CRACKED TOOTH SYNDROME

Transcription

1 CRACKED TOOTH SYNDROME Dr Vijay Salvi We all come across apparently healthy teeth eliciting complex and often bizarre symptoms. The patient will give a long history of undiagnosed but severe pain, and of treatments which failed to provide relief. These symptoms can be attributed to a cracked tooth. This article describes the signs and symptoms, diagnostic techniques, classification and management to what is universally referred to as Cracked Tooth Syndrome. The article will describe those cracks that may have involved the underlying dentin and has the potential to propagate further to the pulp and/or periodontal structure culminating in a fractured tooth but will not refer to superficial enamel cracks which may be secondary to trauma, stress or iatrogenic in nature. People are living longer and keeping their teeth longer. As a result, patients are more likely to have complex restorative and endodontic procedures leaving teeth more susceptible to cracks. Stressful lifestyle resulting in parafunctional habits such as clenching and bruxism and consumption of paan, betel nut etc. are important contributory factors. Additionally, in recent years, practitioners have been more aware of the existence of cracks and, therefore, diagnose more cracks. The key to saving a cracked tooth is to be aware of the characteristic signs and symptoms, diagnose the crack as early in its development as possible and initiate appropriate treatment without delay. CLASSIC SIGNS, CLASSIC CONFUSION Teeth with cracks elicit erratic pain on mastication, especially with release of biting pressure and/or pain to extremes of temperature, especially cold. Generally, there is no pain to percussion, and radiographs are inconclusive. Often patients give history of pain which has been difficult to diagnose and of treatment/s which has failed to relieve their symptoms. Depending on the location, direction, and extent of the crack, the patient may present any one or all of these signs and symptoms making diagnosis confusing. If the pulp is involved, there may be signs and symptoms of irreversible pulpitis or necrosis with periradicular pathosis. If the crack extends to a root surface, there may be a periodontal defect. Many times, cracks go unnoticed until a variety of symptoms are present, a restoration is removed, or a significant periodontal defect is identified. If caught and treated appropriately, many cracks can be stopped or at least slowed down from propagating further, preventing loss of the tooth. Steps should be taken immediately to confirm the presence of a crack, determine the type of crack, and formulate an appropriate treatment plan. DIAGNOSTIC PROTOCOL FOR DETECTION OF CRACKS: In a tooth suspected of having a crack it is important to know if the tooth has undergone endodontic procedure. A cracked root canaled tooth will exhibit only those signs and symptoms associated with periodontal breakdown secondary to crack propagation. Teeth with vital pulp will require further investigations to determine the health of pulp and periodontium once a crack is diagnosed.

2 Dental History A detailed dental history which includes dietary habits, bruxism and clenching of teeth is a must. Check for a history of previous cracked teeth as many anatomical and behavioral factors that predispose teeth to crack affect more than one tooth. History of periodontal disease with extensive bone loss in the area can be an important pointer to diagnosis as decreased bone support has been thought to lead to increased stress on dentin, predisposing the roots of a tooth to cracking. History of any previous trauma can be useful in detecting a cracked tooth. Visual examination: Start with the face, checking for enlarged jaw muscles indicating excessive stress on mastication indicating paranormal functions. Check for wear facets, and any steep cusps or developmental grooves which may predispose teeth to cracks. Finally, check teeth surfaces carefully in a dry field. Note any craze lines or darker cracks. Generally, the darker the stain in a crack, the longer the crack has been present. Also check the cracked restorations or unusual gaps between restorations and tooth structure. Clinical microscope or enhanced magnification and illumination can be helpful in visual identification of a crack. Tactile examination Gently run the tip of a sharp explorer along the tooth surface. The tip may catch in a crack. Palpate the gingiva around the tooth, checking for possible evidence of an underlying dehiscence or fenestration typical of a vertical root fracture. Bite tests Use a rubber wheel, wood stick, or other commercially available instruments (such as Tooth Slooth fracture detector (Professional Results, Inc. CA USA). Place the instrument on each cusp or fossa and ask the patient to bite down with moderate pressure and release. Test several teeth and cusps. Be sure to use controls. Pain during biting or chewing is considered a classic symptom and may be the only conclusive evidence early in the crack s development. The absence of pain during biting, however, does not rule out the possibility of a crack. Periodontal probing Thorough probing in small increments around the entire circumference of the tooth may reveal a narrow periodontal pocket. The narrow pocket that forms along a crack will restrict side to side motion of the probe, making it easy to differentiate from the broad based defect characteristic of a periodontal disease pocket. Staining Cracks may be disclosed through staining (Figs 1 and 2). A dye, such as methylene blue, Seek (Ultradent products Inc.), or To-dye-for (Roydent Dental Products) can be applied to the external tooth surface, in the cavity after restoration removal, or on a surgically exposed root.

3 Figs 1 and 2. Crack disclosed in a molar by staining with a caries detector Transillumination In transillumination, a fiber-optic or other similar light source is applied directly to the tooth surface. The light beam is positioned perpendicular to the plane of the suspected crack. A crack will block the light. Structurally sound teeth, including those with craze lines, will transmit the light throughout the crown. Radiographs Cracks rarely show on radiographs. Mesio-distal cracks can never be seen, and buccolingual cracks will only appear if there is actual separation of the segments or the crack happens to coincide with the X-ray beam. Changes in the pulp chamber, canal or periradicular space, however, may suggest the presence of a crack. Radiographic evidence tends to be conclusive as the crack progresses and a bony defect develops. Taking periapical X rays from more than one angle and taking bite-wings may increase the chance of catching a crack- induced defect early in its development (Figs 3 and 4). Figs. 3 & 4. The patient presented with H/O inability to chew on right side. On examination no abnormalities were detected. Radiograph reveals a healthy tooth with no caries and healthy bone architecture, indicating good periodontal health. However, a periapical lesion with apparently no etiology is indicative of a cracked tooth. Note generalized occlusal wear. A thickened periodontal ligament space or a diffuse radioluscency, especially one with an elliptical shape in the apical area, may indicate a crack. Check also for restorations held in place by dentinal pins, which can predispose teeth to cracking.

4 In root canaled teeth, rare but significant findings include a radio opaque line where gutta percha or sealer has been expressed into the crack during obturation. A consistent radiolucent line along the length of the root canal filling material may indicate space caused by a crack but should not be considered conclusive, because it could be caused by other factors. Root canal sealer expressed in a horizontal plane within the apical third of the root is strongly indicative of a rot fracture. Check root canaled teeth for long posts, short-wide posts, custom metal posts, or posts with threads that bind with tooth structure, as the size, design and placement of posts often contribute to cracks. Restoration removal This allows for visual examination of the cavity. Carefully check the mesial and distal marginal ridges, which tend to be weak areas. Magnification and staining can be helpful. Surgical assessment Surgical exploration allows for visual examination of the root surface for the appearance of a crack and should only be used if the crack is highly suspected and cannot be confirmed by other diagnostic means. Performing diagnostic surgery, however, can help early detection of untreatable situations, sparing the need for endodontic or restorative treatment on an ultimately hopeless case. A consultation with an endodontist or periodontist may be advisable prior to surgical assessment. Whenever a surgery is performed to detect a crack, the patient should be fully informed that it is a diagnostic procedure. CRACK TYPES AND CLASSIFICATION Inconsistent terms have led to confusion in classification. This article proposes a classification for cracked teeth based on absence or presence of pulpal and periodontal apparatus involvement and the extent of crack making treatment planning and prognosis of the affected tooth simpler. The proposed classification is as under: Class A - Crack involving Enamel and Dentin but NOT involving pulp Class B - Incomplete fracture of Crown extending to the pulp but NOT involving periodontal apparatus Class C - Incomplete fracture of crown extending to the pulp and involving periodontal apparatus Class D - Complete division of tooth with pulpal and periodontal apparatus involvement Class E - Apically induced fractures. Classification Involvement of Involvement Involvement Initiation Prognosis Enamel/Dentin of Pulp of Perio. of crack Apparatus Class A YES NO MAYBE CORONAL EXCELLENT Class B YES YES NO CORONAL GOOD Class C YES YES YES CORONAL AVERAGE Class D YES YES YES CORONAL POOR Class E ROOT INVOLVEMENT YES YES APICAL POOR

5 Class A FRACTURED CUSPS AND ENAMEL CRACKS Class A cusp fractures are the easiest to diagnose and has the best prognosis, especially when the crack does not extend below the gingival attachment. The fractured cusp usually results from a lack of cusp support due to a weakened marginal ridge. Occlusally, it is common for the crack to have both a mesio-distal and a bucco-lingual component. The crack will cross the marginal ridge-frequently weakened by a restoration or caries- and continue down a buccal or lingual groove in apical direction. It may terminate parallel to the gingival margin or slightly subgingivally. Generally, only one cusp is affected. Pain- occasionally associated with sensitivity- is mild. Bite tests will elicit brief, sharp pain, especially with release of biting pressure. The pulp is usually vital. Radiographs are inconclusive. The affected cusp may break off during restoration removal, possibly resulting in relief of symptoms when the cusp breaks off. When present on a root canaled tooth, the discomfort is minimal except when the fracture line extends subgingivally. Treatment: The tooth is treated by removing the affected cusp and restoring the tooth with a full crown that covers the crack margin. Root canal treatment is necessary only in the rare event when the crack affects the pulp chamber or has resulted in irreversible pulpitis. Correction of causative factors of crack is essential. Frequently a tooth will show a mesio-distally oriented crack arising from the occlusal surface advancing apically. These cracks may terminate above the CE junction, but frequently will cross the CEJ to continue apically (Figs 5 and 6). If detected early, it is important that these cracks are treated before they spread and involve the pulp or the periodontium. Prognosis is excellent with a bonded restoration. Figs 5 and 6 A lower second molar revealed a crack arising from an old restoration and advancing apically- on exploration it turned out to be a class A crack. Class B and C CRACKED TOOTH The crack runs from occlusal surface apically without separation of the two segments. Occlusally, the crack is more centered than a cusp fracture and, therefore, more likely to cause pulpal and periradicular pathosis as it extends apically. The crack may cross either or both marginal ridges and is more often mesiodistal, shearing toward the lingual/palatal root surface (Fig 7). Rarely, the crack may be buccal-lingual in mandibular molars.

6 The signs and symptoms of a cracked tooth will vary significantly depending on the progress of the crack. Fig 7. A Crack running mesio-distally on a upper left first premolar. This crack on further examination turned out to be a class C crack. Differential diagnosis: The crack will probably be invisible to the naked eye and impossible to disclose with staining initially. The cracked tooth may only exhibit acute pain on chewing or sharp, brief pain to cold. The restorative history of the tooth, while diagnostically helpful for cusp fracture, is not as helpful with cracked tooth. Restorations can contribute to cracked tooth, and the crack may be evident across the cavity floor after a restoration is removed. However, unrestored teeth that are free of caries and teeth with conservative restorations frequently experience these cracks. Teeth with class1 restorations crack as frequently as those with class 2 restorations. If a crack can be detected, gently test for movement of the segments to differentiate a cracked tooth from a fractured cusp (class A) or split tooth (class D). A fractured cusp or a split tooth may break off under slight pressure while the segments of a cracked tooth (Class B or C) will remain in place. Position of the crack may also help differentiate a cracked tooth from a fractured cusp. Tooth crack occurs more toward the centre of the occlusal surface as compared to the cusp fracture which is more peripheral in position. More centered cracks tend to go deeper toward the apex before completely separating the tooth into two segments. If the crack has progressed to involve the pulp or periodontal tissue, the patient may have thermal sensitivity that lingers after removal of the stimulus or slight to very severe spontaneous pain consistent with irreversible pulpitis, pulp necrosis, or apical periodontitis. There may even be pulp necrosis with periradicular pathosis. Treatment planning: The cracked tooth treatment plan will vary depending on the location and extent of the crack. Even when the crack can be located, the extent is still difficult to determine. Endodontic treatment is often indicated, followed by a full crown to bind the cracked segments and protect the cusps. However, many factors can affect prognosis, and each of these must be carefully considered before proceeding with treatment. These include: Periodontal probing: Absence of a defect does not rule out the presence of a crack. Deep probing indicates an adverse prognosis. Radiographic examination: Findings will depend on pulpal and periradicular status but are usually not significant.

7 Vertical or furcal bone loss may indicate a severe crack. Pulp and periradicular tests: If pain on chewing is the only symptom, a tight-fitting band or temporary crown may be cemented to help confirm a cracked tooth diagnosis. The band serves as a splint, holding the crack together. If banding resolves pain on chewing, a full coverage restoration may keep the tooth pain free. If pain continues after banding, further evaluation of the extent of the crack and pulpal and periradicular status should be performed. Any thermal sensitivity probably indicates pulp involvement, and root canal treatment will be necessary prior to restoring the tooth with a crown. Endodontic access: The practitioner may choose to create an endodontic access to determine whether the pulpal floor is cracked. However, an attempt should not be made to chase down the extent of the crack with a bur, because the crack becomes invisible long before it terminates and sound dentin will be sacrificed unnecessarily. Staining the access cavity may help disclose the crack. Magnification and illumination may help confirm the presence of a crack on the pulpal floor. Fig 8 & 9: A lower molar with a class B crack running along distal half of the floor. Binding of the cracked segments during the endodontic procedure will improve the overall prognosis of the tooth. The segments in this case have dentinal pins (Filpin, S J Filhol Dental Mfg Ltd., Ireland) placed and area bonded with resin restorative material after identifying the canals but before biomechanical preparation and obturation. A tightfitting band or temporary crown will serve the same purpose as the dentinal pins. If the crack is partially visible across the floor of the chamber, the tooth may be banded with a temporary crown or orthodontic band. This will aid in determining the prognosis of the tooth and protect it from further deterioration till endodontic therapy is completed and a permanent restoration placed.

8 Fig 10 Fig 11 Fig 12 Fig 13 Fig 14 Figs. 10, 11 radiographs of tooth no 36. Fig 12 class C incomplete crack along the floor of the same tooth. Fig 13 after endodontic therapy and restorative management and, fig 14 with final restoration. A crown will be placed after clinical and radiological evidence of improved periodontal status. If the crack runs across the full width of the floor, the prognosis is poor. An extraction may be considered. If the crack line runs bucco-lingually in a lower molar or involving a single root in an upper molar, a resection of the separated root may be advisable in a strategically important tooth. Prognosis is hopeless in a tooth where the crack line extends to the full length of the floor and has a large periodontal defect associated with it. Class D SPLIT TOOTH The prognosis of a tooth that has split is very poor to hopeless and the entire cannot be saved. These cracks are usually mesio-distal, across both marginal ridges, split the tooth into two segments, and usually is the final stage of progression of a cracked tooth. A split tooth is easily identified by a crack line running across the tooth, usually mesiodistally, with the two segments easily separable with a probe. The patient will complain of pain on chewing and soreness of the gums of the affected area. Periodontal involvement, however, may result in mistaken diagnosis of periodontal abscess. In a few cases of split tooth, the smaller fractured segment can be removed and the remaining segment restored. If the crack extends apically to a significant extent, than the

9 extraction of the segment may leave a large periodontal defect, in which case an extraction may be the only remedy. (Fig 15 and 16) Figs 15 and 16 complete crack of upper molar involving attachment apparatus Class E VERTICAL ROOT FRACTURE [VRF] Vertical root fractures begin in the apical third of the root, usually in the bucco-lingual plane, extending to varying distance in the coronal direction. The crack may or may not extend to both buccal and lingual surfaces. VRF occurs almost exclusively on root canaled tooth. Chief etiological factors are iatrogenic viz. overzealous instrumentation or condensation during obturation and placement of post. VRF present with very few signs and symptoms, hence go unnoticed till periapical or periradicular pathology develops. At that stage it can mimic a failing root canal treatment or a periodontal abscess. The treatment is usually extraction; hence, a conclusive diagnosis is important. Patient may present with mild signs and symptoms. The tooth may or may not be mobile, x-rays do not give a conclusive picture except occasionally, in case of separation of a segment. Widening or breakdown of periodontal space from apical to coronal direction may be indicative of a VRF. Periodontal probing can be helpful as the crack may occur at any level along the root and may not reach from apical to cervical. However, most will allow deep probing in narrow or rectangular patterns typical of a cracked tooth lesion. Deep probing may be only on the facial or the lingual aspect or on both. Some VRFs show normal probing patterns. Percussion and palpation tests may be inconclusive. Surgical assessment: Vertical root fracture may require surgical inspection for conclusive diagnosis. When soft tissue is reflected, a punched-out oblong bony defect filled with granulomatous tissue overlying the root is characteristic. The defect may be a dehiscence or a fenestration. When the inflammatory tissue is removed, the crack is usually evident. In some cases, a crack may be detected when a resected root end is examined under magnification. Even if the crack is not readily detectable, the characteristic bony defect is usually considered conclusive evidence. Treatment: Depending on the type of tooth affected, VRF treatment may involve extraction, root resection or hemisection. To conclude, it may be stated that diagnosis of a cracked tooth can be difficult, but there is no doubt that it must be done with a sense of urgency. Establishing a diagnosis of a cracked tooth to your patient s elusive problem satisfies the patient s reasons for having sought your expertise and helps in initiating appropriate treatment plan.