Principles of Endodontic Surgery

Anatomic Problems

Calcifications or other blockages, severe root curvatures, or constricted canals (e.g., calcific metamorphosis) may compromise root canal treatment (e.g., prevent instrumentation, obturation, or both) ( Fig. 18.4 ). A nonobturated and cleaned canal may lead to failure because of continued apical leakage.

Although the outcome may be questionable, it is preferable to attempt conventional root canal treatment or retreatment before apical surgery. If this is not possible, removing or resecting the uninstrumented and unfilled portion of the root and placing a root end filling may be necessary.

Restorative Considerations

Root canal retreatment may be risky because of problems that may occur from attempting access through a restoration such as a crown on a mandibular incisor. An opening could compromise retention of the restoration or perforate the root. Rather than attempt the root canal retreatment, root resection and root end filling may successfully eliminate the symptoms associated with the tooth.

A common indication for surgery is failed treatment on a tooth that has been restored with a post and core ( Fig. 18.5 ). Many posts are difficult to remove or may cause root fracture if an attempt at removal is made to retreat the tooth.

Horizontal Root Fracture

Occasionally, after a traumatic root fracture, the apical segment undergoes pulpal necrosis. Because pulpal necrosis cannot be predictably treated from a coronal approach, the apical segment is removed surgically after root canal treatment of the coronal portion ( Fig. 18.6 ).

Irretrievable Material in the Canal

Canals are occasionally blocked by objects such as broken instruments ( Fig. 18.7 ), restorative materials, segments of posts, or other foreign objects. If evidence of apical pathosis is found, those materials can be removed surgically, usually with a portion of the root ( Fig. 18.8 ). A broken file can be left in the root canal system if the tooth remains asymptomatic and is not itself an indication for apical surgery.

Procedural Error

Broken instruments, ledging, gross overfills, and perforations may result in failure ( Figs. 18.9 and 18.10 ). Although overfilling is not itself an indication for removal of the material, surgical correction is beneficial in these situations if the tooth becomes symptomatic. Because the obturation of the canal is often dense in these situations, surgical treatment has an excellent prognosis.

Large, Unresolved Lesions After Root Canal Treatment

Occasionally, very large periradicular lesions may enlarge after adequate debridement and obturation. These lesions are generally best resolved with decompression and limited curettage to avoid damaging adjacent structures such as the mandibular nerve ( Fig. 18.11 ). The continued apical leakage is the nidus for this expanding lesion, and root resection with the placement of an apical seal often resolves the lesion.

Unidentified Cause of Treatment Failure

Relying on surgery to correct all root canal treatment failures could be labeled indiscriminate. An important consideration is to (1) identify the cause of failure and (2) design an appropriate corrective treatment plan. Orthograde retreatment is often indicated and offers the best chance of success. Surgery to correct a treatment failure for which the cause cannot be identified is often unsuccessful. Surgical management of all periapical pathosis, large periapical lesions, or both is often not necessary because they will resolve after appropriate root canal treatment. This includes lesions that may be cystic; these also usually heal after root canal treatment.

When Conventional Endodontic Treatment Is Possible

In most situations, orthograde conventional endodontic treatment is preferred ( Fig. 18.12 ). Surgery is not indicated simply because debridement and obturation are in the same visit, although there has been a long-held, incorrect notion that single-visit treatment should be accompanied by surgery, particularly if a periradicular lesion is present.

Simultaneous Root Canal Treatment and Apical Surgery

Few situations occur in which simultaneous root canal therapy and apical surgery are indicated. An approach that includes both of these as a single procedure typically has no advantages. It is preferable to perform only the conventional treatment without the adjunctive apical surgery because the surgery will not necessarily improve the outcome. In some patients the conventional root canal procedure is ineffective at eliminating symptoms. In this scenario, in spite of adequate instrumentation and antibiotics, purulent exudate from the tooth or a vestibular swelling is still present. A combined orthograde obturation with a simultaneous periapical surgery to curette the apical region and seal the tooth can be successfully coordinated and the symptoms resolved. The dentist can instrument and seal the tooth with the plan to see the surgeon that day for definitive periapical surgery. The endodontic filling material is densely condensed and can even be out the apex (to a reasonable degree, not impinging on local anatomic structures) if the surgeon will resect a small portion of the apical region and place a retrograde seal ( Fig. 18.13A–C ).

Anatomic Considerations

Although most oral structures do not interfere with a surgical approach, they must be considered. Expertise in operating around a structure such as the maxillary sinus or the mental nerve region is imperative before undertaking surgery in these regions. Exposure of the maxillary sinus, which occurs in most molar apical surgeries, is itself not a complication but a known consequence of the surgery ( Fig. 18.14 ). Creating a sinus opening is neither unusual nor dangerous. However, caution is necessary not to introduce foreign objects into the opening and to remind the patient not to exert pressure by forcibly blowing the nose until the surgical wound has healed (for 2 weeks). Correct flap design is also crucial to prevent the development of an oral-antral communication. The sulcular flap keeps the incision line far from the sinus opening, thus allowing spontaneous healing.

Surgical procedures around the mental foramen require caution to avoid stretch injury or direct damage to the nerve. In my opinion, exposure of the mental nerve is safer than attempting to estimate its position. Careful subperiosteal reflection of the flap with adequate release allows the surgeon to identify the nerve where it exits from bone. Once identified, staying a safe distance above, anteriorly, or both is crucial to preventing an injury. Important to note is that the nerve may have an anterior loop of 2 to 4 mm, so that distance should be accounted for anteriorly.

When molar apical surgery is performed, the midroot of the molar should be identified by slow removal of bone, which should be carried inferiorly ( Fig. 18.15A–C ). Once reaching the apical region, cautious curettage of the soft tissue lesion is carried out to avoid mechanical injury of the inferior alveolar nerve as it passes under the molar roots (see Fig. 18.15D–G ). As mentioned earlier, it is not necessary to remove the entire area of periapical granulation tissue or cyst, if present, because treating the apical lesion and sealing of the root canal with the retrograde filling cause the apical lesion to heal.

Poor Crown-Root Ratio

Teeth with very short roots have compromised bony support and are poor candidates for surgery; root end resection in such cases may compromise stability. However, shorter roots may support a relatively long crown if the surrounding cervical periodontium is healthy (see Fig. 18.6 ).

Medical (Systemic) Complications

The general health and condition of the patient are always essential considerations. Contraindications for endodontic surgery are similar to those for other types of oral surgery.

Antibiotics

Almost without exception, periapical surgery is performed in an area with mixed acute and chronic infection. Because of the nature of the surgery and the potential for the spread of infection into adjacent spaces, preoperative prophylactic administration of antibiotics should be considered. Risk for infection of the hematoma exists because of the amount of edema expected after the procedure. In addition, inadvertent opening of adjacent structures such as the maxillary sinus is expected to occur with molar surgeries. As discussed elsewhere in the text, the basics of antibiotic prophylaxis are that antibiotics are to be administered before surgery to have any protective benefit. The surgeon should consider a preoperative dose of penicillin V potassium (2 g) or clindamycin (600 mg) 1 hour before surgery. The need for postoperative dosing has not been clearly defined and may not be of benefit to the patient. Other adjuncts, such as the perioperative administration of corticosteroids, may reduce edema and speed recovery. However, the use of corticosteroids may increase the risk of infection, so prophylactic antibiotics may be necessary.

Flap Design

Surgical access is a compromise between the need for visibility of the surgical site and the potential damage to adjacent structures. A properly designed and carefully reflected flap results in good access and uncomplicated healing. The basic principles of flap design should be followed (see Chapter 3 ). Although several possibilities exist, the three most common incisions are (1) semilunar, (2) submarginal, and (3) full mucoperiosteal (i.e., sulcular). The submarginal and full mucoperiosteal incisions have either a three-corner (i.e., triangular) design or a four-corner (i.e., rectangular) design.

Semilunar Incision

Although the semilunar incision is a popular incision among practitioners, this type of incision should be avoided because of the limitations and potential complications. This is a slightly curved half-moon horizontal incision in the alveolar mucosa ( Fig. 18.16 ). Although the location allows straightforward reflection and quick access to the periradicular structures, it limits the clinician in providing full evaluation of the root surface. If a fracture is noted, performing a root resection through this incision or extracting the tooth is impractical. The incision is based primarily in the unattached or alveolar mucosa, which heals more slowly with a greater chance of dehiscence than a flap based primarily in attached or keratinized tissue. In addition, the flap design carries the flap over the inflamed surgical site, and this inflamed mucosa is at a high risk of breakdown. Other disadvantages to this incision include excessive hemorrhage, delayed healing, and scarring; therefore this design is contraindicated for most endodontic surgery.