A review of root fractures: diagnosis, treatment and prognosis

Classification

Horizontal/transverse root fractures are most commonly seen in young adults due to direct physical trauma in the anterior region. They can be further sub-classified on the basis of:

Depending on the position of the fracture line, transverse root fractures can also be classified into three zones10 as follows (Figure 1):

These zones are analogues to crown fracture, cervical-root fracture, and middle/apical root fracture, respectively.

Aetiology

The most common reason for root fractures in the permanent dentition is physical trauma caused during falls, fights or sporting events.3 Any object striking the teeth may also lead to a similar injury. As fights and sporting activities are more common in the first and second decade of life, an increased prevalence of root fractures is observed in a similar age group (11–22 years).1 Usually, horizontal root fractures are observed in anterior teeth with direct trauma. In posterior teeth, it usually occurs as a result of indirect trauma.

In addition, root fractures may occasionally be caused by parafunctional habits, traumatic occlusion, extensive tooth decay and iatrogenic causes.

History

The diagnosis begins by recording the demographics of the patient and taking a brief history of the traumatic event:

Equally important is an overview of the general systemic health of the patient (allergic reactions, epilepsy or bleeding disorders)1 and a neurophysiologic examination of the patient. Traumatic injuries to teeth can be associated with injuries in the head and neck region, presenting with subtle signs and symptoms but with serious neurological consequences. Therefore, it is important to do an initial neurological examination and evaluation of the patient, along with the orofacial structures.

Clinical examination1

Fractures in the middle-third of the root occur with higher frequency, while fractures of the apical- and cervical-thirds occur with equal frequency. Fractures in the apical-third of the root do not show signs of displacement or mobility. Teeth with middle-third fractures are usually slightly extruded with displacement in the lingual direction and lateral luxation of the coronal segment.1 In cervical-third fractures extending below crestal bone, the crown is usually present with minor mobility owing to attachment of the periodontal fibres to the portion of root that has fractured off with the crown.1 In anterior teeth, with fracture line above the crestal bone, the crown is usually extremely mobile or dislodged. In posterior teeth, clinical presentation is of one rigid cusp and one mobile cusp. The tooth may be tender to percussion and/or palpation and show transient crown discoloration.11 A thorough visualization of the subgingival area is also important to detect any fracture line.

Pulpal status

Initially, sensibility and vitality testing may give negative results due to transient or permanent pulpal damage inflicted by trauma.6 A routine follow-up is required to monitor the pulpal status continuously.11,12 More recently, the use of a pulse-oximeter was recommended to evaluate the pulpal status of a recently traumatized tooth (Figure 2). This has better sensitivity and specifity than electrical and thermal tests13 and gives a constant positive vitality reading with time in cases of recently traumatized teeth.14

Radiographic examination13,11

Radiographic examination is indispensable for the confirmation of root fractures. The fracture line is oriented obliquely in the apical- and middle-third of the root and more horizontally oriented in the cervical-third. Therefore these fractures are normally visible only when the central beam is directed within a maximum range of 15–20° of the fracture plane. Any deviation from the fracture plane shows the fracture line as an ellipsoid structure mimicking an intermediary fragment. In addition to the conventional periapical radiograph, two additional periapical radiographs (one with a positive angulation of 15° to the fracture line and the second with a negative angulation of 15° to the fracture line) should be exposed.1 Other suggested protocols to visualize the fracture line accurately are:

In addition to the views listed above, occlusal radiographs may be required to disclose fractures in the apical-third of the root, although cervical-third root fractures are better visualized with periapical radiographs.9 Horizontal root fractures are also often associated with concomitant fracture of the alveolar process (mandibular incisor region).1

Treatment

Root fractures with minor insults and/or damage to pulp (hair line fractures) either lead to concussion injury or non-vitality. In such cases, vitality tests should be performed on a regular basis and the tooth kept under constant observation as there are high chances of re-establishment of pulp vitality via revascularization. In cases of complete horizontal fractures, the treatment principle is the same as for any other fracture, ie reduction of displaced fragment followed by immobilization.1 Often an interdisciplinary/multidisciplinary approach is essential for the functional and aesthetic rehabilitation of a tooth.2 Treatment advocated in a particular case is determined by the extent of subgingival fracture, remaining coronal tooth structure, location of fracture line, pulp vitality and length and morphology of the roots.6,9 In cases of severe neurovascular damage, unfavourable outcomes such as pulp canal obliteration and pulpal necrosis can occur.

Apical-third fracture1,9

In the case of apical-third fractures of the root, there is usually no mobility and the tooth may be asymptomatic. Also, it has been observed that the apical segment of a transversely fractured tooth remains vital in most of the cases. Thus no treatment is required and a watch and observe policy is advocated. If the pulp undergoes necrosis in the apical fragment, surgical removal of the apical fragment is indicated.

Middle-third fracture

The treatment advocated is immediate repositioning of the displaced fragment followed by application of a passive splint. It can be done by simple digital manipulation (finger pressure), or an orthodontic intervention may be required for proper alignment. Resistance to repositioning can occur owing to fracture of the labial socket wall and it should be repositioned before the reduction of root fracture. The position of reduced segments is checked radiographically. Following reduction, a passive splint is applied for a period of 4 weeks to ensure sufficient hard tissue consolidation.1,11 The advocated splinting methods include the use of stainless-steel wire resin-based composite splints or titanium trauma splints (TTS). These are 0.2 mm thick rhomboid mesh structures of titanium that can be easily adapted and stabilized on the teeth. They require less application time, are easy to remove and clean and have been considered to be more comfortable.16

Cervical-third fracture

Treatment options are decided upon by the position of the fracture line, length of the remaining root segment and the presence or absence of a coronal segment. Chances of healing with calcified tissue is poorest in cervical-third fractures.1,17

Crown lengthening (periodontal surgery)

Crown lengthening is performed if the fracture line is not more than 1–2 mm below the alveolar bone crest. This procedure involves removal of 1–2 mm of crestal bone adjacent to the deepest part of the fracture and restoring the normal sulcus depth of 2 mm (Figure 3). It usually leads to apical shifting of gingival margin which may compromise aesthetics. Periodontal and osseous recontouring allows exposure of the fracture margin and sufficient root surface to give an acceptable restorative finish line.

Orthodontic extrusion

This is also known as forced eruption, orthodontic eruption, vertical extrusion or assisted eruption. It is carried out in cases where the fracture line extends deeply in the interproximal or labial surface (up to 6 mm below the alveolar crest) and when crown lengthening would be unaesthetic.

For a successful extrusion and post-treatment restoration, the distance from the fracture line to the apex should not be less than 12 mm and a crown-root ratio of approximately 50:50 must be obtained. This technique involves application of traction forces to the tooth, causing vertical extrusion of the root and marginal apposition of crestal bone (Figure 4). The gingiva, epithelial attachment, and newly formed crestal bone are also extruded, along with the tooth, leading to a coronal shift of the marginal gingiva. Thus there is no loss of any bone or periodontal support. But this coronal shift of gingiva has the following disadvantages:

Therefore, at the end of the procedure, a conservative periodontal surgery is necessary to correct any discrepancy followed by a stabilization period of 7–14 weeks before the orthodontic appliance is removed.1 The techniques used for orthodontic extrusion include the use of removable or fixed orthodontic appliances.23,24

Intra-alveolar transplantation of the fractured tooth

This is mainly performed in cases where time and money are the major determining factors. It is carried out for patients who are treated on an emergency basis, having severe luxation of the fractured root. In this technique, the tooth is carefully extruded to the required position by marginal luxation and stabilized by interdental suturing and surgical dressing.25,26 If the fracture line is more apical on the labial side, a rotation of 180° is given before fixation.27 With this method the bone support around the root is usually lost.

Position and mobility of coronal segment after trauma

Increased dislocation and mobility result in a decreased prognosis. In concussion, a high rate of hard-tissue healing is observed, whereas in cases of luxation, healing with connective tissue is high.31 Immobilization should be done as soon as possible for an optimum consolidation and repair across the fracture line. Optimal repositioning and use of passive flexible splint favours healing.1

Status of the pulp

A vital pulp and positive pulp sensibility at the time of injury are positively related to faster healing and hard tissue repair of the fracture. Pulp in the apical segment of the fractured tooth is vital in almost all cases.

Position of the fracture line

Middle-third fractures are considered to have the best prognostic value. The chance of healing with calcified tissue and survival is poorest when the fracture line is very close to the gingival crevice.29 Zachrisson and Jacobsen32 observed that the location of the fracture line does not influence the outcome, except for fractures that occur too close to the alveolar bone crest (as the tooth support is compromised).

Treatment time

There is apparently no definitive proof of a relationship between treatment time, ie time taken until treatment is initiated, and prognosis.

Communication with the oral environment

If communication develops between the gingival sulcus and the fracture site the prognosis is poor because of bacterial contamination6,33

Age

Young age and immature root formation are increasingly related to pulpal healing and hard tissue formation at the fracture site due to the increased size of pulp and vascularity.

Gender

Girls showed more frequent hard tissue healing than boys as they usually experience less severe trauma and at an earlier age.30

Other factors include:

However, in certain cases, the follow-up examinations may show deviations from the normal pulpal and periodontal healing, leading to pulpal necrosis, pulp canal obliteration and root resorption.

Classification

Vertical root fractures (VRFs) are classified either on the basis of separation of the fragments (complete or incomplete) or on the basis of relative position of fracture to the alveolar crest (supraosseous and intraosseous).36

Aetiology

Diagnosis of vertical root fractures

The fractured tooth may have an extensive carious lesion, large failing occlusal restoration, or wear facets on teeth and restorations.36,49 In posterior teeth, VRF propagate in a crown-down direction, with the fracture line being aligned mesio-distally. Iatrogenic VRF occurs from inner to outer root surface, and is generally aligned in a facio-lingual direction. Intraosseous fracture creates deep, narrow, sharply defined and isolated periodontal pockets (‘precipitous pockets’).46 Patients usually complain of pain on mastication. Other symptoms include gingival inflammation, mobility of fragments and presence of sinus tract or fistula. Initial radiographic examination may reveal unilateral thickening of PDL along the fracture side of the root. As the fracture advances, a characteristic diffuse radiolucency (or halo) is seen surrounding the tooth root uniformly.50

Other radiographic features include:

Sometimes the VRF is associated with displacements of apical portions of the root.52 At times the fracture line may be invisible and can only be detected by a tooth sloth, a burlew disk, transillumination test, disclosing dye, surgical exploration, or by removal of an existing restoration.

Treatment

A variety of approaches have been attempted and used to treat the VRF, including:

However, in most cases of VRF in anterior teeth, extraction is the only available treatment option. For posterior teeth, Luebke36 has proposed four basic categories of treatment.