by Kenneth Koch, DMD, and Dennis Brave, DDS
In our previous two articles, we discussed a number of potential endodontic disasters and how to avoid them. Since our goal is to make your practice stress-free and profitable, let's examine additional situations that can wreak havoc.
In this case, the patient is comfortable ... but you can't find the canals. Generally, this is a result of poor access. Straight-line access is the key to good clinical results. Sometimes, extending access either buccally or lingually allows the dentist to incorporate the missing orifice into the access preparation. Unfortunately, too many practitioners make a small, round hole in the center of the crown, which prevents straight-line access into the canals. They attempt to curve a K-file into the orifice and canal, which doesn't work. This poor access usually prevents the instrument from following the curve, at approximately the 17 mm mark. It will invariably deflect to the side and ledge the canal. Proper straight-line access is absolutely the key to instrumenting curved canals. Remember this axiom: An instrument should curve only once. An instrument that curves upon entrance into an orifice cannot curve again at the 17 or 18 mm point; instead, it deflects to the side. This can create a ledge and lead to further iatrogenic mishaps. Talk about lost time! Do you really need this aggravation? Follow our guidelines and avoid disaster.
Let's turn our attention to another concern - broken instruments and perforations. While neither is a welcome event, they should not be met with dread or fear.
Broken, separated, or "disarticulated" instruments can occur during the day-to-day practice of endodontics. Breaking an instrument is not malpractice; however, failing to inform a patient that a separation has occurred is. You must inform the patient. Here's how to best manage this situation: Calmly inform the patient that, during treatment, a sterile piece of the instrument separated from the file and will be incorporated into the final fill. End of story! If the patient asks the ramifications, reply that the tooth will be re-evaluated at six-,12-, and 24-month intervals - the same as any endodontically treated tooth. A separated file does not mean that the tooth will fail.
Long-term complications following a separation are rare, but can be problematic. If a file separates in the mid or coronal part of the canal, it can often be removed with an ultrasonic. However, rotary instruments will generally separate in the apical 2-3 mm, where they are virtually screwed into the canal.
When a piece of an instrument is lodged in the apical 2-3 mm, it is extremely difficult to remove. A separated rotary file is very different from removing a hand file where the canal or apical constricture might be larger than the file diameter. Attempting to dislodge it can actually destroy the root. Practitioners should try to bypass the instrument, if possible.
Is it really necessary to remove an instrument in the apical 2-3 mm? Carefully evaluate each situation. The process includes determining where the instrument is separated (in the tooth or past the apex), the vitality or nonvitality of the tooth; whether it is symptomatic or asymptomatic, and if the tooth has a radiographic area.
If the tooth is vital and the instrument separated in the apical 2-3 mm, chances are good that it will not be problematic. Obturate the canal and use a little extra sealer, then fill to the separated portion of the file. If the tooth is nonvital or has an area, fill it exactly the same way, but make certain to re-evaluate at six-, 12-, and 24-month intervals. If the tooth is vital and symptomatic, it is less of a concern than if the tooth is nonvital and symptomatic. Even in these cases, it is still important to thoroughly irrigate the canal to the separated portion of the instrument and then fill to that length.
No dentist should have a particular tolerance for broken instruments; however, it is important to know how to treat these incidents and how to explain the situation to the patient. Of course, the best way to avoid a disaster in these cases is through prevention.
Another event that spells disaster for endodontists is the perforation. Perforations generally happen in two situations: difficult patients and geriatric patients. Sometimes, we encounter a difficult patient; we proceed with the case and notice some sensitivity. (Remember the saying, "Bad things happen to bad patients.") The combination of a situation that is difficult to manage, along with less-than-ideal anesthesia, often makes dentists anxious to perform an intrapulpal. In their haste to "see red" and get an effective intrapulpal injection, dentists often go too far and perforate the floor of the chamber. This can rapidly degenerate into an endodontic disaster.
The other common situation is searching for the pulp in an elderly patient and eventually finding red - but it comes from the PDL! Here is another gem: Place your access bur against the preop X-ray to estimate how far you can drill before you reach the chamber.
Perforations do happen - but how do we treat them? Three things are key to perforation repair: time, size, and location.
It is absolutely crucial to repair the perforation as soon as it happens. This applies to both small and large perforations. Do not reappoint the patient!
The second key element is size. Size matters! Obviously, the smaller the perforation, the better the long-term prognosis.
The third key element is location - where did the perforation occur? The more apical the perforation, the better the prognosis. A perforation in the apical third, with a small hand file, can be considered somewhat like an accessory canal. Make certain the canal is clean and then fill in a three-dimensional manner. Although a coronal perforation has a reduced prognosis, the outcome is still usually good. A perforation at the CEJ, however, has a greatly reduced prognosis due to the percolation of oral fluids from the gingival sulcus.
Total disaster can be averted, thanks to materials that can treat the perforation. The best material currently available for this purpose is mineral trioxide aggregate (MTA). This material is superior due to its unsurpassed sealing ability in combination with its biological tolerance. MTA is the only dental material used for perforation repair that does not engender an inflammatory response. If a perforation occurs, seal it with MTA, place a moist cotton ball over the fill, and bring the patient back after four to five hours. The materials require at least this long to set.
Don't panic if a file breaks or a perforation occurs. Prevention is the key, but knowing how to treat these situations and having the confidence to proceed with the remainder of the treatment is the "Real World" maxim.