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Patency and Profound Anesthesia by Richard Mounce, DDS

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When standard anesthetic techniques are not working, you need something more, a “go to” cascading series of alternative techniques to provide profound anesthesia and visual and tactile control over the case. While opinions differ with regard to materials, methods and the time required to create excellent clinical results, the procedure must be executed efficiently. Unnecessary steps and inefficiency are a waste of time and, more importantly, create the environment for clinical and emotional harm. The best clinical events are highly planned, well executed and move in a straight line from the first injection to the placement of the coronal seal.

Profound anesthesia and attainment of patency are the two most vital components of modern endodontic procedures. Master these two foundational components, and a stable platform has been built for the rest of the procedure. Alternatively, less than profound anesthesia leaves the patient uncomfortable, and the clinician twitchy. Never a good combination. A lack of patency is the harbinger of all manner of iatrogenic misadventure.

Of the local anesthetic techniques available for irreversible pulpitis, two techniques have proven indispensible in my hands: the STA Wand (Aseptico) and intraosseous techniques. It provides numerous advantages over a standard syringe. First, a positive aspiration is more definitive with the wand and easier to confirm in the handpiece. It is extremely rare to have an inadvertent intravascular injection. To date, in three years of full time clinical use of the STA, no epinephrine reactions have resulted. Because the injection is much slower than a typical syringe injection and the tactile “feel” of the handpiece is more sensitive, in my experience, there have been no “electric shock” reactions where the needle has grazed the nerve bundle (Fig. 1).

Second, the wand has three injection speeds: extremely slow, very slow and slow. It is simply more comfortable for the patient than a traditional syringe. There is no more-comfortable way to administer local anesthetic. The wand tells you a lot about your patient. For example, if the patient has an exaggerated response to the infiltration of local anesthetic at the slowest speed (four minutes per cartridge) used for initiating injections, you are treating a phobic individual that will be harder to get numb in any case than a patient who is less responsive. Translated, even with profound anesthesia, you are potentially in for a “rougher ride” than someone who tolerates the wand without a blink.

Third, another impressive feature of the wand is the ability to give a PDL injection predictably and comfortably, and without tissue or bone necrosis. Some clinicians do their restorative dentistry with only the PDL injection, which is a valid technique for restorative dentistry, but not useful for the vast majority of endodontic procedures. Having the PDL injection capability clearly reduces the number of intraosseous injections that might otherwise subsequently be required. Again, the tactile control of the wand to give PDL injections is very sensitive and precise.

Fourth, the handpieces are very reasonable in price at just over $2 per cannula. For an irreversibly inflamed lower molar, I use the 27 ga 1 1/4” inch handpiece for the inferior alveolar block, the 27 ga 1” handpiece for a buccal infiltration of articaine and the 30 ga 1/2” handpiece for the PDL injection. Generally, I will use all three injections for irreversibly inflamed lower molar teeth.

In my practice, occasionally I need intraosseous anesthesia. Three methods of providing intraosseous anesthesia are clinically available: the X-tip (DENTSPLY), Stabident (Fairfax Dental) and the Anesto (W&H). In my hands, the X-tip is the most cumbersome, but does have the advantage of a guiding sleeve for needle insertion after cortical perforation. Stabient, with no guide sleeve, is more “bare bones” and finding the entry into cortical bone is slightly more challenging. The Anesto uses the same needle for the cortical perforation as the injection. The Anesto is simple, practical and ergonomic (Fig. 2). Intraosseous anesthesia is discussed in the dental literature and a representative sample of the available articles are referenced here.1-6

Regardless of which intraosseous system one uses, it is important for the clinician to be able to seamlessly move between standard injections to PDL to intraosseous calmly and efficiently.

Profound anesthesia allows immediate and confident canal exploration and negotiation. The method of initial canal negotiation has significant implications for the treatment that follows. If the wrong hand file or too large of a hand file is inserted too forcefully, the canal can become blocked, ledged or otherwise transported quickly and without warning. Many iatrogenic events have, to one degree or another, their source in a lack of straight-line coronal access, lack of adequate canal negotiation and glide path preparation, and inaccuracy in the determination of true working length (TWL). While a comprehensive determination of each of these steps is beyond the scope of this article, using the correct stainless steel hand file, both sequentially and tactilely, is essential for both optimization of negotiation and avoidance of iatrogenic events.

I use only precurved Mani D Finders, Mani K files, and Mani Safe ended K files (Mani SEC O K files) for canal negotiation and glide path creation. D Finders are used for curved and calcified canals. They are stiffer than standard K files. Safe ended K files are especially valuable in canals that are highly curved, apically complex and in which the risk of blockage or iatrogenic events is extreme. Aside from the standard ISO sizes (#6, 8, 10, 15, etc.) I also commonly use medium sizes in the above file types (#12, 17, etc.).

It is noteworthy that stainless steel hand files are a commodity and relatively inexpensive; there is no economy in using them for multiple cases. They lose their sharpness quickly, hence in my hands these are a single use item. For an average case, even one of modest curvature, I will generally use at least three to four packs of Mani hand files, in a severely curved and calcified case, often many more. Mani (Japanese) is a global leader in the dental industry. Mani has excellent manufacturing quality at approximately half the cost of competitive products (Fig. 3).

In vital (irreversibly inflamed) cases, in the initial presence of EDTA gel (ChelCream, MetaBiomed) the orifice is shaped with orifice openers (for example, MounceFile .08/25 Controlled Memory). In non-vital cases, in the initial presence of either ChelCream or sodium hypochlorite, the orifice is similarly shaped. After orifice shaping, the chosen Mani stainless steel hand file is precurved and inserted in every orientation necessary with gentle pressure (watch winding) to make apical progress. Irrigation is copious and frequent throughout negotiation. Irrespective, vital or non vital, starting with a #6 hand file is invaluable because in many cases, if the clinician starts with a larger hand file (#10 or #15, etc.) and cannot make apical progress, they will never know if the canal might have been patent and negotiable with a #6 hand file, if used first.

Once the #6 reaches the estimated working length (EWL) taken from the initial radiographs, the electronic apex locator is used (Foramatron Parkell, iRoot Meta Biomed) to determine the position of the TWL. Using copious amounts of sodium hypochlorite between each hand file, the next larger hand file (#8, #10, #12, #15, #17) is used to the TWL successively until the glide path is prepared, approximately to the size of a #15 or #20 stainless steel hand file.

One useful adjunct for glide path preparation with stainless steel hand files is a reciprocating hand piece (ER-10 NSK, MounceEndo.com). The ER-10 can save minutes per case as it replicates the manual watch winding of stainless steel hand files during glide path preparation. Many clinicians reciprocate safe ended K files for reciprocation as a precaution, although this is an empirical preference. The ER-10 has an E-type coupling that fits on any endodontic motor using this coupling (all corded endodontic motors). I use my ER-10 every tooth, every patient, every day for reciprocation. Along with the STA, it is an indispensible part of my armamentarium (Figs. 4-5).

Once the glide path is created, in my hands, the canal is ready for shaping with nickel titanium in the Controlled Memory (MounceFiles CM, Typhoon CM Clinicians Choice) via either a crown down, step back or hybrid technique (Fig. 6).

Conclusion

I’ve reviewed methods for obtaining profound anesthesia and glide path creation. Emphasis has been placed on moving rapidly to a successful conclusion while avoiding iatrogenic events using needed anesthetic techniques confidently. Once profound anesthesia and straight-line access are obtained, the glide path is created using an increasingly sized sequence of stainless steel hand files starting with a precurved #6, possibly aided by a reciprocating handpiece in the presence of copious irrigation. I welcome your feedback.

References
  1. Med Oral Patol Oral Cir Bucal. 2013 Jan 1;18(1) Root damage induced by intraosseous anesthesia. An in vitro investigation. Graetz C1, et al.
  2. J Am Dent Assoc. 2003 Nov;134(11):1476-84. A comparison of two intraosseous anesthetic techniques in mandibular posterior teeth. Gallatin J1, et al.
  3. Dent Res J (Isfahan). 2013 Mar;10(2):210-3. X-tip intraosseous injection system as a primary anesthesia for irreversible pulpitis of posterior mandibular teeth: A randomized clinical trail. Razavian H1, et al.
  4. J Conserv Dent. 2013 Mar;16(2):162-6. Anesthetic efficacy of X-tip intraosseous injection using 2% lidocaine with 1:80,000 epinephrine in patients with irreversible pulpitis after inferior alveolar nerve block: A clinical study. Verma PK1, et al.
  5. J Endod. 2009 Jan;35(1):15-8. The use of intraosseous anesthesia among endodontists: results of a questionnaire. Bangerter C1, et al.
  6. J Endod. 2012 Apr;38(4):421-5. A prospective randomized trial of different supplementary local anesthetic techniques after failure of inferior alveolar nerve block in patients with irreversible pulpitis in mandibular teeth. Kanaa MD1, et al.
  Author's Bio
Dr. Richard Mounce is in endodontic practice in Rapid City, South Dakota. He has lectured and written globally in the specialty. He owns MounceEndo, LLC, marketing the rotary nickel-titanium MounceFile in Controlled Memory and Standard NiTi. He can be reached at richardmounce@mounceendo.com, www.mounceendo.com or on Twitter @MounceEndo.
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