After reading this chapter, the student should be able to:
Discuss the role of endodontic surgery in treatment planning for a patient.
Recognize situations in which surgery is the treatment of choice.
Define the terms incision for drainage, apical curettage, root-end resection, root-end preparation, root-end filling, grafting, and suturing.
Briefly describe the step-by-step procedures involved in periapical surgery, including those for incision and reflection, access to the apex, apical curettage, root-end resection, root-end preparation and filling, flap replacement, and suturing.
State the different flap designs.
Diagram the various flap designs and describe the indications, advantages, and disadvantages of each.
List the more common root-end filling materials.
Review the different materials for grafting.
Review the basic principles of suturing.
Write out instructions to be given to the patient concerning postoperative care after endodontic surgery.
Review the outcome of apical microsurgery.
A Brief History
Systematic reviews with meta-analysis, studies with large sample sizes, and practice-based research networks studies all indicate extremely high medium-term and long-term survival rates for nonsurgical endodontically treated teeth without intervention. If a nonsurgical endodontically treated tooth fails and cannot be retreated nonsurgically, and it is determined that the reason for failure is not periodontal, traumatic, or restorative in nature, apical surgery (AS) is often the treatment of choice.
Although the origins of AS can be traced to pre-Colombian times, , contemporary endodontic surgery began its journey in the early 1960s along with the recognition of endodontics as a specialty in the United States in 1964. ,
The main purpose of AS is to save a natural tooth. This is accomplished by removing a portion of a root with anatomic complexities laden with tissue debris and microorganisms and/or sealing the canal when a complete seal cannot be accomplished through nonsurgical procedures. Significant advances in the use of magnification and illumination, specifically the introduction of the surgical operating microscope (SOM) in the late 1980s and the supportive armamentarium and materials that followed, have benefited treatment protocols in AS such that teeth that might otherwise have been extracted now have a predictable chance for retention. AS is now considered a microsurgical procedure in the truest sense. The purpose of this chapter is to discuss indications and contraindications for apical microsurgery, procedures involved in apical microsurgery, including those for incision and reflection, access to the apex, apical curettage, root-end resection, root-end preparation and filling, flap replacement, and suturing as well as instructions to be given to the patient concerning postoperative care after endodontic surgery ( ).
Indications for Apical Surgery
The main indications for AS are failing root canal treatments, procedural accidents, irretrievable materials in the root canal or periapical tissues, anatomic complexity of the root canal system that prevents complete cleaning, shaping, and obturation of the root canal system through the coronal access, symptomatic cases, adjunctive surgeries, and exploratory surgery.
Failing Root Canal Treatments
When previous nonsurgical root canal treatment cannot be improved or performed because regaining access to the canal or removing posts would risk a perforation or root fracture and/or create a restorative problem, surgical endodontics is indicated ( Fig. 20.1 ).
Most procedural accidents can be corrected nonsurgically (see Chapter 18 ). However, when nonsurgical correction of these accidents is not feasible or practical, AS is indicated to save these teeth. Procedural accidents that may require AS include ledge formation, root perforation, separated instruments, and underfilled or overfilled canals ( Fig. 20.2 ).
Irretrievable Filling Materials
When obturation materials cannot be removed nonsurgically or are beyond the root canal space and cause problems, AS is indicated to save the tooth ( Fig. 20.3 ).
Anatomic Complexity of the Root Canal System
Complex anatomy, severe curvature, and canal calcifications that cannot be treated nonsurgically are indications for surgical endodontics ( Fig. 20.4 ).
When nonsurgical retreatment does not provide relief of pain and discomfort and nonsurgical retreatment is not possible, AS should be considered to reduce pain and discomfort for the patient ( Fig. 20.5 ).
Adjunctive surgical procedures include root resection, hemisection, crown lengthening, tooth replantation, and transplantation (see Chapter 21 ).
There are some radiolucencies that are not caused by root canal infection and may mimic periapical lesions of endodontic origin. Suspicious and nonhealing lesions require exploratory surgery and the taking of a biopsy for histologic examination (see Chapter 5 ).
Contraindications for Apical Surgery
Contraindications for AS include (1) medical or systemic complications; (2) indiscriminate use of periapical surgery; (3) anatomic factors; and (4) an unidentified cause of treatment failure.
Case Selection and Contemporary Treatment Planning
One of the most important caveats in performing apical microsurgery is in knowing when to perform apical microsurgery. Case selection will heavily affect treatment outcomes, which then influences future treatment choices and long-term success rates. The most important diagnostic tool to this end has been the introduction of cone beam computed tomography (CBCT; see Chapter 3 ). In addition, an appropriate armamentarium and strategic approaches can be prepared well in advance of the actual surgery.
CBCT examination can help us plan treatment by locating the exact position of the apical periodontitis.
Although general practitioners may not perform microsurgical procedures, it is incumbent upon them to understand the armamentarium, materials, and methods so that the best treatment possible can be provided for their patients. In order to understand the objectives of apical microsurgery and the application of armamentaria, materials, and methods, it is helpful to divide the subject into multiple stages or sections ( ).
The first step in AS is designing a flap that allows adequate exposure of the site of the surgery. The following general guidelines and principles should be used during flap design.
The flap should be designed for maximal access to the site of surgery.
An adequate blood supply to the reflected tissue is maintained with a wide flap base.
Incisions over bony defects or over the periradicular lesion should be avoided; these might cause postsurgical soft tissue fenestrations or nonunion of the incision.
The actual bony defect is larger than the size observed radiographically.
A minimal flap, which should include at least one tooth on either side of the intended tooth, should be used.
Acute angles in the flap must be avoided. Sharp corners are difficult to reposition and suture and may become ischemic and slough, resulting in delayed healing and possibly scar formation.
Incisions and reflections include periosteum as part of the flap. Any remaining pieces or tags of cellular nonreflected periosteum will hemorrhage, compromising visibility.
The interdental papilla must not be split (incised through) and should be either fully included or excluded from the flap.
Vertical incisions must be extended to allow the retractor to rest on bone and not crush portions of the flap.
Although there are numerous flap designs, two meet most AS needs: the full mucoperiosteal flap (triangular or rectangular) and the submarginal flap (triangular or rectangular).
Submarginal Curved Flap
The submarginal curved flap is a slightly curved, half-moon-shaped horizontal incision made in the attached gingiva with the convexity nearest the free gingival margin. It is simple and easily reflected and provides access to the apex without impinging on the tissue surrounding the crowns. Its disadvantages include restricted access with limited visibility, tearing of the incision corners if the operator tries to improve access by stretching the tissue, and leaving the incision directly over the lesion if the surgical defect is larger than anticipated. The incision margins of this flap frequently heal with scarring. The submarginal curved flap is limited by the presence of the frenum, muscle attachments, or canine and other bony eminences. Because of its many disadvantages, this design is generally not indicated or used.
Full Mucoperiosteal Flap
The full mucoperiosteal (intrasulcular) flap consists of an incision at the gingival crest with full elevation of the interdental papillae, free gingival margin, attached gingiva, and alveolar mucosa. It may have either one (triangular) or two (rectangular) vertical releasing incisions. It allows maximal access and visibility, precludes incision over a bony defect, and has less of a tendency for hemorrhage. This design permits periodontal curettage, root planing, and bony reshaping, and it heals with minimal scar formation. Its disadvantages include the difficulty of replacing, suturing, and making alterations (height and shape) to the free gingival margin, in addition to possible gingival recession after surgery and exposure of the crown margins.
Submarginal Triangular and Rectangular Flaps
Triangular and rectangular flaps are known as modified submarginal curved flaps . A scalloped horizontal incision (Ochsenbein-Luebke) is made in the attached gingiva with one or two accompanying vertical incisions. This flap is used most successfully in maxillary anterior teeth with crowns. An alternative submarginal flap design is the papilla-based incision, in which the interdental papillae are left intact. Prerequisites are 4 mm of attached gingiva, minimal probing depths, and good periodontal health. Disadvantages are possible scarring and hemorrhage from the cut margins to the surgical site. This design also provides less visibility than the full mucoperiosteal flap ( ).
After anesthesia is obtained, and before incising the surgical flap, the oral cavity should be rinsed with a disinfectant solution such as chlorhexidine. A 0.12% chlorhexidine rinse has been shown to significantly reduce the bacterial count in the oral cavity in advance of operative procedures. For a complete discussion of anesthesia see Chapter 8 .
Microscalpels ( Fig. 20.6 ) (Kerr Endodontics, Orange, CA) are used in the design of the free gingival margin flap to delicately and atraumatically incise the interdental papillae when full-thickness flaps are required. Feather Microsurgical Blades ( Fig. 20.7 , A ) (J. Morita USA, Inc. Irvine, CA) are made of high quality stainless using high precision grinding technology, which produces ultrasharp cutting edges that work with a variety of handles. These blades allow for a very fine incision and minimize the risk of tissue injury ( Fig. 20.7, B–D ).
Historically flaps have been reflected with a Molt 2-4 curette or variation of the Molt 2-4. The recently introduced periosteal elevator ( Fig. 20.8 ) (G. Hartzell & Son, Concord, CA) has two working ends of 2 mm and 3.5 mm and 2 mm and 7 mm and accomplishes the goals of atraumatic flap reflection.
Because we can see better with the SOM, bone removal can be more conservative. Handpieces such as the Impact Air 45 (Kerr Endodontics, Orange, CA) introduced by oral surgeons to facilitate sectioning mandibular third molars are also suggested for AS to gain better access to the apices of maxillary and mandibular molars. When using the handpiece, the water spray is aimed directly into the surgical field, but the air stream is ejected out through the back of the handpiece, thus eliminating much of the splatter that occurs with conventional high-speed handpieces. Because there is no pressurized air or water, the chances of producing pyemia and emphysema are significantly reduced.
Burs such as a Lindemann H161 or H162 bone cutter (Brasseler USA, Savannah, GA) are extremely efficient and are recommended for hard tissue removal. They are 9 mm in length and have only four flutes, which result in less clogging. With the use of an SOM and an Impact Air 45, high-speed surgical burs can be placed even in areas of anatomic jeopardy with a high degree of confidence and accuracy ( Fig. 20.9 ). The size of the osteotomy should be as small as practical so that wound healing will not be impaired, yet large enough to allow for complete débridement of the bony crypt and access for root-end procedures that will follow.
Curettage and Biopsy
It goes without saying that if tissue warrants removal, it warrants examination and diagnosis by an oral pathologist. At no time should a surgeon remove tissue and accept the responsibility of its diagnosis based on clinical impression, color, or consistency. In addition, any foreign material present in the bony crypt should be removed as it could cause persistent irritation and may prevent complete healing of the tissues. For further discussion of radiolucent periapical pathosis see Chapter 5 .
Apical Resection and Resected Apex Evaluation
There is general agreement that the main cause of failure in conventional endodontic treatment is the clinician’s inability to adequately shape, disinfect, and obturate the entire root canal system. The majority of this untreated anatomy is located in the apical 3 mm and for this reason a 3 mm resection is recommended. With the introduction of ultrasonics for creating root-end preparations, a second reason for a 3 mm resection has emerged. Several authors have studied the incidence of craze line, cracks, and fractures in the root and cemental surfaces after ultrasonic root-end preparations. Although all of these studies showed a statistically significant increase, none have shown any clinical significance as a result of their findings.
Historically, a long bevel was created in order to provide access for a microhead handpiece. With the introduction of periapical ultrasonics, little to no bevel is needed. This results in fewer cut dentinal tubules and less chance of leakage. Recent advancements in electric motor design and straight handpieces afford the clinician opportunities for direct visualization of the root-end while performing root resection and the creation of axial bevels that approximate zero degrees ( Figs. 20.10 and 20.11 ).