Department of Endodontics, Nova Southeastern University College of Dental Medicine, Fort Lauderdale, FL, USA
Periradicular surgery is not always a necessary step toward endodontic success; it should never be used as a cure for a poor endodontic root canal technique. Surgery is an integral aspect of endodontic therapy when root canal therapy is not deemed sufficient to remove the infection. Surgery is often assumed to be the most radical procedure; however, sometimes the surgical procedure becomes a conservative effort to avoid further tissue injury and extraction of the tooth. The course of treatment would be better defined as surgical or nonsurgical. The surgical endodontic procedure must never be used as a cure-all or excuse for poor endodontic technique.
Surgery in Endodontic Practice
Unfortunately, surgery has been used in the past as a cure for an extensive periapical radiolucency . However, it has been demonstrated that a large periapical lesion will resolve as completely as a small one if the infection from the canal has been eliminated . The extent of the periapical injury should not be a factor in deciding to perform a surgical intervention. Surgery has been used to identify cysts , because it is not possible to identify them from a radiograph alone. The pathology of the cyst requires examination, and surgery alone cannot identify a cyst. After a root canal treatment has failed and there is a flare-up, surgery should only be considered, if the tooth cannot be retreated to remove the infection . Root canal retreatment in itself may be adequate to resolve the flare-up and save the tooth. A fractured instrument in the apical third of the canal is not a consideration for surgery. All that is needed is future radiographs to check that there is no lesion developing around the fragment of instrument. An accidental or carious root canal perforation was once considered to require immediate surgery for the resection of the root to the point of perforation . However, in many cases without surgery, packing the perforation repair material from within the root canal can solve the problem by restoring the tooth structure.
Resorption of the root canal apex was an indication for surgery to remove necrotic tissue; however, some clinical cases have demonstrated that periapical healing can arrest the resorptive process by nonsurgical root canal therapy . An incompletely developed apex was once assumed to require surgery; however, there are now improved regeneration techniques for saving immature teeth. The accidental extrusion of sealer and obturation core material into the periapical tissues is the only candidate for surgery if they cause a persistent periapical radiolucency, swelling, and pain . A horizontal fracture of the root apex may not require surgery, if the apical canal fragment contains vital tissue. Only if the apical tissue becomes necrotic, then it may be necessary to remove the apical fragment. By trial and error, it has become clear that surgery is not always in the best interests of saving a tooth if a nonsurgical treatment can suffice.
Types of Surgeries
Anatomical redesigning is needed as part of periodontal treatment, for root amputation, hemisection, and bicuspidization . It develops a periodontally maintainable environment for the remaining root or roots.
Apical resection is the removal of the root end of a tooth . This resection procedure is used when a portion of the unfilled root needs to be removed or as a step in the retrofill preparation.
Bicuspidization is the separation of a multirooted tooth by a vertical cut through the furcation .
Diagnostic surgery can be needed after radiographs and a thorough examination have failed to identify the etiology of a problem or pathosis . In these situations, a visual examination of the root by surgical exploration is necessary and may reveal a fracture, malformation, defect or anomaly, missed root canals which were not cleaned, inadequately filled teeth, pieces of instruments, and perforations caused by procedural errors. Often, diagnostic surgery will require collecting a biopsy specimen. Although it is not common to discover a malignancy or serious nonodontogenic condition, the biopsy tissue must be sent to a pathologist for assessment and diagnosis.
Hemisection is the removal of a root and its coronal portion from a multirooted tooth .
Incision and drainage is needed to release exudates from swollen soft tissues . The exudate is released by incision and drainage to relieve the pressure and reduce the pain. Often, the soft tissue swelling is indurated and has a diffuse cellulitis. In these circumstances, an incision may be unsuccessful for immediate relief and reduction of the swelling. A helpful solution is to ask the patient to keep a warm saltwater solution in the inflamed tissue area, to try to bring the exudate to a more fluctuant concentrated area to make it easier to drain. After delivering local anesthesia to the surgical site to numb the tissues, an incision should be made with a sterile scalpel blade. The released exudates may contain blood, but this is not normally a cause for concern. If the swelling is large, a rubber-dam drain may be inserted into the incision to maintain the patency of this surgical opening. The swelling of tissues is an indication of infection which indicates the need for antibiotic therapy.
Intentional tooth replantation may be considered when no other course of root canal treatment is possible and extraction of the hopeless tooth is inevitable . The tooth is extracted, the root canal is retrofilled, and the tooth is replanted back into the socket with care to avoid damaging the root or surrounding bone. The amount of time the tooth is removed from the socket must be minimized to reduce the risk of ankylosis and subsequent replacement resorption, although these are common responses to intentional tooth replantation. The long-term survival of replanted teeth is uncertain, and this procedure can only be recommended as a temporary last resort to save a tooth.
Marsupialization is a decompression technique used to reduce a massive cyst without surgical curettage . This is accomplished by making the epithelial lining of the cyst continuous with the mucus membrane of the attached gingival of the oral tissues. The reduction of the lumen takes place as the cyst epithelium becomes part of the oral epithelium.
Periapical surgery or apicoectomy  has been used as the all-inclusive term for endodontic surgery, but it does not describe all endodontic surgeries. A periapical curettage is performed by removing the pathologic tissues surrounding the apex of a tooth without disturbing the root. It can be the complete treatment, or it may be the initial step in an apical resection or root retrofill. A periapical curettage is performed to release a confined exudate or irritant and remove periapical tissues and cysts that are not healing. A retrofill procedure involves sealing the root canal preparation with a material. This is done when the root canal cannot be adequately filled by nonsurgical root canal treatment. The retrofill preparation, sometimes described as the “pot hole,” must include the entire apical foramen, being sufficient to retain the bulk of the filling material. A bevel needs to be cut into the root to allow the direct access to the apical canal to accomplish its filling. In the past, sealers and amalgam were used as common retrofill materials, but today, MTA is more likely to be used.
Root amputation is the removal of a root from a multirooted tooth, leaving the coronal portion of the tooth intact . Root amputation, hemisection, or bicuspidization is indicated when removal of a root will allow for better periodontal maintenance techniques and when a root or furcation is periodontally untreatable, such as in the case of obstructed canals, untreatable pathologic root defects and resorption, procedural errors, and root fractures. The extent of periodontal disease and bone support for the remaining tooth must be carefully evaluated prior to root amputation surgery.
Trephination requires anesthetic and is the perforation of a cortical plate to release the pressure of an exudate with alveolar bone . This is a minimum usage procedure, to be considered only if the pain cannot be controlled by intercanal procedures, after antibiotics have proven to be ineffective, after rinsing with warm saline has not affected drainage through the cortical plate. The location of the trephination should be close to the apex of the inflamed tooth, and it must avoid anatomical landmarks and adjacent roots. An incision is made to prevent the tissue from being caught or wound by the bur. Only the cortical plate of bone in the area should be penetrated; it is not necessary to reach the apex itself in order to effect relief.
Restorative and Occlusal Factors
After amputation surgery, the patient’s occlusal contact of teeth should be evaluated for problems; if there are contacts with teeth where the roots have been amputated, those teeth may need to be supported by splinting during the healing process.
Guidelines for Surgery
A surgical flap is necessary for access to tissues, visibility, and orientation of the roots in the alveolus.
Removal of the overlying buccal bone may be necessary to assist in extraction of the root.
Directions for root amputation: avoid gouging the remaining root.
Directions for hemisection: the cut is made at the expense of the root to be sacrificed.
Directions for bicuspidization: Maintain the vertical direction of the cut and remain centered over the furcation. Round off any sharp corners of the tooth. Leave adequate space between the roots to allow for the preparation and restoration.