Furcation bone loss can be secondary to periodontal or pulpal disease. The amount of furcation bone loss, as observed both clinically and radiographically, should be documented. Furcation defects should also be recorded as follows:
Class I furcation defect: The furcation can be probed, but not to a significant depth.
|
Class II furcation defect: The furcation can be entered into but cannot be probed completely through to the opposite side.
Class III furcation defect: The furcation can be probed completely through to the opposite side.
Various methods and materials have been used to test the pulp's response to thermal stimuli. The baseline or normal response to either hot or cold is a patient's report that a sensation is felt but disappears immediately upon removal of the thermal stimulus. Abnormal responses include a lack of response to the stimulus, the lingering or intensification of a painful sensation after the stimulus is removed, or an immediate, excruciating painful sensation as soon as the stimulus is placed upon the tooth.
|
page 16
|
|
page 17
|
|
Add to lightbox
|
|
Figure 1-18 Patient has irreversible pulpitis associated with the mandibular right second molar and has found that the only way to alleviate the pain is to place a jar filled with ice water against the right side of his face.
|
|
Heat testing is most useful when a patient's chief complaint is intense dental pain upon contact with any hot liquid or food. In instances where a patient is unable to identify which tooth is sensitive, a heat test is appropriate. Starting with the most posterior tooth in that area of the mouth, each tooth is individually isolated with a rubber dam. An irrigating syringe is filled with a liquid (most commonly plain water) that has a temperature similar to that which would cause the painful sensation. The liquid is then expressed from the syringe onto the isolated tooth to determine whether the response is normal or abnormal. The clinician moves forward in the quadrant, isolating each individual tooth until the offending tooth is located. That tooth will exhibit an immediate, intense painful response to the heat. With heat testing a delayed response may occur, so waiting 10 seconds between each heat test will allow sufficient time for any onset of symptoms.
|
Another method for heat testing is to apply heated gutta-percha or compound stick to the surface of the tooth. If this method is used, a light layer of lubricant should be placed onto the tooth surface prior to applying the heated material to prevent the hot gutta percha or compound from adhering to the dry tooth surface. Heat can also be generated by the friction created when a dry rubber-polishing wheel is run at a high speed against the dry surface of a tooth. This latter method is seldom used today.
|
If the heat test confirms the results of other pulp testing procedures, emergency care can then be provided. Often a tooth that is sensitive to heat may also be responsible for some spontaneous pain. In these cases the patient may present with cold liquids in hand just to minimize the pain (Fig. 1-18). In these cases, the application of cold to a specific tooth may eliminate the pain and greatly assist in the diagnosis.
|
Cold is the primary pulp testing method for many practitioners today. To be most reliable, cold testing should be used in conjunction with the electric pulp tester so that the results from one test will verify the findings of the other test. If a mature, untraumatized tooth does not respond to both electric pulp test and cold test, then the tooth should be considered nonvital.62 However, a multirooted tooth, with at least one root containing vital pulp tissue, may respond to a cold test even if one or more of the roots contain nonvital pulp tissue.62 Cold testing can be accomplished similarly to heat testing, by individually isolating teeth with a rubber dam. This technique for cold testing is especially useful for patients presenting with porcelain jacket crowns or porcelain-fused-to-metal crowns where there is no natural tooth surface (or much metal) accessible. Another benefit of this technique for cold testing is that it requires no armamentarium except for a rubber dam. If a clinician chooses to perform this test with sticks of ice, then the use of the rubber dam is recommended because melting ice will run onto adjacent teeth and gingiva, yielding potentially false-positive responses.
|
Frozen carbon dioxide (CO2), also known as "dry ice" or "carbon dioxide snow," has been found to be very reliable in eliciting a positive response if vital pulp tissue is present in the tooth.29,623,63 One study found that vital teeth will respond to both CO2 and skin refrigerant, with skin refrigerant producing a slightly quicker response.43 Carbon dioxide has also been found to be effective in evaluating the pulpal response in teeth with full coverage crowns for which electric pulp testing is not possible.5 For testing purposes a solid stick of CO2 is prepared by delivering CO2 gas into a specially designed plastic cylinder (Fig. 1-19). The resulting CO2 stick is applied to the facial surface of either the natural tooth structure or crown. Several teeth can be tested with a single CO2 stick. The teeth should be isolated and the oral soft tissues should be protected with a 2 × 2 gauze or cotton roll so the CO2 will not come into contact with these structures. Due to the extremely cold temperature of the CO2 (-69° F to -119° F; -56°C to -98°C) burns of the soft tissues can occur. Investigators5 demonstrated on extracted teeth that CO2 application resulted in a significantly greater intrapulpal temperature decrease than either skin refrigerant or ice. Studies40,68 have also shown that the application of CO2 to teeth does not result in any irreversible damage to the pulp tissues or cause any significant enamel crazing.
|
The most popular method of performing cold testing is with a refrigerant spray. It is readily available, easy to use, and provides test results that are reproducible, reliable, and equivalent to that of CO2.29,43 The current product contains 1,1,1,2-tetrafluoroethane, which has zero ozone depletion potential and is environmentally safe. It has a temperature of -26.2°C.43 The spray is most effective for testing purposes when it is applied to the tooth on a large #2 cotton pellet (Fig. 1-20). In a recent study42 a significantly lower intrapulpal temperature was achieved when a #2 pellet was dipped or sprayed with the refrigerant compared with a small #4 cotton pellet or cotton applicator. The sprayed cotton pellet should be applied to the midfacial area of the tooth or crown. As with any other pulp testing method, adjacent or contralateral "normal" teeth should be tested to establish a baseline response. It appears that CO2 and refrigerant spray are superior to other cold testing methods and equivalent or superior to the electric pulp tester for assessing pulp vitality.5,29
|
page 17
|
|
page 18
|
|
Add to lightbox
|
|
Figure 1-19 ^ CO2 gas being formed into a solid stick/pencil. C, CO2 stick/pencil being extruded from the end of the plastic carrier.
|
|
A recent study63 compared the ability of thermal and electric pulp testing methods to register the presence of vital pulp tissue. The sensitivity, which is the ability of a test to identify teeth that are diseased, was 0.83 for the cold test, 0.86 for heat test and 0.72 for the electric test. This means the cold test correctly identified 83% of the teeth that had a necrotic pulp, while heat tests were correct 86% of the time and electric pulp tests were correct only 72% of the time. This same study evaluated the specificity of these three tests. Specificity relates to the ability of a test to identify teeth without disease. Ninety-three percent of teeth with healthy pulps were correctly identified by both the cold and electric pulp tests, while only 41% of the teeth with healthy pulps were identified correctly by the heat test. From the results of the testing it was found that the cold test had an accuracy of 86%, the electric pulp test 81%, and the heat test 71%.
|
Assessment of pulp vitality is most frequently accomplished by electric pulp testing and/or cold testing. The vitality of the pulp is determined by the intactness and health of the vascular supply, not the status of the pulpal nerve fibers. Even though advances are being made with regard to determining the vitality of the pulp on the basis of the blood supply, this technology is not accurate enough to be used on a routine basis in a clinical setting.
|
The electric pulp tester has limitations in providing information about the vitality of the pulp. The response of the pulp to electric testing does not reflect the histologic health or disease status of the pulp.81,82 A response by the pulp to the electric current only denotes that some viable nerve fibers are present in the pulp and are capable of responding. Numerical readings on the pulp tester have significance only if the number differs significantly from the readings obtained from a control tooth tested on the same patient with the electrode positioned at a similar area on both teeth. Studies81,82 have shown that electric pulp test results are most accurate when no response is obtained to any amount of electric current. This lack of response has been found most frequently when a necrotic pulp is present. The electric pulp tester will not work unless the probe can be placed in contact with or be bridged60 to the natural tooth structure. With the advent of universal precautions for infection control, the patient may be required to place a finger or fingers on the tester probe to complete the electric circuit for some models; however, lip clips are an alternative to having patients hold the tester. The use of rubber gloves prevents the clinician from completing the circuit.3 Proper use of the electric pulp tester requires that the teeth to be evaluated be isolated and dried. A control tooth of similar tooth type and location in the arch should be tested first in order to establish a baseline response and to inform the patient what a "normal" sensation is. The suspected tooth should be tested at least twice to confirm the results. The tip of the testing probe that will be placed in contact with the tooth structure must be coated with a water- or petroleum-based media.56 The most commonly used media is toothpaste. The coated probe tip is placed in the incisal third of the facial or buccal area of the tooth to be tested.9 Once the probe is in contact with the tooth, the patient is asked to touch or grasp the tester probe (Fig. 1-21, A).3 This completes the circuit and initiates the delivery of electric current to the tooth. The patient is instructed to remove his or her finger(s) from the probe when a "tingling" or "warming" sensation is felt in the tooth. The readings from the pulp tester are recorded (Fig. 1-21, B) and will be evaluated once all the appropriate teeth have been tested and the results obtained from other pulp testing methods.
|
page 18
|
|
page 19
|
|
Add to lightbox
|
|
Figure 1-20 A, Refrigerant spray container. B, A cotton roll can be used to form a large cotton pellet, or a size #2 (large) cotton pellet can be used to apply the refrigerant spray to the tooth surface. The small #4 cotton pellet does not provide as much surface area as the #2 cotton pellet so it should not be used to deliver the refrigerant to the tooth surface. C, A large cotton pellet that has been sprayed with the refrigerant and is ready to be applied to the tooth surface.
|
|
|
Add to lightbox
|
|
Figure 1-21 A, View of an electric pulp tester with probe. The probe tip will be coated with a media such as toothpaste and placed into contact with the tooth surface. The patient will activate the unit by placing a finger into contact with the metal shaft of probe. B, View of the electric pulp tester control panel: The knob on the right front of the unit controls the rate at which the electric current is delivered to the tooth. The plastic panel on the left front displays the digital numerical reading obtained from the pulp test. The digital scale runs from 0 to 80.
|
|
If a complete coverage crown or extensive restoration is present, a bridging technique can be attempted to deliver the electric current to any exposed natural tooth structure.60 The tip of an endodontic explorer is coated with toothpaste or other appropriate media and placed in contact with the natural tooth structure. The tip of the electric pulp tester probe is coated with a small amount of toothpaste and placed in contact with the side of the explorer. The patient completes the circuit and the testing proceeds as described previously. If no natural tooth structure is available then an alternative pulp testing method, such as cold, should be used.
|
page 19
|
|
page 20
|
As noted previously, studies29,62,63 have shown that there does not appear to be any significant difference between the pulp testing results obtained with the electric pulp tester and those obtained with the thermal methods, although cold tests have been shown to be more reliable than electric pulp tests in younger patients with less developed apices.62 However, unlike electric pulp testing, cold testing can reveal the health and integrity of pulp tissue (i.e., no response, a momentary response, or a prolonged, painful response after the thermal stimulus is removed). This is why it is a good rationale to verify the results obtained with one testing method to those obtained with the other method. Until such time that the testing methods used to assess the vascular supply of the pulp become less time consuming and technique sensitive, thermal and electric pulp testing will continue to be the primary methods for determining pulp vitality.
|
Laser Doppler Flowmetry (LDF) is a method used to assess blood flow in microvascular systems. Attempts are being made to adapt this technology to assess pulpal blood flow. A diode is used to project an infrared light beam through the crown and pulp chamber of a tooth. The infrared light beam is scattered as it passes through the pulp tissue. The Doppler principle states that the light beam will be frequency-shifted by moving red blood cells but will remain unshifted as it passes through static tissue. The average Doppler frequency shift will measure the velocity at which the red blood cells are moving.71
|
Several studies23,39,55,71,73 have found the LDF to be an accurate, reliable, and reproducible method of assessing pulpal blood flow. Even with these positive findings, the technology is not advanced enough for this method to be used on a routine basis in a dental practice. In one clinical trial23 fabricating the individualized stabilization jig, making the LDF recordings took approximately 1 hour, a finding not unique to this study. If technology can be developed whereby the testing with the LDF can be accomplished in minutes, it will likely replace the thermal and electric pulp testing methods.
|
As will be discussed in Chapter 16, certain luxation injuries will cause inaccuracies in the results of electric and thermal pulp testing. LDF has recently been shown to be a great indicator for pulpal vitality in these cases.86
|
Another noninvasive method that has been investigated as a method to determine pulpal blood flow uses a pulse oximeter, which is designed to measure the oxygen concentration of the blood and the pulse rate. The oximeter works on the principle that two wavelengths of light transmitted by a photoelectric diode detect oxygenated and deoxygenated hemoglobin as they pass through a body part to a receptor. The difference between the light emitted and the light received is calculated by a microprocessor to provide the pulse rate and oxygen concentration in the blood.74
|
Attempts to use the pulse oximeter to diagnosis pulp vitality have met with mixed results. Some studies74,92 have reported that the pulse oximeter is a reliable method for assessing pulp vitality. Others92 have stated that in its present form the pulse oximeter is not of predictive diagnostic value for diagnosing pulp vitality. Most of the problems appear to be related to the present available technology. The devices used for pulp testing are too cumbersome and complicated to be used on a routine basis in a dental practice.45,74,92
|
^
|
Percussion and bite tests are indicated when a patient presents with pain while biting. Occasionally the patient may not know which tooth is sensitive to biting pressure, and percussion and bite tests may help to localize the tooth involved. The tooth may be sensitive to biting when the pulpal pathosis has extended into the periodontal ligament space, creating a periradicular periodontitis, or the sensitivity may be present secondary to a crack in the tooth. The practitioner can often differentiate between periradicular periodontitis and a cracked tooth or fractured cusp. If periradicular periodontitis is present, the tooth will respond with pain to percussion and biting tests regardless of where the pressure is applied to the coronal part of the tooth. A cracked tooth or fractured cusp will elicit pain only when the percussion or bite test is applied in a certain direction to one cusp or section of the tooth.14,70
|
|
Add to lightbox
|
page 20
|
|
page 21
|
|
Figure 1-22 To determine which tooth is sensitive to mastication and which part of the tooth is sensitive, having the patient bite on a specially designed bite stick is often helpful.
|
|
For the bite test to be meaningful a device should be used that will allow the practitioner to apply pressure to individual cusps or areas of the tooth. A variety of devices have been used for bite tests, including cotton applicators, toothpicks, orangewood sticks, and rubber polishing wheels. Today several devices are specifically designed to perform this test. The Tooth Slooth (Professional Results, Inc., Laguna Niguel, CA) (Fig. 1-22) and Frac Finder (Hu Friedy Co., Chicago, IL) are just two of the commercially available devices used for the bite test. As with all pulp tests, adjacent teeth should be used as controls so that the patient is aware of the "normal" response to these tests. The small cupped-out area on these instruments is placed in contact with the cusp to be tested. The patient is then asked to apply biting pressure with the opposing teeth to the flat surface on the opposite side of the device. The biting pressure should be applied slowly until full closure is achieved. The firm pressure should be applied for a few seconds; the patient is then asked to release the pressure very quickly. Each individual cusp on a tooth can be tested in a like manner. The practitioner should note if the pain is elicited during the pressure phase or upon quick release of the pressure. A common finding with a fractured cusp or cracked tooth is the frequent presence of pain upon release of biting pressure.
|
The test cavity method for assessing pulp vitality is very seldom used today. This method is used only when all other test methods are deemed impossible or the results of the other tests are inconclusive. An example of a situation where this method might be used is when the tooth suspected of having pulpal disease has a full coverage crown. If no sound tooth structure is available to use a bridging technique with the electric pulp tester and cold test results are inconclusive, a small class I cavity preparation is made through the occlusal surface of the crown. This is accomplished with a high-speed #1 or #2 round bur with proper air and water coolant. The patient is not anesthetized while this procedure is performed, and the patient is asked to respond if any painful sensation is felt during the drilling procedure. If the patient feels pain once the bur contacts sound dentin, the procedure is terminated and the class I cavity preparation is restored. This sensation signifies only that there is some viable nerve tissue remaining in the pulp, not that the pulp is totally healthy. If the patient fails to feel any sensation when the bur reaches the dentin, it is a good indication that the pulp is necrotic and root canal therapy is indicated.
|
In order to determine the presence of a crack in the surface of the tooth, the application of a stain to the area is often of great assistance. Shining a very bright light on the surface of the tooth is also very helpful. This will be elaborated on later in this chapter in the discussion of the detection of cracks and fractures.
|
When symptoms are nonlocalized or referred, the diagnosis may be very challenging. Sometimes the patient may not even be able to specify whether the symptoms are emanating from the maxillary or mandibular arch. In these instances, when pulp testing is inconclusive, selective anesthesia may be very helpful.
|
If the patient cannot determine which arch the pain is coming from, then the clinician should first selectively anesthetize the maxillary arch. This should be accomplished by using a periodontal ligament (intraligamentary) injection. The injection is administered to the most posterior tooth in the quadrant of the arch that may be suspected, starting from the distal sulcus. The anesthesia is subsequently placed more forward, one tooth at a time, until the pain is eliminated. If, after an appropriate period of time, the pain is not eliminated, the clinician should similarly repeat this technique on the mandibular teeth below. It should be understood that periodontal ligament injections may inadvertently anesthetize an adjacent tooth, and thus are more useful for identifying the arch rather than the specific tooth.
|
^
|
Few diagnostic tests provide as much useful information as dental radiography. For this reason, the clinician is sometimes tempted to prematurely make a definitive diagnosis based solely on radiographic interpretation. However, the image should be used only as one sign, providing important clues in the diagnostic investigation. When not coupled with a proper history and clinical examination and testing, the radiograph alone can lead to a misinterpretation of normality and pathosis (Fig. 1-23). Since treatment planning will ultimately be based upon this diagnosis, the potential for inappropriate treatment may be great if the radiograph alone is used for making this diagnosis. The clinician should not subject the patient to unnecessary multiple radiation exposures; often two preoperative images from different angulations are sufficient. But in extenuating circumstances, especially when the diagnosis is difficult, multiple exposures may be necessary in order to determine the presence of multiple roots, multiple canals, resorptive defects, caries, restoration defects, root fractures, and the extent of root maturation and apical development.
|
The radiographic appearance of endodontic pathosis can sometimes be very subjective. In a study by Goldman et al,31 there was agreement of pathosis in only 50% of the radiographically evaluated cases, as interpreted by two endodontists, three second-year residents, and an associate professor in radiology. Additionally, when the cases were evaluated several months later, the evaluators agreed with their own original diagnosis only 75% to 83% of the time. Again, this emphasizes the necessity for other objective diagnostic tests, as well as the importance of obtaining and comparing older radiographs.
|
page 21
|
|
page 22
|
|
Add to lightbox
|
|
Figure 1-23 Radiograph of what appears to be a periapical lesion associated with a nonvital tooth; however, the tooth is vital. The appearance of apical bone loss is actually secondary to a cementoma.
|
|
|
Add to lightbox
|
|
Figure 1-24 Radiographic images are only two dimensional, and often it is difficult to discriminate the relative location of overlapping objects. A, When the source of the radiation is directly perpendicular to overlapping objects, the image is captured without much separation of the objects. However, when the radiation source is at an angle to offset the overlapping objects, the image is captured with the objects being viewed as separated. B, The object that is closest to the film (or sensor) will move the least, with the object closest to the radiation source appearing farthest away.
|
|
In the practice of medicine, computerized axial tomography (CAT) scans can give the clinician a virtual three-dimensional image that can be rotated in a multitude of directions in order to better visualize and interpret anatomic structures and pathosis. This type of imagery will eventually be miniaturized and available for the dental office (see Chapter 9 for examples). For now clinicians must rely on x-ray visualization in only two dimensions. Clinicians basically project X-radiation through an object and capture the image on a recording medium-either x-ray film or a digital sensor. Much like casting a shadow from a light source, the image appearance may vary greatly depending on how the radiographic source is directed. Therefore, the three-dimensional interpretation of the resulting two-dimensional image requires not only knowledge of normality and pathosis but also advanced knowledge of how the radiograph was exposed. By virtue of "casting a shadow," the anatomic features that are closest to the film (or sensor) will move the least when there is a change in the horizontal or vertical angulation of the radiation source (Fig. 1-24). This may be very helpful in determining the existence of additional roots, the location of pathosis, and the unmasking of anatomical structures. Changes in the horizontal or vertical angulation may help elucidate valuable anatomic and pathologic information; it also has the potential to hide important information. An incorrect vertical angulation may cause the buccal roots of a maxillary molar to be masked by the zygomatic arch. An incorrect horizontal angulation may cause roots to overlap with the roots of adjacent teeth, or it may incorrectly create the appearance of a one-rooted tooth, when two roots are actually present.
|
Generally, when endodontic pathosis appears radiographically, it appears as bone loss in the area of the periapex. The infection in the pulpal space transgresses through the pulpal canal and into the associated bone. The pathosis may present merely as a widening or break in the lamina dura-the most consistent radiographic finding when a tooth is nonvital,44 or it may present as a radiolucent area at the apex or in the area of a lateral or furcation canal. Occasionally there may be no radiographic change at all, even in the presence of an acute periradicular abscess.
|
page 22
|
|
page 23
|
The variability in the radiographic expression of osseous pathosis has much to do with the relative location of the root of the tooth and how it is oriented with respect to the cortical and cancellous bone. Radiographic changes from bone loss will not be observed if the bone loss is only in cancellous bone. However, radiographic evidence of pathosis will be observed once this bone loss extends to the junction of the cortical and cancellous bone, as was illustrated by Bender and Seltzer10 whereby artificial lesions were created in cadaver bone and evaluated radiographically. As a follow-up to this study, the authors reported why certain teeth are more prone to exhibit radiographic changes than others, depending on their anatomic location.11 Their findings revealed that the radiographic appearance of endodontic pathosis is correlated with the relationship of the periapex of the tooth and its juxtaposition to the cortical-cancellous bone junction. Most anterior and premolar teeth are located very close to the cortical-cancellous bone junction. For this reason, periapical pathosis from these teeth is exhibited sooner. By comparison, the distal roots of mandibular first molars and both roots of mandibular second molars are generally positioned more centrally within the cancellous bone, as are maxillary molars, especially the palatal roots. Periapical lesions from these roots have to expand more before they reach the cortical-cancellous bone junction and are recognized as radiographic pathosis. For these reasons, it is important not to exclude the possibility of pulpal pathosis in situations in which there are no radiographic changes.
|
Many factors can influence the quality of the radiographic interpretation, including the ability of the person exposing the radiograph, the quality of the radiographic film, the quality of the exposure source, the quality of the film processing, and the quality of how the film is viewed. Controlling all of these variables can be a difficult challenge but is paramount for obtaining an acceptable radiographic interpretation.
|
One technique for controlling many of the variables in the diagnostic quality of conventional radiography has been the advent of digital radiography. This technology has been around for about 20 years but has recently been refined with better hardware and more user-friendly software. Digital radiography has the ability to capture, view, enhance and store radiographic images in an easily reproducible format that does not degrade over time.
|
Digital radiography uses no x-ray film and requires no chemical processing. Instead, a sensor is used to capture the image created by the radiation source. This sensor is either directly or remotely attached to a local computer, which interprets this signal and, using specialized software, translates the signal into a digital image that can be displayed and enhanced. The image is stored in the patient's file, typically in a dedicated network server, and can be recalled as needed. Further information about digital radiography may be found in Chapters 5 and 26.
|
|
Add to lightbox
|
|
Figure 1-25 Digital radiography has as an advantage over conventional film in that the image can be enhanced and colorized, a useful tool for patient education.
|
|
The viewing of a digital radiographic image on a high resolution monitor allows for rapid and easy interpretation for both the clinician and the patient. The image appears almost instantly, with no potential for image distortion from improper chemical processing, since there is none. The clinician can zoom in to different areas on the x-ray image, digitally enhance the image in order to better visualize certain anatomic structures, and in some cases, the image can even be colorized, a useful tool for patient education (Fig. 1-25).
|
Until recently, x-ray film has had a slightly better resolution than most digital radiography images, at about 16 line pairs per millimeter (lp/mm).57 However, some sensor manufacturers are now claiming to have resolutions beyond that of film and up to 22 lp/mm. However, under the best of circumstances, the human eye can only see about 10 lp/mm, which is the lowest resolution for most dental digital radiography systems. The digital sensors are much more sensitive to radiation than conventional x-ray film and thus require 50% to 90% less radiation in order to acquire an image, an important feature for generating greater patient acceptability of dental radiographs.
|
The diagnostic quality of this expensive technology has been shown to be comparable to, but not necessarily superior to, perfectly exposed and perfectly processed conventional film-based radiography.22,47,61 However, digital radiography has the advantage over conventional film in that there is no diminution in diagnostic quality caused by developing and processing errors, and it has the ability to enhance, magnify, store, and electronically send the images, as well the ability to duplicate the original radiograph as a perfect copy. In 1998, the American Association of Endodontists stated that "digital radiography will rapidly replace conventional dental X-rays."2 The reader is referred to Chapter 26 for more information on digital radiography.
|
|
