I Just Broke a File – Now What?

You Just Broke a File – Now What?


Separated files, busted files, broken files, and my all time favorite “Disarticulated files” (Do files actually “articulate”?!) all mean the same thing – part of the instrument has fractured off in the canal space. If you do endodontics, you know the feeling. You remove that last file and all of a sudden it is shorter than it was when it was inserted. Your heart races, your stomach churns and the perspiration starts. You pick up the endo ruler and gingerly measure just how much of the instrument has been “eaten” by the canal. You shake your head. You may even curse (under your breath). All the while, you try to formulate a way to tell you patient that things haven’t gone “exactly as planned”. This month’s EndoFiles Fax deals with the anxiety of “file separation”. Don’t panic, things are not always as bad as they first appear.

File breakage is a fact of life. Are you going to break the tips of .06s .08s and an occasional .10? Yes. And if anyone says they don’t, they’re either: (1) lying, (2) they don’t do much endo on anything other than “easy” anteior teeth or (3) they’ve never tried to negotiate into multiple foramina or lateral canals – especially on molars and in elderly patients. Those small fragments don’t usually cause too much of a problem, it’s the bigger fragments that cause most of the headaches. Ni Ti rotary files have been engineered with greater flexibility than stainless steel but they can break too – even at $10 a piece. Bu they need to be used wet. NEVER use them dry. Always use them with NaOCL in combination with a lubricant. Many preparations are available: RC Prep, Slide, Glide, File-Eze, ProLube are all examples that can be purchased through suppliers. These files should also be cleaned often and not allowed to accumulate debris in the flutes that increases friction. There is no such thing as too much irrigation.

Manufacturer’s defects are also a factor that must be considered. Instrument technology has produced some remarkably flexible instruments but these defects do occur and some clinicians have suggested that they play a much greater role in file breakage than we may have initially thought. When you think about it, how much can you expect from a stainless steel file that costs about $1 or 2 US each to purchase? Microfractures created during the manufacturing process can propagate when the file is put under stress and can cause file breakage, even in a brand new file. When you consider purchasing the “El cheapo”, gray market or No Name brand of file, remember: You get what you pay for. Is it worth it when you’re working on that critical abutment?

OK the file just broke in the canal – Now what do you do?

1. Where is the fragment?
Locate the file fragment visually and/or on a radiograph. What is the position of the file? Can you see it from the access? Files located in the straight or cervical portions of canals can often be seen visually (with high levels of magnification such as an SOM) and have a reasonable chance of being removed without compromising the root dentin. Files broken past curves of the root often cannot be seen visually (even with a scope) and frequently cannot be removed because of lack of direct vision.

2. Risks vs. Benefits
Whenever we consider whether to attempt removal of a broken file, we always have to keep in mind that there will likely be compromise of root dentin (at least to some extent) during removal attempts and possibility of perforation or eventual root fracture. This is especially true with thin or very curved roots (eg./ mandibular molars.) The cost/benefit ratio has to be constantly kept in mind. Is a surgical alternative more feasible or desirable? (Especially in anterior teeth) In the case of a tooth with easy surgical access to the apex (a very curved s shaped maxillary lateral incisor, for example), it may be better to treat the case surgically. The canal is treated conventionally to the point of the file breakage and then a minimal surgical resection and retrofill is performed to ensure apical seal. Once the apex is resected, the file fragment can often be removed during ultrasonic retropreparation (from the apex). It is sometimes a better choice to sacrifice a bit of resected apical dentin rather than risk strip perforation or dentin compromise during attempted instrument removal in a conventional manner. This is especially true with critical abutments and thin roots.

3. Do You have enough magnification?
File removal requires high levels of magnification -most often with a surgical operating microscope. Using engine driven instruments blind is a sure way to ruin your chances of salvaging the tooth. I cannot emphasize this too strongly; loupes are NOT enough magnification – in all but the easiest cases. You have to be able to see what you are doing deep inside the tooth – and that most often means a scope. Ultrasonics have revolutionized our ability to work very far into the canal space- almost to the apex in many cases. Small, Titanium tips of varying lengths (Such the CPR (Spartan) Carr (EIE) and ProUltra (Tulsa) series) allow us to see along side the ultrasonic instrument while we remove small amounts of dentin and/or attempt to dislodge the broken file. That is not possible when using a contra-angle handpiece because the handpiece blocks our view (even when using surgical length or Mueller burs). In this situation, a good Ultrasonic unit, high magnification and VERY high levels of canal illumination are absolutely essential. Headlamps are often not enough, especially when using a mirror to see the canal.

4. Vital or Non-vital case
Surprisingly little research has been performed on the effects of leaving file fragments in the canal space. The minimal research that has been performed suggests that it does not affect the prognosis in many cases. (Crump and Natkin JADA 1970). More recent in vitro dye study research (Saunders, Eleazer et al JOE 30:3: 177-179 March 2004) suggested that:
(a) separated instruments do not play a large role in sealing ability of the obturation material and
(b) success might be more affected by lack of coronal seal and residual apical irritants present beyond the level of the broken instrument. But this was an “in vitro” study and it might not be clinically relevant.

The general consensus appears to be that file breakage in vital cases seems to result in better outcomes than in non-vital cases but this empirical opinion is not supported by any published research, to my knowledge. Obviously, if there is sterile tissue apical to the file, it is reasonable to assume that there is less of chance that the case will become symptomatic compared to those cases with infected, bacteria filled canals. The determining factor (as with all endodontic cases) appears to be the critical “threshold” of bacterial reduction. If enough of the canal has been cleaned then perhaps the bacteria level has been reduced to the point where a few mms of unfilled canal might not matter- IF the file fragment and rest of the canal seal the coronal aspect of the canal system. (Emphasis mine- ed.) However, we all have cases that appear to be well cleaned and filled (radiographically) yet, fail to heal or go on to develop lesions. (We also see apparently poorly done endodontics that shows no pathology and is asymptomatic!) While there may be some question as to when to attempt remove broken files, there is no doubt that optimal results are best obtained when they can be removed with minimal damage to the tooth. This allow for optimal canal cleaning, shaping and obturation.

5. Bypass vs. Remove
One strategy of dealing with broken files is not to attempt to remove them at all; it involves bypassing the broken fragment and incorporating the broken file into the canal obturation. This is the strategy that I used for many years before getting a scope. It can work very well, especially when the file that is broken has large spaces between the flutes that can be bypassed with a small .06 or .08 file. But this process is very time-consuming and requires a lot of patience. You must never become frustrated and never rush. You can easily go through dozens of .06 or .08 files before regaining patency. At that point the rest of the case is also done with hand files, mostly with a “pull out/reaming” motion. (Never try to use one Ni-Ti rotary file to remove another broken file!) Carefully examine the path of file insertion before placing the next file. Be careful not to place larger size hand files directly over the file fragment – you can easily jam the embedded file deeper into the canal, plugging the canal again. At that point you will have to try to regain patency and go through the entire file series again. (Frustration!!). Perseverance and determination are necessary.

Tell the Patient!
File fractures do happen. One of the biggest mistakes I see is when patients are not told of file fractures. This is not only unacceptable from a referral standpoint; it fails to satisfy the legal concept of informed consent. If you break a mm or two of a #.06 or #.08 file in the canal, is it important to tell the patient? Probably not. – Unless it severely compromises the case. (Ie/, prevents access into the majority of the canal system, makes you treat very short, etc.) On the other hand, leaving half of a Ni-Ti rotary file at the apex of a symptomatic necrotic tooth with a lesion (especially when the canal system has not been cleaned completely) will probably necessitate further treatment. That may mean instrument removal, bypass or surgery. It is VERY important that this be told to the patient AT THE TIME THAT IT OCCURS. That means that if you cannot solve the problem (bypass or remove it) you sit the patient up, remove the rubber dam and explain what has happened. (In the case of the radiographically visible bypassed instrument, it is still important to inform the patient, if only to prevent this from being ‘discovered” by another clinician in a subsequent examination.) Only then will you satisfy the legal requirement that the patient is fully informed and able to make a judgment as to how (and if) they wish to proceed with treatment. Be honest with them. Treat them how you would wish to be treated. Most patients are very understanding IF you take the time to explain the complexities and difficulties involved with Endo treatment to them.

Should you break a file in a case and are considering referral to your endodontist for treatment:

1. Take a good radiograph of the tooth after the file has broken. Show it to the patient. This not only allows the patient and referral to see where the file is, it provides legal protection for you. You now have a record that the file was at “this” position when you noted it broke and that the patient was fully informed. Don’t hide the fact that the file has broken. If you chose to refer the case at that point, make sure to inform the subsequent clinician. No one likes to get “surprises” or “presents” inside canals that have been referred.

2. Keep the rest of the file in the chart. It offers proof of the fracture and could be beneficial in the unlikely situation that the case goes “legal”. (Rare but a distinct possibility in the US.)

3. Try to explain the complexities of the canal system to the patient. Emphasize that we are dealing with very small structures and that although our instruments are flexible, sometimes the canals are so tortuous that the instruments cannot negotiate them adequately. When they see the size of the files, most patients will understand the fragility of the instrument.

4. If you choose to refer – Phone your Endodontist and tell them what happened. Don’t be embarrassed. (We break files too!) We are here to help you, not to berate you for the break. (On the other hand, if this kind of referral is the ONLY thing that you send to your endodontist, or if these cases occur routinely, you should expect some ” gentle recommendations” on how to avoid this problem in the future.)

5. Fees – This is a very controversial subject. Some dentists feel obligated to pay for the case when they break a file and refer it out. This places the endodontist in a very awkward position. These cases frequently require tremendous amounts of time to treat – FAR IN EXCESS of a “NORMAL” CASE. Instrument bypass or removal can sometimes necessitate several hours of concerted effort, just to gain canal patency. It is unfair to expect a “professional courtesy discount” when these cases are referred. Expect to pay a full fee. Remember, the endodontist is bailing you out on this one. If the patient’s insurer has already paid you, it is unlikely that the insurance company will pay for the procedure twice. Please discuss this with the patient or their insurer prior to referral. It is not the job of the endodontist to explain the reason for denial of the patient’s claim.

File Bypass – Technique:

The key to bypassing a file is establishing patency with small instruments. You must balance the small size of the file with the stiffness necessary to get past the broken file. That means that initial attempts are made with a #.06 or .08 file. In order to get past the broken fragment it is necessary to put a SMALL sharp rounded bend at the very end of the instrument. This is the KEY and it is one of the most important skills you learn in endodontics. (This bend is also used to get by ledges and other obstructions. The bigger the ledge or the tougher the obstruction, the sharper and smaller the bend should be. I mean REALLY small!) You will go through and discard MANY files. This is normal. After a while you will find a “catch”. This is the file negotiating past the instrument. It is very important NOT to remove the file at this point. Use VERY small in and out movements (with lots of irrigation). Very often the file will kink and/or you will not be able to place it in the canal to the same depth. Use a new file, with a new similar bend and repeat the procedure until you feel the file slide deeper. If necessary use small watch-wind ¼ turn and push/ pull motions to move the instrument toward working length. Resist the urge to move up to a #15 file. This file is stiffer and it will feel like you are making progress when in fact the chances are that you are perforating the root. Once you have established patency with a small #10 file, stick with it. If it kinks or bends, don’t get frustrated – toss it, bend another file and repeat. If you lose patency, you may have loosened and jammed the broken fragment, go back to the smallest file and repeat the series.

Once you have patency with a#15 instrument, go to K reamers. Use a “place – pull/rotate/withdrawal” movement rather than a filing motion. You will notice two things: (1) The reamer will be deflected by the fragment and you will need to find a consistent path of instrument insertion that is probably different than the initial path (2) Every time you rotate the reamer, you will hear a “clicking” sound as the flutes brush up against the file fragment. This is normal. As the canal size increases so does the risk of pushing the fragment deeper (especially larger fragments). You must avoid placing an instrument directly on top of the broken file. This can push it deeper and you can lose patency. If this happens, you will have to regain patency by going back to the smallest file you initially used. If the file is visible at this point it is sometimes possible to use a small tipped ultrasonic instrument or ¼ turn withdrawal-type handpiece (AET – Canal Finder) to dislodge and remove it. DO NOT TRY TO REMOVE A BROKEN FILE BY USING ANOTHER ROTARY NI-TI IN AN ATTEMPT TO LOOSEN IT – YOU WILL JUST BREAK THE SECOND FILE AS WELL.

File Removal:

There is one hard and fast rule for file removal: If you cannot CLEARLY see it visually – you should not attempt to remove it. Like it or not, this means using a Surgical Operating Microscope in almost all cases. Hoping to dislodge it by working “blind” invariably will results in making the situation worse through perforation or compromise of the root dentin. In order to attempt file removal, a staging platform is created with a specially modified flat-ended Gates Glidden bur. This platform needs to be clearly visualized. It creates a flat area of dentin surrounding the file fragment. Small tipped Ultrasonic instruments (See last month’s Fax) are used to trough around the instrument and eventually vibrate the file out of the canal. The tip is used in a counter clockwise motion (opposite to the way the file was turned when it broke) to loosen the file. Irrigation combined with ultrasonics can frequently flush it out at this point. If sufficient file is exposed, an instrument removal system (such as Tulsa’s IRS or Masserann kit) can be tried. My experience with them has been mixed. Many times the root is thin and a lot of dentin has to be removed to get the tube to properly seat over the instrument so it can grab. It is very easy to strip perf a curved canal when trying to get these instruments to fit. A second method is to use a similar tube, this time with core paste or Cyanoacrylate glue. The tube inserted into over the exposed file fragment and the core paste/glue is allowed to cure. The tube is removed and (hopefully) the fragment is embedded in the hardened paste. The key is getting the tube to sufficiently seat over the file fragment- not an easy task.

Surgical Treatment :

For broken files that are “behind the curve” this is often the only way to treat the case. The problem is that the file fragment is not visible because of the curve of the root OR so much dentin has to be removed to allow for visualization that strip perforation is almost certain. This is most common in mesial roots of mandibular molars curved MB roots of maxillary molars and maxillary first premolars