Understanding the risks surrounding endodontic treatment - and how to manage them - can help minimise the potential for complications encountered by both patients and dental professionals.

Endodontic treatment can be a source of worry for dental professionals. This might partly be due to the easily explainable risks, such as file fracture, but also because of the unpredictability when treatment planning, such as unexpected problems finding canals, and difficulties of this type can lead to further complications such as a perforation and even a hypochlorite injury.

Knowing when to stop is the obvious answer, but that's often easier said than done when you feel you have very nearly overcome the problem you were faced with. Nevertheless, with careful planning it may be possible to anticipate the majority of potential complications and mitigate the associated risks as far as possible.

Endodontic treatment from a personal perspective

To begin with, we hear from Professor Nick Barker, who offers an expert personal perspective on managing the risks associated with providing endodontic treatment.

Before treatment

From experience, preparedness is key. Endodontic treatment is commonly initiated by the patient suffering severe pain. It is important, therefore, that patients are able to access care without the need to circumnavigate a complex communication system that may form a barrier to arranging an appointment.

In addition, it is beneficial to ensure zoning of appointment books that allows sufficient time for acute urgent care to be arranged. A patient able to access care smoothly and swiftly generally develops a good rapport with a clinician - unlike one who has struggled to get an appointment and has been left in severe pain for some time.

At initial presentation, the use of a 'surgical sieve' to gather a comprehensive history is beneficial. Many clinicians use SOCRATES (site, onset, character, radiation, associations, time course, exacerbating/relieving factors and severity) as an acronym to gather as much information as possible. A good history in itself can often lead to a provisional diagnosis that will then be supplemented by further assessments.

The assessments can include clinical examination as well as the use of sensibility testing, assessment of periapical health through the application of axial pressure and radiography amongst many other investigations. Accurate recording of all of the above is key to being able to review these findings as treatment progresses, as well as if future care is required to this tooth, either by yourself or other clinicians.

The final stage is establishing a diagnosis and prognosis and treatment plan to be presented to the patient. This is another key element that should be well documented as it will involve providing the patient with clear information as to each and outlining the risks and benefits of this treatment, along with any other treatment options that may be available.

Again, the patient may be in acute pain at this stage and treatment to relieve symptoms may be needed urgently. However, this does not remove the need to provide the patient with sufficient information to inform them of the plan, which may involve initial relief of symptoms at this stage by accessing the source of infection to remove the bacterial load and dressing the tooth.

That may then provide good opportunity to review the patient at a further appointment when the prognosis and treatment plan can be revisited and further discussions can take place. It is important to bear in mind that treatment planning, and thereby consent, is an iterative process that should be reviewed regularly.

Finally, to assist in ensuring the patient has been provided with full and clear information, it can be beneficial to provide a patient information leaflet outlining the treatment planned. Many dental professionals use electronic systems that can easily print out a leaflet at the same time as producing a treatment plan.

During treatment

A methodical approach to care is equally important in order to attempt to make its provision as fluid and uneventful as possible. Endodontic care can be broken down into phases; initial access, establishing a working length, creating a glide path, shaping of the root canal system whilst maintaining apical patency, ensuring good working length has been achieved and then obturation.

However, underlying all of this is disinfection. This may be easily overlooked, and therefore it is important to maintain a regular irrigation of the root canal system using a suitable disinfectant. My approach is to introduce further irrigant between each step of cleaning and shaping of the canal, including maintaining apical patency. In that way, irrigant is introduced twice as frequently as either the patency or shaping file.

The use of an apex locator with or without radiography helps to ensure an accurate working length is achieved, and then further checked along the principles of 'measure twice, cut once'. This also helps to ensure that a patent canal is maintained, which reduces the risk of blockage, ledging and other complications, which in turn significantly affect the chances of achieving a good end result.

The use of rubber dam should be included within the treatment wherever possible. This allows for a clear and clean field to be achieved while undertaking treatment, as well as reducing the risk of inhalation or ingestion of undesirable objects or substances.

After treatment

At the end of treatment, it is beneficial to go over again the potential outcomes of care, the prognosis and any further treatment that was planned, alongside what the patient should expect to experience in the form of symptoms. This will help in establishing patient expectations once more so that if further care is needed, it will not come as a shock to them.

In my experience, it is helpful to arrange a follow-up conversation with the patient in the next few days so that any subsequent clarification or questions that may have arisen can be answered - and again, well documented.

Professor Nick Barker


The initial conversation

Having a discussion with the patient first means they're aware of the complexities of the particular circumstances of their case, the possible complications, and what impact this can have on the outcome. This in turn can reduce your stress levels if difficulties do arise, because you've already pre-empted the situation by explaining its possibility before you started.

If the patient is aware you're doing your best for them and they already know what might happen if problems are encountered, the result should (in most circumstances) be a relatively accepting patient. That being said, we work in a field with a huge number of variables that are not always controllable, even with the best will in the world.

Dento-legal considerations

From a dento-legal perspective, there are a few areas to consider in order to reduce the potential risks arising from endodontic treatment, and of any potential complaint or claim succeeding.

Safety: airway/GI tract protection

One of the most serious adverse incidents encountered during endodontic treatment is swallowing or inhaling instruments. However, if proper precautions have been taken, the risk of an adverse incident involving a swallowed or inhaled instrument is low. If the worst happened and an unforeseeable incident occurred, such as a sudden tear of a rubber dam, the defence would be strengthened by protective measures having been used, but which failed.

Nevertheless, although some aspects of dentistry are predictable and controllable, both patients and the general circumstances surrounding their treatment introduce variables that can complicate matters. The scenario may present itself where a patient is unable to accept rubber dam use, or it is not possible for you to place one.

If it's decided that continuing to provide endodontic treatment is in the patient's best interests, it would be advisable to risk-assess the presenting situation. This might include considering using alternative measures to protect the airway, reducing the potential for contaminants to enter the root canal system, and reducing the potential for irrigant solutions to contact soft tissues.

In these circumstances it would be advisable to document why it was not possible to place rubber dam, the action taken as a result, and the alternative measures that were used (for example, throat sponge and tying hand instruments).

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Discussions with the patient

As part of the consent process, it's important to discuss the possible complications that may be encountered during the particular treatment the patient requires.

One approach may be to run through a list of every possible complication associated with endodontic treatment, but doing so runs the risk of losing control of the discussion and missing the opportunity to emphasise what you would consider are the most important areas to fully discuss.

It's not uncommon to think a patient has understood an explanation, but it becomes clear during a later conversation this wasn't the case, so making sure the patient is aware of what you consider to be important for the patient you are treating may reduce the potential for misunderstanding later on.

For example, if one of the canals being treated is curved and narrow, the risk of file fracture may be considered to be a relatively high risk compared to a straight and wide canal - so it may be one of the main points you think needs to be emphasised when discussing the treatment with a patient.

Nevertheless, emphasising specific complications should not deter you from explaining the generally accepted or broader risks. When assessing the tooth, consider discussing complications such as the potential for ledge formation or canal blockage, which may present difficulties in completing the treatment to a standard consistent with achieving a reliably good prognosis. Providing the patient with information about what action may need to be taken if this happens can help reduce the chances that the patient will worry.

Gauging patient expectations before starting treatment can certainly help guide the type of discussion that may suit the situation.

Explaining potential complications to a patient before the treatment is started, and what this may mean for the treatment, also affords the opportunity for a discussion to take place about what you anticipate. It also allows you to gauge what the patient is expecting. Some patients will be aware the treatment is difficult and accept it does not carry a guarantee of success, but others will expect it to be as predictable as a mechanical repair.

Gauging patient expectations before starting treatment can certainly help guide the type of discussion that may suit the situation. This can help you to give the patient a realistic likelihood of any potential difficulties that may be experienced along the way and what you might need to do to overcome them.

If you suspect a patient doesn't accept that difficulties might arise with their treatment, you could discuss a referral to a specialist, along with the likelihood of acceptance, waiting lists under NHS provisions, and the cost of a private referral. Document discussions like this carefully.

If the situation arises where a patient clearly lacks trust in you to provide the treatment, but declines a referral to a specialist and insists you provide it, it may be best to contact the DDU helpline as soon as possible for advice.

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One difficulty facing general dental practitioners is knowing when and how to refer. General dental practitioners are expected to be competent enough to provide endodontic treatment with a degree of complexity and to a good standard, but the option of specialist treatment should form part of the discussions with the patient. If you don't feel capable of achieving a good result, explain to the patient why you consider it in their best interests to make a referral for specialist treatment if they wish to retain the tooth in question.

Patients being treated under NHS provisions, or who are on private capitation schemes that don't contribute toward specialist care, may be less accepting of the charges they would incur for specialist treatment on a private basis. It might be possible to refer for NHS specialist treatment, but it's advisable to be aware of referral criteria for your area and waiting lists so you can give the patient accurate information to help manage their expectations.

It's also important to remember that a referral may be rejected if it is felt to be within the capabilities of a general dental practitioner, and this could cause patient management difficulties.

Fractured files

Fractured files are probably one of the most common adverse incidents relating to endodontic treatment. Very small portions of files can fracture, and might not always be noticed immediately, so one solution is to measure files after use and document the measurements.

If you become aware a file has fractured, inform the patient as soon as possible and discuss the options of what to do next, whether that involves attempted retrieval, bypass, acceptance or referral. And as ever, always document your discussions carefully.

Unfortunately, dentists treating the patient at a later date might not have all of the available information which can lead to problems. For example, radiographs with crossing canals can be misinterpreted and in turn lead to complaints being raised.

It's not uncommon to think a patient has understood an explanation, but it becomes clear during a later conversation this wasn't the case

Hypochlorite injuries

These can range from minor injuries to severe. This is likely to be an infrequent occurrence, but because the injuries can be significant it's advisable for all staff to be trained in the emergency procedures needed after an unintended hypochlorite exposure.

If an injury is suspected, document the emergency procedure followed in detail, along with any follow-up appointment necessary with yourself or with a medical professional, and your discussions with the patient.

For example, if the injury involves the lower premolar region and lasting nerve damage is a possibility, it may be advisable to arrange follow-up care with an appropriately trained colleague. This would make sure the patient is well supported and that you are made aware of any potential lasting nerve damage as soon as possible.

In circumstances like this, we would encourage you to contact the DDU helpline as early as possible so we can advise on any action that may be necessary.

Canal length measurement

Radiographs obviously form an important part of endodontic treatment. However, with the use of accurate apex locators becoming more common, the need for working length radiographs to determine working length has diminished. Nevertheless, if there was any doubt about the reading from an apex locator, it would generally be accepted as prudent to use other means as well as the apex locator (such as a master cone fit radiograph) before obturating to reduce overfill/underfill situations.

If you are achieving inconsistent results with your working length measurements, it might be worth considering undertaking regular audits to help identify any inaccuracies in the system used and reduce the number of less than ideal obturations as a result.

Obturation difficulties

Under or over filling is a complication that happens even to the best operators. It is important to explain what has happened to the patient and if there are any potential consequences, or further treatment required, as a result. Indeed, if difficulties such as sclerosis or canal zipping/blockages were encountered during treatment, this should also be documented, as it may prove to be important if criticisms are raised about an incomplete obturation.

In addition to the difficulties with the obturation itself, because of the hot instruments used during obturation - whether those are heated pluggers or other hot instruments used to cut excess gutta percha - another difficulty we see occurring on a regular basis is the patient being burned.

As you can imagine, a burn across the vermillion border is rarely well accepted by the patient, but being aware of the immediate emergency treatment to provide, arranging follow-up care with an appropriate medical professional, and of course informing the patient immediately and documenting the discussion in the records, can help limit the vulnerability to being justifiably criticised.

Postoperative X-rays

Ideally, postoperative radiographs should routinely be taken to confirm the quality of the obturation. There are many situations where the preparation may have been excellent, but the resultant obturation, or at least the radiographic appearance, is less so. You should explain this to the patient as soon as you become aware, and any potential impact on their treatment, review period or immediate treatment required explained and documented.

Case study

The following case study is fictitious, but based on the issues discussed above and on the types of cases members can face.

The scene

A DDU member provided root canal for the lower right first molar on a long standing patient. Before starting the treatment, the member explained what the success rate was thought to be for lower first molars, but emphasised that success could not be guaranteed. The treatment progressed well and the post obturation radiograph showed a good standard of obturation.

The patient moved to another area of the country and subsequently experienced discomfort from the tooth. After taking a periapical radiograph the new dentist told the patient there was a fractured file in one of the mesial canals and if the patient wanted to retain the tooth a referral to a specialist would be required for retreatment.

The patient complained to the DDU member. He was particularly upset that he thought he had not been informed of a file fracture, and that the further treatment he had been advised was a direct result of this.

DDU advice

The DDU member contacted us for assistance. His records were of a good standard, and because he had experienced similar difficulties earlier in his career, he had documented the lengths of all files used at the end of each relevant appointment . He had also clearly documented his discussions with the patient, including that he advised of the approximate success rates for endodontic treatment of the tooth and that he was unable to guarantee success.

We helped the member draft an initial response to the patient to explain the care he had provided and also request copies of the subsequent treating dentist's records in order to allow further comment.

The outcome

On reviewing the copies of the radiographs forwarded by the patient, it appeared the patient had been mistakenly informed by the subsequent treating dentist of the presence of a fractured file because of a misinterpretation of the mesial canals 'crossing' on the radiograph, resulting in a higher radiopacity in this area.

The DLA drafted another response for the member to consider sending to the patient to explain this, and to suggest seeking the opinion of the specialist endodontist the patient had been referred to, after which our member would comment further.

The endodontist confirmed for the patient there was no fractured file present in the canals and was supportive of the standard of treatment provided by our member. The patient wrote to our member with these findings and thanked him for providing a professional response to the misunderstanding.

This page was correct at publication on 22/10/2021. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.