Nonsurgical Treatment Success

A simplified definition of favorable outcomes with nonsurgical treatment procedures might be: If there is no radiographic evidence of periradicular pathosis prior to root canal treatment, no radiographic signs of pathosis should ever appear following treatment (Fig. 5-1).¹¹ If there is radiographic evidence of periradicular pathosis at the time of treatment, periodic postoperative reexamination radiographs should indicate that the pathosis is healed or is healing.¹¹ As characterized radiographically, this would mean a return to a normal periodontal ligament space and lamina dura, and a normal bony pattern surrounding the root apex (Fig. 5-2). Subjective and clinical corollaries to these findings would refer to the presence or absence of objective signs or patient symptoms. If there are no preoperative symptoms, none should arise postoperatively. Conversely, any preoperative symptoms should resolve completely with treatment.

FIGURE 5-1 A, Routine endodontic case without radiographic evidence of periapical pathosis at the time of treatment in February 1978. B, Reevaluation June 2006. The tooth is asymptomatic with normal function.

FIGURE 5-2 A, Large periapical lesion secondary to necrotic pulp on a mandibular right first molar. Lesion appears to have a periodontal complication, but clinical probings were normal. There was a draining sinus tract on the edentulous ridge distal to the tooth. B, One-year posttreatment reexamination. The apical and distal bone is completely restored along with a periodontal ligament space of uniform and normal width.

With these concepts for success in mind, a clinical diagnostic case involving a mixed dentition of root-treated treated and untreated teeth would require a separate and distinct evaluation of the treated teeth, as opposed to just dismissing them as not being the cause of the patient’s symptoms.

CLINICAL PROBLEM

Problem

A 46-year-old patient complained of a periodic dull pain in the lower right quadrant. There was discomfort on chewing but no history of thermal sensitivity. The radiograph indicated previous root canal treatment of the mandibular second premolar and second molar, which according to the patient was completed 7 to 10 years previously (Fig. 5-3, A). Radiographs from the time of the original treatment were unavailable. The only questionable radiographic finding was a slightly widened apical periodontal ligament space on the apex of the distal root on the second molar. The patient had acute tenderness to percussion on the mandibular first molar, but the second premolar and second molar had no discomfort. Periodontal probings indicated moderate general periodontal bone loss, but there was no evidence of defects potentially related to a vertical root fracture on any tooth.

FIGURE 5-3 A, Mandibular left posterior dentition in which patient is experiencing pain. Note questionable radiographic appearance of apical periodontal ligament space on distal root of second molar. B, Post treatment of first molar, which clinical examination identified as the cause of symptoms. The two adjacent teeth were judged to have successful root canal treatment.

Solution

The challenge was to arrive at the correct diagnosis. The differential diagnosis included bruxism, possible recurrent periapical pathosis on either of the treated teeth, or pulpal disease in the first molar. Occlusion was evaluated, and no occlusal prematurities were found that would account for the percussion tenderness on the first molar. Thermal sensibility tests on the first molar failed to elicit a response. The diagnosis of pulpal necrosis of the first molar was made; root canal treatment of the other two teeth was judged to be successful. The completed root canal treatment of the first molar is seen in Fig. 5-3, B. All symptoms subsequently resolved.

Incomplete Nonsurgical Treatment

Occasionally the cause of periapical pathosis on a multicanal pulpless tooth can easily be identified when it is obvious that one of the canals has no root filling. It is a matter of semantics whether or not to label this condition as a treatment failure, since the canal in question was never treated. At the same time, it is clearly a failure on the part of the clinician to locate and treat all canals present in the tooth.

CLINICAL PROBLEM

Problem

The patient was a 55-year-old female with an acute apical abscess. She gave a history that the maxillary left first molar had root canal treatment approximately 3 years previously (Fig. 5-4, A). Clinically there was acute apical palpation tenderness over the apex of the mesial buccal root. There was a radiolucency around the apex of the mesial buccal root; bone associated with the other two apices appeared to be normal.

FIGURE 5-4 A, Apical lesion at apex of mesiobuccal root of an endodontically treated maxillary left first molar. B, Endodontic file in an untreated second mesial buccal canal. C, Post treatment. Existing root canal treatment of the other canals was judged adequate.

Solution

What was the differential diagnostic parameter? The root canal filling material in both buccal roots suggested that the canals were adequately but not ideally cleaned and shaped, and therefore a true failure was a possibility. A more likely diagnosis for this root was the presence of a second canal or irregular canal configuration.^3,47 Fig. 5-4, B shows a file in a second canal clearly separate from the previously treated canal. Fig. 5-4, C shows the completed treatment of this canal only. Arguably, this canal may be the most frequently overlooked canal, owing to its small diameter, the lack of radiographic signs of its presence, and the fact that it is not present in all cases (Fig. 5-5, A to D). Nevertheless, if a maxillary molar presents with a lesion only around the apex of the mesial buccal root in an otherwise adequately treated tooth, an untreated second mesial buccal canal must be the first diagnostic consideration. An uncleaned, contaminated second canal would be one of several possible etiologies for pathosis in a case of inadequate root canal treatment involving the mesiobuccal root (Fig. 5-6).

FIGURE 5-5 A, Cross-section of typical mesial buccal root, indicating a treated mesial buccal canal and an untreated second mesial buccal canal connected by an isthmus (arrows). B, Radiographic view palatal root (left) and lateral view buccal root (right) of same tooth. C, Pulp chamber with identification of mesial buccal, distal buccal, and palatal canals. D, Identification of the second mesial buccal canal.

FIGURE 5-6 A, Inadequate root canal treatment of a maxillary left first molar in which there is also an untreated second mesial buccal root. Clinically, there was local swelling and palpation tenderness localized to the area over the apex of the mesial buccal root. B, Completed revision. Note treatment of second mesial buccal root.

One of the more perplexing clinical circumstances with the maxillary first molar (and any other tooth that may have a second canal located in the buccal-lingual dimension) is when there is no radiolucency seen on the radiograph, or when the presence of a radiolucency is questionable no matter what angle the film is exposed. In these cases, there may be a lesion present directly behind the root, which is blocked from view by the widening of the mesial buccal root as it approaches the cervical portion of the tooth. An example would be the mesial buccal root of a maxillary first molar with a small palatally located second canal orifice well below the mesial buccal apex. Clinically, the only finding may be tenderness to percussion that is different on the mesial buccal root than on the other roots. Some cases may exhibit localized tenderness to palpation over the root as well. In these cases, it is reasonable to consider either nonsurgical or surgical revision of this root, the choice depending on the other circumstances surrounding the case.^20,62

A second common way in which infected/inflamed pulpal tissue in untreated canals causes a symptomatic clinical problem is the onset of acute thermal sensitivity.⁵⁷ Symptoms will be typical of acute or chronic pulpitis, and thermal stimulation will cause lasting pain. Episodes of spontaneous pain are also typical, but there are seldom any radiographic signs. The diagnostic challenge is to determine which tooth is causing the symptoms. It should not be assumed that a multirooted tooth should be eliminated from consideration because it has had root canal treatment. Thermal sensibility tests should be conducted on all teeth in the area, including the root-treated tooth.⁵⁷ Since the onset of an abnormal reaction to thermal stimulation may be delayed in cases of untreated canals, it is wise to test one tooth and pause before continuing to the next tooth. If tests are conducted too rapidly, it may be difficult to identify which tooth is the cause of a delayed response.

In the evaluation of recurrent pathosis on root-treated teeth, it is important to consider an untreated canal in any tooth that anatomically could have one. These generally are present in a buccal-lingual dimension, as discussed earlier with the maxillary first molar.⁴ Mandibular molars commonly have two distal canals and occasionally two distal roots (Figs. 5-7 and 5-8). Mandibular incisors and all premolars may also have two canals or sometimes even three canals (Figs. 5-9 through 5-11).

FIGURE 5-7 A, Previously treated mandibular right first molar with an apical lesion on the distal apex. An untreated second canal in the distal root was the suspected etiology. B, Postrevision radiograph indicating treatment of two distal canals.

FIGURE 5-8 A, Mandibular left second molar with a lesion caused by failure to treat a second distal root. The endodontic treatment present in the other three canals was judged to be adequate. B, Post revision radiograph.

FIGURE 5-9 Mandibular right lateral incisor with two canals.

FIGURE 5-10 Mandibular first premolar with two canals.

FIGURE 5-11 A, Root treated maxillary first premolar with an apical lesion. B, Postrevision radiograph indicating treatment of a third canal that was the cause of continuing pathosis.

(Courtesy Dr. Ryan Wynne.)

A second concept of incomplete root canal treatment may be identified as any treatment falling far below the standard of care with respect to obturation as evaluated on a good periapical radiograph. Cleaning and shaping are undoubtedly included as a cause of failure, but inadequacy of obturation is most obvious upon radiographic examination (Fig. 5-12). Root canal procedures completed with such disregard for traditional and proven concepts of cleaning, shaping, disinfecting, and sealing are doomed to failure.

FIGURE 5-12 A, Maxillary central incisor with inadequate root canal treatment. B, Mandibular first molar with inadequate root canal treatment and continuing periapical pathosis.

CLINICAL PROBLEM

Problem

A 42-year-old patient had a maxillary second molar with only one large canal (Fig. 5-13). The original root treatment was incomplete and led to failure. In addition, there was significant loss of periodontal attachment on the tooth that resulted in increased mobility. The resultant lesion was large, and the prognosis for revision was doubtful.

FIGURE 5-13 A, Maxillary left second molar with inadequate root canal treatment. Patient was seen for an acute apical abscess. B, Reexamination image at 28 months indicates complete restoration of normal osseous anatomy around the apex.

Solution

Following removal of the original gutta-percha filling material, copious purulent drainage was observed. The canal was cleaned, and a calcium hydroxide intracanal dressing was placed. Fortunately all symptoms resolved quickly. After 1 month, sulcular probing depths had returned to normal, mobility had disappeared, and there was no drainage from the canal upon reentry. The revision was completed and a 31-month reexamination indicated complete regeneration of bone in the previous periapical radiolucency (see Fig. 5-13, B).

Alternative Diagnoses Often Confused With Treatment Failure

If the possibility of incomplete root canal treatment has been eliminated from the differential diagnosis, alternative diagnoses should be considered. These entities have clinical and radiographic features that mimic those of root treatment failure but in reality are unrelated. The two categories are lesions associated with root fracture and lesions associated with chronic periodontal pathosis.

Chapter 4 provides a broader and more detailed discussion of root fractures, but it is appropriate to review those aspects of lesions associated with fractures that might be confused with failure of root canal treatment. Vertical fractures of the root are almost always associated with root-treated teeth, although some can be seen in other circumstances. The typical lesion associated with a root fracture is a narrow periodontal defect which develops along the course of the fracture line. In many cases, it will resemble a halo or J and is often referred to as a J-shaped lesion (Fig. 5-14).⁵³ The periodontal probe will be of great value in the discovery and diagnosis of these lesions. If the fracture line extends through the sulcus, the clinical manifestation will be a narrow, deep periodontal pocket usually found on the midfacial or midlingual/palatal surface of the root (Fig. 5-15, A to C). In some cases, if the fracture extends completely through the root, defects will be found on both the buccal and lingual surfaces.

FIGURE 5-14 A, J-type radiographic lesion (dashed line) associated with vertical root fracture.

FIGURE 5-15 A, Normal probing depth found to the mesial of midlabial. B, Normal probing depth found to the distal of midlabial. C, Probing to the apex in the midlabial position.

It is common to find chronic sinus drainage tracts associated with these lesions; oftentimes two tracts will appear.^49,52 The buccal and lingual locations of these fractures and superimposition of the narrow defect over the root itself seldom offer any radiographic evidence of the fracture itself. Infrequently, in cases of complete fracture through the root, the fractured segments may separate, and the fracture line may become visible (Fig. 5-16). Other than exploratory surgery, periodontal probings are often the only means by which root fracture can be differentiated from a developing periapical lesion of pulpal origin.

FIGURE 5-16 Vertical root fracture line visible in the distal root of a mandibular molar.

Clinical and radiographic changes that typify vertical fractures often take time. Tenderness to percussion or continuous low-grade pain may begin at the time the fracture occurs, but development of a periodontal defect that can be probed may not occur for weeks or months. Radiographic changes will not occur until there has been a sufficiently wide zone of bone resorption along the fracture line. The patient in Fig. 5-17 presented with a toothache in the mandibular left first molar and was referred to the endodontist with the presumptive diagnosis of root canal treatment failure (see Fig. 5-17, A). The patient elected to postpone the endodontic examination. One month later, the patient was seen on an emergency basis, having developed an acute infection. A second periapical radiograph documents significant loss of bone around the distal root (see Fig. 5-17, B). The lateral location of the bone loss is an important distinction from lesions that develop with the failure of root canal treatment, which tend to involve the periapical tissues. Nevertheless, occasional lesions associated with vertical fracture can be difficult to diagnose radiographically (Fig. 5-18). A detailed analysis of the radiographic interpretation of these lesions is found in Chapter 3.

FIGURE 5-17 A, Mandibular left first molar referred with provisional diagnosis of “endodontic failure.” B, One month later, new radiograph displays bone loss consistent with vertical root fracture.

FIGURE 5-18 Maxillary central incisor with apparent apical lesion. Note vertical fracture line visible in apical third. Lesion was found to probe as a sinus tract–type probing in both midlabial and midpalatal positions. This probing pattern is consistent with a complete fracture through the root.

CLINICAL PROBLEM

Problem

The patient was a 63-year-old female with a recent history of local swelling and tenderness in buccal gingival tissues in the mandibular right molar area. The tooth was an abutment for a fixed bridge in place for many years. The radiograph indicated that the tooth had had root canal treatment. There was also a widening of the periodontal ligament space around the distal root (Fig. 5-19, A).

FIGURE 5-19 A, Mandibular second molar with history of recurrent local swelling. Tentative diagnosis was “endodontic failure.” Normal probings were found around mesial half of root. B, Probing to the apex on the buccal of the distal root. C, Probing to the apex on the lingual of the distal root that completes a probing pattern consistent with a vertical fracture extending completely through the distal root from buccal to lingual.

Solution

Periodontal probings were made in 1-mm increments circumferentially around the tooth. A normal sulcus depth of 3 mm was found circumferentially on the mesial half of the tooth. Deep narrow periodontal defects on both the buccal and lingual aspects of the distal root indicated a through and through vertical fracture (see Fig. 5-19, B and C). A joint decision made between the patient and clinician was to reflect the buccal soft tissue and examine the bone and root. This diagnostic surgical procedure confirmed the presence of a vertical root fracture. The crown was />

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