Legal Cases: Root canal with inferior alveolar nerve injury

By William S. Spiegel and Marc R. Leffler, DDS, DrBicuspid.com contributing writers

September 21, 2015 -- DrBicuspid.com is pleased to present the next column from two lawyers who spend every day defending dentists in litigation and before the licensing board. The purpose of this column is to offer our readers a fresh perspective on common practice and risk management issues from attorneys who litigate these issues in the real world.

A patient presented to a general dentist, who became the defendant, with complaints of increasing pain in her lower left quadrant. She reacted to percussion on teeth Nos. 18 and 19, but the symptoms were much worse on No. 18. A radiograph revealed large amalgam fillings in both teeth, but there was no clear impingement on the pulp.

Both teeth had very slight periapical pathology and some widening of the periodontal ligament (PDL). The inferior alveolar canal appeared within 1 mm to 2 mm of the apices of the roots in this area. The dentist prescribed antibiotics and pain medication, and advised the patient to return in five days for root canal therapy (RCT) on No. 18.

William S. SpiegelMarc R. Leffler, DDS
William S. Spiegel and Marc R. Leffler, DDS, are both partners at the law firm Spiegel Leffler in New York City.

The patient returned as scheduled, having taken the medications as prescribed. By that time, according to her testimony, she had isolated the pain as coming from tooth No. 19. The dentist, who had performed many RCT procedures during his 10 years in practice, disagreed with this testimony. He proceeded with the RCT of tooth No. 18.

He gave the patient an Endodontic Consent Form, asked her to read it, and gave her a chance to ask questions. The form contained a number of risks associated with lower molar RCTs, including temporary or permanent numbness. The patient contested this testimony and argued that she was simply told by the front desk to sign the document along with several other papers.

A mandibular block injection was given on the left side. The dentist isolated the tooth and then entered into the pulp chamber of tooth No. 18. He then extirpated the pulp tissue and filed the tooth with the aid of an apex locator; no radiographs were taken during the procedure. Gutta-percha was used to fill the canals and the postoperative film showed the fill just short of the apex.

The next day, the patient telephoned the office advising that she was still numb on her left lower lip and chin, and that she still had excruciating pain in the lower left. The dentist evaluated the patient, and found that she was profoundly numb on the lip and chin and was percussion-tender on tooth No. 19. He proceeded with a RCT of No. 19 and advised the patient that the numbness would likely resolve over the next couple of months, but that if it did not, she would be referred to an oral surgeon.

The patient never returned to the office and her subsequent records over the next two years confirmed unresolved moderate to severe paresthesia.

Legal stance

The patient filed suit claiming lack of informed consent, that the dentist was negligent in performing RCT on the wrong tooth, failing to refer to an endodontist and oral surgeon, failing to use a rubber dam, and improperly performing the procedure so as to cause an inferior alveolar nerve injury.

Issues raised

Among the issues raised were the following:

  • Informed consent: The patient claimed that she was so uncomfortable at the time she signed the consent form that she did not read it. It was her testimony that the form was buried among various other forms so as to keep her from paying any particular attention to it. Furthermore, she argued that the dentist did not discuss risks with her or go over the form in any way.

  • Apex locator versus radiographs: Using an apex locator does not provide documentary evidence of the files staying within the canals, whereas radiographs document at least that the working lengths used were proper at the times that the films were taken. Here, the dentist was left with nothing, neither x-rays nor chart notes, to show that he had accurately determined the apex lengths and that he had not gone beyond those lengths when filing.

  • The proper tooth to treat: Diagnosing the proper tooth to treat is a frequent issue in dentistry, as patients sometimes have difficulty focusing the source of symptoms; that problem is magnified when there are no clear-cut clinical or radiographic indicators. In this case, the dentist took the precaution of medicating the patient and waiting before he treated; while this was certainly helpful in defending the case, equally harmful was the dentist's failure in performing a full array of pulp testing modalities and basing his choice solely on percussion testing.

  • Technique: At his deposition, the dentist testified to standard and appropriate RCT treatment. He testified to filing each of the canals to the length he established based upon the apex locator, properly preparing each one for the fills, and then placing gutta-percha with cement to the previously established lengths. Similarly, he testified to appropriate mandibular block technique, accurately responding to the plaintiff's attorney's deposition questions regarding the anatomical landmarks for giving such an injection.

  • Failure to refer: As is often the case, the plaintiff's attorney argued that because the tooth involved was a molar, the RCT would have been better handled by an endodontist. The attorney also argued that the dentist should have referred the patient to an oral surgeon immediately when paresthesia was noted.

Verdict: For the dentist

Despite the potential risks in taking this case to a jury, the dentist, who had a consent clause in his malpractice insurance policy, refused to settle. There was no evidence of an overfill of any canal, nor was there proof that he overinstrumented. At trial, experts weighed in for the opposing sides, with the expert for the plaintiff arguing that the injury alone was proof of malpractice. The defense argued that a properly delivered mandibular block injection can cause paresthesia and that this is not necessarily negligence.

The jury deliberated for two days, so clearly their decision was not an easy one. In the end, they felt that the signed consent form carried a lot of weight, and they didn't believe the patient when she said she had no idea what she was signing. This was particularly so because there was a sentence in bold just above her signature that read, "By signing below I indicate to the dentist that I have read and understand the above risks and give my consent for this treatment with full knowledge of the above."

Practice tips

“The value of a strong informed consent process ... cannot be overstated.”
  • Informed consent: The value of a strong informed consent process, by way of both a solid form to be signed by the patient and a verbal interaction between dentist and patient, cannot be overstated. Patients must be educated about what is going to happen, what risks are associated, and what alternatives are available to them.

    The law requires that consent be obtained, but most states do not have laws requiring consent to be in writing. However, if you were a juror, wouldn't you be more inclined to side with the dentist if a written consent was signed by the patient?

  • Apex locator versus radiographs: There is an ongoing debate in the dental community to reconcile the issues of x-ray exposure and medicolegal documentation. Some dentists use working length films, while others use an apex locator. Other dentists use both. Whatever your approach, protect yourself by documenting the canal lengths and proper instrumentation of the canals.

  • Diagnosis: The diagnostic process is not a step for shortcuts. As obvious as the conclusion may seem at first blush, a complete set of diagnostics must be undertaken, with documentation of the results in the patient's chart. Always discuss why you are performing the RCT.

  • Referring to a specialist: While a general dentist is trained in performing RCTs on all teeth and is permitted to do so, there should always be a point in time before beginning any procedure when any practitioner should ask if they feel fully comfortable completing the procedure. Are the canals calcified? Curved? Are they possibly impinging on the inferior alveolar nerve canal?

    Here, the plaintiff testified that, had she known of the risk of a permanent nerve injury, she would have wanted to have the procedure done by a specialist, but that option was never given to her.

Next case: Orthodontics case involving severe root resorption and tooth loss.

William S. Spiegel, Esq., is a partner at the law firm Spiegel Leffler in New York City. He is a former assistant corporation counsel to the City of New York -- Medical Malpractice Division.

Marc R. Leffler, DDS, Esq., is also a partner at Spiegel Leffler. He received his dental degree from Columbia University, completed a residency in oral and maxillofacial surgery at New York University, and is a diplomate of the American Board of Oral and Maxillofacial Surgery.

Disclaimer: Nothing contained in this column is intended as legal advice. Our practice is focused in the state of New York, and there are variations in rules of practice, evidence, and procedure among the states. This column scratches the surface on many legal issues that could call for a chapter unto themselves.

The comments and observations expressed herein do not necessarily reflect the opinions of DrBicuspid.com, nor should they be construed as an endorsement or admonishment of any particular idea, vendor, or organization.


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