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Diagnostic errors: three case studies

15 September 2023


Dr Nuala Carney, Dentolegal Consultant at Dental Protection, looks at three cases involving diagnostic errors, all with very different outcomes.


“I think I have a wisdom tooth problem…”

A 27-year-old patient attended her practice complaining of discomfort around her lower right wisdom tooth (48). She had had recurrent bouts of pericoronitis in the past, and wanted the tooth removed. She was planning to head off on a round-the-world  trip in a month’s time, and wanted to have the issue dealt with before then. The practitioner took a periapical and agreed that it was suitable for him to remove, once the acute infection had settled. He prescribed antibiotics and booked her in for an appointment ten days later to extract the tooth.

On the day of the extraction, the practitioner was running late and was very stressed. He went through the consent issues briefly, just mentioning the risks of lingual and labial paraesthesia and postoperative swelling and pain. The patient was not shown the radiograph or given any specific warnings in relation to her tooth.

The extraction turned out to be much more difficult than anticipated and although there seemed to be some movement from the tooth, it just would not deliver. Finally, after 45 minutes of struggling, there was a popping sound and the tooth finally came out, much to everyone’s relief. The dentist packed the socket, stitched it, and prescribed some antibiotics and painkillers. He warned the patient that there might be some swelling and pain for a few days, which would then settle. He wrote some very brief notes and got on with his day – now well behind schedule.

The patient returned later that week with severe pain in the area of the extraction. The dentist who had seen her originally was not working that day, and his colleague reviewed the notes and diagnosed a dry socket. He explained what the problem was, irrigated the area and prescribed stronger pain killers. He explained it usually takes seven to ten days for dry sockets to settle and so reassured her that she should be fine in a few more days, and that there was no risk to her long-distance flights abroad, now only two weeks away.

Unfortunately, the pain did not settle, and later the following week the patient returned, now very distressed and angry. She saw the original dentist, who reviewed the area and confirmed that there was still a dry socket. He apologised for the complication, irrigated the area,replaced the dressing, and prescribed further antibiotics. The patient was not reassured however and decided to seek an opinion from a local oral surgeon, as her trip was now imminent. The oral surgeon took a radiograph and confirmed that the curved tip of the distal root was in fact retained and that this was probably the cause of the non-healing socket. He advised her that it could be removed but it would require a GA, and could only be done when the acute infection had settled and a GA slot was obtained for her.

This was subsequently arranged for three weeks’ time in a local private hospital, involving an overnight stay, and the surgeon removed the troublesome root tip. Healing then took place without any further complications. However, at this point the patient had had to completely rearrange her travel plans, including flights and accommodation for the first month of her trip. A claim was subsequently received by the dentist. His notes proved to be sparse, with no evidence of adequate warnings or consent, and a poor-quality radiograph that did not show the full extent of the roots. The matter had to be settled on his behalf for a considerable amount.

Learning points

Tight timeframes: be wary of carrying out any treatments that may have a risk of postoperative complications, or not reaching the patient’s expectations where there is a tight timeframe, such as an impending holiday or wedding. If treatment is absolutely necessary, make sure that the patient is fully informed of the risks and challenges that may arise, and allow them time to decide whether they wish to proceed or change their plans.

Radiographs and consent: make sure that the radiographs you take are of diagnostic quality and provide the full information needed to plan the treatment appropriately. Consent needs to be tailored to the specific risks for the patient and treatment involved.

Confirmation bias: if a patient presents with a postoperative complication or emergency, don’t rely on the previous recent notes for a diagnosis – ensure you take other potential causes into consideration.



Which tooth?

Dental Protection commonly receives complaints from patients who have presented with pain in a tooth, but the dentist cannot identify which tooth is the cause of the problem. This can be extremely frustrating for both the dentist and the patient. Patients will sometimes try and put great pressure on the dentist to intervene with irreversible treatment- against the dentist’s better judgement – which can later come back to haunt them.

A patient presented with severe pain in the upper right anterior region. He had a habit of bruxism and was not diligent about wearing his nightguard. He also had a very stressful job on television and was frequently in the public eye. Having carried out a thorough clinical examination the dentist identified that the 12  was not responding to electric pulp tests and the canal appeared to be sclerosed. The other anterior teeth were all heavily restored and worn down. Both upper right premolars were very sensitive to cold and had large amalgams.

The patient was insistent that the pain came from the anterior region around his lip. He was aggressive and short tempered due to the pain and the dentist felt under significant pressure to “sort it out”. Having explained that she was not 100% sure of the diagnosis, the dentist agreed that she would start a root treatment on the 12, which seemed the most likely culprit. She suggested trying to carry out a test cavity without anaesthetic – which the patient flatly refused. Accessing the canal was extremely difficult and the appointment ran well over time, causing the dentist to be even more stressed. She managed to negotiate the canal to the apex, placed some calcium hydroxide and sealed the tooth.

Four days later the patient returned, saying that he had not slept in four days and was utterly frustrated that the pain was worse than ever. Still unable to localise the pain, the dentist decided a second opinion was needed and rang a local endodontist, with whom she had a longstanding relationship. The patient was given an urgent appointment the following day. The endodontist repeated all the tests on all the upper teeth and carried out a CBCT scan. She noted a radiolucency of the palatal aspect of 14  and explained to the patient that she was of the opinion there was a crack on this tooth. The large restoration was removed and a crack was confirmed. She carried out a pulpectomy in order to relieve the symptoms, which settled almost immediately, and a plan was made to extract the tooth and replace it with an implant.

The dentist subsequently received a letter of complaint from the patient seeking the cost of the root canal treatment to be refunded, along with the cost of the post crown, which was now required, to be covered by the dentist.

Having reviewed the records carefully, we identified that the dentist was vulnerable because there had been insufficient testing with heat/cold, EPT or probing had been carried out on the premolars, which would likely have picked up the crack at an earlier stage. Although it is unusual for referred pain to move forward two teeth, clinicians must always be conscious of the fact that pain can be referred anywhere along the maxillary and mandibular divisions of the trigeminal nerve, and that other causes, such as trigeminal neuralgia, might be causing acute pain.

If the clinical signs and symptoms do not add up, it is wiser to either inform the patient that you are not able to make an accurate diagnosis and need the problem to localise so that your diagnosis is supported by evidence – or seek a second opinion urgently. It was agreed with the patient that the cost of the remedial treatment required on the 12  would be provided at no cost and no charge was made for the root canal treatment. The patient accepted this as a gesture of goodwill, recognising that the dentist had carried out the treatment in difficult conditions.

Learning points

  • Carrying out a thorough examination and special tests of all teeth is essential when trying to pinpoint the cause of potential pulpitis.
  • Ensure that the results and evidence of all these tests are clearly recorded.
  • If the evidence is not making sense and confirming the diagnosis, refrain from carrying out irreversible treatment until you have evidence to back up your decision-making.
  • Refer for a second opinion if the clinical picture remains unclear – a second pair of eyes, different experience and a second brain are always helpful.



Missed CA

Sadly, we occasionally receive claims for malignancies that the patient feels should have been picked up earlier which, might have avoided significant surgery. These are always complex cases, leaving both the patient and often the dentist, devastated by what has happened.

A patient, who was a smoker, was having a new chrome cobalt lower denture made with his dentist because he was complaining of irritation from the old, poorly fitting, acrylic one. The denture replaced 35 36, 45 and 46. Following a successful try-in, the new denture was fitted. The patient returned several times complaining of irritation of the tongue on one side. The dentist could see nothing obvious and trimmed the lingual cusps of the acrylic teeth and polished them.

Four months later the patient returned, now complaining of an ulcer on his tongue, which he thought had been there for about two weeks. It appeared to be traumatic and the dentist wondered if he was catching his tongue when chewing or at night when asleep, as the patient admitted he was not taking his denture out at night. He advised the patient to leave the denture out, for three weeks and return at that point if it had not completely healed. He took photographs and measured the lesion. He warned that if it was not gone, he would be referring him for a biopsy to check that nothing more sinister was going on. He made it clear that non-healing ulcers need to be followed up and gave the patient an appointment for three weeks later.

The patient failed to attend the appointment and efforts to contact him were unsuccessful. The practice made multiple phone calls, which were recorded in the notes, and sent two emails.

The dentist received a solicitor’s letter two years later explaining that the patient had subsequently developed squamous cell carcinoma of the tongue, which had been diagnosed the following year in another part of the country. He had had a radical neck dissection. After looking at the records, the member rang and sought our advice.

When the records were reviewed by our dentolegal team, it was clear that the dentist had managed the appearance of the ulcer appropriately and had done everything possible to follow up. There was clear evidence that he had warned the patient of the potential dangers of a non-healing ulcer and had made a definitive appointment to follow this up. When the patient did not attend, the practice went to considerable lengths to contact the patient, all unsuccessful. The dentist had therefore satisfied his professional responsibilities and the fault lay with the patient for not having followed up when the ulcer did not heal. We were able to write a strong letter in the member’s defence, showing exactly what clinical evidence had been gathered, the advice given to the patient and the failure on his part to follow up as advised. The solicitors did not pursue the matter.

Sadly, there are sometimes cases where the advice given to the patient is unclear, and the lesion is not followed up due to communication or administration errors. Unfortunately, in these cases, the patient may be able to show that the dentist failed in their duty of care to the patient, and that this had directly led to a worsening of the prognosis due to the delay in diagnosis. These cases can lead to long, drawn-out, and expensive legal claims.

Learning points

  • With any suspect lesion, take a careful history and explain risk factors clearly to the patient.
  • Document the lesion carefully: take photos if necessary and measure it. Check carefully for nodal involvement.
  • Clearly explain the risks that might eventuate if the lesion is not carefully followed up and document this. Give the patient a definite appointment for review according to the relevant guidelines.
  • Make sure the team are aware that if the patient cancels this appointment or fails to attend that another appointment must be given, or the patient must be contacted to arrange a follow up.
  • Keep a careful record of all phone calls made and letters sent trying to re-establish contact with the patient. 



These case studies are based on real events and provided here as guidance. They do not constitute legal advice but are published to help members better understand how they might deal with certain situations. This is just one of the many benefits Dental Protection members enjoy as part of their subscription. 
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