Percussion

The percussion test may reveal whether there is any inflammation around the periodontal ligament. The clinician should remember that the percussion test does not. give any indication

Lateral Mirror Intraoral

FIG. 1-3 Palpation. A, Bilateral intraoral digital palpation aids the clinician in detecting comparative changes in contour or consistency of the soft tissue and underlying bone. A "mushy" feeling detected during palpation around the mucolabial fold maty be the first clinical evidence of incipient swelling. B, Bimanual extraoral palpation to tactilely search for the extent of lymph node involvement when there is a mandibular dental infection. The clinician should palpate the submandibular nodes (as shown here), the angle of the mandible, and the cervical chain of nodes.

FIG. 1-3 Palpation. A, Bilateral intraoral digital palpation aids the clinician in detecting comparative changes in contour or consistency of the soft tissue and underlying bone. A "mushy" feeling detected during palpation around the mucolabial fold maty be the first clinical evidence of incipient swelling. B, Bimanual extraoral palpation to tactilely search for the extent of lymph node involvement when there is a mandibular dental infection. The clinician should palpate the submandibular nodes (as shown here), the angle of the mandible, and the cervical chain of nodes.

of the health or integrity of the pulp tissues; it indicates only whether there is inflammation around the periodontal ligament. Before the test, the patient should be instructed that making a small audible sound or raising a hand is the best way to let the clinician know when a tooth feels tender, different, or painful with percussion.

Before tapping on the teeth with the handle of a mouth mirror, the clinician is advised to use the index finger to percuss teeth in the quadrant being examined (Fig. 1-4, A). Digital percussion is much less painful than percussion with a mouth mirror handle. The teeth should be tapped in a random fashion (i.e., out of sequence) so the patient cannot anticipate when "the tooth" will be percussed. If the patient cannot discern a difference in sensation with digital percussion, the handle of a mouth mirror should be used to tap on the occlusal, facial, and lingual surfaces of the teeth (Fig. 1-4, B). Using the most appropriate force for percussing is one of the skills that the clinician will develop as part of the art of endodontic diagnosis. Percussing the teeth too strongly may cause unnecessary pain and anxiety for the patient. The clinician should use the chief complaint and dental history as a guide in deciding how strongly to percuss the teeth. The force of percussion need be only great enough for the patient to discern a difference between a sound tooth and a tooth with an inflamed periodontal ligament. The proprioceptive fibers in an inflamed periodontal ligament, when percussed, help the patient and the clinician locate the source of the pain. Tapping on each cusp can, on occasion, reveal the presence of a crown fracture.

A positive response to percussion, indicating an inflamed periodontal ligament, can be caused by a variety of factors (e.g., teeth undergoing rapid orthodontic movement, a recent high restoration, a lateral periodontal abscess, and, of course, partial or total necrosis of the pulp). However, the absence of a response to percussion is quite possible when there is chronic periapical inflammation.

Mobility

Using the index fingers, or preferably the blunt handles of two metal instruments, the clinician applies alternating lateral forces in a facial-lingual direction to observe the degree of mo-

FIG. 1-4 Percussion test to determine whether there is any apical periodontitis. If the patient has reported pain during mastication, the percussion test should be conducted very gently. A, First only the index finger should be used. The teeth should be percussed from a facial as well as an incisal direction. B, If the patient reports no tenderness when the teeth are percussed with the finger, a more definitive, sharper percussion can be conducted with the handle of the mouth mirror.

FIG. 1-4 Percussion test to determine whether there is any apical periodontitis. If the patient has reported pain during mastication, the percussion test should be conducted very gently. A, First only the index finger should be used. The teeth should be percussed from a facial as well as an incisal direction. B, If the patient reports no tenderness when the teeth are percussed with the finger, a more definitive, sharper percussion can be conducted with the handle of the mouth mirror.

bility of the tooth within the alveolus (Fig. 1-5). In addition, tests for the degree of depressibility arc performed by pressing the tooth into its socket and observing if there is vertical movement. First-degree mobility is barely discernible movement; second-degree is horizontal movement of 1 mm or less; third-degree is horizontal movement of greater than 1 mm, often accompanied by vertical mobility. Tooth movement usually reflects the extent of inflammation of the periodontal ligament.

The pressure exerted by the purulent exudate of an acute apical abscess may cause some mobility of a tooth. In this situation the tooth may quickly stabilize after drainage is established and the occlusion adjusted. There are additional causes for tooth mobility—including advanced periodontal disease, horizontal root fracture in the middle or coronal third, and chronic bruxism or clenching.

Radiographs

Radiographs are essential aids in endodontic diagnosis. Unfortunately, some clinicians rely exclusively on radiographs in their attempt to arrive at a diagnosis. This obviously can lead to major errors in diagnosis and treatment.2 Because the radiograph is a two-dimensional image of a three-dimensional object, misinterpretation is a constant risk, but with proper an-

FIG. 1-5 The degree of mobility can be most effectively determined by applying lateral forces with a blunt-handled instrument in a facial-lingual direction.

gulation of the cone, accurate him placement, correct processing of the exposed film (Fig. 1-6), and good illumination with a magnifying glass, the hazards of misinterpretation can be substantially minimized. The full benefit of periapical radiographs for diagnostic purposes can be achieved if the technique described here is employed.

After correct film placement, either bisected-angle or long-cone methods are effective for film exposure. It is important to expose two diagnostic films. By maintaining the same vertical cone angulation and changing the horizontal cone angu-lation 10 to 15 degrees for the second diagnostic film, the clinician can obtain a three-dimensional impression of the teeth that will aid in discerning superimposed roots and anatomic landmarks. (Refer to Chapter 5 for further discussion of this phase of dental radiology.)

The state of pulpal health or pulpal necrosis cannot be determined radiographically; but any of the following findings should arouse suspicion of degenerative pulp changes: deep carious lesions, deep and extensive restorations, pulp caps, pulpotomies, pulp stones, extensive canal calcification, root resorption, radiolucencies at or near the apex, root fractures, thickened periodontal ligament, and periodontal disease that is radiographically evident.

Radiographic interpretation

Interpretation of good-quality diagnostic radiographs must be done in an orderly and consistent manner. With good illumination and magnification the clinician can detect nuances of change that may reveal early pathologic changes in or around the tooth. First, the crown of each tooth and then the root(s) are carefully observed, then the root canal system, followed by the lamina dura, bony architecture, and finally the anatomic landmarks that may appear on the film. When posterior teeth are being investigated, a bite-wing film provides an excellent supplement for finding the extent of carious destruction, the depths of restorations, the presence of pulp caps or pulpoto-mies, and dens invaginatus or evaginatus. Generally it is true that the deeper the caries and the more extensive the restoration the greater is the probability of pulpal involvement. Following the lamina dura usually reveals the number and curvature of the roots. A root canal should be readily discernible; if the canal appears to change quickly from dark to light, this indicates that it has bifurcated or trifurcated (Fig. 3-7, A). The presence of "extra" roots or canals in all teeth (Fig. 1-7, B) is

FIG. 1-6 A, An improperly exposed or poorly processed radiograph like this one is difficult or impossible to interpret. B, The condition of the crown, roots, and surrounding tissue can be seen only with a properly prepared radiograph.

much more common than was previously believed. If the outline of the root seems unclear or deviates from where it ought to be, an extra root should be suspected.24 Accordingly, at least one canal (or root) mnore than the radiograph shows must always be suspected until clinically proved otherwise. Three -rooted mandibular molars (Fig. 1-7, B) and maxillary premo-lars as well as two-rooted canines will be found with greater frequency as the examiner's dental anatomic acumen, index of suspicion, and diagnostic sophistication improve.

A necrotic tooth does not cause radiographic changes at the apex until the periapical pathosis has destroyed bony trabecu-le at theirjunction with the cortical plate.21 Thus a great deal of bone destruction may occur before any radiographic signs are evident. A radioluccnt lesion need not be at the apex of the root to indicate pulpal inflammation or degeneration. Toxins of pulp tissue degeneration exiting from a lateral canal can cause bone destruction anywhere along the root. Conversely, a lateral canal can be a portal of entry for potentially harmful toxins in teeth with advanced periodontal disease (Fig. 1-8). If periodontal bone loss extends far enough apically to expose the foramen of a lateral canal, the toxins from the periodontal disease can gain entry into a vital healthy pulp via the lateral canal and cause irritation, inflammation, and even pulpal necrosis in a sound tooth. Periodontal disease extending to the apical foramen definitely causes pathologic pulpal changes (see Chapter 18).

Pulp stones (Fig. 1 -9, A) and canal calcifications are not necessarily pathologic; they can be mere manifestations of degenerative aging in the pulpal tissue. However, their presence may cause other insults to the pulp and may increase the difficulty of negotiating the root canals. The incidence of calcifications in the chamber or in the canal may increase with periodontal disease, extensive restorations, or aging. As the percentage of the population categorized as elderly increases, clinicians

FIG. 1-7 A, A sudden change from dark to light indicates bifurcation or bifurcation of the root canal system (arrow), as shown by B, premolar with a bifurcated root canal system and a mandibular first molar with three roots.

FIG. 1-8 A and B, Radiolucent lesions indicates pulp degeneration. These radiographs illustrate how toxins of pulp tissue degeneration may exit from a lateral canal, causing bone destruction along the side. Conversely, this lateral canal could be a portal of entry for toxins that might destroy the pulp and create a periapical lesion.

FIG. 1-8 A and B, Radiolucent lesions indicates pulp degeneration. These radiographs illustrate how toxins of pulp tissue degeneration may exit from a lateral canal, causing bone destruction along the side. Conversely, this lateral canal could be a portal of entry for toxins that might destroy the pulp and create a periapical lesion.

FIG. 1-9 A, Pulp stones and the extent and depth of restorations can be detected more clearly with a bite-wing film. B, Periapical osteosclerosis, possibly caused by a mild pulp irritant. C, Dens in dente. D, Internal resorption, once detected, must be treated promptly before it perforates the root. E, Horizontal root fractures can usually be detected with a good-quality radiograph. F, Vitality tests on a tooth with an immature apex may yield erroneous results.

FIG. 1-9 A, Pulp stones and the extent and depth of restorations can be detected more clearly with a bite-wing film. B, Periapical osteosclerosis, possibly caused by a mild pulp irritant. C, Dens in dente. D, Internal resorption, once detected, must be treated promptly before it perforates the root. E, Horizontal root fractures can usually be detected with a good-quality radiograph. F, Vitality tests on a tooth with an immature apex may yield erroneous results.

should be more attuned to detecting pulp stones and calcification of the canal space30 (see Chapter 24).

Internal resorption (Fig. 1-9, D) (occasionally seen after a traumatic injury) is an indication for endodontic therapy. The inflamed pulp, expanding at the expense of the dentin, must be removed as soon as possible lest a lateral perforation occur. Untreated internal resorption leading to root perforation increases the probability of eventual tooth loss (see Chapter 16).

Radiographs are important for identifying teeth with immature apices (Fig. 1-9, F) and teeth with lingual development grooves (Fig. 1-10). The clinician must have this information before conducting thermal and electric pulp tests because teeth with immature apices often cause erroneous readings with vitality testing (Chapter 23).

Root fractures may cause pulpal degeneration. Fractures of the root can be difficult to detect on a radiograph. Vertical root fractures (Fig. 1-11, A and B) are seldom identified with the radiograph except in advanced stages of root separation. Most horizontal root fractures can be readily identified with prop erly exposed and processed radiographs; however, horizontal fractures may be confused with linear patterns of bone trabecule. The two phenomena can be differentiated by noting that the lines of bone trabeculae extend beyond the border of the root, whereas a root fracture often causes a thickening of the periodontal ligament.

Finally, the clinician must realize that there are occasions when periapical, bite-wing, and panoramic films may not suffice. Other types of cxtraoral films, described in greater detail in Chapter 5, may be necessary (especially when there has been a traumatic incident) before a diagnosis can be made.

Radiographic misinterpretation

A dental humorist once claimed that if a clinician looked at a radiograph long enough he would find whatever he was looking for. This overstatement suggests a sound rule for radiographic interpretation: be wary—but not necessarily disbelieving—of what appears to be obvious radiographically. Radiographic interpretation is often quite subjective, as illustrated by a study of more than 250 cases in which the same endodontists interpreted

FIG. 1-10 A, Lingual development groove. The radiograph shows the canals of both central incisors to be distinctly different. Arrows point to the groove traced along the root. B, Silver cone in the sulcular defect tracing the groove toward the apex. C, Although the tooth was vital, only extraction could resolve this problem. In the near future, lasing these grooves may allow these types of teeth to be retained.

FIG. 1-10 A, Lingual development groove. The radiograph shows the canals of both central incisors to be distinctly different. Arrows point to the groove traced along the root. B, Silver cone in the sulcular defect tracing the groove toward the apex. C, Although the tooth was vital, only extraction could resolve this problem. In the near future, lasing these grooves may allow these types of teeth to be retained.

FIG. 1-11 Vertical fractures arc rarely evident radiographically until there is advanced root separation. A, Distal root with vertical fracture. B, Following extraction, the fracture can be seen (arrow).

the same radiographs at intervals of 6 to 8 months. The three endodontists in this study agreed with themselves only 72% to 88% of the time.10 In an earlier study six endodontists all agreed with each other less than half the time.9 The radiographic phenomena that caused misinterpretations were these:

1. Radioluccncy at the apex (Fig. 1-12). At first glance this might appear to be a periapical lesion. However, a positive response to vitality tests, an intact lamina dura, the absence of symptoms and probable cause, and the anatomic location clearly show it to be the mental foramen. Only the confirmed absence of pulp vitality will reveal which tooth is the source of the periapical lesion (Fig. 1-13).

2. Well-circumscribed radiolucency at or near the apex (Fig. 1-14, A-C). At first glance (Fig. 1-14, B) it might appear to be a periapical lesion. However, changing the horizontal angulation and exposing a second radiograph show the lesion to have moved (Fig. 1-14, C). Because the tooth was asymptomatic with lack of probable cause and because of a positive response to vitality tests and anatomic location, this was positively identified as the nasopalatine canal.

3. The periapical radiolucency over the lateral incisor suggests the incisor is the source of the lesion, but vitality testing showed it was the canine that was nonvital. En-dodontic treatment remineralized the radiolucency over the lateral incisor (Fig. 1-15).

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Responses

  • gregorio romani
    Which lesion shows tender on percussion?
    1 year ago
  • Dennis
    How to percuss a tooth apically?
    7 months ago

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