Click here to enlarge imageWe hold these truths ...
Instruments shape, irrigants clean. This adage is absolutely true and is as applicable today as it was 30 years ago. The key to endodontic success is thorough debridement of the root canal system. The key to thorough debridement is proper irrigation. Instruments shape the canal to let the bleach work effectively. The introduction of the crown-down technique, along with rotary files that allow dentists to create a tapered preparation, has made thorough debridement available to all practitioners. We prefer a continuously tapered .06 preparation, which allows the irrigation agent to work most effectively. Additionally, a .06 preparation allows the primary cone fit to be a straightforward, easy procedure.
Always follow the dentinal map. This "gem" is a great tip when trying to locate canals. Finding canals can be very challenging and, at times, you may feel lost in the tooth. This is the time to follow the dentinal map. Have you ever noticed the thin, dark lines on the floor of the chamber? This is what we refer to as the dentinal map. The lines lead to orifices that naturally take you to the occluded canal. So, the next time you are having problems locating a canal, find the dentinal map and trace the lines until you reach an orifice. A good instrument to use when tracing the map (and searching for canals) is a Stewart probe (Premier). This probe is specifically designed to get into these calcified canals. It is both strong and very sharp.
Always trace a fistula. Diagnosis is the most difficult aspect of endodontics. If you see a fistula (or sinus tract), always trace it with a gutta percha point. Generally, you can use a no. 35 cone or a fine-medium accessory point. Place the gutta percha point into the fistula and gently advance it until it stops. This is atraumatic to the patient. Sever the end of the gutta percha cone so that only a modest amount remains outside the fistula. This prevents the patient's lips from dislodging the cone. Leave enough cone so that it does not get sucked into the fistula. Take a radiograph of the cone in the fistula. The X-ray will demonstrate the cone taking you to the "source" of the lesion. This is very important. The source of the lesion will let you know what tooth is involved and whether it is perio or endo. One last thing: Remember to remove the cone from the fistula before you dismiss the patient!
Take the X-ray before breaking the instrument. The best way to avoid separation is through prevention. Failure to understand the true anatomy of the tooth is one of the most common ways to break a rotary file. Canals that come together, or bifurcated canals, can be a major source of separated instruments. A good, angled pre-op X-ray will help you determine whether the tooth has troublesome anatomy. Angled X-rays (15-20 degrees) give you far more information than "straight-on" shots. Look for ligaments and canals that suddenly stop. Knowing the true shape of the canal will keep you out of trouble!
Bad things happen to bad patients. This is absolutely true! This is because management demands sometimes overwhelm clinical judgment. For example, pulpal floor perforations occur most commonly in geriatric patients and difficult people. With geriatric cases, the pulp chamber has receded and the canals are especially difficult to find. However, the difficult patient is different. Generally, they are "still feeling something" and are in distress. In your haste to get sufficient anesthesia, you make an access with a round bur. Unfortunately, it is not into the pulp chamber but through the floor of the tooth. To prevent this nightmare, keep your wits about you when treating difficult patients and be certain to obtain sufficient anesthesia. We suggest that all clinicians performing molar endodontics be familiar with intraosseous anesthesia. Two popular systems are the Stabident System (Fairfax Dental) and the X-Tip. Intraosseous anesthesia can be a tremendous help with difficult patients.
Debunking the myths
"It's calcified." This is an endodontic cop-out! There is a tendency to dismiss as calcified those cases where you don't want to spend the necessary time to get to length, or where you have ledged or blocked yourself out. The truth is calcification normally occurs from the coronal down to the apical. Once you have passed the coronal calcification, the canal is patent. Many times what feels like "calcification" is actually a severe curve or bifurcated canal. The one instance where we "buy" apical calcification is in those cases of long-standing periodontal disease. Normally, the term "calcification" is an excuse.
Placing pulp caps on teeth prepared for crowns. Get real! Pulp caps can do well on young people because of their increased pulpal vascularity. However, the three-year success rate of pulp caps on permanent teeth is very low. If you are prepping a tooth for a crown and you get an exposure, do the root canal. With today's rotary instruments, you can do the root canal quickly and properly. Patients are seldom ecstatic when they learn that their treatment plan just increased by a few hundred dollars. But they do understand when you tell them you have to do the root canal now, to avoid going through their new crown at a later date!
Always leave a draining tooth open. The problem word is "always." "Sometimes" might actually make this myth true. We generally try to close all teeth when doing multiple-visit endodontics. However, if a tooth continues to drain, have the patient sit in the chair for 15 minutes using warm salt-water rinses. Place a quarter teaspoon of salt in an eight-ounce glass of warm water. The patient should rinse repeatedly with the solution, which will draw out the purulence. Once the drainage stops, you can close the tooth. The only time we would leave a tooth open is if we can't stop the drainage. In these cases, place a large cotton ball in the chamber (to prevent the entry of food) and place the patient on a regimen of rinsing 15 minutes every hour. Prescribe a course of antibiotics and see the patient within 48 hours. Try to close the tooth as soon as possible.
All endodontically treated teeth need a post and core. This is one of the most popular myths. The weakening of a tooth following a root canal is due not to dehydration, but rather the access preparation. The problem with this myth is that posts do not strengthen teeth — they weaken teeth! The purpose of a post is to retain the core. An alternative is an intracanal buildup. Remove four to five millimeters of gutta percha from the palatal canal and take out two millimeters from the buccal canals. Condense a core material such as Herculite (Kerr) or Ti-core (EDS) into the preparation. An intracanal core buildup is far kinder to the tooth than a post and core. These buildups work very well. Another key component of the restoration of endodontically treated teeth is the ferrule effect. This basically means that the final crown margins should be on natural tooth structure, not core material. At times, a crown lengthening procedure may be indicated to achieve this requirement.
Hopefully, we have cleared the fog surrounding these truths and myths. Next month, we will introduce some new endodontic products that may have a profound effect on your practice.
Drs. Kenneth Koch and Dennis Brave will present "Read World Endo" on February 14 during the Cosmetic Dentistry 2002 conference in Las Vegas.
