Cracked Tooth: How to manage it in daily practice

Endodontics - Endoperio
5 Feb 2016

Tooth Fractures are not rare, surface cracks, or craze lines, are relatively common in teeth. In most of cases they do not cause problems. Sometimes, however, a cracked tooth evolves into cracked tooth syndrome. This syndrome may be difficult to diagnose and is a frequent source of frustration for both the dentist and the patient.
A pulpal and periapical diagnosis is dependent on the extent of the crack and the duration of the symptoms. The pulp of cracked teeth might become inflamed because of irritation resulting from micro leakage, which induces thermal sensitivity.
Crack propagation might eventually lead to irreversible pulpitis. Cracked teeth can have a variety of symptoms, ranging from slight to very severe spontaneous pain consistent with irreversible pulpitis, pulp necrosis, and apical periodontitis. Even an acute or chronic apical abscess may be present if the pulp has undergone necrosis. In other words, once the fracture has extended to the pulp, severe pulp and peri-apical pathology will likely be present. Cracks occur frequently in individuals within the age range of 30–50 years, with a tendency in females. The most commonly affected tooth is the first mandibular molar followed by the maxillary premolars, first maxillary molar, and mandibular premolar. In addition in restored teeth, the occurrence of a cracked tooth is more frequent in non-bonded restorations and the sharp internal line angle associated with amalgams and gold restorations. It is assumed that micro-cracks form as a result of cusp flexion caused by occlusal load stress during mastication and the repeated thermal expansion of the restorative materials. In contrast, occlusal stress can be distributed through the bonding layer in bonded-type restorations. Age is also a contributing factor to tooth fractures, in fact, the resistance of human dentin to the propagation of a crack decreases with both age and dehydration.

The American Association of Endodontists, in a document titled `cracking the cracked tooth code´ show 5 kind of tooth fracture as shows in the pictures 1, 2 and 3.

Fig. 1

Fig 1.- Craze line and cuspal fracture

Fig. 2

Fig 2.- Cracked tooth

A cracked tooth is indicative of a crack-line propagating from the occlusal surface of the tooth apically without separation of the two fragments. The crack is generally located at the center of the tooth in a mesiodistal direction and may involve one or both marginal ridges.

Fig. 3

Fig 3.- Cracked tooth, occlusal view after amalgam removal.

Fig. 4

Fig 4.- Vertical root fracture

In cases of cracked teeth, the patient should be fully informed that cracks might continue growing and eventually separate. Although treatment will succeed in many cases, some cracked teeth might evolve into split teeth and require extraction.

A 47-year-old woman complained of spontaneous persistent pain of 1 week duration. The pain was confined to the maxillary right second molar and irradiated to the maxillary right zygoma. She also reported a history of bruxism. Visual examination revealed a composite infiltrated restoration and some structural cracks. The tooth was sensitive to touch and responded to cold pulp testing. Radiographic examination revealed no observable changes in tooth structure or the surrounding bone area.

Fig. 5

Fig 5.- Rx and mesial view of the tooth.

Fig. 6

Fig 6.- Occlusal view, infiltrated 10 year composite restoration.

Fig. 7

Fig 7.- Probing revealed a 6mm attachment loss at the level of fracture line.

With the clinical examination, radiographic assessment and clinical history, the diagnosis of cracked tooth was suspected.

Fig. 8

Fig 8.- The old Restoration was removed under anesthesia and the crack line was explored by using a high-speed bur and traced to reveal pulpal involvement.

Fig. 9

Fig 9.- Crack Line end into the pulp chamber

Fig. 10

Fig 10.- Root canal treatment was performed with Protaper Universal, the vestibular canals were shaped until F1 and the palatal canal was shaped until F2, all canals were sealed with Thermafil

The patient was advised of the problem and the tooth was considered to have a relatively low prognosis. Root canal treatment was chosen instead of an extraction. To minimize cost for the patient a cuspal protection with a direct restoration was performed.After 30 days symptoms disappeared and the patient was called for follow-ups

Fig. 11

Fig 11.- At the 5-year recall after the endodontic treatment, the tooth was asymptomatic, and functioning. In contrast with the first visit tooth show less probing depth. Radiographically no lesions were detected.

Case 2: A 53 year old man had localized pain in the maxillary right second molar and irradiated pain to the maxillary right zygoma. Visual examination revealed a non-infiltrated amalgam restoration and some structural cracks. The tooth was sensitive to touch and gave a positive response to cold pulp testing. Radiographic examination revealed no observable changes in tooth structure of the surrounding bone area.
With the clinical examination, radiographic assessment and clinical history, the diagnosis of cracked tooth was suspected.
The old restoration was removed under anesthesia and the crack lines were opened using a high-speed bur and traced to reveal pulpal involvement.
The patient was advised of the problem and the tooth was considered to have a relatively low prognosis. Root canal treatment was chosen instead of an extraction.

Fig. 12

Fig 12.- Right X-ray after Pulpotomy and Ca(OH) dressing. Left, completed endodontic treatment

Root canal treatment was performed with Protaper Universal, vestibular canal was shaped until F1 and Palatal canal was shaped until F2 all canals were sealed with Thermafil, After few days symptoms disappeared and the patient was called for follow-ups.

Fig. 13

Fig 13.- After 2 years under observation the patient came with pain, and was diagnosed a vertical root fracture. The tooth was extracted and substituted with an implant.

Case 3
A Patient Came to the office with abscess symptoms: pain and edema on mandibular left posterior area.
Percussion test was positive for tooth 36, vitality test was negative.

Fig. 14

Fig 14.- Preoperative Rx

An endodontic access was performed the same day. During this procedure under rubber dam isolation a lot of purulent exudation came out from the tooth, Shaping was performed during the same visit and irrigation with sodium hypochlorite and an endovac macrocannula.
After 45 minutes Paper point was inserted into the canal and showed still purulent exudation. A cotton pellet and provisional restoration was placed.
Patient was followed for 30 days each three days, for irrigation procedures. Canals did not stop excreting. Patient had again a severe swelling, as the first days.
We decided to extract the tooth.

Fig. 15

Fig 15.- After the extraction, the tooth showed an important fracture line in the distal root.

Fig. 16

Fig 16.- Close up of the fracture, CEJ and periodontal ligament can be visualized.

Many authors show that Cracked tooth Syndrome treatment have a success ranging from 80 % to 90 % in five years, depending on the extension and the position of the fracture in vital teeth. The cracked tooth treatment plan will vary depending on the location and extent of the crack (which can be difficult to determine) and other factors shown in chart 1.

In case of vital teeth performing root canal treatment must be dependent on the determination of pulpal and periapical diagnosis. The clinician should observe the scenario, evaluate and determine a prognosis, if a crack is evident on the cavity floor and/or proximal external surface, the following should be considered:

• Cavity Floor—Removal of the fracture line only in the area of the cavity floor that would include the beginning of an ideal endodontic access opening is helpful in determining the apical extent of the crack and whether the pulp is involved. However, keep in mind that if the fracture is small and invisible at its furthest extent (even after staining), it will unlikely continue deeper into the dentin than can be visualized.

• Proximal Surface—Removal of the fracture line on the proximal external surface portion of the tooth below the level of the cement-enamel junction is not usually indicated. More information on the extent of the crack may be obtained, but it also is likely to cause the tooth to become non restorable.
Many cracks can be observed in the dentin, sometimes they do not show on the root surface. After using stain we can see that the crack is only inside the tooth and the cementum is not involved.
Removal of the proximal marginal ridge and tooth structure associated with the fracture takes away sound tooth structure, thereby decreasing tooth strength and resistance to fracture. However, keep in mind that not removing the crack on the proximal surface may allow bacterial penetration to continue, which could eventually lead to the need for root canal treatment or extraction.

Ricucci et al. confirmed that cracks are routes of bacterial entry to the pulp and can predispose the pulp to severe inflammation and symptoms. Bacterial invasion of dentinal tubules occurs more rapidly in teeth with nonvital pulps than with vital pulps. Berman and Kuttler suggested that: if the pulp necrosis is secondary to a longitudinal fracture that extended from the occlusal surface and into the pulp it is termed a `fracture necrosis´ Based on the findings of Kuttler and the currently available literature on root fractures, it is suggested that the prognosis for teeth having a fracture necrosis may be considered hopeless.

Fig. 17

Fig 17.- Histologic image courtesy of Dr. Domenico Ricucci (Italy)

Longitudinal sections were taken on a buccolingual plane.

SX image show crack involving secondary dentin, tertiary dentin (formed by underneath deep composite restoration) and crossing the pulp chamber floor. The tissue in the pulp chamber appears unstructured; bacteria in the crack line and in pulpar chamber floor are visible (blu).

DX image is a magnification of the area demarcated by the rectangle in SX. The crack space is filled with a structured bacterial biofilm (original magnification 100x).
(Taylor’s modified Brown and Brenn, original magnification 16 x).

While Cuspal protection provides optimal tooth safety, does not guarantee success, but is certainly beneficial in most cases.
During Endodontic Treatment Endodontist have to avoid excessive removal of intraradicular dentin; minimize the internal wedging forces. The use of Thermafil sealing generates less force than the Warm Vertical Condensation and Cold Lateral Technique.

Metallic posts increase the fracture risk.

Recently, some studies that outline chances for successful outcomes for cracked teeth have been published, but they have been limited only for some specific conditions. One 2006 study evaluated a small number (n=50) of root filled cracked teeth with a diagnosis of irreversible pulpitis and determined a two-year survival rate of 85.5 percent. This study indicated that the only significant prognostic factors were teeth with multiple cracks, terminal teeth in the arch and periodontal probing before treatment.

Another study done in 2007 evaluated 127 patients with teeth diagnosed with reversible pulpitis that had a cracked tooth. The treatment was a crown restoration without performing root canal treatment. Twenty percent of these cases evolved to irreversible pulpitis or necrosis within the next six months and required root canal treatment, with none of the other teeth requiring root canal treatment over a six-year evaluation period.

Fig. 18

Chart 1.- Factors influencing prognosis

 

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