Endodontic procedures often are provided for teeth that have pulpal or periapical disease during the acute phase of care because the patient is experiencing pain or swelling. During the definitive phase, however, the fol- lowing situations may suggest endodontic therapy even in the absence of symptoms:
• Apical pathology associated with a necrotic pulp represents a prime indication for root canal therapy. The patient and the dentist may not detect such a problem until the tooth darkens in appearance or distinctive signs are visible on periapical
radiographs.
• Teeth that have deep or large restorations, or that have had direct or indirect pulp capping may benefit by receiving endodontic therapy before extensive restoration with a crown or service as an abutment for a fixed or partial denture. Similarly the tooth that is severely broken down may benefit from endodontic therapy and subsequent restoration with a foundation or post and core to restore missing coronal tooth structure and retain the final restoration.
• Elective endodontics should be considered for teeth that will be devitalized in the process of overdenture construction or for those hypererupted teeth in which the pulp is likely to be devitalized in the process of altering the occlusal plane.
• Re-treatment of a previously endodontically treated tooth may be necessary when signs of failure appear, usually detected radiographically (see the In Clinical
Practice box).
In Clinical Practice
When Is Endodontic Re-Treatment Necessary? diminishing success rates with additional treatment, but the expectation of a positive outcome is still reasonably good, and generally warrants the recommendation. Obviously there are exceptions, such as vertical root fractures, severely debilitated systemic health (ASA IV), or patient unwillingness to undergo the treatment. In these cases, extraction may be the best and only alternative.
A greater treatment planning challenge arises when ra- diographic evidence shows that apical inflammation and chronic infection persist even in the absence of symptoms. Usually unaware of any problem, the patient may be reluctant to agree to re-treatment in the absence of symp- toms. Should this choice be left up to the patient? The best response is “sometimes.” If the patient has an immunocom- promising condition or is in otherwise debilitated health (ASA III or IV), it would not be prudent to allow the infec- tion to continue even if currently dormant. If an indirect restoration (onlay or crown) is planned for the tooth, the failed root canal treatment should be replaced and, ideally, the apical lesion resolved before the final restoration is attempted. On the other hand, if the patient is healthy, the tooth does not require extensive restoration, and the patient is fully cognizant of the possible consequences of no treat- ment, it is often appropriate to leave the treatment versus no treatment decision up to the patient. In any case, it remains the dentist’s responsibility to reevaluate the lesion at speci- fied intervals and to confirm that it is resolving (as in the case of a re-treatment) or at least not worsening. It is the patient’s responsibility to bring to the dentist’s attention any new symptoms or changes.
Patients may present with teeth that have had root canal therapy that appears problematic. Most commonly, the first signs are detected radiographically, for example, endodonti- cally treated teeth that have been filled with pastes or silver points or conventionally filled root canal treatments that are short or inadequately condensed. If these teeth are sympto- matic or if active infection is present, re-treatment is advis- able. In the absence of symptoms or active infection, however, it may be appropriate to include the “no treatment” alterna- tive when describing options to the patient.
Decision-Making Parameters
Has the previously treated tooth been symptomatic? Are there clinical or radiographic signs of ongoing or recur-
rent infection (fistula, apical periodontitis, or rarefying osteitis)?
Does the patient have a systemic health condition that could result in significant health risk if the root canal problem (infection) is left untreated?
What problems might arise if the tooth is left untreated? Will the tooth be an abutment for a fixed or removable
prosthesis?
What is the patient’s attitude toward dental treatment? Reaching a Decision
If the patient has an endodontically treated tooth that devel- ops new signs or symptoms consistent with failure of the earlier treatment, then it is logical for the dentist to recom- mend re-treatment. The patient must be informed of the
Procedures for Treating Nonacute Endodontic Problems
Root Canal Therapy Root canal therapy can permit a patient to retain a tooth with pulpal problems when the only other option might be extraction. The procedure is indicated as a treatment option when irreversible pulpi- tis, pulpal necrosis, apical periodontitis, or acute apical abscess is diagnosed. The technique involves removing pulpal tissue; cleaning and shaping the root canals; and filling the canals with a thermoplastic material, usually gutta-percha or an acid-etched resin material.
Apical Surgery Apical surgery involves laying a gin- gival flap and removing a portion of the root and associ- ated soft tissue, then sealing the root canal or canals, usually with amalgam or a glass-ionomer cement, at the tooth apex level (Figure 8-21).
This procedure may be necessary when conventional root canal therapy has been unsuccessful, or when calci- fication, an irretrievable cemented post, or other restora- tive material blocks access to the root canal system through to the crown of the tooth.
Keys to Decision Making
Professional Modifiers Before proceeding with endodontic therapy, the dentist must first assess the clin- ical significance of the involved tooth in relation to the other teeth and to the overall treatment plan. Although an important goal of dentistry is to help patients retain teeth, it may not be in the patient’s best interest to spend time and money on endodontic therapy. An extreme example is a patient with one remaining tooth in an arch. Although endodontic therapy may save the tooth, its soli- tary position in the arch makes extraction the simplest and preferred treatment. A more common example is the
patient whose third molars require root canal therapy. The position of these teeth in the arch and their often complex canal anatomy make them difficult to treat with root canal therapy. Again, extraction may be the best alternative.
After establishing the value of retaining the tooth, the dentist’s next concern is whether the tooth can be restored. Endodontically treated teeth are often inher- ently fragile as a result of the loss of tooth structure to caries, large restorations, cuspal fractures, and even the root canal therapy itself. A full coverage restoration, such as a crown, is often needed to restore the tooth to func- tion. Not all severely broken down teeth can be restored and, before beginning endodontic therapy, the dentist must be sure that an acceptable restoration is possible.
The restorative prognosis depends on the degree of tooth loss, especially near the level of the alveolar bone. When questions about restorability or periodontal prog- nosis arise or when placement of the restoration margin relative to the bone crest is uncertain, a bite-wing ra- diograph should be made before beginning root canal therapy. If the radiograph demonstrates caries extending below the alveolar crest, chances are poor that sound tooth structure is sufficient to provide a good marginal seal for the final restoration (Figure 8-22). The peri- odontal health of the tooth may also be compromised in this situation. Although removing bone (crown length- ening) may be an option, the tooth may, because of the diminished bone support, have a guarded or questionable long-term prognosis.
Posterior teeth with carious involvement into the fur- cation areas have a very poor prognosis in terms of restor- ability. In questionable cases, it may be necessary to first remove extensive caries to determine restorability. A
Figure 8-21 Apical surgery. (Courtesy Dr. A. Sigurdsson, Chapel Hill, NC.)
Figure 8-22 The bite-wing radiograph is a helpful adjunct to estab- lish the relationship of a proximal carious lesion to the bone crest, as with this lower first molar, because it helps to assess the need for a crown lengthening procedure and it helps determine the restorative prognosis for the tooth. (Courtesy Dr. J. Ludlow, Chapel Hill, NC.)
tooth with a crown:root ratio of less than 1:1, as a result of caries or periodontal bone loss, constitutes a poor can- didate for endodontic therapy. The prognosis may also be poor if dilacerations of roots, calcified canals, or poor access for treatment (e.g., third molars) compromise endodontic treatment.
Ideally the final restoration should promptly follow completion of endodontic therapy. For patients who have significant caries or periodontal disease control needs, however, several months may elapse between the start of endodontic treatment and the final definitive restoration. In these situations, it is critical to protect the tooth by: • reducing the occlusion and placing a temporary
restoration.
• advising the patient to be cautious when eating and to avoid excess forces on the tooth.
• examining the tooth at regular intervals for signs that the restoration is leaking or the tooth is breaking down.
Patient Modifiers The endodontic prognosis, final restoration plan, and anticipated fees must be presented to the patient before beginning endodontic treatment. For some patients, the added cost of the procedures required to restore the tooth to function—such as crown lengthen- ing, a post and core, and a crown—may make the expense of the root canal treatment prohibitive. The patient may instead choose to have the tooth extracted. For medical- legal reasons, the dentist should document in the patient’s record that all treatment options, including endodontic therapy, have been discussed before moving to extraction. Some patients may choose to have root canal therapy to retain a tooth, but then delay the final restorative treatment because of cost considerations. Providing care in such a manner may worsen the prognosis for severely broken down teeth, leaving them more susceptible to fracture and endodontic treatment failure. Patients should be informed of this risk, and the conversation should be documented in the record.