The surgical removal of impacted mandibular third molars, the wisdom teeth, is the most common surgical procedure carried out by oral surgeons in the UK. Therefore it is not surprising that a significant number of claims for damages for alleged clinical negligence arise from the removal of impacted wisdom teeth.

In order for surgeons to reduce the risk of litigation and minimise their risk of a claim being made against them, it is important to understand the nature of the allegations currently being made.

Causes of claims

A review was recently undertaken of the claims notified to the DDU relating to the removal of impacted wisdom teeth in general dental practice over the last three years. Not unexpectedly, nerve damage accounted for 25% of the claims notified, but the most frequent cause for a claim was consent (28%). Although this review related to the removal of wisdom teeth in general dental practice, this pattern is reflected in claims relating to wisdom teeth that have been removed in UK hospital practice that are now being managed by NHS Resolution.

In addition to claims relating to consent and nerve injury, claims are also now regularly being made relating to coronectomy and failure of post-operative care. Claims of breach of duty for a lack of informed consent and for failure to act once a nerve injury has occurred are also becoming more frequent.

Consent

It is essential that the patient is fully informed of all the potential risks involved and that their consent is obtained before an impacted third molar is removed. Although often neglected, no treatment is always an option.

Once the decision has been made to remove the wisdom tooth, the risks and potential complications should be explained to patients, and that they have been fully informed of the risks should be documented in the records. Although the patient will have been told of the risks, in particular the risk of nerve injury, studies have clearly shown that patients often simply do not remember being given warnings, even when they have been given written information.

Therefore, as well as providing verbal warnings it is probably good practice to give the patient an information leaflet on wisdom tooth removal, which should include all the potential surgical risks. Again, document that an information leaflet has been given to the patient.

NHS guidelines state that all patients should be sent a copy of any letters and correspondence that the surgeon sends to the referring dental practitioner or general medical practitioner. If that letter contains a statement that the patient has been warned of the possibility of complications, particularly of nerve injury, it is more difficult for a claimant to allege that they were not warned of the risks.

The final stage of the process of informed consent is the actual consent form itself. When a consent form is used, the potential risks and complications should be clearly written on the form and discussed again with the patient before they sign it.

The surgical removal of the wisdom tooth

Injury to the inferior alveolar nerve, which runs within a bony canal within the mandible running close to the root apices, will occur in about 6% of third molar removals; one in ten of these will not recover. Permanent lingual nerve injury occurs in approximately 1 in 200 wisdom tooth removals. I ran a monthly clinic dedicated to patients with lingual nerve and inferior alveolar nerve injuries for over 25 years. A large number of lingual nerve injuries were caused by surgeons of all grades including many consultants, some patients having been treated in private hospitals.

The incidence of lingual nerve injury during wisdom tooth removal was not dependent of the grade or experience of the surgeon carrying out the surgery, and therefore my opinion has always been that this is an unfortunate complication of the surgery rather than being due to inexperience or negligence on the part of the surgeon.

Although some surgeons may argue that it is negligent to cause a lingual nerve injury, I don't believe there is any surgeon who has removed a reasonable number of impacted wisdom teeth in their career who if they are being completely honest has not occasionally been relieved to hear a patient say, 'My tongue feels fine,' the day after their wisdom tooth has been removed.

The patient has a nerve injury

We know that injuries to the lingual and inferior alveolar nerves do occur during third molar removal and that patients with a permanent nerve injury will understandably make claims of negligent surgery, which can hopefully be successfully defended. It is therefore not unexpected that claimants' solicitors instead make claims for negligence due to a lack of informed consent as discussed above, and also for breach of duty for a failure to manage the nerve injury once it has occurred. These can be more difficult to defend, so surgeons should ensure that their patients are treated promptly and with due care and attention.

Patients complaining of numbness must never be dismissed, as this is almost guaranteed to generate a claim. It is the patient who feels that their concerns are being ignored, and that they are not being listened to, who will pursue litigation. In my experience the concern of the vast majority of patients who have sustained a nerve injury is not litigation, but regaining their sensation. They want to know when their sensation will return to normal, and if not, what treatment is available and how soon can they have it.

Patients who have sustained a nerve injury must be reviewed after surgery and their nerve injury fully assessed. The review or follow-up after third molar removal, or more accurately the absence of any follow-up, is now a common allegation of breach of duty.

Patients are routinely given very clear post-operative instructions to contact the treating clinician/department where treatment was provided if they have any immediate problems. But what happens when the patient has been told their numbness may last several weeks or months? They may not understand or know whether to contact the unit, often being re-referred by the dentist months later when the opportunity of treatment has diminished, which can then lead to claims for breach of duty of care. Ideally, mechanisms need to be in place for any patient with a nerve injury to be identified and reviewed within a couple of weeks of their surgery.

Referral

By three months at the latest after the wisdom tooth has been removed, it should be possible to determine whether the nerve injury is temporary and will recover or be permanent. If it is deemed permanent, either treatment should be offered or the patient should be referred to a centre that can provide treatment. Failure to refer is a common allegation of breach of duty and can be very difficult to defend.

When making the decision to refer a patient it is important to ensure that the patient will be offered the full range of available treatment. Failure to provide all the treatment options, or at the very least giving the patient the option of a referral to another centre where the treatment is routinely carried out, is probably a failure of duty of care to patients and a significant risk of litigation on those grounds. Following Montgomery, it is no longer acceptable to only offer the treatment your unit can provide.

Needlestick injuries

The other potential cause of both lingual and inferior alveolar nerve injury is the needlestick injury caused by the injection of dental local anaesthetic solution. This may be used as the only anaesthetic for wisdom tooth removal or as an adjunct when treating patients under general anaesthetic.

If the patient does sustain a nerve injury, in view of very low incidence of needlestick injury, and on the balance of probability, it is likely to be the result of the third molar surgery itself. However, where there is a clear indication that a needlestick injury may have occurred it should be considered as part of any defence.

In my experience needlestick injuries can be responsible for the most severe nerve injuries of the inferior alveolar and lingual nerves and they cause very severe dysaesthesia which is often unresponsive to most of the available pharmacological drugs. When teaching dental students to give an inferior dental nerve block injection, I could not stress upon them enough the importance of withdrawing the needle immediately if the patient reported any sharp shock like pain, rather than injecting as they have 'found the nerve'.

Needlestick injuries also of course produce numbness of the lower lip and chin and the tongue. Many injuries do recover, but they tend to take much longer than crush injuries. From a dento-legal point of view they are an unfortunate and rare complication of dental local anaesthetic injections.

Any report by the patient of pain, which may be severe electric shock type sensation or burning sensation experienced during an injection, should be documented in the patient records and explained to the patient. This may make the defence of a numb tongue or lip a little easier.