Recent advances in endodontic instrument design and obturation techniques have made the outcome more predictable, but not guaranteed.
Root canal therapy is a treatment that is currently offered by a large number of dentists with results that are now more predictable.
This is important since the cost of failure is high; particularly when failure results in the loss of a tooth which might further impact on the available restorative options./p>
Radiographic evidence
If endodontic treatment has been carried out in line with current teaching and recognised procedures, then any adverse outcomes are defensible, but the onus remains on the practitioner to demonstrate that those accepted procedures and guidelines have been closely followed.
Frequently, however, the evidence points to a lack of care in the treatment.
Radiographs provide a lasting chronicle of endodontic successes and failures. Even though modern endodontic teaching places more emphasis on what is removed from the root canal system rather than what is used to obturate the space, it must be remembered that incomplete obturation does not bode well in cases where litigation is concerned. The radiograph remains a key component of good record keeping in endodontic procedures.
The pitfalls of success
The media frequently reports advances in medical science.
Sometimes the coverage is slanted to deliver a headline-grabbing story.
The corollary is that patient expectations rise and successful outcomes are assumed. In such a prevailing culture, it is all too easy to ignore the fact that the outcome of endodontic treatment can never be guaranteed, even though success rates can be well over 90% in competent hands.
But success can sometimes induce complacency, particularly if the complexity of endodontic procedures is underestimated. Patients should be fully informed from the outset of all the options for treating a particular tooth, along with a warning of the potential for the treatment failing and the reasons for it. Remember the old adage that information given before the event will be perceived as an observation, but information given afterwards may be seen as an excuse. It should be emphasised that it is not possible to give a 100% guarantee on the success of the procedure and if there is any potential for an early failure then this should be thoroughly discussed. This is particularly true of repeated endodontic treatments.
Potential problems
In general terms, any likely causes of potential failure should be explored with the patient before starting treatment. For example, retreatment of a tooth, which has undergone previous aggressive preparation of the root canal space, may be more prone to fracture under loading than a tooth that had been treated more conservatively during the canal preparation. There have been cases where so-called 'perfect' root treatments have failed as a result of fracture of the tooth due to excessively aggressive canal preparation.
In addition to discussing the possible causes of failure in sub-optimal circumstances, it is important to warn the patient about the potential for postoperative discomfort that may result from endodontic procedures. Explain other possible sequelae such as tooth discoloration, potential for cuspal fracture and the subsequent need for a cast full-coverage restoration to protect the weakened tooth substance. It is important that you document all such discussions.
Risk management in endodontics
Dento-legal problems in endodontics fall into two broad categories with the following commonly associated problems:
Problems of diagnosis and treatment planning
- Misdiagnosis of the problem (treating the wrong tooth)
- Postoperative irreversible pulpitis (patient blames dentist for the need for endodontics when pulpitis develops following a deep restoration)
- Restoration of the tooth after endodontic therapy
Problems of procedure
- Broken instruments
- Failure to warn about the potential for early failure in compromised situations
- Overfilling and underfilling
Separated instrument
The most common dento-legal problem involving endodontic procedures is probably the broken instrument.
'Fracture' and 'breakage' are particularly emotive words and so phrases such as 'separated instrument' are preferable.
Whilst instrument separation is not itself automatically considered negligent practice, any failure to recognise the complication and to advise the patient that it has occurred can seriously undermine any defence.
Perhaps the commonest reason for instrument separation is over-use of the instrument or incorrect use of the instrument in relation to its design. In particular, rotary nickel titanium files are designed for use in a very precise way within defined rotational speed ranges.
If rotational speeds are exceeded, then instrument separation is more likely.
If it can be shown that the instrument was incorrectly used, or that the technique deviated from the manufacturer's instructions, it is possible that instrument separation per se may be considered negligent.
It is absolutely essential that operators understand and adopt correct procedures as far as their instrument use is concerned. Read and follow the manufacturer's instructions with great care and discard instruments at the first sign of damage.
This applies to all techniques whether they involve hand instrumentation, rotary techniques or reciprocatingaction handpieces.
Pre-cementation checks
Good pre and postoperative radiographs are essential for accurate record keeping.
In addition there have been many debates about the need for pre-cementation check radiographs since the advent of electronic apex locators. There is little doubt that the more recently introduced apex locators can be very accurate when determining the working length. Some work in moist environments and whilst in many cases there may be no clinical need for a pre-cementation check, it is advisable to take an intermediate radiograph whenever there may be any doubt about the working length determination. Every case should be assessed on its merits.
Accurate record keeping is important. If canal access is restricted due to sclerosis or blockages, then this observation should also be recorded as it may prove to be a critical part of the defence if the postoperative radiographs show incomplete obturation.
Obturation
There have been many new obturation techniques introduced in recent years and many of these involve the use of thermoplastic injection techniques.
Needless to say, these should be used with great caution as any injection technique relies on an adequate apical stop to prevent the extrusion of gutta-percha into the apical tissue. Thermoplastic techniques, which rely on the application of an external heat source to gutta-percha already placed in the root canal, should be used with caution to prevent injury to neighbouring soft tissues.
There have been many cases over the years where extrusion of cytotoxic sealers has resulted in permanent injury to the inferior dental nerve. In many of these cases, the working length determination had been undertaken 'by feel' and without the aid of periapical radiographs or apex locators. Overfill with paste root filling materials containing potent neurotoxic agent(s) can cause permanent nerve damage in that area. The threat of litigation is very high and the vast majority of these cases have to be settled at an early stage.
Postoperative x-rays
Postoperative radiographs should always be taken to confirm the quality of the obturation. If there has been incomplete obturation of the root canal space because canal access has been restricted, then the patient should be informed and the information clearly recorded in the clinical records. If it can be shown that the dentist has taken adequate measures to ensure the effective and adequate cleansing of the negotiable part of the root canal system to eliminate pathogens, a 'short' root filling in itself does not present a threat to the dentist. It should be emphasised however that this scenario applies only to cases where there is demonstrable evidence that no further access was possible. For example, it is not true of cases where the patency of a root canal is evident on a radiograph or where another practitioner subsequently had successfully retreated the tooth.
Modern endodontic techniques advocate maintaining apical patency and it is increasingly common to see extrusions of gutta-percha beyond the main body of the canal - particularly with the use of thermoplastic techniques.
Whilst clinical opinion may be divided on the merits of extrusion of gutta-percha it is possible that in the event of failure, it is likely that any overfill would be viewed less favourably if other causes of failure can be eliminated.
Meanwhile it is generally accepted that extrusion of sealer is acceptable because it will resorb in time.
Rubber dam of course
All endodontic procedures should be carried out with appropriate airway protection and this means using rubber dam. If proper precautions have not been taken and there is an adverse incident involving a swallowed or inhaled instrument, then any action would be indefensible.
It is interesting that the Dental Board in Victoria, Australia, has stated that rubber dam must be used for all endodontic procedures, and failure to comply may be regarded as professional misconduct.
Recent advances in endodontics have excited clinicians the world over and are helping patients to keep their teeth longer.
The techniques may be new and the materials and instruments more advanced than they used to be, but the precautions remain exactly the same.
Case study
A 56-year-old male patient attended his dentist complaining of pain. Widespread gingival recession in the upper left quadrant made the diagnosis difficult, but the dentist decided to root treat the upper left first molar. The treatment was carried out at a single visit during which a rotary file separated in the mesiobuccal canal.
The patient was not informed, as the dentist was confident that the canal was clean and the instrument would not cause any harm. The palatal canal was sealed using a low-temperature thermal obturation technique and there was significant extrusion of gutta-percha into the apical tissues. The practitioner was unable to access the distal canal. The patient was in considerable discomfort the evening after the treatment and sought the help of an emergency dentist. After taking an x-ray the second dentist advised the patient that:
- There had been an overfill of the palatal canal
- The distal canal has not been treated
- There was a separated instrument in the mesial canal, which was also protruding through the apex
The patient received remedial treatment and brought an action for negligence against the first dentist.
Conclusion
This case serves to highlight the following points discussed in module.
- The patient had not been told about the separated instrument.
- The poor angulation of the radiograph did not show the apex of the mesial root so the original dentist was not aware that it had perforated the apex.
- No comments had been made about the distal canal.
- No discussions or warnings had been given in relation to the proposed treatment.
- It was also discovered that the rotary file had been used in a 1:1 slow handpiece and had probably been operating at approximately sixty times the recommended rotational speed.
- Although there was an overfill of the palatal canal this was not treated by the specialist as it did not appear to compromise the long-term prognosis of the tooth at the time. The practitioner had used ultra sound with copious sodium hypochlorite and it was thought that further intervention of the palatal root was not necessary.