As it has been stated many times before, there are 2 things in life you can count on: death and taxes. A diluted dental school version of this saying is the following: there are 2 things you can count on in dental school…you will not learn much about orthodontics or endodontic surgery. No offense is meant to my esteemed orthodontic and endodontic educational colleagues. A dental student may have some exposure to these specific fields within dentistry during his or her dental school education, but not enough to perform these procedures competently after dental school without a lot of continuing education courses or a postgraduate specialty program.
As far as endodontic surgery is concerned, I was never clinically exposed to this procedure during dental school. It was my postgraduate endodontic training that enabled me to learn how much of this procedure I did not know. Unfortunately, it wasn’t until after graduate school that I realized what I did learn about surgery would change dramatically in the years following my training.
The purpose of this article is to present current techniques and thought processes in endodontic surgery for dentists who are performing the procedure or to help dentists who are referring their patients for surgical treatment better understand endodontic surgery.
SPECIFIC TYPES OF ENDODONTIC SURGICAL PROCEDURES
The most common type of endodontic surgery is the removal of periradicular pathology in conjunction with the resection of a root, with or without placement of a retrofill material. Other endodontic surgical procedures are performed for perforation repair, root fracture identification, and evaluation and exploration of a previous failed surgery.
PRESURGICAL CASE ASSESSMENT
Prior to any endodontic surgical procedure, it is important that the tooth is properly restored. Looking back over my endodontic surgical training during my residency, the lack of proper tooth restoration prior to surgery was one of the main reasons for many of my surgical treatment failures (Figure 1). If an endodontically treated tooth has a radiographic periradicular lesion, but has a prior restoration that does not have a good marginal seal, further restorative and conventional endodontic re-treatment must be considered as a possible treatment plan prior to endodontic surgery. By not addressing the coronal seal, leakage can work its way down through the root to the periradicular region, causing a lesion to occur. If the same tooth has restorative treatment with good marginal seal, and the prior conventional endodontic treatment is satisfactory, surgical endodontic treatment can then be considered as a treatment option.
|Figure 1. Performing endodontic surgery on a tooth that is not properly restored will ultimately lead to failure.||Figure 2. Vestibule depth has a correlation to osseous thickness.|
Anatomical considerations also need to be addressed prior to surgery. If the mandibular region is the surgical site, the depth of the vestibule should be palpated with your index finger to get an estimate of the osseous thickness. The deeper the vestibule, the thinner the cortical bone is for surgical access (Figure 2). A panoramic radiograph should be taken to help visualize the mandibular nerve canal and mental foramen region. This radiographic perspective will provide the clinician an overall view of the surgical anatomy. If the maxillary arch is the surgical site, the vestibule depth should also be checked with an index finger to estimate osseous thickness. A panoramic radiograph should be taken if there is concern about the sinus or any other anatomical structures, but it is not as crucial for the maxilla as it is for the mandible due to differences in surgical anatomy. When a palatal root of a maxillary molar is the surgical site, the palate vault height should be noted. The deeper the palatal vault, the less cortical bone that will need to be removed to gain access to the root.
During my endodontic residency, endodontic surgery was performed like any other endodontic treatment. No thought was given to the use of magnification or enhanced illumination of a treatment field. It was not until after my training that I began to understand that endodontic surgery is a microsurgical procedure. The basic finding upon which all microsurgery is based is the illumination and magnification of a treatment field that enables the mind to interpret, so the hands can perform intricate micromanipulations.
With the understanding of endodontic surgery as a microsurgical procedure, I recommend the use of 2 to 2.5x loupes to reflect the gingival tissue, remove the cortical and medullary bone, and for isolation of the root end. Loupes magnify beyond the ability of the naked eye, but anything greater than 2.5x magnification will decrease the depth of field for the operator. Once the root end or surgical site has been isolated, higher magnification can be achieved with the microscope or endoscope. This will provide critical magnification and illumination to aid in identifying and treating the etiology.1
Periodontal considerations must be addressed when performing endodontic surgery. The gingival tissue should be clinically evaluated for anatomy and flap design. It is important to note that attached gingival tissue is a more delicate tissue than the alveolar mucosa gingival tissue. Thus, the attached gingival tissue can tear, easily causing bleeding into the surgical site. Also, despite our dental school education, a wide base flap design is contraindicated. The reason is that the collagen and blood supply of the gingival tissue run vertically. This means that although the wide base flap will not compromise the blood supply to the reflected flap, it will affect the blood flow to the nonreflected tissue. A vertical release will provide very little compromise of the blood supply to both the reflected and nonreflected gingival tissue (Figure 3).
|Figure 3. Vertical release of gingival tissue.|
The basic flap designs used for endodontic surgery are the full-thickness triangular, envelope, or submarginal flap. Each flap design has its advantages and disadvantages. The overall advantages of these specific flap designs are good surgical access, minimal disruption of blood supply, and low occurrence of any postoperative sequelae. The disadvantage of the triangular and envelope flap designs is the possible loss of soft-tissue attachment and crestal bone height. The disadvantages of a submarginal flap design are increased bleeding due to the incision being made across the vertical gingival vascular supply, difficulty in suturing, and possible shrinkage and scarring of the gingival tissue due to improper healing of the collagen fibers. A study by Harrison and Jurosky2 found that at 14 and 28 days postoperative, there was no difference in the healing of the gingival tissue when a submarginal flap or triangular flap was performed. The study also reported that a 45º incision in the horizontal portion of a submarginal flap would reduce the chance of scarring of the gingival tissue.
It is important when reflecting the gingival flap that the periosteum tissue is elevated off the cortical bone injunction with the gingival tissue. The periosteum tissue carries part of the osseous vascular supply. If it is not properly reflected, it will greatly increase the bleeding of the surgical treatment field (Figure 4).
|Figure 4. Increased bleeding due to improper reflection of periosteal tissue.|
One of the problems I struggled with in endodontic surgery during my training was bleeding from the reflected flap. I did not understand that good preoperative anesthesia with vasoconstrictor was important to control hemostasis. In addition to the “routine” local anesthetics (ie, 2% Xylocaine with 1:100,000 epinephrine, 2% Polocaine with 1:20,000 Levonordefrin, or Marcaine with 1:200,000 epinephrine) used to provide anesthesia to a surgical field, 2% Xylocaine with 1:50,000 epinephrine (except if the patient’s medical history contraindicates) should be infiltrated into the papilla, vertical release area, and horizontal gingival tissue incision region if a submarginal flap is the design of choice. Caution needs to be taken not to inject local anesthesia with vasoconstrictor into the muscles of the maxillary vestibule or the mandibular vestibule. The alpha-adrenergic receptor in the muscle provides vasoconstriction, but the beta-adrenergic receptor causes vasodilation. Since epinephrine acts 50% on the alpha-receptors and 50% on the beta-receptors, injecting anesthesia into the muscle can therefore cause an increase in bleeding into the surgical field.3
During flap reflection, the clinician should incise, and using a periosteal elevator, begin reflection of the horizontal component of the flap before the vertical component is incised (Figure 5). This will provide better control of hemostasis in a triangular flap. The vertical gingival flap component should then be incised to the cortical bone. After the flap is reflected with a periosteal elevator, the retracted gingival tissue should be maintained with the retractor placed on the bone, not on the gingival tissue. This will reduce the occurrence of any postoperative swelling of the gingival tissue. The surgeon can groove the cortical bone to help stabilize the gingival retractor if indicated.
|Figure 5. Reflection of horizontal component of gingival flap prior to release of vertical flap component.|
After the flap is reflected and stabilized with the retractor, the cortical and medullary bone over the root end should be removed with an Impact Air 45 handpiece. This high-speed handpiece directs the water along the bur shaft while ejecting the air out of the back of the handpiece to help prevent air emboli from occurring.4 A round carbide bur should be used with a light brush stroke to remove the osseous tissue5 (Figure 6). The entire root should be isolated before any resection is completed (Figure 7).
|Figure 6. Round carbide bur used to remove osseous tissue.||Figure 7. Isolation of entire root before any resection.|
Removal of Pathology
The granulomatous tissue, cyst, or other pathology present in the periradicular region should be removed for better visualization of the root and to aid in hemostasis. I used to think that granulomatous tissue had no vascularity; after all, isn’t this necrotic tissue? But in reality, there are capillaries that surround the periphery of the granulomatous tissue as part of the body’s chronic struggle to remove this pathology. A spoon excavator can assist the dentist in removing apical pathology, but the use of an ultrasonic handpiece will aid in the speed of removing granulomatous tissue. This type of tissue can be very adhesive to the surrounding medullary and cortical bone. Although we tend to try to diagnose what type of apical pathology it may be from a preoperative radiograph or by physically observing it, the only correct method to diagnose any pathology accurately is to take a sample for biopsy.
APICAL ROOT RESECTION
Once the pathology is removed, the root end can be better isolated. The root-end isolation can be confirmed by using an endodontic explorer to feel the periodontal ligament space around the root or by visual inspection. A study by Nedderman, et al6 demonstrated that the use of a high-speed fissure bur produced a smoother root-end surface. In graduate school, I was taught to reduce the root arbitrarily without any scientific rationale. The goal of root resection is to remove approximately 3 mm of root. According to Kim4, the last 3 mm of the root has the greatest number of deltas, isthmuses, and iatrogenic blockages.
HEMOSTASIS AND IDENTIFICATION OF ETIOLOGY
The control of bleeding within a surgical field is paramount. It is important to note that no one type of hemostatic agent can universally be used to provide hemostasis in a surgical field. Common hemostatic agents used in endodontic surgery are epinephrine, collagen-based materials, ferric sulfate, and calcium sulfate.
Identification of etiology is one of the most important aspects of endodontic surgery. Methylene blue stain should be used in conjunction with high-power magnification and illumination (microscope or endoscope) to aid in the identification of etiology.7 It took me many years after graduate school to figure out that magnification and differentiation (Figures 8a and 8b) need to occur together in order for surgical endodontic etiology to be detected better.
|Figure 8a. Magnification only.||Figure 8b. Magnification and differentiation with methylene blue stain.|
The procedure of root-end preparation has definitely changed over the years. The days of using a microhandpiece have passed, and the use of ultrasonic instrumentation is today’s choice for root-end preparation8 (Figure 9). An ultrasonic root-end preparation technique produces a more conservative preparation and reduces the chance of a root perforation when compared to the use of a microhandpiece bur preparation.9 Mehlhaff10 demonstrated that ultrasonic root-end preparation needed less beveling of the root as compared to handpiece bur preparations. The goal of resecting a root as close as possible to perpendicular to the root surface will allow for less dentinal tubular exposure and hence reduce potential avenues for leakage. A retropreparation deeper than 3 mm does not provide any greater benefits, but a retropreparation shorter than 3 mm may jeopardize the long-term success of the apical seal.11
|Figure 9. Use of ultrasonic for root preparation.|
Although the use of gutta-percha and sealer as obturating materials in nonsurgical endodontic therapy is nearly universal, no single surgically placed root-end filling material has achieved widespread acceptance. Over the last 10 years, Super-EBA, Diaket, MTA, or Geristore have replaced the use of amalgam as a retrofill material. It is important to understand that the retrofill material is secondary to identification of the etiology.
Thinking that the retrofill material was the primary prevention against canal leakage or the cause of etiology was one of the misnomers that I was taught as a resident. An example of this was when I would surgically attempt to retreat a failing previous surgery that had an amalgam retrofill. The clinical and didactic thinking of the day was that treatment failure was due to the amalgam retrofill leaking, and therefore the retrofill needed to be replaced. I would treat this patient by replacing the amalgam retrofill without having the knowledge to identify the real etiology with proper staining and magnification. More often than not, the result would be the same for every one of this type of patient profile that I would treat. The surgery would fail again over time.
It wasn’t until the use of advanced magnification and illumination (microscope and orascope) and staining for differentiation and etiology was introduced into the field of endodontics that I began to realize that surgical failure etiology wasn’t necessarily a prior retrofill material or gutta-percha that was leaking. Often the etiology was an unidentified isthmus or second canal portal of exit that was the source of periradicular contamination (Figure 10).
|Figure 10. Etiology can be from an isthmus and not from the area of the gutta-percha.|
Today, I better understand that although retrofill materials do serve an important function, they are not the primary reason why endodontic surgery fails or succeeds as a treatment. Also, a retrofill material is not always necessary in every surgical case. An example of this would be if an endodontist removes the approximate 3 mm of root end, stains with methylene blue, then identifies the etiology with advanced magnification and illumination and he or she does not see any evidence of leakage (blue stain) around the existing gutta-percha filling or any isthmus or secondary canal portals of exit. In this type of case scenario, the rationale can be that the etiology was eliminated with the root resection. As stated above, many of a tooth’s isthmuses and secondary portals of exit are within the last 3 mm of the root.4
Care must be taken to replace the gingival flap properly before suturing. I was trained to use nonresorbable silk sutures. The problem with this type of suture material is that it is made up of multiple filaments that can cause a “wicking” effect (Figure 11). The filaments absorb the tissue fluid and oral debris. This accumulation can become an irritant to the gingival tissue, hence causing a delay in healing and discomfort to the patient upon suture removal.
|Figure 11. A multiple filament suture can have a “wicking” effect and retard the gingival healing process.|
The suture material of choice is gut. Gut suture material is collagen that is derived from the submucosa of sheep or bovine intestine. It is a monofilament and is resorbable within 3 to 8 days. This helps to eliminate any “wicking” effect of the suture and does not retard the gingival healing process. The patient follow-up visit to remove the sutures is less traumatic than with silk sutures because most of the sutures will be resorbed. It is important to note that gut treated with chromium trioxide increases the resorption time, but does not offer an advantage in endodontic surgery as it might in other specialties of dentistry or medicine. Also, before the clinical use of gut sutures, they should be soaked in saline prior to placement. The reason for this is that the manufacturer packages the sutures in isopropyl alcohol. Hydration of the suture prevents it from drying out and becoming brittle, thus making the suture material more manipulative.
Pain is usually minimal following endodontic surgery. This is primarily due to the fact that there is not a lot of nerve innervation in the osseous tissue surrounding a root end. Postoperative pain is short in duration and reaches its maximum intensity on the day of surgery. A significant reduction in pain usually occurs on the first postoperative day, followed by a steady, progressive decrease in discomfort each succeeding day.12 As in conventional endodontic postoperative pain control, the goal is to prevent the inflammatory response of the body from occurring. This is best accomplished by prescribing anti-inflammatory medications like ibuprofen or naproxen to prevent the cyclo-oxygenase pathway from producing prostaglandins. It is the prostaglandin that attracts the body’s inflammatory mediators that cause fluid buildup in the surgical site. This buildup puts pressure on the peripheral nerve endings, causing postoperative pain. A mistake of my surgical training was to put a patient on only narcotic analgesics. A narcotic such as Vicoden does not have any anti-inflammatory component in its pharmacological makeup.
The literature is inconclusive as to the use of antibiotics following endodontic surgery. Due to the lack of clinical studies on the use of antibiotics after surgery, there is no decisive support for or against usage. It has been stated in the literature that amoxicillin is the antibiotic of choice for local infections following surgery.13 Amoxicillin is a broader spectrum antibiotic than penicillin. For patients who are allergic to amoxicillin, clindamycin is recommended.
I have learned a lot about endodontic surgery since graduate school. The advances in endodontic surgical research, technology, and procedure have been significant over the last 13 years. I better understand that improper presurgical case assessment can have a direct or indirect effect on the prognosis of the surgical treatment. Also, not addressing the hemostatic, microsurgical, and periodontal concerns during surgery will increase the difficulty of performing endodontic surgery.
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13. Kim S, Pecore G, Rubinstein R. Color Atlas of Microsurgery In Endodontics. 1st ed. St Louis, Mo: W.B. Saunders; 2001: 29.