is another alternative, which can be carried out either orthodontically (forced eruption) [99] or surgically (intra-alveolar transplantation) [100].

Orthodontic extrusion of teeth with subgingival fractures was introduced more than 40 years ago [101] and is considered a viable conservative treatment option in these cases [102, 103]. Circumferential supracrestal fibreotomy is essential to avoid coronal migration of the gingival tissue and bone [104, 105]. However, the level of evidence for orthodontic extrusion is low and based solely on case reports [99].

For surgical extrusion, the root is extracted, replanted after 180-degree rotation, and splinted in a position sited further coronally [27] (Figure 30.7). Most crown-root fractures typically extend into the infraosseous region on the palatal side. In contrast, the bone level of the alveolar process in the maxillary anterior region is more coronally on the palatal side compared to the labial side. For that reason, rotation of the root by 180 degrees before replantation is ideal to expose the defect margin on both aspects while minimising the extrusion distance at the same time [106]. A further significant advantage of surgical extrusion is that the inspection of the entire root surface can be performed easily, and additional fractures are found. Provided that an atraumatic extraction technique is employed, there is little mechanical damage to the root cementum. Additionally, preoperative orthodontic extrusion may be considered to facilitate atraumatic extraction of the fractured root [107]. Periodontal healing (without ankylosis) can be expected [108]. Aesthetic rehabilitation includes all methods of restorative treatment ranging from composite build-ups to the placement of crowns, depending on the residual tooth substance.

Figure 30.7 (a) Crown-root fracture of the maxillary right central incisor. (b) Surgical extrusion: the root is extracted, replanted after 180° rotation. (c) Splinting. (d) Restorative treatment with placement of a post. (e) Restoration immediately after rubber dam removal. (f) Situation after 6 months. (g) Smile of the patient. (h) Radiograph after 6 months.

Eleven clinical studies demonstrated favourable success rates after surgical extrusion of teeth with subgingival fractures or carious decay during the past 40 decades [109–119]. Nevertheless, the available evidence remains rather limited because it is based mainly on case series. Overall, publication bias favouring positive results has to be considered. Some studies published by the same author groups may have included overlapping groups of patients. In most clinical studies, surgical extrusion was performed mostly in patients younger than 30 years. However, it was shown that surgical extrusion can be successfully performed even beyond the fifth decade of life [113].

Two systematic reviews summarised the clinical evidence [100], and the adverse events of surgical extrusion based on 11 case reports and 8 case series [120]. Overall, non-progressive root resorption was the most common finding, with an event rate of 30%, followed by tooth loss (5%), slight mobility (4.6%), marginal bone loss (3.7%), and progressive root resorption (3.3%). An axial extrusion technique, which avoids compression of the periodontal tissues during extraction, might further reduce the occurrence of biological complications [113].

An animal study compared experimental surgical and orthodontic extrusion in dog teeth. The histologic evaluation of the root surfaces demonstrated more initial signs of transient resorption in the surgical extrusion group compared to the orthodontic extrusion group, but functional repair with normal periodontal ligament and no ankylosis was evident in both groups after 120 days [121].

Although the treatment of crown-root fractures is one of the most technically demanding procedures in dental traumatology and is considered in many cases rather as a long-term temporary restoration, even tooth conservation up to the age at which implants can be placed is accepted as success.

30.6 Splinting of Traumatised Teeth (Root Fractures and Luxation Injuries)

Splinting after dentoalveolar trauma aims to stabilise the affected teeth after repositioning in their original position in order to optimise healing outcomes for periodontium and the pulp [122].

For decades, it was assumed that splinting of traumatised teeth should follow the same principles as immobilisation of bone fractures and implied the use of rigid splints for several months. In the 1980s, an animal study demonstrated that avulsed teeth that were exposed to a normal masticatory function after replantation were less prone to develop ankylosis [123].

Today, there is consensus that splints should be passive, be of short duration, and allow physiologic tooth mobility to aid in PDL healing [122, 124, 125]. Furthermore, a dental trauma splint should:

• be easily applied and removed,
• allow pulp sensitivity testing and an endodontic access preparation, and
• not interfere with oral hygiene and the occlusion.

Various types of flexible splints including thin (orthodontic) wires, nylon lines, fibre splints, or dedicated trauma splints have been recommended [122]. Particularly, the titanium trauma splint (TTS; Medartis, Basel, Switzerland), which was specifically designed for this purpose seems to meet all requirements [126, 127] and has become a standard for the fixation of traumatised teeth since the early 2000s.