The often confusing and frustrating signs and symptoms that have been associated with incompletely fractured teeth have been responsible for a variety of diagnostic terms found in the dental literature. "Cuspal fracture odontalgia1," "green stick fracture2," "cracked tooth syndrome3-5," "incomplete crown-root fracture6," "vertical crown-root fracture7," "split root syndrome8" and "incompletely fractured teeth9" are all terms that described similar clinical situations, that is, an incompletely fractured tooth.
The following terms have been adopted from a recent American Association of Endodontists publication on cracked teeth,10 and will hopefully help to standardize the nomenclature puzzle:
A) Craze Lines: These are small cracks that have been said to be confined to the enamel, cause no clinical symptoms and thus require no dental treatment (other then for esthetic concerns). Longitudinal craze lines are commonly observed on anterior teeth in adults. In posterior teeth however, craze lines are evident crossing the marginal ridges and/or extending along buccal and lingual surfaces. As such, these are often confused with deeper cracks. However, craze lines will not block the light from transillumination, as do cracked cusps or teeth (Fig. 1). This aids in obtaining a correct diagnosis.
B) Cuspal Fractures: The fractured cusp usually results from a lack of cusp support due to a weakened marginal ridge secondary to extensive dental caries and/or Class II restorations. There is generally mild, but sharp pain that occurs with stimulation, especially upon release of biting pressure. Typically, the fractured cusp is removed and the tooth can then be properly restored to health. The dental pulp is usually not involved as the fracture does not typically extend into the pulpal chamber. However, long-standing teeth with cuspal fractures that have gone undiagnosed, may develop symptoms of irreversible pulpitis.
C) Cracked Tooth (no separation): This crack extends from the occlusal surface of the involved tooth apically, without separation of tooth segments (Fig. 2). This crack is more centrally located than that seen on a cuspal fracture, usually crosses one or both marginal ridges and is more likely to cause pulpal and periodontal inflammatory reactions. The most commonly involved teeth in descending order of frequency are the mandibular 2nd molars, mandibular 1st molars, maxillary 1st molars, maxillary 2nd molars and then maxillary premolars.3,5-7 Endodontic treatment is often required as is full coverage or cuspal protected restorations. However, the full apical extent of this fracture is difficult to determine clinically. This will affect the long-term prognosis of the involved tooth as progressive loss of attachment may occur with time and continued progression of the fracture. Vertical osseous defects and deep periodontal probings indicate an extensive fracture with a poor/ hopeless prognosis. Additionally, cracks observed across the entire pulp chamber floor following access cavity preparation, also indicates a poor/hopeless condition (Fig. 3). However, cracks that are seen on one wall of the pulp chamber but do not extend apically to the level of the canal orifice, perhaps have a better long-term prognosis, as a root fracture component may only partially exist.
D) Split Tooth (with separation): This entity is the result of long-term progression of the cracked tooth, where there are now two distinct and moveable segments (Fig. 4). Movement of the segments may readily be apparent, or can be confirmed clinically with the aid of an explorer or plastic instrument. Split teeth can never be saved intact, but the position and apical extent of the crack will determine the prognosis and treatment.
E) Vertical Root Fracture: This type of fracture begins in the root and may vary in length (Fig. 5). Two causes have been identified as etiological factors: post placement and excessive forces during gutta-percha compaction. Typically, only mild symptoms develop as most of these teeth have been endodontically treated. As a result of the minimal symptomatology, they often go undiagnosed until periradicular breakdown occurs. Periodontal probings may aid diagnosis as most vertical root fractures will eventually extend to the sulcular area and vertical osseous defects will develop. Over time and after continued exposure to salivary contamination, extensive loss of bone will occur adjacent to the length of the root fracture, and will be readily evident upon radiographic examination.
SIGNS AND SYMPTOMS
Discomfort to biting or chewing, especially upon release of biting pressure, appears to be the most frequent symptom of a cracked tooth.1-10 Patients may also complain of sensitivity to cold and/or hot stimulation,3-9 depending upon how far the crack has propagated into the dentin and the length of time the crack has been exposed to salivary contamination. Initially, there is no pain to percussion and radiographs will appear normal. These findings have been described as the classic signs of cracks. However, as the dimensions of the crack propagate over time, and the effects of continual exposure to salivary contaminants continues unchecked, the underlying pulpal tissues will develop irreversible inflammatory changes. Eventual pulpal necrosis with root canal infection will develop, as will periradicular pathosis. Tenderness to percussion and apical palpation will then be observed clinically. If the crack extends onto the root surface, apical to the base of the gingival sulcus, a narrow periodontal probing defect will develop. Therefore, thorough clinical probing is essential for accurate assessment and a timely treatment plan. Continued periodontal breakdown will of course adversely effect the long-term prognosis of the incompletely cracked tooth.
A) Dental History: Questions regarding the patients chief complaint and history of present illness are of course necessary to obtain a thorough understanding of the extent and nature of their present situation. The patient should be questioned if there was a specific incident (ie: biting on a hard object) that first caused discomfort to the affected tooth. Ask if the patient has had occlusal adjustments with only temporary relief of symptoms and inquire about parafunctional habits. Also, inquire about other cracked teeth as many patients have more than one cracked tooth.3-10
B) Visual Examination: The teeth should be properly dried for better visual inspection. Wear facets, abnormally steep cusps and inclines and developmental grooves should be noted. Craze lines, cracks, restorations with failing margins should be explored and documented. Homewood5 recommends the use of the rubber dam for enhanced visual acuity as he was able to identify almost all tooth cracks after proper isolation. Enhanced magnification with illumination using loupes or a dental microscope will significantly aid in the detection of cracks.9,10 The visual examination should include the use of a dye, such as methylene blue, to help identify cracks.
C) Bite Challenge Tests: Burlew disks, orange-wood sticks and cotton rolls have all been used in an attempt to replicate the pain on chewing associated with cracked teeth.2-7 Commercially available devices, (Frac-Finder and Tooth Sleuth) are also available for this purpose. Essentially, this type of device is placed on each cusp, fossae and marginal ridge, and the patient is instructed to bite down and then release. Generally, it is best to test non-involved teeth first. If a painful response is elicited, inquire if it is similar to their chief complaint. It is important to note that the absence of symptoms when performing these test does not rule out the possibility of a crack.7,10
D) Radiographic Examination: Both periapical and bite-wing radiographs should be taken of the involved quadrant. However, it is well known that that cracks rarely are identified on routine radiographs. Mesio-distal cracks defy radiographic detection as the crack is perpendicular to the path of the x-ray beam. When there is loss of bone associated with a subattachment root crack or a vertical root fracture, the radiograph will be of significant value.4,5,7,8,10
E) Transillumination: A fiberoptic light source when placed directly against an intact tooth will illuminate the entire coronal tooth structure. If a crack is present, the light will not cross the crack, and the opposite side of the tooth will not be illuminated.10
F) Removal of Restorations: If a restoration is in place on a tooth with a suspected crack, it should be removed. Ehrmann et al4 have indicated that when this is done, it is not unusual to have part of the tooth or cusp splinter off. When this occurs, the pain on biting will most often immediately disappear and the tooth can be restored. Furthermore, once the restoration has been removed, a crack may be easily visualized across the dentin (Fig. 6).
G) Exploratory Surgery: Surgical exploration will allow for direct visual examination of the root surfaces for cracks and other defects. If the crack is directly interproximal, adequate visualization will be quite difficult. This type of diagnostic surgical procedure can offer early detection of untreatable conditions, and may thus spare the patient unwarranted endodontic and restorative procedures.10
Diagnosing tooth cracks and root fractures can be a time-consuming, challenging and frustrating experience for both the patient and dentist. The longer the duration of pain before the diagnosis of an incompletely cracked tooth was established, the more diffuse was the distribution of pain.9 A detailed history and a thorough examination are required in order to arrive at the correct diagnosis and certainly must occur prior to the commencement of any type of treatment. Cracks that extend apical to the cemento-enamel junction may have a poor long-term prognosis. The patient should be properly advised of the guarded long-term prognosis associated with many cracked teeth and therefore alternate treatment plans should be openly discussed.
Dr. Barnett is currently an Associate Professor of endodontics at Albert Einstein Medical Center in Philadelphia, Pennsylvania. He also maintains a private practice in endodontics in West Chester, PA.
Oral Health welcomes this original article.
1. Gibbs JW. Cuspal fracture odontalgia. Dent Digest 1954; 60: 158-60.
2. Sutton PRN. Greenstick fracture of the tooth crown. Brit Dent J 1962; 112: 362-6.
3. Cameron CE. Cracked tooth syndrome. J American Dent Assoc 1964; 68: 405-11.
4. Ehrmann EH, Tyas MJ. Cracked tooth syndrome: diagnosis, treatment and correlation between symptoms and post-extraction findings. Australian Dent J 1990; 35: 105-12.
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9. Brynjulfsen A, Fristad I, Grevstad T, Hals-Kvinnsland I. Int Endod J 2002; 35: 461-6.
10. American Association of Endodontists Publication. Cracking the cracked tooth code. Fall/Winter 1997. Colleagues for Excellence. http://www.AAE.org/fw97ecfe.html