Replacing Luck, or Finding the Occasional Acorn in Endodontics: The Choice Is Yours

Dentistry Today


Suunto brand scuba diving computers have as their slogan, “Replacing Luck.” Anyone who has ever been involved in scuba diving beyond certification can or should appreciate the need for a dive computer to track one’s decompression profile. Interestingly, the more experienced the diver and certainly the more technical the dive, it is common see people carry up to 3 computers and carry out dive planning in the most conservative manner possible. Doing so can maximize all safety variables and minimize the chances of decompression illness. Divers taking these precautions are “replacing luck” in every way possible.
In clinical endodontics, strategies and equipment can allow the clinician to also replace luck and to make excellent results more predictable. At any given point in treatment, there is most often one single best way to proceed, especially when something untoward may have occurred. The converse is also true. Certain approaches and mentalities to endodontic treatment carry with them a high risk of accident if optimal equipment, techniques, and methodologies are not observed. In my endodontic residency, we had a saying: “Even the blind squirrel finds the occasional acorn.” Translated, this meant, “I got lucky.” While this is a joy for the blind squirrel, merely hoping that an endodontic outcome will be predictable is obviously ill-advised.
This paper was written to provide 7 strategies that are consistent with excellent endodontic results and 7 that are the harbingers of untoward outcomes.

Strategies that rely upon luck

1. Only taking one angle of radiograph before beginning, or not taking any radiographs. Using a digital radiography program like the DEXIS digital x-ray system (DEXIS) allows the clinician to take multiple views for the particular case to fully map out the anatomy before starting. Digital radiographs are taken in an environmentally sustainable manner at reduced radiation, an unbeatable combination. A single paper film severely limits the amount of information available to the clinician before starting. Using digital radiography in the form of a program like DEXIS provides a user-friendly platform to provide an image that can be manipulated, and as such give optimal diagnostic information at any stage.

Figure 1. Clinical case with multiple risk factors. Referral indicated.

2. Believing that you can start anything and always refer later. As a general practitioner, starting every case that may present itself irrespective of its risk factors is relying heavily on luck. Teeth and, more importantly, patient relationships are very rarely in better condition than if they had been started and completed in the best possible environment from the beginning (a patient who has given consent, whose medical and dental history has been fully evaluated, a tooth that has been carefully studied to evaluate possible risk factors during treatment, etc). A wise person once said, “Think very hard, do very little surgery,” which is akin to the construction mantra, “measure twice, cut once.” The wisdom transfers to endodontics; it is far better to refer than lose the patient and his or her trust by attempting to treat cases that are beyond the clinician’s resources, for whatever reason (Figure 1).
Trying to remove separated files, repair perforations, treat open apices or resorption, perform complex retreatment, and other advanced clinical entities such as apical surgery without the skills, equipment, training, experience, and time needed to do them to the highest level is always counterproductive. Recently, I saw a patient who had had a horizontal incision made at the apex of a lower second bicuspid. It had been made by a clinician who intended to curette out an apical lesion. The tooth had been accessed several times and left open without resolution of the patient’s pain. The attempted curettage lead to the patient saying she experienced a pain during the process that was so intense and so challenging that she almost passed out. It resulted in a numb lower lip over the distribution of the mental nerve. Clearly, the “lesion” observed was the mental foramen, and the clinician had actually attempted to curette out the mental nerve as it exited the mental foramen. Very fortunately for this patient and the doctor, the sensation returned and no blood vessels were cut.
As an experienced endodontist, I occasionally may wish to refer cases (surgery that requires IV sedation) for various reasons, and do so. An honest evaluation with oneself to give the patient the best possible service is always advised.

Figure 2. Gross and unnecessary extrusion of sealer caused by lack of apical control and inappropriate methods of introduction.

3. Relying on unproven materials and empirical strategies not validated by the endodontic literature is simply dangerous. Paste root canal fillings, blowing air into canals to dislodge obstructions, violation of basic surgical principles, etc, all certainly have the possibilities for significant morbidity.
Once, at a continuing education class I was giving, I had a clinician argue that it was acceptable to use 7 cartridges of articaine for a lower mandibular block on a given patient at a single appointment. At another course, I had a clinician recommend locking the irrigating syringe tip at the apex and under pressure forcing hydrogen peroxide through teeth with fistulas so that the peroxide would exit the fistula to heal it. I have visited an office where cartridges of anesthetic were kept in the cold, sterile solution so that the unused cartridges that had come off the tray of a previous patient could be used for a subsequent one. Obviously, all these practices are not only unproven and ill-advised, but they carry extreme risk and cannot be defended (Figure 2).

Figure 3. Skini Syringe (amber color) pictured with PermaFlo flowable composite for bonding the pulp chamber.

4. Ignoring the vital importance of coronal seal in endodontics. While a future, separate article in Dentistry Today will be devoted to this subject, I have begun to routinely place approximately 3 mm of PermaFlo (Ultradent Products) into the coronal orifices of canals in either a pink or purple variety. Under a surgical operating microscope (SOM), placing PermaFlo is simple and easy with a Skini syringe and Navi tip (Ultradent Products; Figure 3). All too often throughout my career, I have treated a case with gutta-percha, a cotton pellet, and a temporary filling, and at some later time the patient returns with the temporary having fallen out and the tooth either fractured or in need of retreatment due to leakage. Placing a flowable composite into the coronal orifice under the rubber dam and under the SOM gives the clinician complete control of material placement and eliminates one of the most significant modes of endodontic failure, and does so predictably. If an endodontist fills the orifices in this manner, it still allows the general practitioner to place the buildup as desired. Coverage of the orifices allows the endodontist to protect the root canal should the patient not get the tooth properly restored, for whatever reason. The endodontic literature is absolutely clear that the placement of a coronal seal protects the canals from microleakage and is a variable that increases clinical success. The above notwithstanding, ideally, the buildup should be placed at the time of completion of the RCT under a rubber dam and under visualization provided by the SOM, irrespective of whether the RCT is done by an endodontist or general dentist.
5. Delaying treatment when it is clearly indicated. Many patients have arrived at my office over the years who have been in pain for a period of days to weeks with clear and unmistakable signs of pulpal pathology. In almost every case of irreversible pulpitis, for example, patients will say something akin to, “My doctor couldn’t find anything on the x-ray,” or that their tooth was hurting and the doctor decided to put a crown on the tooth so the symptoms would go away. If the patient has lingering pain to hot or cold, localized spontaneous pain, or sensitivity to chewing in combination with the other symptoms, the patient needs a root canal. The irreversible pulpitis condition is not visible on radiographs. Delayed treatment because of a radiograph, in the presence of symptoms, can diminish trust, especially when the patient sees another doctor who diagnoses the problem immediately, correctly, and relieves pain through efficient root canal treatment.

6. Making speed and profitability the guiding philosophy of endodontic treatment. Not using a rubber dam, not ensuring that the patient is profoundly numb prior to making access, skipping steps at any level in the procedure (a lack of irrigation, recapitulation, glide path creation, etc) all are the precursors to iatrogenic events and subsequent diminished clinical success. One can be very adroit at endodontics or very fast, but one cannot reliably be both. The most skilled endodontists I know and trust generally attempt to do at most 4 cases in a given day, and I would echo their attempted production as optimal. While all endodontists are different, this case level on average would allow the clinician to approach each case in a focused and fully alert manner, treating one person at a time. Given everything there is to do correctly—testing anesthesia, rubber dam placement, achievement and maintenance of patency, etc—it is difficult to envision doing more than this at the very highest level of care.

7. Neglecting to allow enough time for proper treatment. The issue in many iatrogenic events is not bad luck or lack of skill; it is lack of time. A shortage of time and rushing treatment, especially with difficult patients, is a prime factor in keeping the clinician from achieving the results of which he or she is capable. Especially with challenging patients, there can be a natural inclination to hurry treatment. Resisting this tendency and simply taking the time or breaking the treatment into the needed number of visits to do it right (or referring) is a proven strategy to achieve solid clinical results. Trying to save time through skipping steps is always unprofitable. There are no shortcuts to an excellent result.


Figure 4. The Elements Diagnostic Unit.

1. Know where you are within the root canal system at all times. During file advancement, increased tactile resistance is generally encountered apically. Interpreting the increased resistance with regard to position in the canal is essential. Negotiation of the canal down to the minor constriction (MC) of the apical foramen and a subsequent accurate assessment of its exact position can go far toward providing excellence in cleaning, shaping, and obturation. The MC represents the point at which all irrigation/instrumentation/ irrigation should cease. Other than patency files to ensure that the canal is left open and negotiable through its terminus, this vital landmark is left at its original position and size. The MC is the natural barrier toward which all endodontic procedures are focused. The value of its correct location and management cannot be overstated. Instrumentation carried out short of or beyond this landmark is the origin of many iatrogenic events (debris collection, ledging, instrument separation, etc). As a result, use of an apex locator in every case, in my empirical opinion, is the standard of care. I am an advocate of the Elements Diagnostic Unit (SybronEndo) for its state-of-the-art electronics and stability in obtaining a reading. As the file advances apically, the digital readout can literally be used to dial in the position of the MC (Figure 4).
The true working length (TWL) as provided by an apex locator is confirmed by multiple means (possibly a bleeding or moisture point at the MC, radiographic means, tactile sensation, a preoperative estimate of the TWL, etc). An initial estimated working length (EWL) should be derived from the initial radiographs. The TWL, once determined, should be very close (within 1 mm) of the EWL. No single measure of TWL is used with blind faith.

Figure 5. DiaLUX fiber-optic transilluminator.

2. Get a surgical operating microscope; there is no substitute for its capabilities. I use my SOM for every patient, every tooth, and throughout every procedure from the access to the placement of the coronal seal. The SOM also doubles as my overhead light source in the operatory. At every level of every procedure, the visualization and magnification the SOM provides is unparalled. I use the Global SOM (Global Surgical) for its excellent optics, reasonable cost, modular and efficient design, reliability, and service. In my career, I have bought numerous Global Surgical SOMs, and all have performed well. Other than possibly expanding these instruments with video cameras, assistants’ viewing ports, etc as desired, these instruments require no maintenance. Cost and inertia are usually the 2 biggest reasons that clinicians shy away from making the investment needed to bring the SOM into their operatory. The higher standard to which procedures can be performed under the SOM creates a far greater long-term profitability relative to any up-front costs. Using an accessory light source such as the DiaLUX (KaVo) to examine the tooth for coronal fractures and caries can give even greater illumination under the SOM (Figure 5).

Figures 6 and 7. The Endo-Bender pliers (top) and hand files modified by snipping their ends.

3. Get a pair of EndoBender pliers (SybronEndo) and habitually precurve hand files before use in gaining patency at all stages of canal negotiation. Learn to snip hand files 1 to 2 mm at a time from their tips to make them stiffer and improve the tactile control over the file end during exploration. I will take 1 to 2 mm off the tip of 21-mm hand Nos. 6, 8, and 10 (case dependent) in a given canal until an ideal tactile control and sense can be gained over the given obstruction or canal anatomy. In my hands 25-mm hand files are too long for all but the very longest roots in negotiation, as my tactile control is diminished. Such modified and customized hand files can help bypass obstructions and ledges, and negotiate calcified canals that otherwise might not be negotiable (Figures 6 and 7).
In canal negotiation, with or without modified hand files, which hand files are used is secondary to how they are used. Generally in canal negotiation—especially in calcified canals and bypassing obstructions like silver cones, warm carrier-based products, and ledges—the stiffer the file the better, as long as the file is used with passive intention and does not exacerbate an iatrogenic issue, should one already exist. The value of using hand files extensively first to set the stage for rotary Ni-Ti (RNT) use cannot be overstated. Irrespective of the brand, using RNT files as pathfinders without first opening canals to the needed minimal diameter (usually a No. 15 hand K-file) is highly likely to cause instrument fracture, ledged canals, debris blockages, etc, and is contraindicated.

Figure 8. The Elements Obturation unit.

4. Have a backup plan for achieving a given clinical objective instead of just one way to accomplish a given clinical goal. In obturation, for example, having just one method of filling canals is problematic, as one size does not fit all. A technique like SystemB is universal in that if one has the skills and equipment to perform this well, it is a simple matter to expand the technique to fit various clinical indications. For example, SystemB can be adapted into a classic warm vertical technique, cold lateral placement of points, followed by a warm down-pack, etc. In essence, the SystemB technique and its attendant equipment (SystemB heat source, Elements Obturation unit [both SybronEndo]) give the clinician a wide range of options to allow various canal configurations and prepared canal anatomy to be obturated in 3 dimensions (Figure 8). Conversely, having just one method to fill canals is very limiting. For example, in placing warm carrier-based products, a limitation in access to a difficult canal (an upper second molar mesial-buccal canal in a patient with limited opening) can make carrier placement challenging. Having additional methods at the ready can give options to fit the clinical indications. In addition, relying just on cold lateral condensation or a cold single-cone technique will translate into a reliance on sealer to take up all the space within the canal that is not filled by the cones. Predictable dispersion of sealer in these scenarios is wishful.

5. Treatment is only initiated when a thorough history and clinical examination has been performed and the patient’s symptoms reproduced. When in doubt, a second opinion is sought.

6. Know your equipment, materials, and methods. Practice frequently in extracted teeth. Irrespective of the instrumentation or obturation system, it is enlightening to prepare canals on extracted teeth, section the canals either in cross-section or longitudinally, and evaluate the amount of debris left, whether the canal has been transported, how much of the canal wall has been left untouched, if voids are present, etc. Spending time with hand files in extracted teeth in the manner described above has value for becoming familiar with their use to achieve patency. Such practice can educate and troubleshoot potential iatrogenic events that might occur in a live patient. This in vitro practice is especially important when trying to integrate a new RNT file system into the flow of daily practice. Frequently inspect your RNT files for evidence of wear and any defects, and if these are observed, they should be immediately discarded.

Figures 9 and 10. Clinical cases performed with the key principles advocated in this article.

7. Treat patients like they were your parents or most cherished loved one. It is the straightest path to excellent results and satisfaction with one’s practice life (Figures 9 to 10).


As a diver, I wear at least 2 computers, and often 3, on technical dives. Novice divers have looked at me a little strangely at times, but the experienced divers are also carrying 2 to 3 computers. When accidents happen, knowing how to use the computer when it matters and having backup in the case of a faulty computer can prevent significant injury. In endodontics, we can also cover ourselves to the greatest extent possible with utilizing proven strategies, ultimately with the goal of “replacing luck.”

Dr. Mounce lectures globally and is widely published. He is in private practice in endodontics in Vancouver, Wash. Among other appointments he is the endodontic consultant for the Belau National Hospital Dental Clinic in the Republic of Palau, Koror, Palau (Micronesia). He can be reached at