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The Broken Drill Bit


All health care providers in Ontario must obtain informed consent from patients (or their guardian, parent or other decision maker). Failure to properly obtain informed consent before physical or other examination, before treatment and at regular logical intervals, such as upon learning new facts or upon change of treatment plan, can often amount to professional misconduct and even expose the health professional to a lawsuit. Do you know how and when to properly obtain and document informed consent? Dr. Keith (names changed to protect confidentiality) has learned a valuable lesson about informed consent.

A Case of Informed Consent.

In November 2014, Carol visited Dr. Keith, her family dentist.  She had pain in her upper right bicuspid area. Dr. K. recommended a root canal.  He explained the procedure in some detail. He told Carol it involved removing the nerves in a tooth and then refilling the tooth. He did not inform her that there was a possibility that a drill bit might break during the procedure.

In December Carol returned to Dr. K.   He exposed the two canals in the upper right second bicuspid (tooth #15) and prepared it for filling.  Carol returned in January 2015.   While Keith was filling one of the canals the drill bit broke and became tightly lodged there.   Keith tried, without success, to remove it. He then completed the procedure.  He used the drill bit as a portion of the filling. He did not advise Carol of the incident.

The tooth remained asymptomatic until June 2016.  When Carol was planning a holiday to Washington, D.C. the tooth started aching. Carol consulted Dr. K about the pain. Because Carol wished to continue with her holiday plans, Dr. K. prescribed penicillin. He told her if the tooth did not settle down to see him on her return. During the trip to Washington the pain became intense and while there Carol saw two dentists. The second dentist, an endodontist, took an X-ray of the tooth. It showed the drill bit embedded in the filling. On Carol’s return home in July 2016 she saw Dr. K.  She confronted him with the X-ray.  Dr. K acknowledged that indeed the drill bit had broken off in the tooth and that he had sealed it in a canal. Carol went to see an endodontist.  The endodontist removed the filling used in the root canal by Dr. K and removed the drill bit.  He then refilled the tooth whereupon Carol’s discomfort ended.

Most general practitioners know that drill bits occasionally, if not often, break when a root canal is performed.  It takes considerable skill to remove a drill bit so lodged in a root canal.  A tooth may be damaged beyond repair in the attempt to remove the drill bit. When a drill bit cannot be removed without damage to the tooth there are three available alternatives. The first and most common procedure is to do as Dr. K. did -- leave the broken drill bit in the tooth and complete the filling. The second alternative would be referral to an endodontist in a further attempt to remove the drill bit. The third alternative is to refer the patient to an oral surgeon to perform an apicoectomy. There is, of course, a fourth alternative, namely, to remove the tooth.

Carol had made it clear to Dr. K. from the beginning that she was anxious for this fourth alternative not to happen.  She wanted to retain her natural teeth. Dr. Keith believed that the endodontic procedure held a greater risk of damage to the tooth and that his procedure offered the greatest hope of saving the tooth.

Carol believed that Dr. Keith performed the first procedure competently.   She said Dr. Keith was under no obligation when initially describing the procedure to inform her of the possibility of a drill bit breaking. So what was her main complaint?  She felt that, once the drill bit broke the risk became material and then Dr. Keith was obliged to inform her of that fact and of the various treatment alternatives open to her. In other words, the situation evolved into one where there was a duty to disclose.  Although she admitted that the risk is minimal when compared to cases involving death, stroke and paralysis, it was a material risk in the context of this case and ought to have been disclosed.

Informed consent has two components. Two questions must be answered.

  1. Was the risk one which ought to have been disclosed to the patient and,
  2. if so, would a reasonable person in Carol’s position after having been fully informed of the risk have consented to the procedure if so informed?

Carol decided that a judge must help decide whether she had been given informed consent.

At the trial able counsel for Dr. Keith argued that the duty to disclose occurs before the procedure commences.   If something occurs during the course of a procedure he submitted the question of liability does not arise provided the dentist exercised his judgment in accordance with accepted dental practice.

Judge Scales found that Dr. Ketith did act in accordance with accepted dental practice. However he decided that if the risk is one, which ought to have been disclosed, and the various alternatives can be discussed with an alert patient and these risks are material, they must be disclosed.

This case is distinguished from most, if not all, other recent informed consent cases in that, here it is alleged that a risk which initially need not have been disclosed occurred during the course of the procedure while the patient was fully alert and able to discuss the consequences with the dentist.  In this case, something occurred, which would not ordinarily have to be disclosed, during the procedure when the patient is alert and able to be consulted about the alternatives, which are open.   Judge Scales found no reason why Dr. K should not have told Carol of the incident so she could participate in the decision.

The test is said to be an objective one -- on a balance of probabilities would a reasonable person in Carol’s position and being fully informed of the risks have decided to leave the broken drill bit in place. But the test takes into account the circumstances of the particular case. Here we must consider the relationship between patient and dentist, her confidence in the dentist, which she demonstrated earlier by accepting his advice and the fact that the procedure, which he took on his own accord, was the one, which would most likely save the tooth.

Scales having decided that there was a duty on Dr. Keith to disclose, dealt with the question of causation. Namely, would a reasonable person in Carol’s position, after being fully informed, have consented to the drill bit being left in the tooth?  This would be determined on the basis of a reasonable person's choice being made based on a person being in the Carol’s position.

The judge reviewed the relationship between Carol and Dr. K. It was long-standing in that he had been her dentist and her children's dentist for five years. Her confidence in Dr. K was illustrated from the following passages of her evidence:

Q. Do you know why he suggested a root canal procedure?
A. He looked at the x-ray and saw that it had had a filling previously. It was his professional judgment that was the procedure that was required. I had never had a root canal before and I was trusting his professional judgment to give me the benefit of his expertise. And at that time I asked him, you know, what that implied, was he going to pull out the tooth, and he said no, that wasn't required. The idea was to allow the tooth to remain in place but it would be essentially a non-living tooth.
Q. And you elected to use the root canal procedure? Why?
A. Well, for one thing I was in pain and I did not seek relief, and because it was his area of expertise and I took his advice for that reason.


Judge Scales concluded that a reasonable person in Carol’s position would have accepted Keith’s advice. The evidence cited above disclosed confidence in her dentist. The procedure adopted by Dr. K was the one most likely to save the tooth. By adopting this method he left open to Carol the other alternatives in the event that the tooth did flare up -- although later it involved removing the filling and refilling the tooth. Thus it is likely that a reasonable person in Carol’s position, if fully informed of the consequences, would have elected the alternative adopted by Dr. Keith.

So, Carole’s claim was dismissed. Dr. Keith was exonerated by the wise Judge Scales! However Dr. Keith learned a lesson. He will from this day forward obtain informed consent in writing and authorization to proceed whenever his patient’s are alert and conscious.