Dentist not required to disclose low risk of chronic pain from root canal: B.C. Court of Appeal

Severe, chronic, nerve-related pain is not a material, special, or unusual risk associated with a root canal procedure that a dentist is required to disclose, the British Columbia Court of Appeal has found.

In Parhar v. Weaver, 2022 BCCA 134, Dr. Brennan Weaver was Karunbir Parhar’s dentist. In 2014, Weaver performed a root canal procedure on one of Parhar’s molars. Parhar was not asked to sign a consent form, but Weaver testified that he would have given a standard description of the procedure. Weaver did not advise Parhar of the possibility of chronic nerve pain, since it was not taught in dental school, nor had he encountered it in practice. After the procedure, Parhar’s pain intensified, which led to further procedures.

Parhar sued Weaver, seeking damages in negligence for failure to obtain informed consent. At trial, there were competing expert opinions about chronic nerve-related pain following a root canal.

After weighing the evidence, the trial judge ruled that while the risk of nerve-related pain exceeded three percent, the incidence of this pain being severe and chronic was “extremely low, to the point that the risk cannot be meaningfully quantified.”

The trial judge dismissed the claim, ruling that Parhar failed to establish that the pain was “a material, special, or unusual risk associated with a root canal procedure” and therefore was not a risk that Weaver was required to disclose. The judge also concluded that Parhar failed to establish that “he would not have consented if informed of the risk, nor did he establish that his pain was a result of the undisclosed risk materializing.”

Parhar appealed, alleging that since the risk of chronic nerve pain exceeded three percent, Weaver should have been required to disclose it.

The Court of Appeal disagreed.

The judge’s finding that the risk of chronic, nerve-related pain was not a material, special, or unusual risk that required disclosure is entitled to deference on appeal, said the court. Further, contrary to Parhar’s assertion that review is closer to correctness, the standard of review in this case is palpable and overriding error, said the court.  

The appeal court concluded that the judge’s findings were open to him based on the evidence presented. Parhar failed to demonstrate palpable or overriding error that warranted appellate intervention, said the court.