Key points

Preoperative planning

Although endodontic care typically is successful, in approximately 10% to 15% of cases, symptoms can persist or spontaneously reoccur. It is known that many endodontic failures are due to the failure to place an adequate coronal seal. Therefore, there is the competing interest of observing the tooth after endodontic treatment to ascertain successful treatment versus placing a definitive restoration with an adequate coronal seal. Many endodontic failures occur a year or more after the initial root canal treatment, often creating a situation where a definitive restoration already has been placed. This creates a higher value for the tooth because it now may be supporting a fixed partial denture. A decision then is needed to determine if orthograde endodontic retreatment can be accomplished, should periapical surgery be recommended or consideration of extraction of the tooth with loss of the overlying prosthesis.

Causes of endodontic failures often can be separated into biologic issues, such as a persistent infection, or technical factors, such as a broken instrument in the root canal system ( Fig. 1 ), transportation of the apex, perforation, and ledging of the canal. Failure of endodontic treatment is due most commonly to lack of an adequate coronal seal with the presence of bacteria within the root canal system and apical leakage. Continued infection also may result from debris displaced out the apex during the initial endodontic treatment. Technical factors alone are a less common indication for surgery, comprising only 3% of the total cases referred for surgery, yet it is this author’s opinion that there is a higher success rate in these cases.

Two examples of technical factors requiring apical surgery. Although less frequent in occurrence, the success rate usually is high because the canal system likely is well obturated. ( A ) Overfill of gutta percha causing symptoms, including chronic sinusitis. ( B ) Broken endodontic instrument in apical third with pain and drainage.

( From Lieblich SE. Current concepts of periapical surgery. Oral Maxillofac Surg Clin North Am. 2015;27(3):384; with permission.)

Prior to surgery, discussions with patients are critical in order for a patient to give appropriate informed consent. The particular risks of surgery based on the anatomic location (sinus involvement or proximity to the inferior alveolar nerve) need to be reviewed and documented. It is important to stress the exploratory nature of periapical surgery to the patient. Depending on the findings at surgery, a limited root resection with retrograde restoration may be placed. The patient and surgeon, however, also must be prepared to treat fractures of the root and/or the entire tooth. Plans must be made preoperatively on how such situations will be handled should they be noted intraoperatively.

Diagnostic tools, such as a focused periodontal examination of the tooth in question, are necessary to determine if a tooth is worth saving via the apical surgery procedure. Poor prognostic factors, such as significant loss of attachment and mobility, likely would drive a recommendation to extraction with implant placement. Consideration for a localized cone beam radiology examination of the involved area also may provide preoperative evidence of a fracture, which would reduce the likelihood of successful outcomes of the surgery.

Surgical endodontics success rates have dramatically improved over the years with the developments of newer retrofilling materials and the use of the ultrasonic preparation. Previously cited success rates of 60% to 70% now have increased to more than 90% in many studies, due to the routine use of ultrasonic retrograde preparation and the use of mineral trioxide aggregate as a filling material. This significant improvement makes apical surgery a more predictable and valuable adjunct in the treatment of symptomatic teeth. Most significantly, studies show that once the periapical bony defect is considered healed (reformation of the lamina dura or cases of healing by scar), the long-term prognosis is excellent. They reported 91.5% of healed cases still successful after a follow-up period of 5 years to 7 years. Therefore, with adequate radiographic follow-up, a surgeon should be able to predict the long-term viability of the tooth and its usefulness to retain a prosthetic restoration.

There is some controversy in the endodontic literature that the use of magnification may improve outcomes in surgical management of endodontic failures. In a 2-part article by Setzer and colleagues, ^, a meta-analysis was reviewed on this subject of endodontic surgery. In part 1 (2010), they compared outcomes with traditional root end preparation with a rotary bur and amalgam filling versus more contemporary surgery with ultrasonic preparation and improved root end filling materials (Super-EBA [Alumina reinforced intermediary restorative material, Bosworth Company, Warwichshire, England] and MTA [Mineral trioxide aggregate ProRoot MTA Dentsply Sirona,Charlotte, North Carolina]). With the more contemporary surgery techniques, the outcomes improved from 59% to 94%. They then divided the literature into 2 groups in 2012: those using no magnification or loupes up to 10×, and those using the operating microscope or an endoscope with magnification greater than 10×. The nonmagnification group had a cumulative success rate of 88% whereas the group with use of magnification had a pooled success rate of 93%. No difference in success was noted for treatment of anterior teeth or premolars with or without magnification but there was some improved success for molars (98% vs 90%, respectively).

The primary option for the treatment of symptomatic endodontically treated teeth is that of conventional retreatment versus the surgical approach. An algorithm for a decision regarding retreatment versus surgery versus extraction is presented in Fig. 2 . In discussions with patients, the option of conventional retreatment should be discussed. Clinical studies, however, have not shown retreatment to be more successful than surgery and 1 prospective study found surgical treatment to have a higher success rate. Another study found a higher success rate with surgery from 2 years to 4 years (77.8% vs 70.9%, respectively), but from 4 years to 6 years it reversed to a success rate of 71.8% with surgery and 83% with conventional retreatment. Although endodontic retreatment seems more conservative, the removal of posts, reinstrumentation of the tooth, and removal of tooth structure increase the chance of fracture. Surgical treatment of failures also provides the opportunity to retrieve tissue for histologic examination to rule out a noninfectious cause of a lesion ( Fig. 3 ).

Algorithm for apical surgery. Prep, preparation; RCT, root canal treatment.

( Adapted from Lieblich SE. Periapical surgery: clinical decision making. Oral Maxillofac Surg Clin North Am. 2002;14(2):181; with permission.)

Atypical radiolucency along the lateral aspect of the root and not truly involving the apex. Although correctly treated at the time of referral due to the nonresolving radiolucency with periapical surgery, the suspicious nature of the lesion warranted submission of the tissue for histologic examination. Confirmation with the original treating dentist revealed the indication for the endodontic treatment was solely the incidental finding of a radiolucency and vital pulp tissue was noted. The final pathology was a cystic ameloblastoma. ( A ) preoperative radiograph, note lateral radiolucency not associated with the apex. ( B ) post surgery shows good apical seal but residual lateral pathology.

( From Lieblich SE. Current concepts of periapical surgery. Oral Maxillofac Surg Clin North Am. 2015;27(3):386; with permission.)

The option of extraction with either immediate or delayed implant placement also must be discussed as an alternative to periapical surgery. There is no debate in dentistry that implants can outlast tooth supported restorations. It is valuable, therefore, to have data to predict the expected success of the endodontic surgery so that patients can use them in their decision-making process. Factors that improve success are noted in Box 1 . In cases of an expected poorer success rate, such as the presence of severe periodontal bone loss (especially the presence of furcation involvement), the decision to extract the tooth and place an implant may be a more efficacious and clinically predictable procedure.

There is a body of literature that supports the duration of restorations fabricated on endodontically treated teeth. Blomlof and Jansson found surgically treated molars with healthy periodontal status had a 10-year survival rate of 89% and Basten and colleagues reported a 92% 12-year rate. The factors most associated with failures are long posts in teeth with little remaining coronal structure. Thus, the condemnation of a tooth because it can be replaced with an implant is not that clear.

An economic analysis may be indicated in order to guide a patient’s decision. If the tooth has a final prosthetic restoration already in place, it usually is easier to recommend surgical intervention. If the symptoms do not resolve, patients have only expended additional time, operative risk, and expense of the surgical portion of their care because they already have a definitive restoration. The surgeon should review the factors in Box 1 to help predict the likelihood of the surgical intervention being successful. If a tooth has multiple factors that indicate the success of the surgical intervention would be compromised and/or a tooth has a poor expectation for 10-year survival, then extraction with implant placement is a more efficacious means of care.

The surgeon may be called on to treat teeth that cannot be negotiated for conventional orthograde endodontics. The treatment of teeth with calcified canals may be managed appropriately with apical surgery alone with a retrograde filling if the tooth is critical to a restorative treatment plan. Danin showed at least a 50% rate of complete radiographic healing and only 1 failure in 10 cases over a 1-year observation period in cases treated surgically only and without endodontic treatment. Bacteria still remained in the canals of the tooth in 90% of these cases, which may lead to a later failure.

Determination of success

More complicated decisions are involved with teeth that have not been definitively restored. In that situation, the surgeon not only has to consider the preoperative potential for the apical surgery to be successful but also often must determine when a case is deemed successful and can proceed to the final restoration. Once a final restoration is placed, considerably more time and expense have been invested and subsequent failure is more troublesome to the patient.

Rud and colleagues retrospectively reviewed radiographs after apical surgery to determine radiographic signs of success. Their work showed that with a retrospective review of cases over at least 4 years postsurgery, once radiographic evidence of bone fill occurs, noted as successful healing in their classification scheme, that tooth was stable throughout the remainder of their study period (up to 15 years). A waiting period of more than 4 years is not acceptable in contemporary practice, but their classification scheme has been validated over shorter observation times. They found that if radiographic evidence of bone fill of the surgical defect is noted, then the tooth remained a radiographic success over their observation periods. Many of the partially healing cases, noted as “incomplete healing” in their study, tended to move into the complete healing group during the 2 years after surgery, with little change throughout the next 4 years of observation.

An appropriate follow-up protocol is to obtain a repeat periapical film 3 months after surgery with critical comparison with the immediate postoperative film. If significant bone fill has occurred, mobility has decreased, pain is resolved, and no fistula is present, the case can proceed to the final restoration. If significant bone fill has not been noted, however, the patient should be recalled again at 3 months for a new film. Rubinstein and Kim found complete healing in 25.3% of cases in 3 months, 34% in 6 months, 15.4% in 9 months, and 25.3% by 12 months. Small bony defects healed faster than large bony defects, which showed significant differences in their prospective study. In contrast, any increase in the size of the radiolucency or no improvement should caution a dentist about making a final restoration. If the situation is not clear at that time (6 months postsurgically), a temporary restoration, loaded for a least 3 months, often is a good litmus test of the success of the surgery and predictive as to whether the final restoration will last for some time.

The cracked or fractured tooth

Preoperative radiographs and a careful clinical examination should be done with a high index of suspicion of a vertical root fracture (VRF) prior to undertaking surgery. Mandibular molars and maxillary premolars are the teeth that most frequently present with occult VRFs. Although surgical exploration may be needed to definitively show the presence of a fracture ( Fig. 4 ), subtle radiographic signs may alert the surgeon that a fracture is present and the surgery is unlikely to be successful. Tamse and colleagues looked at radiographs of maxillary premolars for comparison with the clinical findings at the time of surgery. Few (1 of 15) teeth with an isolated, well corticated periapical lesion had a VRF. In contrast, a halo-type radiolucency almost always was associated with a VRF ( Fig. 5 ). This type of radiolucency also is known as a J type, where a widened periodontal ligament space connects with the periapical lesion creating the J pattern.

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