ENDODONTIC MICROSURGERY: To see better is to do better.

Published: BFUDJ, Volume 5, Number 3, Oct. 2014.

ABSTRACT:

With the advent of Microscopes in endodontics the outcome of surgical endodontics has changed drastically. The endodontic microscope is used from the incision to the root end filling. There is reduced incidence of post operative symptoms when microscope is used during endodontic surgery. This article describes the various differences between the traditional and microsurgical techniques.

Introduction:

 

”It takes twenty years for anything new to really catch on, not because it takes that long to convince the establishment, but because it takes that long for there to be a changeover to people who have grown up with the new idea as being accepted.” ¹

The classic view that endodontic surgery is a last resort is based on past experience with accompanying unsuitable surgical instruments, inadequate vision, frequent postoperative complications, and failures that often resulted in extraction of the tooth. Fortunately, this changed when the microscope, micro instruments, ultrasonic tips, and more biologically acceptable root-end filling materials were introduced in the last decade. These developments marked the beginning of the endodontic microsurgery era that began in the 1990s.²

Indications for Endodontic Microsurgery:¹⁴

Indications for microsurgery when nonsurgical endodontics has been unsuccessful are clear in many situations. For instance:

1. Adequately executed endodontics but failed with a persistent periapical radiolucent lesion.

2. Adequately executed endodontics with constant pain with or without swelling.

3. Apical transportation, ledges and other iatrogenic problems with persistent pathology and symptoms.

4. Tooth with a large post and crown restoration completed, especially maxillary anterior teeth.

5. Calcified canals with or without symptoms and periapical radiolucency.

6. Broken instrument in apical half of the root.

7. Failed traditional surgery.

8. Overfilled canal with periapical radiolucency.

9. Complex/compound apical curvatures that are inaccessible from an orthograde approach.

Differences between traditional and microsurgical approaches:²

Although the basic principles of endodontic surgery have not been dramatically changed, advances in armamentarium and micro techniques have attempted to keep pace with the demands of today’s endodontic microsurgical environment: greater ergonomic flexibility, more efficient preparation and placement of the root end filling (REF), and more biocompatibility of the materials used.³

	TRADITIONAL	MICROSURGERY
OSTEOTOMY SIZE	Approx. 8-10mm	3-4mm
BEVEL ANGLE DEGREE	45-65 degree	0-10 degree
INSPECTION OF RESECTED ROOT SURFACE	None	Always
ISTHMUS IDENTIFICATION AND TREATMENT	Impossible	Always
RETRO-PREPARATION	Seldom inside canal	Always within canal
RETRO-PREPARATION INSTRUMENT	Bur	Ultrasonic tips
RETRO-FILLING MATERIAL	Amalgam	MTA / super-EBA
SUTURES	4x0 silk	5x0, 6x0 monofilament
SUTURE REMOVAL	7 days post op	2-3 days post op
HEALING SUCCESS (OVER 1 YEAR)	40-90 %	85-96.8%

ANESTHESIA AND HEMOSTASIS:

The main purpose of anesthetics in clinical dentistry, in particular endodontics, is for local anesthesia. In endodontic surgery, however, local anesthesia has two distinct purposes: anesthesia and hemostasis.

The administration of a long-acting anesthetic agent such as bupivacaine as a block technique to obtain a sustained level of anesthesia beyond the duration of the surgery. In studies examining the effectiveness of lidocaine versus bupivacaine, it was shown that lidocaine was faster in onset of lip numbness while bupivacaine resulted in longer duration.⁸

A high concentration of vasoconstrictor containing anesthetic, e.g. 1:50,000 epinephrine, is preferred to obtain effective vasoconstriction for lasting hemostasis ^{4, 5, 6.} Because a higher concentration of epinephrine is used, there is a concern as to its effects on the systemic circulation⁷.

FLAP DESIGN: ⁹

Using microsurgical scalpel blades under the microscope even at minimum magnification, the surgeon can make a very precise incision with minimum damage to the soft tissue.

If enough attached gingiva is present, the mucogingival incision is preferable, in order to preserve the existing epithelial attachment. If there is limited attached gingiva or if there are short roots or large periapical lesions, the flap of choice is the triangular or rectangular flap with sulcular incision.

In both flaps, the elevation must be undermined, to reduce the trauma to the soft tissue: the elevation begins at the vertical releasing incision and continues to the coronal margins in an apical-coronal direction. The mucogingival incision is scalloped, to facilitate reapproximation.

ERGONOMICS AND POSITIONING (PATIENT/SURGEON):

One of the most frustrating aspects of microscopic surgery is the correct positioning of the DOM relative to the patient and operative field. Indeed, a recent survey indicated almost 77% of those responding claimed some difficulty in access and visualization using the operating microscope. ¹⁰

To begin, the patient is positioned in a supine to slightly Trendelenberg attitude so that the surgical osteotomy site is most superior in the operating field.The surgeon then takes position at the head of the patient, the 11 to 12 O’clock orientation. The patient’s chair is then raised or lowered so that the surgeon can maintain his or her elbows close to his body, passively bent at a neutral 90 degree.³

After Flap retraction is complete and stable, the patient is readjusted so that the cortical plate/tooth long axis of the surgical site is parallel to the floor and most superior in the field.³

ROOT END RESECTION:

The carpenters’ axiom of ‘‘measure twice, cut once’’ has great significance, as root structure cannot be replaced once it has been removed, so careful consideration must be given to the length and angle of the resection process.³

As the accompanying diagram shows, a resection level of 3 mm from the anatomic apex will eliminate 93% of lateral canals and 98% of any other ramifications such as deltas, fins, and so forth.2 Coupled with a root end preparation depth of 3 mm, 6mm of infectious etiology in the canal space will have been effectively treated.

BEVEL:

Before the introduction of the microscope, resected root ends were routinely beveled to enable the surgeon to visualize the resected surface(s). The root tip should be resected with little or no bevel.¹²

Gilheaney and colleagues¹³ in 1994 concluded that: (1) the amount of leakage increased as the slope of the bevel increased; (2) increasing the depth of the retrograde filling decreased the microleakage; and (3) optimum/ minimum depths for the retrogrades were as follows:

 0 degree = 1 mm, 

30 degree = 2.1 mm, 

45 degree = 2.5 mm.

ROOT END PREPARATION:

More effective microsurgical root-end preparations have been made possible by specially designed ultrasonic tips that permit accurate preparation along the long axis of the root canal without blocking visibility during preparation. This technique permits the placement of root-end fillings in the proper position to seal the root canal as well as a sufficient filling depth (3mm) or thickness to effectively seal the canal, dentinal tubules and accessory canals that may be present.¹³ A minimum of 3mm preparation depth is needed to prevent leakage, therefore the ideal ultrasonic tip length is 3mm long, such as the KiS tip. ¹⁴

ROOT END FILLING:

An ultrasonically prepared 3mm class I cavity preparation must be filled with a material that guarantees a hermetic seal. Although every restorative material has been used, at one time or another, as a Root end filling, selection today’s is predicated on whether it is contained within a root end preparation (REP) or not. For situations whereby a REP can be created, the material of choice is Mineral Trioxide Aggregate (MTA). This compound is easy to mix, not cumbersome to place, and extremely biocompatible.^15-21

SUTURING/CLOSURE:

After the site has been cleansed of all debris, the underside of the flap(s) is gently rinsed with sterile saline and co apted back to the original positions. The flap is secured with either interrupted or sling sutures; the choice of type and size is dictated by the flap design and retention requirements.³

SUMMARY:

Endodontic surgery has evolved into endodontic microsurgery. By using state-of-the-art equipment, instruments, and materials that match biological concepts with clinical practice, endodontic surgeons are able to render a level of service with confidence and great precision that 20 years ago would have seemed unattainable by any standard.²² With continued education of the patient population and referring dentists, endodontic microsurgery should be a predictable and viable altenative for saving teeth.

REFERENCES:

      1.       Shelton M. Working in a very small place; the making of a neurosurgeon. New York: W.W. Norton & Company; 1989. p. 91–3.

      2.       Syngcuk Kim and Samuel Kratchman. Modern Endodontic Surgery Concepts and Practice: A Review. JOE — Volume 32, Number 7, July 2006.

      3.       Stephen P. Niemczyk.Essentials of Endodontic Microsurgery. Dent Clin N Am 54 (2010) 375–399.

      4.      Kim S, Pecora G, Rubinstein R. Comparison of traditional and microsurgery in endodontics. In: Kim S, Pecora G, Rubinstein R, eds. Color atlas of microsurgery in endodontics. Philadelphia: W.B. Saunders, 2001:5–11.

      5.       Buckley JA, Ciancio SG, McMullen JA. Efficacy of epinephrine concentration on local anesthesia during periodontal surgery. J Periodontol 1984;55:653–7.

      6.       Gutmann JL. Parameters of achieving quality anesthesia and hemostasis in surgical endodontics. Anesth Pain Control Dent 1993;2:223– 6.

      7.       Troullos ES, Goldstein DS, Hargreaves KM, Dionne RA. Plasma epinephrine levels and cardiovascular response to high administered doses of epinephrine contained in local anesthesia. Anesth Prog 1987;34:10 –3.

      8.       Hargreaves KM, Khan A. Surgical preparation: anesthesia and hemostasis. Endodontic Topics 2005;11:32–55.

      9.       Arnaldo castellucci. Advances in surgical endodontics. L’informatore Endodontico, 2003. vol. 6, no. 1.

     10.    Creasy JE, Mines P, Sweet M. Surgical trends among endodontists: the results of a web-based survey. J Endod 2009;35:30.

     11.    Kim S., G. Pecora and R. Rubinstein. Color Atlas of Microsurgery in Endodontics, W.B. Saunders Co., A Harcourt Health Sciences Company, 2001.

     12.    European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. International Endodontic Journal, 39, 921–930, 2006.

     13.    Gilheany PA, Figdor D, Tyas MJ. Apical dentin permeability and microleakage associated with root end resection and retrograde filling. J Endod 1994;20:22–6.

     14.    American Association of Endodontists. Contemporary Endodontic Microsurgery:Procedural Advancements and Treatment Planning Considerations. Endodontics: Colleagues for Excellence. Fall 2010.

     15.    Torabinejad M, Pitt Ford TR, McKendry DJ, et al. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endod 1997;23:225.

     16.    Chong BS, Pitt Ford TR, Hudson MB. A prospective clinical study of mineral trioxide aggregate and IRM when used as root-end filling materials in endodontic surgery. Int Endod J 2003;36(8):520–6.

     17.    Bernab_e PF, Gomes-Filho JE, Rocha WC, et al. Histological evaluation of MTA as a root-end filling material. Int Endod J 2007;40(10):758–65.

     18.    Holland R, de Souza V, Nery J, et al. Reaction of dogs’ teeth to root canal filling with Mineral Trioxide Aggregate or a Glass Ionomer sealer. J Endod 1999;25:728.

     19.    Lindeboom JA, Frenken JW, Kroon FH, et al. A comparative prospective randomized clinical study of MTA and IRM as root-end filling materials in single-rooted teeth in endodontic surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100(4):495–500.

     20.    Saunders WP. A prospective clinical study of periradicular surgery using mineral trioxide aggregate as a root-end filling. J Endod 2008;34(6):660–5.

     21.    Camilleri J, Montesin FE, Papaioannou S, et al. Biocompatibility of two commercial forms of mineral trioxide aggregate. Int Endod J 2004;37:699.

     22.     Kratchman,S.I. Endodontic Microsurgery. Compendium, July 2007;28(7):399-406 

     

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