UPDATE
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Date Added: 20 February 2007
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A novel use for ultrasonography-differentiating periapical cysts from granulomas
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Radiography is an essential tool in the delivery of endodontic care. At a minimum, radiographs are exposed and interpreted as an aid in preoperative diagnosis, in working length estimation, and to evaluate obturation during nonsurgical endodontic therapy. Later, radiographs provide information as to the health of the periradicular tissues when endodontic recall is performed. Several studies have addressed the poor performance of conventional intraoral radiography in determining the exact nature of periapical disease1-4 and, particularly, the inability to differentiate between granulomatous tissue and cysts.5 This has implications for preoperative treatment planning and postoperative determination of healing.
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A recent clinical study by Gundappa et al.6 has assessed the potential use of ultrasonography in differentiating periapical lesions. Fifteen patients who were scheduled for root-end surgery on mandibular or maxillary anterior teeth with histopathologic examination were included in the sample. Preoperative radiographic evaluations included conventional and direct digital imaging with standard techniques. Interpretation of the radiographs was provided by two oral radiologists and one endodontist. Ultrasound examination was performed by an ultrasonographer using a high-definition, multifrequency, 40-mm linear foot print ultrasound probe operating at a frequency of 8-11 MHz. When sufficient vestibular space was available, the probe was placed against the labial mucosa intraorally. In all cases, the probe also was placed extraorally on the skin overlying the periapical region of interest. The probe position was changed as needed to obtain an adequate number of scans to outline the bony defects. The echo characteristics of the bony lesions also were noted. After surgery, apical specimens were processed for routine histopathologic evaluation.
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Radiographic and ultrasonographic imaging showed the presence of periapical lesions in all 15 cases. Ultrasound examination disclosed seven cysts, seven granulomas, and one combined lesion; these results agreed completely with the biopsy evaluation.
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Although these study results are promising, the diagnosis of periapical cyst is variable, depending on the criteria used by the oral pathologist. The present study found nearly a 50% prevalence of cysts and granulomas. This is in concert with early investigations by Lalond and Luebke7 and Bhaskar.8 Contemporary studies with more stringent criteria have found closer to a 15% prevalence of cysts.9,10 Curettage of periapical lesions during surgical endodontic therapy results in a high rate of success, regardless of the presence of cystic or granulomatous lesions, especially when the source of continued apical inflammation (bacteria and their by-products in the root canal) is addressed.
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1. Bender IB: Roentgenographic and direct observation of experimental lesions in bone. J Am Dent Assoc 62:152, 1961.
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2. Kaffe I, Gratt BM: Variations in the radiographic interpretation of the periapical dental region. J Endod 14:330, 1988. Medline Similar articles
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3. Goldman M, Pearson A, Darzenta N: Reliability of radiographic interpretations. Oral Surg 38:340, 1974.
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4. Bender IB: Factors influencing the radiographic appearance of bony lesions. J Endod 23:5-14, 1997. MedlineSimilar articles
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5. Shrout MK, Hall JM, Hildebolt CE: Differentiation of periapical granulomas and radicular cysts by digital radiometric analysis. Oral Surg Oral Med Oral Pathol 76(3):356-361, 1993.
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6. Gundappa M, Ng SY, Whaites EJ: Comparison of ultrasound, digital and conventional radiography in differentiating periapical lesions. Dentomaxillofac Radiol 35:326-333, 2006. MedlineSimilar articles
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7. Lalonde ER, Luebke RG: The frequency and distribution of periapical cysts and granulomas: An evaluation of 800 specimens. Oral Surg Oral Med Oral Pathol 25(6):861-868, 1968.
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8. Bhaskar SN: Oral surgery-oral pathology conference No. 17, Walter Reed Army Medical Center. Periapical lesions—types, incidence, and clinical features. Oral Surg Oral Med Oral Pathol 21(5):657-671, 1966.
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9. Ramachandran Nair PN, Pajarola G, Schroeder HE: Types and incidence of human periapical lesions obtained with extracted teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 8:93-102, 1996.
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10. Simon JH: Incidence of periapical cysts in relation to the root canal. J Endod 6(11):845-848, 1980.
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Because of the wide variety of different types of cracks in teeth, there may be a myriad of symptoms and presentations, making the diagnosis of a crack often difficult. The extensiveness of a crack may directly alter the prognosis assessment for a given tooth. Therefore, any possible crack should be examined prior to dental treatment. These cracks may be as innocent as a superficial enamel craze line, or they may be as prominent as a fractured cusp. The crack may progress into the root system to involve the pulp, or it may even split the entire tooth into two separate pieces. The crack may be oblique, extending cervically, such that once the coronal segment is removed the tooth may or may not be restorable. Any of these situations may present with mild, moderate, or severe symptoms or possibly no symptoms at all. Because of the high prevalence of fractures and cracks in teeth and how they can directly alter the prognosis for a tooth, an extensive review is presented.
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There have been many attempts in the literature to classify cracks in teeth, trying to differentiate the extent to which the crack has progressed into the tooth structure. By defining the type of crack present, an assessment of the prognosis may be determined and treatment alternatives may be planned as fully described in Chapter 16. Unfortunately, it is often impossible to determine how extensive a crack is until the tooth is extracted. Therefore, the determination of a crack is often more of a prediction, rather than a definitive diagnosis.
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Cracks in teeth can be divided into three basic categories:
Craze lines
Fractures (also referred to as cracks)
Split roots
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Craze lines are merely cracks in the enamel that do not extend into the dentin and either occur naturally or develop secondary to trauma. They are more prevalent in adult teeth and usually occur more in the posterior teeth. If light is transilluminated through the crown of such a tooth, these craze lines may show up as fine lines in the enamel with light being able to transmit through them, indicating that the crack is only superficial. Craze lines typically will not manifest with symptoms. No treatment is necessary for craze lines unless they create a cosmetic issue.
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Fractures extend deeper into the dentin than superficial craze lines and primarily extend mesially to distally, involving the marginal ridges. Dyes and transillumination are very helpful in visualizing potential root fractures.
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Symptoms from a fractured tooth range from none to severe pain. A fracture in the tooth does not necessarily dictate that the tooth has split into two pieces, but left alone, especially with provocations like occlusal prematurities, the fracture may progress to a split root. A fractured tooth may be treated by a simple restoration, endodontics, or even extraction, depending upon the extent and orientation of the fracture, the degree of symptoms, and whether or not the symptoms can be eliminated. This makes the clinical management of fractured teeth difficult and sometimes unpredictable.
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A definitive combination of factors, signs, and symptoms that, when collectively observed, allows the clinician to conclude the existence of a specific disease state is termed a syndrome. However, given the multitude of signs and symptoms that fractured roots can present with, it is often difficult to achieve an objective definitive diagnosis. For this reason, the terminology of cracked tooth syndrome13 should be avoided.1 The subjective and objective factors seen in cases of fractured teeth will generally be diverse; therefore a tentative diagnosis of a fractured tooth will most likely be more of a prediction. Once this prediction is made, the patients must be properly informed as to any potential decrease in the prognosis of the pending dental treatment. Since treatment options for repairing fractured teeth have only a limited degree of success, early detection, prevention, and proper informed consent are crucial.4,18,46,59,75,78,87
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Split roots occur when a fracture extends from one surface of the tooth to another surface of the tooth, with the tooth separating into two segments. If the split is more oblique, it is possible that once the smaller separated segment is removed, the tooth might still be restorable, e.g., a fractured cusp. However, if the split extends below the osseous level or involves the pulp, the tooth may not be restorable and endodontic treatment may not result in a favorable prognosis.
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Proper prognosis assessment prior to any dental treatment is imperative, but is often difficult in cases of cracked teeth. Because of the questionable long-term success from treating cases of suspected or known fractures, the clinician should be cautious in the decision to continue with treatment and should avoid treating cases of definitive split roots.
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page 25
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Figure 1-26 Poorly fitting intracoronal restorations can place stresses within the tooth that can cause a vertical root fracture. ^ The tooth pulp tested nonvital, and there was an associated 12-mm-deep, narrow, isolated periodontal pocket on the buccal aspect of the tooth. After the tooth was extracted, the distal aspect was examined. C, Upon magnification (16x) the distal aspect of the root revealed an oblique vertical root fracture. Similarly, the placement of an ill-fitting post may exert intraradicular stresses on a root that can cause a fracture to occur vertically. D, This radiograph depicts a symmetrical space between the obturation and the canal wall, suggesting a vertical root fracture. E, After the tooth is extracted, the root fracture can be easily observed.
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Certainly, of the previous three categories, fractured teeth are the most variable in presentation, in that the extent of the fracture is often difficult to determine. One of the more common reasons for recurrent endodontic pathosis is the vertical root fracture, a severe crack in the tooth that extends longitudinally down the long axis of the root. Often it extends through the pulp and to the periodontium. It tends to be more centrally located within the tooth, as opposed to being more oblique, and typically traverses through the marginal ridges. These fractures may be present prior to endodontic treatment, secondary to endodontic treatment, or they may develop after endodontic treatment has been completed. Because diagnosing these vertical root fractures may be difficult, they often go unrecognized. Typically, these cracks lead to a split root, leaving the tooth with a poor prognosis. Therefore, diagnosing the existence and extent of a vertical root fracture is imperative prior to any restorative or endodontic treatment since these cracks can dramatically affect the overall success of treatment. Because the presence of vertical root fractures play such an important role in the prognosis assessment of teeth, a detailed analysis of vertical root fractures is presented here.
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Etiology of a Vertical Root Fracture
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Vertical root fractures may arise from a physical traumatic injury, occlusal prematurities,13 repetitive parafunctional habits of heavy stressful chewing,93 or resorption-induced pathologic root fractures.7 However, the most common cause of vertical root fractures may be iatrogenic dental treatment.7,13,65 Dental procedures such as the placement of posts and pins28,54 or the tapping into place of a tightly fitting post or intracoronal restoration may induce a vertical root fracture (Fig. 1-26). The most common dental procedure contributing to vertical root fractures is endodontic treatment.7 Preoperatively, teeth that are about to undergo endodontic treatment may be predisposed to vertical root fractures since quite often the tooth is already compromised from extensive coronal restorations, caries, resorption, or trauma. Teeth were once thought to be more susceptible to fracturing after endodontic treatment because of a decrease in hydration.36 However, later studies found no difference in the dentin properties after endodontic procedures.38,77 Although the physical characteristics of the dentin may not be compromised by endodontic treatment, the over-enlarging of an endodontic access and excessive canal shaping will result in an increased amount of dentin removal. Consequently, the root may become weaker and may be more predisposed to vertical root fractures. Intracanal forces from excessive compaction pressure during obturation may also contribute to an increased incidence of vertical root fractures.7,54
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