Modern Endodontic Surgery Concepts and Practice: A Review

Samuel Kratchman

2006, Journal of Endodontics

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23 pages

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Endodontic surgery has now evolved into endodontic microsurgery. By using state-of-the-art equipment, instruments and materials that match biological concepts with clinical practice, we believe that microsurgical approaches produce predictable outcomes in the healing of lesions of endodontic origin. In this review we attempted to provide the most current concepts, techniques, instruments and materials with the aim of demonstrating how far we have come. Our ultimate goal is to assertively teach the future generation of graduate students and also train our colleagues to incorporate these techniques and concepts into everyday practice. (J Endod 2006;32: 601-623)

Figures (34)

Figure 1. Pictoral representation of endodontic microsurgery. From top center clockwise: micromirrors, isthmus, ultrasonic KiS tip, KiS tip positioned for root-end preparation, radiograph of resected apex, and MTA root-end filled apices.

TABLE 1. Differences between traditional and microsurgical approaches *Other materials such as SuperEBA are also being used. For details see section on root-end filling.

Figure 2. According to Nair (11, 12), 15% of all periapical radiolucencies are some type of cyst. The radiograph shown does not correspond to the histological section, but illustrates the relationship in general. surgical endodontic therapy (11, 12, 15). Only a subsequent surgical intervention will result in healing of such a lesion. Thus, from a purely pathological point of view, approximately 10% of all periapical lesions require surgery in addition to endodontic treatment. In addition, failed re-treatment cases because of apical transportation or procedural er- rors, often the result of using NiTi rotary files, are in many cases, best treated by surgical endodontics, especially if they have post restorations (Fig. 3). Further, the complexity of the canal anatomy does not allow 100% success in nonsurgical endodontic therapy, even if the cysts are pocket cysts (Fig. 2). Considering these situations one may wonder why so few surgeries were performed and why surgery was not taught more assertively in the specialty training programs. Fortunately, with the ad- vent of microsurgery, the approach to the management of periapical lesions is changing. Teaching the use of the magnification is now an accreditation requirement of the ADA for endodontic specialty pro- grams. As a result, more private specialty practices have incorporated

Figure 3. Clinical cases requiring surgical endodontics. The cause of failure in Aand Cis apical transportation, which is not easy to correct nonsurgically. (B) Shows well executed endodontics, and another attempt of nonsurgical retreat- ment would most likely fail. (D) Shows a failed traditional technique surgery.

Figure 4. A modern clinical environment in which the microscope provides not only a clinical but also an ergonomic advantage.

TABLE 2. Magnifications for different surgery stages

Figure 6. Schematic diagram illustrating hemostatic techniques employed at the University of Pennsylvania. (Reprinted with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 7. Micro-suturing with 5 X 0 and 6 X 0 monofilament sutures (top left); suture removal after 48 h (top right) and tissue healing 1 wk postoperatively.

Figure 8. The Groove Technique: a small narrow horizontal groove is made just above the mental foramen. A KP#1 retractor is firmly seated in the groove protecting the nerve during the osteotomy.

Figure 9. The ideal osteotomy measures ca. 4 mm in diameter allowing a 3 mm ultrasonic tip to move freely within the bone crypt. This by the microsurgical osteotomy is compared with a much larger traditional size osteotomy. (Re- printed with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 10. A comparison of a large osteotomy and acute bevel angle made by the traditional bur method (left) with a smaller osteotomy without bevel angle, made by the microsurgical method (right). The image at right is 10 larger than the left image.

TABLE 4. Comparison of bevel angles created by traditional and microsurgical techniques

Figure 11. Frequency of apical ramifications and lateral canals. A 3-mm apical resection was needed to eliminate the majority of apical ramifications and lateral canals. (Reprinted with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 12. A digital image of a 3 mm apical resection on a maxillary premolar. (Photo by Dr. F. Maggiore, Germany.)

Figure 13. Inspection of this resected root surfaces shows several types of apical configurations, isthmi and anatomies.

Figure 15. Inspection of resected root surfaces of extracted teeth reveals many different types and shapes of isthmi. (A) Shows an infrequently seen round apex. (B) Shows a modified type 1. (C) has several apices with a type | isthmus. (D) Is a type IL isthmus, (£) is a type IV, and (F) a type V. The classification is based on Hsu and Kim (55). The majority of molar isthmi are types IV and V.

Figure 14. An example of a canal isthmus in the mesial root of the mandibular 1st molar (type V) is presented. An actual clinical example is reflected in the micromirror. (Reprinted with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 16. A great number of complete (type V) and incomplete (type IV) isthmi are located between 3 and 4 mm from the apices of the mesiobuccal roots of maxillary first molars. (Reprinted with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 17. Failed traditional surgical case (A). High magnification of root-end preparation with an isthmus (B). Obturation of root-end in C with SuperEBA shown at 16X magnification. Note elongated root-end filling covering two apices and connecting the isthmus (C). Radiograph immediately after surgery (D) and 1 yr postsurgery (Z), showing complete healing. (Reprinted with permission from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 18. Traditional root-end preparation instruments with burs (top and center) and modern ultrasonic instrument (bottom). (Reprinted with permis- sion from Color Atlas of Microsurgery in Endodontics, by S. Kim with G. Pecora and R. Rubinstein. W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.)

Figure 20. Histological images of root-end preparations in dogteeth by a bur (left) and ultrasonic tip (right). The bur preparation nearly resulted in a lingual perforation, while the ultrasonic preparation preserved the integrity of the root apex because of the co-axial preparation within the root canal.

Figure 19. Microsurgical root-end preparation of a maxillary canine with a KiS #1 ultrasonic diamond coated tip (16x).

Figure 21. MTA root-end filled apex (mesial root) of a dog tooth showed complete healing at 5 months postoperative (left X-rays). The histological pictures show new bone formation at the surgical site (center) and the absence of inflammatory cells (right) , suggesting a complete resolution of the pathology. The distal apex, showing incomplete healing, is filled with SuperEBA (left X-rays).

Figure 22. Histological sections of dog teeth root-end filled with MTA show remarkable bone regeneration (yellow frame). At large magnification (right) numerou: PDL-like projections are seen from the bone toward the MTA filling. From the MTA side, numerous PDL-like projections with fibroblasts forming a columnar patterr are seen (left). The regenerated PDL has the same width of ca 0.38 mm, as a normal PDL. Although additional studies are needed to test wMTA, the pub- lished findings so far indicate that WMTA is comparable to gMTA. The sealing ability was compared using the bacterial leakage test on perforation repair sites. Ferris et al. (101) tested the ability of both types of MTA to seal off the perforation site and showed that there was no significant difference between the two materials. Also a bacterial leak-

Figure 24. Scanning electron microscope images of gray MTA (4), MDPC23 mouse odontoblast cells (B), and cells grown on MTA (C). MDPC23 cells without MTA appear normal, of a round shape and attached to the plate surface (B). MDPC23 cells grown on gray MTA have a flat appearance, showing robust growth, suggesting that MTA may stimulate cell growth. Electron dispersion analysis was used to differentiate cells from MTA by comparing the Ca”* content. than it appears on the radiograph (108). A thorough knowledge of the anatomy of the region, as well as taking angled radiographs are essen- tial. It is also essential that the vertical releasing incision is long enough to expose the mental foramen after a careful dissection. Once the fora- men is identified, a retractor is placed to protect the foramen and under the microscope, a horizontal groove is cut just above the foramen (Fig. 8). Although injuring the nerve is extremely rare, transient parasthesia may occur even if the surgical site is far from the nerve. Inflammatory swelling of the manipulated tissues may cause impingement on the mandibular nerve, resulting in transient ipsilateral paresthesia. Normal sensation generally returns within few weeks. Thus, performing surgery on mandibular posterior teeth should not be of great concern, provided that proper preparations are made. At our institution, there has been no case of permanent parasthesia in more than 450 mandibular molar cases since 1992, when microsurgery was first taught and performed by endodontic graduate students. Generally, the mental foramen is located below and between the apices of the second premolar and the mesiobuccal root of the first molar. More precisely, its most common location is inferior to the crown of the second premolar (62.7%) (107), and it is always larger

Figure 23. The same preparation as in Fig. 22 shows newly generated cemem- tum-like projections covering the MTA. At large magnification (right) a growing cementum-like entity, closely linked to the MTA, can be seen. With time the cementum-like projection will close over the MTA, forming a biologically barrier.

Figure 25. MDPC23 odontoblasts grown on MTA proliferated significantly faster (about 60%) than those in the control. This test was done using the MTT assay.

TABLE 5. Radiographic checkup of resected teeth in the maxillary posterior region (1 = 146) 6—42 months postoperatively

Figure 27. A long-term 8 yr follow-up of a #19 using microsurgical techniques and gray MTA as root-end filling material. Complete radiographical and clinical resolution of the pathology with total absence of symptoms.

TABLE 6. A Summary of Selected Microsurgical Studies

Figure 28. An example of unusual apical anatomy of a #19. The tooth was retreated twice with persistent clinical and radiographical problems. Inspection of the resected root surfaces at high magnification revealed three separate canals in the mesial root and an isthmus in the distal root. The case was performed under strict microsurgical protocol with MTA as the root-end filling material. (Courtesy Dr. G. Guess, La Jolla, CA.)