Surgical treatment of periodontitis. Acute suppurative odontogenic periostitis. Diagnosis of periodontitis. Treatment. Odontogenic sinusitis. X-ray diagnostic and treatment complications oroantral plastic combinations
Introduction
In the past decade the field of endodontics has seeumerous advances, the scope of which have reached all facets of endodontic treatment in both conventional and surgical aspects. These technological advances have introduced new instruments and materials that did not exist before and revolutionized the way endodontic treatment is performed. This change could not be more evident than in the field of surgical endodontics, where both theoretical and practical aspects have completely transformed. The purpose of this chapter is to present to the surgical-minded general dentist the current standards and techniques in performing apical surgery with evidence-based rationales.
Problems with Traditional Endodontic Surgery
Traditional apical surgery is viewed as an invasive, difficult, and less successful procedure than conventional endodontic treatment. Many reasons contribute to this, examples of which include working on a conscious patient in an area with restricted access, limitations in visibility, and operating on minuscule microstructures that are often obscured by bleeding. To manage these challenges, operators had to prepare large osteotomies to gain sufficient access that would accommodate the large surgical instruments that were traditionally utilized. This unnecessary removal of healthy buccal bone structure sometimes resulted in incomplete healing. The root apex was routinely resected with a 45-degree bevel angle with no biological or clinical imperative. Such a practice was performed merely to allow visualization of root canal anatomy and to facilitate retropreparation and retrofilling. This steep-bevel angle root resection created more problems than solutions. It exposed more dentinal tubules, which translated into an increase in apical leakage.1, 2 In addition, this method sacrificed more periodontal support of the buccal root surface, shortening the distance between the base of the gingival sulcus and the osteotomy site. This further predisposed the tooth for an endodontic-periodontal communication. This resection technique also frequently resulted in an incomplete root resection in which the root apex was merely beveled rather than excised and in which the lingual aspect of the root was never resected. Surgeons thus neglected to eliminate apical ramifications and lateral canals and failed to identify more lingually situated additional canals.3, 4 Finally, it produced a distorted and elongated view of the internal root canal anatomy that makes it harder to clearly and accurately identify and treat the apical anatomy. Figure 6.1 illustrates most of the common problems associated with conventional apical surgery and how microsurgical techniques can address and correct these deficiencies.
Comparison of Traditional Surgery to Microsurgery
Introduction of the surgical operating microscope and ultrasonics paved the way in changing how endodontic surgery is performed (see Figures 6.2 and 6.3). The microscope provides illumination and magnification of the surgical site where it is most needed. The ultrasonic tips allow a coaxial preparation of the root canal system to a depth of 3 mm that provides an optimum apical seal.1 These two advances led to the miniaturization of surgical instruments. The net result of all the previously mentioned developments revolutionalized the traditional technique into a more precise method—an apical surgery with minimal healthy bone removal and a conservative shallow-bevel angle root resection. This transformation allows periradicular surgery to be performed on a solid biological and clinical basis.
The Need for Endodontic Surgery
The success rate of endodontic treatment varies and has been reported to be as high as 94.8 percent or as low as 53 percent (see Figure 6.4). This variability stems from many factors, such as the type of study, sample size, pulpal and periapical status, followup period, and number of treatment visits. Conventional retreatment has a lower success rate that ranges between 48 percent and 84 percent (see Figure 6.5). One important fact remains—a certain percentage of failures will be encountered even when the root canal treatment has been carried out to the highest quality. The following etiological factors explain why some conventional endodontic treatments fail and eventually necessitate surgical intervention.
ANATOMICAL FACTORS Careful examination of the root canal system reveals enormous complexities such as accessory canals, C-shaped canals, fins, and isthmuses (see Figure 6.6). These microstructures are more abundant in the apical onethird of the root5, 6 and are farthest away from the operator’s control. By providing a safe haven for bacteria from biomechanical instrumentation, these anatomical complexities can impair the treatment outcome in cases in which the pulp space is infected. This contributes to the lower success rate of endodontic treatment in infected cases.
Surgical Technique
ANESTHESIA AND HEMOSTASIS The ability to achieve profound anesthesia and hemostasis in the surgical site is crucial in microsurgery. Profound anesthesia will eliminate patient discomfort and anxiety during, and for a significant time following, the procedure. Excellent hemostasis will improve visibility of the surgical site, allow microscopic inspection of the resected root surface, and minimize the surgery time. Hemostatic control can be divided into preoperative, intraoperative, and postoperative phases. These phases are interrelated and dependent on each other.
Preoperative Phase
An anesthetic solution containing a vasoconstrictor is indicated to achieve anesthesia and hemostasis.21 While 2 percent lidocaine with 1:100,000 concentrations of epinephrine is recognized as an excellent anesthetic agent, clinical evidence suggests that 1:50,000 concentration offers better hemostasis.22, 23 The amount of the anesthetic solution containing 1:50,000 epinephrine that is necessary to achieve anesthesia and hemostasis is dependent on the size of the surgical site; however, 2.0 to 4.0 ml is usually sufficient. This amount of local anesthetic should be slowly infiltrated using multiple injections. Solution should be deposited throughout the entire submucosa superficial to the periosteum at the level of the root apices in the surgical site. It is worth mentioning that there is a narrow margin of error in delivering local infiltration. Skeletal muscles respond to epinephrine with vasodilation instead of vasoconstriction as they contain blood vessels that are mostly innervated with _-2 adrenergic receptors. Thus, great care should be taken to avoid infiltrating into deeper skeletal tissue beyond the root apices and over basal bone instead of alveolar bone. In the maxilla, anesthesia and hemostasis are usually accomplished simultaneously by local infiltration in the mucobuccal fold over the apices of the tooth in question and two adjacent teeth both mesial and distal to that tooth (5 teeth total). This should be supplemented with a nerve block near the incisive foramen to block the nasopalatine nerve for surgery on maxillary anterior teeth, or near the greater palatine foramen to block the greater palatine nerve for surgery on the maxillary posterior teeth (see Figures 6.32 and 6.33). 
In the mandible, anesthesia and hemostasis are usually achieved separately. Anesthesia is established by a regional nerve block of the inferior alveolar nerve, using 1.5 cartridges of 2 percent lidocaine with 1:100,000 epinephrine. Hemostasis is established with two cartridges of 2 percent lidocaine with 1:50,000 epinephrine at the surgical site via multiple supraperiosteal injections into the mucobuccal fold. An additional supplement of 0.5 cartridge is also injected into the lingual aspect of the tooth. The rate of injection will relate to the degree of hemostasis and anesthesia obtained. A rate of 1–2 ml/min is recommended.24 Injecting at a faster rate results in localized pooling of the solution, delayed and limited diffusion, and less than optimal anesthesia and hemostasis. It is essential to allow the deposited solution sufficient time to diffuse and reach the targeted area to produce the desired effects before any incision is made. The recommended wait time is usually 10–15 minutes, until the soft tissue throughout the surgical site has blanched (see Figure 6.35).
Intraoperative Phase
The most important measure in achieving hemostasis is effective local vasoconstriction. Following osteotomy, curettage, and root resection, hemostasis needs to be established again as newly ruptured blood vessels emerse the bone crypt and the buccal plate with blood. The use of a topical hemostatic agent is frequently needed at this point of surgery to control bleeding. Such an agent maintains a dry surgical field that will allow microscopic inspection of the resected root surface, adequate visibility during ultrasonic retropreparation, and good isolation during retrofilling material placement. Many topical hemostatic agents are available. The two most widely used by endodontists are epinephrine cotton pellets and ferric sulfate solution. The following is a presentation of the properties of these two chemical agents and their mechanisms of action.
Epinephrine pellets.
Racellets are cotton pellets containing racemic epinephrine HCl (Pascal Company, Inc.,
Ferric sulfate.
This is another chemical hemostatic agent that has been used for a long time in restorative dentistry. Its mechanism of action is not completely clear, but it is believed to be due to agglutination of blood proteins when in contact with this very acidic solution (pH 0.21). The agglutinated proteins form plugs that occlude the capillary orifices to achieve hemostasis. Ferric sulfate is commercially available in different solutions with different concentrations. The recommended solution for endodontic surgery is Cutrol, which contains 50 percent ferric sulfate (see Figure 6.37). Cutrol is an excellent surface hemostatic agent on the buccal plate of bone and inside the bone crypt. It should be applied directly to the bleeding point with a microapplicator tip or a cotton pellet (see Figure 6.38A). Upon contact with blood, this yellowish solution immediately turns dark brown. This color change is helpful in identifying any remaining bleeders that need to be addressed in the same manner (see Figure 6.38B). Ferric sulfate is a very effective hemostatic agent that works instantly, but it is also cyto toxic and causes tissue necrosis. For this reason, it should not come in contact with the flap tissue. The use of this agent should be limited as an adjunct to other hemostatic measures. For example, if bleeding persists after using the epinephrine cotton pellet technique. When used correctly as described in the previous paragraph, systemic absorption is unlikely since the coagulum stops the solution from reaching the blood stream. Ferric sulfate also has been proved to damage bone and delay healing when used in large amounts and left in situ after surgery (Lemon 1993). It should therefore only be used in small amounts and should be immediately and gently irrigated with saline after application. If the coagulum is thoroughly removed and irrigated before closure, there is no adverse reaction.27 The following steps outline the most effective method to achieve local hemostasis quickly during apical surgery: 1. Complete all the cutting necessary (osteotomy and root resection) and then thoroughly remove all granulation tissue from the bone crypt. 2. Place a small Racellet #3 cotton pellet in the bone crypt and firmly pack it against the lingual wall (see Figure 6.39A). 3. In quick succession, additional Racellet pellets are packed in against the first pellet, until the entire crypt is filled with pellets (see Figure 6.39B). Depending on the size of the crypt, this can take a variable number of pellets. A study by Vickers26 has shown that up to seven Racellets #3 pellets can be safely used to fill the crypt. If more are needed due to the large size of the crypt, then some sterile cotton pellets should be added until the crypt is completely filled. 4. Pressure is applied on these pellets with a blunt instrument (for example, back of a micromirror handle) for 2–4 minutes until no further bleeding is observed (see Fig 6.39C). 5. All pellets are removed one by one, except the last epinephrine pellet, which is left inside the crypt to avoid reopening of the ruptured vessels (see Figure 6.39D). This pellet should only be removed at the end of the surgical procedure before final irrigation and flap closure. 6. If small bleeders are still present on the buccal plate or inside the crypt, then Cutrol should be applied directly to the bleeding areas. Without disrupting the coagulum, the solution is quickly rinsed with saline to remove any excess. The coagulum formed should be left intact dur ing the surgical procedure but must be thoroughly curetted and the corresponding area rinsed before closure.
Postoperative Phase
Periradicular surgery should be performed within a reasonable amount of time so that complicated and hemostasis-dependent steps are completed before reactive hyperemia occurs. As restricted blood flow returns to normal, it rapidly increases to a rate well beyond normal to compensate for localized tissue hypoxia and acidosis. Reactive hyperemia is clinically variable and unpredictable. It can be prevented or reduced by compressing the flap tissue for three minutes and applying firm finger pressure with saline-soaked gauze pads placed over the surgical site. This is done to induce hemostasis, prevent hematoma formation, and enhance good tissue reapproximation.28 Flap compressions should be followed immediately with postsurgical cold compressions to the cheek.
FLAP DESIGNS
The semilunar flap used to be the flap of choice for apical surgery (see Figure 6.40)
.
It is not advocated today for a number of reasons. The semilunar flap provides a restricted surgical access and has limited potential for further extension if deemed necessary. It also carries the danger of postsurgical defects by incising through tissues that are not supported by underlying bone.29 Furthermore, this type of incision results in maximum severage of periosteal blood vessels. This compromises the blood supply, which could lead to shrinkage, gapping, and secondary healing. Another disadvantage to the semilunar flap is the close proximity of the incision to the osteotomy site, which makes hemostatic control more challenging. The following are flap designs recommended for periradicular surgery.
Full Mucoperiosteal Tissue Flap
There are strong biological reasons to use this kind of flap whenever possible.18, 30 It maintains intact vertical blood supply and minimizes hemorrhage while providing adequate access. It allows a survey of bone and root structures, which facilitates excellent surgical orientation. However, since this flap involves the gingival papilla and exposes the crestal bone, it can carry a few potential risks including loss of tissue attachment, loss of crestal bone height, and possible loss of interdental papilla integrity. The two recommended designs of full mucoperiosteal tissue flaps for periradicular surgery are the triangular and rectangular (trapezoidal) designs. The triangular flap design is the most widely used flap design in periradicular surgery, and it is indicated in the anterior and posterior regions of both the mandible and the maxilla. It requires a horizontal intrasulcular incision and a single vertical releasing incision (see Figure 6.41).
The horizontal incision is made with the scalpel held near a vertical position, extending through the gingival sulcus and the gingival fibers down to the level of the crestal bone. When passing through the interdental region, care should be taken to ensure that the incision is separating the buccal and lingual papillae in the midcol area. A microblade will ease this separation if the embra sure space is narrow (for example, mandibular anterior area). A clean incision located exactly midcol is vital to prevent sloughing of the papillae due to a compromised blood supply and to prevent the unaesthetic look of double papillae.18 The vertical releasing incision is prepared between the root eminences parallel to the long access of the roots. In anterior surgery, the vertical incision is prepared in the flap perimeter closest to the surgeon. In posterior surgery, it always constitutes the mesial perimeter of the flap. It is important to keep the base of the flap as wide as the top so that the vertical incision is kept parallel to the vertically positioned supraperiosteal microvasculature and tissue-supportive collagen fibers.31 In this manner, the least number of vessels and fibers are severed, which will translate into faster healing without scarring (see Figure 6.42).
Vertical incisions should terminate at the mesial or distal line angles of teeth and never in the papillae or the midroot area. It also should meet the tooth at the free gingival margin with a 90-degree angle (see Figures 6.41 and 6.43).
The advantages of the triangular flap design are simplicity, rapid wound healing, ease of flap reapproximation, and ease of suturing. A disadvantage, on the other hand, is the limited surgical access. In situations where more access is warranted, either the horizontal or the vertical incisions can be extended to allow some additional mobilization of the flap. Alternatively, a rectangular flap design should be considered if maximum access is required. The rectangular flap design is very similar to the triangular design except for the addition of a second vertical releasing incision (see Figure 6.44).
The rectangular flap design is indicated for anterior surgery when more access is needed. It is also used when multiple teeth will be operated on or when the roots are long (for example, cuspid). Potential disadvantages associated with this flap design include technique sensitive wound closure and a higher chance for flap dislodgment.
Limited Mucoperiosteal Tissue Flap (Scalloped Flap)
This limited tissue flap does not include the marginal and interdental gingival within its perimeter. It is indicated in teeth with existing fixed restorations and in cases where aesthetics are a major concern. The limited tissue flap can be used in both the maxillary anterior or posterior regions but only when sufficient width of attached gingiva is available. It is usually contraindicated in the mandible since the attached gingiva is narrow in that region and aesthetics are not a major concern. An absolute minimum of 2 mm of attached gingiva from the depth of the gingival sulcus must be present before this flap design is selected32 (see Figure 6.45). This submarginal flap design is formed by a scalloped horizontal incision and one or two vertical releasing incisions depending on the surgical access needed (see Figure 6.46). The scalloped incision reflects the contours of the marginal gingiva and provides an adequate distance from the depth of the gingival sulci.18 It also serves as a guide for correctly repositioning the elevated flap for suturing.25 All the flap corners, either at the scalloping or at the junction of horizontal and vertical incisions, should be rounded to promote smoother healing and minimize scar formation. The angle of the incision in relation to the cortical plate is 45 degrees to allow the widest cut surface as well as better adaptation when the flap is repositioned (see Figure 6.47). This 45-degree bevel at the scalloped horizontal incision is made with the tip of the scalpel pointing away from the gingival sulcus. This adds an additional safety measure to protect the minimum 2 mm of attached gingiva. The submarginal flap has the advantage of leaving the marginal and interdental gingiva intact in addition to leaving the crestal bone unexposed. The major disadvantage is the severance of supraperiosteal vessels, which could leave the unreflected tissue without blood supply. This can be prevented by preserving an adequate width of unreflected gingival tissue, which will derive secondary blood supplies from the PDL and intraosseous blood vessels. The healing of this flap seems to be quite similar to the full mucoperiosteal flap.
ELEVATION AND RETRACTION
Tissue elevation always starts in the attached gingiva of the vertical incision (see Figure 6.48A and 6.48B). This allows the periosteal elevator to apply reflective forces against the cortical bone and not the root surface while elevating the tougher fibrous tissue of the gingiva. Special attention should be directed to ensure that the periosteum is entirely lifted from the cortical plate with the elevated flap (see Figure 6.49). The elevator should then be moved more coronally to elevate the marginal and interdental papilla atraumatically using the undermining elevation technique.18 In this technique, all reflective forces should be applied to the bone and periosteum, with minimal forces on the gingival tissue (see Figures 6.50A and 6.50B). Subsequently, the elevation continues in a more apical direction into the submucosa to expose the root tip area and to render the flap more flexible and movable.
At this point a retractor should be used to provide access to the periradicular tissue. The retractor tip should rest on bone with light but firm pressure and without any trauma to the flap soft tissue. The surgeon must ensure that minimal tension exists at all perimeters of the flap before the osteotomy. If tension exists, then one or both of the releasing incisions should be extended or the reflected tissue should be elevated further. It is important to evaluate the cortical plate bone topography (flat, convex, or concave) to choose the right retractor tip—a shape that will fit the anatomy to maximize stable anchorage (see Figure 6.51A and 6.51B). For example, if the cortical bone anatomy is convex such as the area of the canine eminence or the zygoma, then a retractor with a concave or V-shaped tip will best fit this anatomy (see Figure 6.52). An appropriate retractor tip will allow maximum surface contact between the retractor and bone to prevent unintentional retractor slippage and possible flap impingement. For posterior mandibular surgery, the groove technique should be used to provide a stable anchor for the retractor. In this technique, a 15 mm shallow horizontal groove is prepared using the Lindemann bur. This groove is prepared beyond the apex for molar surgery and above the mental foramen for premolar surgery. The use of a plastic cheek retractor underneath the surgical retractor provides better access and visibility to the surgical site while protecting the patient’s lips at the same time (see Figure 6.53). The amount of time that the tissue is retracted is an essential factor in the speed of healing. Although related literature does not give a specific answer, it seems logical to keep this time to a minimum. On the other hand, operators should take sufficient time to solve the clinical goals of the surgical procedure. 29 By keeping the surgical site well hydrated with sterile saline, there seems to be no specific time limit to the procedure.
OSTEOTOMY
The purpose of the osteotomy in endodontic surgery is to deliberately and precisely prepare a small window through the cortical plate of bone to gain direct visual and instrumental access to the periapical area. The osteotomy should allow identification of the root apex and thorough enucleation of the periapical lesion. The osteotomy size should be as small as possible but as large as necessary.33 However, a minimum diameter of 4 mm is absolutely essential. This is very important in order to allow a 3-mm root resection and to accommodate free manipulation of microsurgical instruments inside the bone crypt. An ultrasonic tip can be used to verify if the osteotomy is adequate. Ideally, the ultrasonic tip (which is 3 mm long) should fit freely inside the crypt without any contact on bone (see Figure 6.54). When a larger lesion is encountered, the osteotomy might have to be further extended to ensure complete curettage of the lesion. The osteotomy should be accurately prepared over the root apex to prevent any unnecessary overextension. This is an easy task when fenestration through the cortical plate is present. On the other hand, when the buccal cortical plate is intact and the lesion is
limited to the medullary bone space, a careful assessment should precede any osteotomy preparation. An important clinical clue in finding the apex is the estimated root length, which can be measured from a preoperative radiograph or simply be obtained from working length recorded in the patient’s chart. The length measurement is then transformed to the buccal plate using a file or periodontal probe (see Figure 6.55A and 6.55B). In addition to the length, the radiograph should be carefully examined for root curvature, position of the apex in relation to the cusp tip, and proximity of the apex to the adjacent apices or anatomical structures (mental foramen, mandibular nerve, and maxillary sinus). In most cases, a visual inspection of the buccal bone topography will reveal the root location and direct the surgeon to the root apex. In other cases, osseous palpation using an endodontic explorer is recommended in an attempt to penetrate through the thinned cortical plate into the lesion to confirm the exact location of the apex (see Figure 6.56A and 6.56B). If the operator is still unsure about the exact location of the apex, the following procedure can provide better orientation. Using
a surgical #1 round bur, an indentation is prepared on the cortical plate over the estimated location of the apex. The indentation is then filled with a radio-opaque material such as gutta-percha or tin foil. A radiograph is taken with the marker in place to ascertain the location of the apex in relation to the marker (see Figure 6.57A and 6.57B). The osteotomy is usually accomplished with a Lindemann bone cutter bur mounted on a surgical high-speed handpiece such as the Impact Air 45. It is used in a brushstroke fashion coupled with copious saline irrigation (see Figure 6.58). The Lindemann bur has fewer flutes than conventional burs, which results in less clogging and more efficient cutting with minimal frictional heat
produced. The Lindemann bur also produces a smoother bone surface with divergent walls and fewer undercuts in comparison to a round bur. The advantage of the Impact Air 45 handpiece is that water is directed along the bur shaft while air is ejected out of the back of the handpiece, thus minimizing the chance of emphysema. During the osteotomy preparation, it is essential to use the microscope at a lower magnification (4_ to 8_) in order to make the distinction between bone and root tip. The root structure can be identified apart from bone by texture (smooth and hard), color (darker yellowish), lack of bleeding upon probing, and the presence of an outline (PDL). When the root tip cannot be distinguished, the osteotomy site is stained with methylene blue dye, which preferentially stains the periodontal ligament (see Figure 6.59) and identifies the root apex.25, 33, 34
PERIRADICULAR CURETTAGE
It is important to emphasize that periradicular curettage alone does not eliminate the origin of the lesion but, rather, temporarily relieves the symptoms. The purpose of the curettage is only to remove the reactive tissue, whether it is a periapical granuloma or cyst. It is usually performed prior to or in conjunction with root-end resection. Curettage is accomplished with bone curettes (#2/4 Molt), with the concave surface of the instrument facing the bony wall first18 (see Figure 6.59). Pressure is applied only against the bony crypt until the tissue is freed along the lateral margins (see Figure 6.60A–E). Then, the bone curette can be rotated around and used in a scraping motion. Once loosened, tissue forceps are used to grasp the tissue and transfer it directly to the biopsy bottle. Periodontal curettes (
apex.
APICAL ROOT RESECTION
This is also referred to as apicoectomy. Apical root resection is performed to ensure the removal of aberrant root entities and to allow microscopic inspection of the resected root surface. Similar to the osteotomy, it is usually accomplished with the Lindemann bur in an Impact Air 45 handpiece using copious saline spray and under low range of magnification (4_ to 8_) (see Figure 6.61). The smooth resected root surface produced by the Lindemann bur facilitates and eases microinspection (see Figure 6.62). There are two important factors to con
sider with this procedure: the extent of apical resection and the bevel angle.
Extent of Apical Resection
The amount of root resection depends on the incidence of lateral canals and apical ramifications. Apical resection of 3 mm at a 0-degree bevel has been shown to reduce lateral canals by 93 percent and apical ramifications of lateral canals, deltas, and isthmi by 98 percent25 (see Figure 6.63). Additional resection does not reduce this percentage significantly. The level of root resection may need to be modified due to the presence of the following factors: • Presence and position of additional roots (for example, a mesiopalatal root of a maxillary molar that is shorter than the mesiobuccal root). • Presence of a lateral canal at the root resection level (see Figure 6.64)
.
• Presence of a long post and the need to place a root-end filling (see Figure 6.65A and 6.65B). • Presence and location of a perforation. • Presence of an apical root fracture. • Amount of remaining buccal crestal bone (a minimum of 2 mm should remain to prevent periodontic-endodontic communication). • Presence of an apical root curvature (see Figure 6.65C and 6.65D)
Bevel Angle Apical root resection should be performed perpendicular to the long axis of the root (see Figure 6.66). This 0-degree bevel will ensure equal resection of the root apex on both buccal and lingual aspects.35 In some situations, a 0-degree bevel might not be possible (for example, severe lingual inclination of an anterior tooth, wide roots in a buccolingual dimension). In these cases, the operator should use a small bevel angle (up to 10 degrees). This bevel should be kept to the smallest angle possible, since the real bevel angle is almost always greater than
what it appears to be depending on the angle at which the tooth is proclined in the alveolus. For example, mandibular and maxillary anterior teeth have lingual inclinations. Surgeons might resect the root at what seems to be a 10-degree bevel, but in reality the root is being resected with a bevel of 20 degrees or more. The surgeon should compensate for this distortion of perspective by minimizing the angle of the bevel, keeping it as close to 0 degrees as possible.3, 35 An important advantage of the perpendicular root resection is the minimal exposure of dentinal tubules, which results in a reduction in apical leakage1 (see Figure 6.67). In addition, the root canal anatomy is no longer elongated in a buccolingual direction as it is by traditional wide-angled methods (see Figure 6.68A–B), thus facilitating retropreparation and retrofilling procedures. Figure 6.69 shows apical root resection being performed on tooth #4. An adequate osteotomy is prepared to expose the apical 3 mm of the root prior to resection (see Figure 6.69A). Root resection is performed at a 0–10-degree bevel angle (see Figure 6.69B). The root tip is completely separated and is removed (see Figure 6.69C and 6.69D)
RETROGRADE FILLING
The purpose of retrograde filling is to provide an adequate apical seal that will prevent the leakage of remaining bacteria and their by-products from the root canal system into the periradicular tissue. Ideal properties for retrograde filling material as proposed by Grossman are summarized in Table 6.3. Amalgam has previously been the most widely used root-end filling material. It is easily manipulated and readily available and seems to provide a good initial seal. Amalgam use is no longer recommended due to its corrosion, leakage, staining of soft tissue, persistent apical inflammation, and lack of long-term success.36, 37 The two retrograde filling materials currently recommended are Super EBA and MTA.
Super EBA In 1978, Oynick and Oynick38 suggested the use of Stailine (later marketed as Super EBA) as a retrograde filling material. They reported that Super EBA is unresorbable and radiopaque. Histological evaluation showed a chronic inflammatory reaction, which is considered normal in the presence of a foreign body, but it also showed the possibility of collagen fibers growing over the material. Super EBA is a modified zinc oxide eugenol cement (see Table 6.4). The eugenol is partially substituted with orthoethoxybenzoic acid to shorten the setting time. Alumina is added to the zinc oxide powder to make the cement stronger. Super EBA has a neutral pH, low solubility, and high tensile and compressive strength.39 Several in vitro studies demonstrated that Super EBA has less leakage than amalgam and IRM.39–41 Advantages of Super EBA include fast setting time, dimensional stability, good adaptation to canal walls, and the ability to polish. However, it is a difficult material to manipulate because the setting time is greatly affected by temperature and humidity.
Preparation and Placement of Super EBA The liquid and powder are mixed in 1:4 ratio over a glass slab. Small increments of powder are incorporated into the liquid until the mixture loses its shine and the tip of EBA does not droop when picked up with an EBA carrier. When the right consistency is reached, the EBA mix is shaped into a thin roll over the glass slab. A 3-mm-long segment is picked up by the carrier and placed directly into the dried retroprepared cavity under midrange magnification (10_ to 16_) (see Figure 6.82). Using a microplugger of appropriate tip size and angulation, the EBA is gently condensed into the cavity (see Figure 6.83). Placement and packing are repeated until the entire retroprepared cavity is filled. At this point, a microball burnisher is used to further condense the material and to seal the margins while at the same time pushing aside any extra filling material (see Figure 6.84). A periodontal curette can be used to carve away excess Super EBA (see Figure 6.85). A dry field is maintained from the start of the retrofilling process until the Super EBA is completely set. Once the material sets, it can be polished with a composite finishing bur to a smooth finish (see Figure 6.86).
Although polishing the Super EBA will remove extra filling material and produce an esthetically pleasing image of the retrofilled root-end, a recent study suggests that burnishing the EBA without polishing provides a better seal.42
Mineral Trioxide Aggregate (MTA) This relatively new material was developed by Torabinejad and coworkers in 1995 and has proven to be superior to other retrofilling materials. MTA is mainly composed of tricalcium silicate, tricalcium aluminate, and tricalcium oxide in addition to small amounts of other mineral oxides (see Figure 6.87). Bismuth oxide is added to render the mix radiopaque. MTA is biocompatible and hydrophilic and seems to provide excellent sealing properties that are not affected by contamination with blood.43–45 MTA has a high pH, similar to calcium hydroxide. It is the only material with the ability to promote regeneration of the periodontal apparatus where new cementum is formed directly over MTA. The two disadvantages of MTA are long setting time (48 hours) and the difficult handling of the material. Due to the long setting time and solubility, the bone crypt area cannot be flushed with saline. Otherwise, the material would be washed out. The difficulty in the handling of MTA is due to its loose granular characteristics; it sticks very well neither to itself nor to any instrument. Fortunately, the handling problem has been solved with the introduction of the MTA pellet-forming block. To use a system of MTA placement utilizing the pellet-forming block, the MTA should be mixed to the proper consistency. If the MTA mix is too wet, the pellet will not form. If it is too dry it will be crumbly and unmanageable. A proper mix should have a matte finish and not a watery gloss. This system is simply composed of a block and a placement instrument (see Figure 6.88). The block has precision grooves into which properly mixed MTA can be loaded using a spatula46; then any excess material outside the groove should be wiped off using a cotton swab (see Figure 6.89). Finally the placement instrument, which perfectly fits the groove, should be used to gently slide out the MTA (see Figure 6.90). This forms a small pellet—shaped like the groove—that should stick to the tip of the placement instrument (see Figure 6.91). This MTA pellet can be precisely inserted into the root end preparation and condensed with a microplugger and a ball burnisher. The excess material can be simply removed using a wet cotton pellet (see Figure 6.92A–E).
WOUND CLOSURE
Wound closure after surgical procedure has three stages: reapproximation and compression, stabilization with sutures, and suture removal. Reapproximation and Compression After surgery, the surgical site is thoroughly rinsed with copious saline to ensure the removal of any debris or blood clots. This should apply to the entire surgical field, including the surrounding buccal plate of bone, the periradicular bone cavity (except where MTA has been used), and the underside of the reflected flap. If ferric sulfate was used, it should be curetted and rinsed until fresh bleeding is observed. When epinephrine Racellet cotton pellets are used they should be removed before final irrigation. Any loose cotton fibers should be removed from the bone crypt with the aid of microscopic inspection. Undetected cotton fibers left in situ will induce inflammation and retard healing.35 Accurate reapproximation of the tissue aids in the initiation of healing by primary intention. After the flap is repositioned, saline-soaked gauze is used to compress the wound site, using firm finger pressure for three to five minutes. This is essential for the creation of a thin fibrin clot between the flap and the bone and between the wound edges18, 47 (see Figure 6.93).
Stabilization with Sutures and Suture Removal
A variety of suture materials are available, each demonstrating advantages and disadvantages. Suture materials are divided into absorbable and nonabsorbable. They can also be monofilament or multifilament. Silk sutures have been used for years. They are easy to handle and inexpensive. Unfortunately, since silk sutures are braided, they exhibit a wicking effect in which they attract fluid and bacteria in as early as 24 hours postoperatively, making them highly inflammatory to the wound.48, 49 However, with smaller suture sizes (5-0 or 6-0), proper suture placement, use of chlorhexidine rinse, and timely suture removal in 48–72 hours, this problem can be minimized.18 Chromic gut sutures are resorbable. The treatment of this type of suture with chromic acid prolongs its retention in tissues. Nevertheless, they are difficult to handle. The use of synthetic monofilament sutures such as nylon is desirable. They are nonresorbable and available in small sizes and cause minimal tissue reaction. They are the sutures of choice in areas with higher esthetic demand. The only disadvantage is their high cost. Of the many suturing techniques available, the interrupted and sling suturing techniques seem to be the ones most commonly used because they are simple and effective. The interrupted suturing can be used for the vertical releasing incision, while the sling suture technique can be used for the sulcular incision. Suture knots should always be placed away from the incision line to minimize microbial colonization in that area (see Figure 6.94). The minimal number of sutures that provide adequate flap reapproximation should be used. All sutures should be removed in 48–72 hours
POSTSURGICAL CARE
Postoperative patient instructions should include the following: 1. Intermittent application of ice pack to the surgical site (30 minutes on, 30 minutes off ) starting immediately after the surgery and continuing for six to eight hours. 2. Strenuous activity, smoking, and alcohol should be avoided. 3. Normal food is permitted with emphasis on the avoidance of hard, sticky, and chewy food. 4. Do not pull the lip or facial tissues. 5. Continue the use of analgesics given presurgically (600 mg ibuprofen every 6 hours as needed). Slight to moderate discomfort is expected for the first 24–48 hours. Narcotic analgesics are provided and used only as an adjunct to ibuprofen if needed. 6. Oozing of blood from the surgical site is normal for the first 24 hours. It can be managed with application of a wet gauze pack to the site, pressed in place with an ice pack. 7. The day following the surgery, chlorhexidine rinses should be used twice a day, continuing for three to four days. Warm salt water rinses can be used every two hours. 8. Brushing of the surgical site is not recommended until the sutures are removed. Cotton swabs can be used to clean the surgical site.
SURGICAL SEQUELAE AND COMPLICATIONS
Oral and written postoperative instructions will minimize the occurrence and severity of surgical sequelae and will reduce patients’ anxiety when and if problems develop. Pain, swelling, and hemorrhage are the most common postsurgical complications. They can be easily managed with NSAIDs, pressure, and ice application. After two to three days, if signs of infection are present (for example, fever, pain, and progressive swelling with pus drainage), antibiotics should be considered. If patients develop a serious facial space infection, they should be immediately referred for emergency medical care and intravenous antibiotics. Rarely, ecchymosis can develop. It is characterized by a discoloration of the facial and oral soft tissue due to the extravasation and subsequent breakdown of blood in the interstitial subcutaneous tissue. Usually it occurs below the surgical site due to gravity. It can also develop in a higher site like the infraorbital area (see Figure 6.95). Paresthesia can develop when surgery is performed near the mental foramen even when the surgical site is far from the nerve. It is usually transient iature and is mainly caused by the inflammatory swelling of the
surgical site that impinges on the mandibular nerve. If the nerve has not been severed, normal sensations usually return in few weeks, but it can take up to a few months. On rare occasions paresthesia can be permanent.
Microsurgery Success Rate
Periradicular microsurgery is a predictable and successful treatment of endodontic failure when the previous root canal treatment and coronal restoration are of adequate quality. (The reasons for an endodontic failure are not obvious.) Surgical treatment is, however, not always successful. Possible etiological factors for failure are as follows: • Poor case selection • Incomplete root canal space debridement • Incomplete debridement of the canal isthmus • Inadequate apical seal • Missed canals • Failure to manage the root-end or retrofilling material properly • Vertical root fracture • Endodontic periodontic communication • Recurrent cystic lesion Other uncertain factors can also play a role such as infected dentinal tubules, type of root canal filling, more coronally located lateral canals, and failure to use antibiotics. When appropriate case selection criteria are used, endodontic microsurgery seems to have great success. One study showed a success rate of 96.8 percent after a one-year follow- up.50With longer follow-up periods of up to 8 years of the same surgical cases, a success rate of 91.5 percent was achieved.51 Similar results are reported with other longterm prospective studies.52
Conclusion Periradicular surgery in the hands of operators who can perform the procedure accurately can be a great service for patients. With the presentation of this chapter, the author would like to bring a more thorough understanding of contemporary endodontic surgical techniques to general dentists who have an interest in incorporating this procedure into their practices. Needless to say, materials and methods in dentistry are changing constantly. It is the author’s hope that readers will continuously enrich themselves with evidence-based literature relating to the study of endodontics in the grand scheme of providing better patient care.
Bilozetskyi Ivan
