Treatment Options

After initial root canal therapy, unsatisfactory short-term and long-term outcomes are primarily due to three causes: (1) nonhealing, (2) recurrence of endodontic disease, and (3) development of new disease and complications.

With nonhealing, a tooth with endodontic disease continues to have a problem after initial endodontic therapy. This may result from many factors, which are described in more detail throughout this chapter.

Recurrence of endodontic disease is found when healing occurs from the initial treatment, but bacteria subsequently regain entrance to the root canal system and reinfect the tooth. The tooth initially is comfortable, with no signs of disease, but later the patient may complain of symptoms. Both radiographic and clinical evidence of new endodontic concerns also may be seen.

With the third main cause, namely development of a new problem after initial successful treatment of a tooth, complications arise that are not directly related to the root canal treatment. An example of such a situation is an endodontically treated tooth that develops a vertical root fracture (VRF). These fractures typically occur sometime after initial root canal treatment and may be recognized as lateral lesions instead of the usual apical lesions associated with root canal infections ( Fig. 20.2 ). A VRF can occasionally be traced using a periodontal probe if the fracture extends coronally to the crestal bone. Although single-rooted teeth that develop VRFs usually need to be extracted, the failure in this case is not directly related to the root canal treatment. A similar situation is the endodontically treated tooth that may need to be extracted for periodontal reasons; the reason for extraction is unrelated to the endodontic procedure. Other endodontic surgical procedures may be used to salvage portions of multirooted teeth that are not affected by the VRF.

A, Vertical root fractures occur mostly in endodontically treated teeth and typically originate from the apical end and progress toward the crown. They run mostly in a faciolingual direction, in contrast to infractions, which run mesiodistally. The radiograph shows a vertical root fracture (arrow). B, The extracted tooth also shows the presence of the fracture.

(© Dr. Robert Handysides. All rights reserved.)

When initial root canal treatment fails to promote healing, the treatment options to save the tooth include nonsurgical retreatment with or without apical surgery, apical surgery, intentional replantation, and extraction. If the tooth is restorable, nonsurgical retreatment is usually the preferred treatment strategy. This option may allow an opportunity to better disinfect the root canal system or to address areas of reinfection due to bacterial leakage associated with poor coronal restorations. Because orthograde endodontic retreatment may not allow access to all areas of canal infection, or if extraradicular infection is present, apical surgery may be a required part of the retreatment.

Surgical treatment may be considered a first choice in the presence of canal obstructions or extensive fixed prosthetic appliances or when removal of extruded filling materials is indicated. However, surgical endodontic treatment may not eliminate surviving microorganisms in inaccessible areas of the root canal system. Even when surgical treatment is required, nonsurgical retreatment prior to surgical treatment has been shown to improve healing and to help achieve a successful outcome.

Intentional replantation of teeth is a treatment option that has a long history in dentistry. When properly planned and executed, intentional replantation has been shown to be quite successful in providing patients with additional years of service from their teeth. This procedure can be considered for teeth that are not badly broken down but in which the initial root canal treatment has not allowed access to all of the root canal system, and apical surgery is complicated by anatomic difficulties. It also allows an opportunity to examine the roots of teeth for possible vertical fracture lines.

Retreatment procedures are usually more difficult to perform than those used in the initial treatment. They frequently require advanced instrumentation, magnification systems, and special training. Endodontists have extensive training and practice in evaluating and managing teeth with apparent lack of healing after initial root canal therapy and teeth developing new lesions. Much of this chapter discusses procedures performed by specialists. This discussion is intended to provide information on the techniques used by someone trained in such procedures. The emphasis in this chapter is on recognizing nonhealing and the recurrence of endodontic disease and on developing an understanding of what can be achieved.

Indications for Nonsurgical Endodontic Retreatment

The following describes a typical situation of a nonhealing initial root canal treatment based on a diagnosis of pulp necrosis and symptomatic apical periodontitis. The patient complains that the symptoms have not improved since the time of initial treatment and that the discomfort has in fact increased. Chewing and biting are painful, but the pain may also occur spontaneously. Radiographic examination reveals an emerging apical radiolucency not present at the time of initial treatment.

Clinical examination of teeth with nonhealing endodontic disease may reveal palpation and percussion sensitivity, localized swelling, recurrent caries, leaky provisional restorations, and substandard or missing coronal restorations. Radiographic evaluation may show the presence of untreated canals, poor canal obturation with voids, separated instruments, recurrent caries not located during the clinical examination, or defective restorations with open margins. All such findings can contribute to nonhealing associated with the previous treatment. Any combination of clinical symptoms and radiographic and clinical findings may indicate nonhealing. Nonhealing can also be present without any contribution from the aforementioned conditions.

Retreatment is considered the primary treatment option when the tooth is found to be periodontally stable; there is adequate remaining tooth structure with no detectable vertical fractures; and access to the root canal system is feasible. After disassembly of any defective restorations and post and core materials and the removal of all caries, tooth restorability must be determined. This initial assessment includes periodontal probing, mobility tests, and periapical and bitewing radiographs to determine the crown to root ratio, presence of supporting bone, health of the soft tissue, and need for crown lengthening procedures.

It is important for the chairside staff to be familiar with retreatment procedures so that endodontic care can be delivered in a professional and effective manner. The office must be equipped with the necessary illumination and magnification systems, ultrasonic units and appropriate tips, rotary handpieces, endodontic files, solvents, dental dams, various post extraction kits, and irrigation systems. The clinician must have high levels of skill, experience, and training to execute retreatment in an effective manner. Because these cases are commonly complex and challenging, the best interest of the patient should be considered when the decision is made to offer treatment or to recommend referral to a specialist.

Contraindications to Nonsurgical Endodontic Retreatment

A major factor when nonsurgical retreatment is considered is the restorability of the tooth after the necessary removal of preexisting restorative materials. Additional tooth structure may be lost during caries removal and removal of post and core materials. Lack of adequate tooth structure to support a postendodontic restoration is a contraindication to nonsurgical retreatment. The restorability decision often requires extensive disassembly of existing restorations and evaluation of the remaining root canal system. Other contraindications include the presence of extensive periodontal involvement of the tooth that weakens the tooth support and/or the presence of problematic coronal or radicular fractures.

Indications for Surgical Retreatment

Further contraindications to nonsurgical root canal retreatment include intracanal complications. For instance, access to the canals may not be possible due to the presence of obstructions. These obstructions include large, tight-fitting, prefabricated or cast posts and cores, root canal calcifications, and other obstructions that may prevent access. In such situations, surgical retreatment may offer the best available option. Examples of possible root canal obstructions are the presence of separated instruments that cannot be bypassed or retrieved, filling materials that cannot be adequately removed, and teeth that after orthograde retreatment exhibit nonresponding periapical lesions. Teeth with iatrogenic mishaps that cannot be adequately addressed, such as nonnegotiable ledges, transportation of the canal or apex, or perforations that cannot be repaired internally, also may be candidates for a surgical approach.

Teeth with external root resorption associated with a history of trauma and infected pulp tissue that were inadequately treated previously may be retreated in an orthograde approach. Surgical repair of resorptive areas on the external aspects of the roots is usually not indicated.

Extraction usually is indicated for teeth diagnosed with a VRF. An exception may be a multirooted maxillary molar that develops a VRF in one of the roots. Because replacement with a dental implant may be difficult due to the type or absence of alveolar bone, surgical amputation of the root with a VRF can provide a tooth that may serve satisfactorily for many years. Each clinical situation is unique to the patient with the endodontic problem, and treatment options must be evaluated by carefully taking into account all aspects of the patient’s situation.

Risks and Benefits of Retreatment

The patient must be informed of the risks, benefits, alternatives, and consequences of the various treatment modalities prior to initiation of treatment. The discussion with the patient must include the importance of good oral hygiene and regular evaluation of the teeth. Because retreatment is often time-consuming, the cost of treatment must be explained.

Nonsurgical root canal retreatment procedures have many potential risks. These include fracture of a porcelain crown during the access procedure, fracture of the root during post removal procedures, iatrogenic perforations during core and obturation material removal, and dislodgement of the crown that may necessitate replacement. In addition, retreatment procedures may cause extensive removal of tooth structure that may further weaken the tooth, create ledges, or cause canal transportation. The separation of an instrument may impede the ability to completely remove obturation materials also. All of these complications may affect the retreatment outcome and potentially lead to necessary extraction. The benefits of retreatment include the preservation and retention of the patient’s natural tooth structure and the avoidance of more extensive clinical treatment.

Endodontic Retreatment Procedures