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A lucky escape

06 November 2019

Mrs H, who is 69 years old, attended a new dentist as she was struggling with her lower denture that replaced her missing 35, 36 and 37. She had no other missing teeth apart from third molars, and the space at the lower left was very noticeable to her as she had a broad smile that showed her missing teeth on the lower left side.

Dr L established that Mrs H had lost her 37 due to extensive caries when she was in her late teens. The 37 had been extracted and then replaced with a single cantilever bridge with 36 as the abutment. From the information gathered, it sounded like the 36 had lost vitality and a number of endodontic treatments were attempted but unsuccessful. The 36 was eventually extracted when Mrs H was in her early 20s. She requested that Dr L restore the area with implants.

Mrs H had also brought a panoral x-ray from a few years ago and Dr L noted the reduced bone height, but he considered there was enough to allow for a safety margin beneath the planned implants. Dr L suggested placing two implants at 35 and 36, with a view to providing an implant retained bridge with 37 as the pontic. Dr L had time to do the treatment the same day and, during the surgery, Mrs H felt intense pain as one of the implants was inserted, even though sufficient local anaesthetic had been administered. The following day, a very agitated Mrs H telephoned the surgery and reported numbness on the lower left side of the lip. As a parting comment she remarked that should her symptoms not improve, she would contact the police.

Dr L immediately contacted Dental Protection to request assistance and it was suggested that he immediately arrange a referral to a maxillofacial specialist. Mrs H was seen promptly and a cone-beam computed tomograph (CBCT) scan was taken, which confirmed the implant fixture at 36 had penetrated the inferior dental canal and had probably mechanically traumatised the left inferior dental nerve (IDN). Sensory nerve testing carried out on the lips indicated that Mrs H could not discern directional stroking or cold stimulus. The specialist removed the implant fixture at 36 without delay, prescribing steroids and NSAIDS, and he was hopeful a prompt intervention might reduce the risk of permanent nerve damage.

After the implant fixture was removed, Mrs H noted an improvement in her symptoms at three months and was kept under review.

Learning points

  • When Dr L’s case was reviewed by his dentolegal consultant it became apparent the assessment and planning fell short of accepted practice. He had not confirmed the date of the panoral; it was subsequently confirmed he was working from a six-year-old panoral. On reflection, he now realised that an up-to-date preoperative panoral should have been taken and a CBCT scan would have been beneficial to further reduce the risk of IDN injury.
  • The dentolegal consultant also identified that the treatment records did not show any evidence of a discussion of the risks associated with the treatment. When asked, Dr L could not recall with any certainty whether he had discussed the risks and the potential consequences should that risk materialise.
  • Dr L also reflected that it would have been good practice to contact Mrs H following treatment by way of review, so that if any issues arose, steps could be taken to address her concerns or symptoms.
  • With hindsight, Dr L recognised that insufficient time had been taken to complete an adequate preoperative assessment and to give Mrs H a cooling off period during which she could think about the treatment and the associated risks.
  • He also appreciated the swift recommendation to refer to a specialist, once the nerve injury had been identified, which probably contributed towards the resolution of the IDN damage and perhaps averted any long-lasting damage to his professional reputation.
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