|Year : 2014 | Volume
| Issue : 3 | Page : 107-113
Vertical root fractures: An update review
Anu Dhawan, Sumit Gupta, Rakesh Mittal
Department of Conservative Dentistry and Endodontics, Sudha Rustagi Dental College, Faridabad, Haryana, India
|Date of Web Publication||29-Oct-2014|
Department of Conservative Dentistry and Endodontics, Sudha Rustagi Dental College, Faridabad - 121 002, Haryana
Source of Support: None, Conflict of Interest: None
Vertical root fractures are the most common cause of tooth loss. These fractures have a multifactorial etiology. They lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. Clinical signs and symptoms are often elusive in nature and may be difficult to detect. In this review, the etiology, diagnosis, prevention and management of vertical root fractures is discussed.
Keywords: Etiology, management, vertical root fractures
|How to cite this article:|
Dhawan A, Gupta S, Mittal R. Vertical root fractures: An update review
. J Res Dent 2014;2:107-13
| Introduction|| |
According to the American Association of Endodontists " A "true" vertical root fracture is defined as a complete or incomplete fracture initiated from the root at any level, usually directed buccolingually".  It starts from an internal dentinal crack, and develops over time, due to masticatory forces and occlusal loads.
Fractures or splits represent the third most common reason for tooth loss. However, the primary pathogenic cause is not always clear as it develops over a long period. Average time between root filling and the appearance of a vertical root fracture (VRF) has been estimated to be between 39 months  and 52.5 months  with a range of three days to 14 years.
| Incidence|| |
Gher et al. have reported a low incidence of 2.3%.  Highest incidence has been observed in endodontically treated teeth and in patients older than 40 years of age.  But, VRF can also be observed in vital teeth.
Teeth with flat or thin roots of smaller mesio-distal diameter and an oval diameter in a bucco-oral direction, such as those in maxillary and mandibular premolars; mesio-buccal roots of maxillary and mesial roots of mandibular molars; and mandibular incisors, are more susceptible to fracture. Testori et al.  reported premolars to have the highest incidence of VRF in endodontically treated teeth; however, Chan et al.  reported first molars to be the teeth most frequently fractured. On the other hand, canines had the lowest incidence. VRF is rare in vital anterior teeth, possibly because the direction of masticatory force is usually more lateral than vertical. Fracture most commonly occurs in bucco-lingual direction in individual roots of molar teeth. Mesio-distal fractures are less common. In anterior teeth, the fractures are most commonly in a bucco-lingual direction. 
VRF in vital teeth occurs more frequently in males due to factors such as stronger masticatory force, increased attrition, habitual chewing of hard food and less pliable supporting bone. 
An overall prevalence of 3% to 5% has been reported in retrospective studies. , However, the percentage of extracted teeth with VRF has been reported to be much higher - 10-20%. ,, Improved diagnostic knowledge on the subject has led to increased prevalence being reported in recent studies. Higher prevalence is noted in patients of middle and older age.
| Discussion|| |
VRFs have a multifactorial etiology that can be divided into predisposing and iatrogenic factors (summarized in [Figure 1] and [Figure 2]).
Predisposing factors for endodontically treated teeth
- Root anatomy- The unique anatomy of the susceptible roots, i.e. roots with narrow mesio-distal diameter, root curvature , and root depressions in mesial root of mandibular molars and the buccal root of bifurcated maxillary premolars,  predisposes these roots to fracture, especially at a later stage when additional tooth structure is removed during root canal and dowel preparations Canal and root shape combined with dentine thickness affect tensile stress distribution during intracanal procedures. Canal shape is the most important factor of the two since the area of reduced curvature radius is strongly influenced by stress concentrations 
- Loss of healthy tooth substance - Combined with tooth loss due to caries, the result of intraradicular procedures, the remaining tooth structure is directly related to the ability of endodontically treated tooth to resist fracture ,
- Moisture loss in pulpless teeth  was reported to make the endodontically treated teeth more brittle. However, it was not supported ,
- Change in architecture of an endodontically treated tooth makes the tooth more prone to fracture and require a restoration (full cuspal coverage) that will protect the tooth during function 
- Loss of bone support due to periodontal disease, pre-endodontic and prosthetic treatment can result in reduced ability of the tooth to withstand functional stresses 
- Pre-existing cracks
- Biochemical properties of root dentin- In a study on stress-strain response in human dentin, it was found that the dentin adaptation to functional stress-strain distribution results in greater mineralization in the bucco-lingual areas. This may increase the likelihood for a fracture to propagate in this direction, compared with less mineralization and more collagen in the mesio-distal areas. 
The iatrogenic cause of VRF is mainly attributable to different phases of root canal treatment:
- Excessive cutting during various phase of root canal treatment ,
- Increased stress generation with threaded and tapered posts ,
- Increased wedging forces with lateral compaction of gutta-percha accounts for 48%  to 84%  of cases of VRFs. The development of these stresses initiates crack introduction and propagation, leading to final root fracture. 
Fracture occurring directly during root canal treatment as a result of excessive force is rare as forces required for provocation of fractures vary according to the tooth type (approximately 10 to 12 kg), and are well above those that are clinically relevant (1 to 3 kg)  during root canal treatment. However, stress caused in dentin may initiate dentinal cracks, which can extend to complete fractures under functional load.
Non-endodontically treated teeth
In non-endodontically treated teeth, fractures might be related to special diet patterns or chewing habits,  excessive, repetitive and heavy masticatory stress  referred to as "fatigue root fractures." So the physical trauma is the most common cause for tooth/root fracture in vital teeth. Other predisposing factors are enumerated in [Figure 3].
As VRF progresses to the periodontal ligament, soft tissue growth into the fracture space increases the separation of the root segments. On communication with the oral cavity through the gingival sulcus, bacteria obtain access to the fracture area and an inflammatory process is induced in the adjacent periodontal tissue, resulting in periodontal ligament breakdown, alveolar bone loss and granulation tissue formation. 
Along the fracture line the periodontal ligament disintegrates, followed by bone loss, which is progressive especially in thin buccal bone plate.
Clinical signs and symptoms
The clinical signs and symptoms vary (according to the position of the fracture, tooth type, time elapsed since fracture, periodontal condition of the tooth and the architecture of the bone adjacent to the fracture) and are difficult to detect or reproduce during patient examination. The patient's symptoms may mimic many other possible diagnoses such as sinus problem, vague headaches or ear pain.
Pain and swelling
Local chronic inflammation due to infection leads to discomfort and soreness, mild to moderate pain, pain on biting, bad taste and swelling of soft tissues.  Some swelling of soft tissues is usually present. The swelling is usually broad-based, and mid-root in position compared to apical location in peri-apical abscess. Palpation will often show swelling and tenderness over the root itself.
A sinus tract is commonly found in VRF cases (13-42%)., In VRF, sinus tract is located close to the gingival margin as opposed to non-vital teeth where sinus tracts are located more apically (differential diagnosis from endodontic infections). The presence of two sinus tracts (at both buccal and lingual aspects) or multiple sinus tracts is almost pathognomonic for a VRF.
Deep, narrow, isolated periodontal pockets are commonly found in vertically fractured roots. Deep probing in one position around the circumference of tooth in presence of otherwise normal attachment usually indicates that the tooth is fractured (as opposed with periodontal disease, where the pocketing is generalized around a large part of the tooth). Deep probing in two positions on opposite sides of the infection is almost pathognomonic for the presence of a fracture.
Occasionally, sharp cracking sound during condensation of gutta percha ,, or during cementation of a post  may be felt by the patient. Bleeding or lack of resistance within the canal during condensation of a root filling material, repeated dislodgement of a well-fitting post  are also signs of VRF.
VRF poses a diagnostic challenge because
- Fracture line may not be visible as long as it has not extended to the cervical region. Early radiographic detection is also difficult
- Signs and symptoms are often similar to those found in failed root canal treatment or in periodontal disease.
Early and correct diagnosis is imperative, as bone resorption around a fractured root continues with time until the tooth/root is removed or lost.  Delay in diagnosis will result in limited success rate of any treatment modality due to loss of supporting bone and presence of a weakened periodontium. Diagnosis is based on: (summarized in [Figure 4]).
- History of facial trauma (for example, in patients with seizure disorders, stroke, heart attack or any other ailment that might have resulted in lack of consciousness) could result in a VRF if the trauma is directed accordingly
- History of pain, swelling, presence of sinus tract, mobility, or any history of post or restoration dislodgement. ,,
- A thorough clinical examination, including age and gender of patient; involved tooth, its location, pulp vitality; history of previous dental treatment (including endodontic and restorative treatments); and type of restoration (with or without post and crown) using glass ionomer cement, resin-based composite or amalgam.
Clinical diagnostic tests
Direct visual examination (with good illumination and magnification) of tooth especially the marginal ridges (areas most predisposed to crack) is important. When excess coronal structure is missing, or when a crown has dislodged, fracture may be directly viewed by examining the remaining tooth structure. Fracture is clearly visible when separation of fragments has occurred. A sharp probe may aid in identifying the fracture line where separation has not occurred.
Disclosing dyes stain the fracture line and aid the clinician to visualize a suspected crack. Also, cleaning the occlusal surface with a cotton pellet moistened with 70% isopropyl alcohol, washes away the food coloring on the surface, but the food coloring within the fracture line remains and becomes apparent.
Pulp vitality tests can be helpful in diagnosing a VRF (especially in ostensibly sound teeth) as fracture line may extend to the pulp causing inflammation and necrosis. Diagnostic information may be obtained when the patient complains of a sharp, sudden pain, especially while chewing. 
Rubber wheels, cottonwood sticks or aids such as Tooth Slooth may be used to reproduce the biting pain described by the patient.  This test is performed tooth-by-tooth or cusp-by-cusp. Usually the patient feels relaxed on biting and pain starts while releasing the pressure.
Fiberoptic light may be used to visualize a crack. Light is deflected at the crack, reducing its transmission through the tooth, making the fractured segment appear darker.
Periodontal probing test
Probing with periodontal probe or a no. 25 silver cone may reveal a narrow, isolated, periodontal defect in the gingival attachment.
Tracing the sinus tract
Gutta percha, endodontic explorer, etc., may be used to trace the sinus tract back to its origin.
- Fracture (radiolucent) Lines: Separation of root fragments makes fracture clearly visible. Proliferation of granulation tissue between the separated fragments often results in the rapid movement of the fragment away from the remaining root 
- Radiolucent Lines along the root fillings or post: Appearance of a vertical space adjacent to the root filling material (in an otherwise well-obturated canal) or a space between the edge of a root canal, which may be coated with cement, and the post itself may be indicative of VRF
Direct evidence of fracture line is often difficult to visualize. For the fracture to be seen the X-ray beam must pass almost directly down the fracture line. Even small changes in horizontal angulation (+4°) may render the fracture undetectable  Fracture line deviating from long axis of the canal may be radiographically more obvious, as compared to fracture line running parallel and adjacent to a root filling 
- Double images: When separation of fragments occurs in a direction other than parallel to the X-ray beam, overlapping of fragments may result in double images of the external root surface. But this effect is sometimes seen in normal teeth, for example, in the mesial concavity of maxillary premolar teeth.
- Extrusion of cement or filling: Extrusion of cement or root filling material may occur into the fracture site or apically When the fracture is present prior to filling, or occurs during the root filling procedure.,
- Dislodgement of retrograde filling material: May occur in fractured roots. ,,
Patterns of bone loss
The amount of bone loss is dependent on the nature and duration of the fracture.
- Widening of periodontal ligament space: Around the whole length of the root may indicate VRF. It is different from bone loss seen in a peri-apical lesion where bone loss occurs apically but without destruction of the lamina dura along the root surface
- Radiolucent halos: 'Halo-like' radiolucency running around whole of the root surface is a classic sign of VRF.  The radiolucent area may travel almost completely up the side of the root, resulting in a "J-type" lesion.
- Step-like bone defects: Obliquely oriented fractures often lead to a characteristic step-like bone defect which may mimic endodontic lesions resulting from causes like post perforations and vertical grooves
- Isolated horizontal bone loss in posterior teeth: Mesio-distally oriented vertical fractures can cause bilateral horizontal bone loss in an isolated tooth
- Unexplained bifurcation bone loss: Furcation bone loss may occur in molars with fracture, in absence of apical pathosis or overt periodontal disease and without any apparent reason (e.g. perforation)
- V-shaped diffuse bone loss: Diffuse V-shaped radiolucency (wider coronally, narrowing towards the apex) is a common radiographic image in vertically fractured buccal roots of maxillary molars or the roots of lower molars. Confined to a single root or a single tooth in the mouth, it is almost pathognomonic.
Lustig et al.  described the typical bone resorption patterns in teeth with VRF. In 90% of teeth with VRF extracted during exploratory surgery, buccal bone dehiscence along the entire root length was noted. In 10% of the maxillary premolars and mesial roots of mandibular molars, fenestration type of bone loss was noted.
The radiologic signs are highly non-specific and not detectable during early stages, in which there are subtle fissures with no separation.  These develop late as sequelae of chronic inflammation induced by the fracture. Only approximately one-third of fractures may be visualized directly at dental radiography.  Mesio-distally oriented fractures are not visualized directly on a typically exposed radiograph.
Computerized tomography (CT)
CT is superior to conventional radiography in the assessment of VRF  as the plane of axial sections is perpendicular to the fracture line. CT findings are characterized by a separation of the adjacent root segments visualized on at least two contiguous sections without continuation of the hypo-attenuated line into the adjacent tissue. However, high radiation dose, limited availability and increased costs limit its use in dentistry. 
Cone beam computed tomography (CBCT) scans provide high-contrast three-dimensional images at reduced dose and costs (alternative to CT scans in endodontics). 
Endodontic status after healing has occurred
Rapid deterioration of endodontic status of a tooth after a long time without symptoms, or reappearance of radiolucencies after healing has previously taken place, is indicative of fracture.
Laser in diagnosis
Kimura et al.  have suggested that root fracture could be diagnosed by DIAGNOdent with methylene blue (MB) dye solution. In a further study, they proposed that the use of detergent allows better penetration of dye thereby enhancing the detection of root fractures. 
An exploratory surgical procedure helps in definitive diagnosis, if VRF is strongly suspected from clinical and radiographic signs. Gentle soft tissue retraction may be sufficient to view the fracture line, and a dye material may also be used for better visualization of the fracture line. As a probe is passed over the fracture line, 'clicking' sound may be heard.  Reflection of a small full thickness flap may be required in some cases. There are cases where even flap surgery does not help.
Avoiding or correcting all the etiological factors provides the best prevention. This may include:
- Extensive cutting of dentin during preparation of the canal at curvatures weakens the root structure  and prone to fracture. So over-instrumentation should be avoided especially in the teeth and roots most susceptible to fracture, i.e. the maxillary and mandibular premolars  and the mesial roots of the mandibular molars 
- Over-preparation of the canal for a dowel, selection of an improper dowel and traumatic seating of intra-canal restorations may also cause VRF. An ill-fitting post may exert intra-radicular stresses leading to fracture. Use of either prefabricated, parallel-sided posts with round edges and passive insertion, or the fiber-reinforced resin based composite posts that have the same modulus of elasticity as dentin is recommended ,
- Nightguards may be used in patients with bruxism to minimize the risk of VRFs. Early reinforcement by castings with cusp coverage or by internal splinting with adhesive ceramic restorations should be done for teeth at risk.
In a multi-rooted tooth with VRF, resecting the root (root amputation or hemisection) can save the tooth. , However, in single rooted teeth with VRF, the prognosis is unfavorable. Extraction may be required (because of extensive bone loss and uncertain prognosis). However, many innovative attempts to treat and retain anterior teeth have been described in various case reports.
Extraction and replantation after bonding: Studies have reported successfully treating tooth with VRF by extracting the fractured tooth atraumatically, bonding the fragments, and then replanting the tooth either directly or with a 180 degree rotation (especially in case of anterior teeth).  It was advocated that the deep and narrow periodontal pockets along the fracture line may remain if teeth with VRF are replanted without rotation  as intentional rotational replantation avoids contact with the area where periodontal ligament was lost and area where the bone was lost in the treatment of VRF.  The rotation of the tooth was suggested to connect the remnants of the healthy periodontal membrane, remaining on the root, with the connective tissue in the periodontally involved socket wall.
Application of a bio-resorbable membrane to reinforce periodontal healing, by preventing any gingival connective tissue from making contact with the curetted root surfaces during healing and allowing for regeneration of periodontal ligament cells around the teeth has been suggested in few reports. , This membrane also prevents the ankylosis after replantation.
Other treatment options like use of composite resins  , Mineral Trioxide Aggregate  and silver glass ionomer cement  for bonding the fracture line have also been tried. Calcium hydroxide to promote tissue repair and resolve osseous defects before the roots were restored has also been used.  Poor long-term prognosis has been reported with teeth cemented extra-orally with cyanoacrylate. 
Other alternative attempts at treating VRF include:
- Bonding the fractured segments with glass ionomer bone cement and replanting the tooth in conjunction with an e-PTFE membrane 
- Two-stage surgical procedure of bonding with silver glass ionomer cement, placement of a bone graft material and GTR therapy 
- Combined technique of glass fiber-post and composite for aesthetic and functional results 
- Use of 4-META/MMA-TBB resin through the root canals to bond the fractured teeth 
- Use of dual-cured adhesive resin cement is preferred for bonding the fractured fragments, as it has a controlled polymerization and is easy to apply 
- Use of orthodontic elastics to join the buccal and palatal segments of fractured tooth followed by sealing with a photocured resin liner to allow the tooth to be endodontically treated and restored with a cast crown 
- Fitting of orthodontic bands before endodontic treatment to prevent propagation of a crack or fracture
- Use of CO 2 and Nd.YAG laser to fuse fractured tooth roots. 
| Conclusion|| |
Many of the treatment options reported involve extensive procedures often with poor outcomes. Where successful outcomes have been claimed, the long-term prognosis has yet to be proven. All case reports published so far that describe a treatment rationale do not include enough teeth to ascertain the efficacy of any procedure. Therefore, there is a need for further clinical research on the treatment of teeth that with VRF.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]