Is Informed Consent Necessary For Mandibular Blocks?

Case Study

Marc Leffler, DDS, Esq.
February 28, 2022

Reading time: 7 minutes

A woman receiving dental treatment with mandibular blocks.

Background Facts

A 42-year-old healthy woman, Mrs. B, presented to her general dentist, Dr. W, on a scheduled visit for a Class 2 restoration on tooth #30, due to recurrent decay having developed adjacent to an open margin on an amalgam restoration placed decades earlier. Likely as a result of her meticulous home care and regular hygiene visits, she had very little dental work in her mouth, and whatever she had was performed many years prior. She was, therefore, nervous about her upcoming treatment and did not remember enough of her previous treatments to know what to expect.

After updating the patient’s medical history, reviewing recent radiographs with the patient, confirming the treatment planned – an MO composite – with the patient, and advising the patient that she would be receiving an injection to “numb up” the lower right portion of her mouth, Dr. W confirmed with Mrs. B that she was ready to have the treatment proposed go forward. With nothing more said, Dr. W proceeded to give a right-side inferior alveolar (“mandibular”) block, using 1 carpule of 2% lidocaine, 1:100,000 epinephrine. During the administration, the patient felt a “jolt”, and simply groaned, but did not move. The restoration was placed uneventfully.

The following day, the patient called the dental office, advising Dr. W that she still felt numb on the right side of her chin, lower lip and the gums just inside the lip. Dr. W assured her patient that the effects of local anesthesia sometimes remain for a short period of time, but everything should be back to normal by the next day, at the latest. But that next day, the numbness had not improved at all, so Mrs. B again called to speak with Dr. W. The dentist was perplexed at the circumstances, but told the patient that she had heard of rare cases of normal feeling never returning. The patient began to cry and asked why she had not been told of this prior to the start of treatment. Dr. W had no response other than to say that she has never had such a discussion with any patient about to receive that type of injection. Dr. W made no treatment recommendations. Mrs. B never returned to see Dr. W.

On her own, Mrs. B sought, within a month, the care of a neurosurgeon, who saw no other way to treat this condition than with medications to ameliorate what had become a sometimes painful and uncomfortable alteration of sensation, which the patient described as feeling like bugs crawling under the skin of the right side of her face, while simultaneously being unable to feel her right lower lip and chin at all; it was diagnosed as a “traumatically induced dysesthesia”. Despite modifications in the medications and their doses, the symptoms never abated.

Legal Status

About a year later, with no change in her physical status, Mrs. B and her husband contacted and retained an attorney skilled in handling dental malpractice cases, who sued Dr. W on their behalf. The claims asserted against the dentist were that she failed to give a proper block injection, thereby causing permanent injuries, and that she failed to obtain the patient’s informed consent prior to the start of treatment.

The case proceeded forward, with depositions taking place. With the dentist having been well prepared for her deposition, she articulated quite well the manner in which she administered the injection, and was able to correctly respond to questions regarding local anatomy. She claimed to have obtained informed consent, by simply receiving the patient’s approval to go forward. Dr. W testified that she was not aware of any requirement for a formal informed consent process for performing a restoration with local anesthesia. She also did not dispute the claim that the injection, and nothing else, caused the inferior alveolar nerve injury.

The Applicable Legal Statute

While States vary as to the requirements for informed consent, the State in which Dr. W practiced had a statute which stated, in essence, that prior to the performance of any invasive procedure, the practitioner performing the procedure must advise the patient, in language understandable to that patient, of the foreseeable risks, benefits and viable alternatives associated with the planned procedure, in such a manner permitting the patient to make a knowledgeable decision. The patient must then agree to move forward before the practitioner may do so. The statute is silent as to whether the consent obtained must be memorialized in writing.

Trial Lead-Up and Events

The dentist continually maintained that she had done everything according to the applicable standards of care, and that she was not required to go through a formal informed consent process each and every time she administered a mandibular block injection. Immediately before jury selection began, the plaintiff’s attorney made an unusual strategic decision: because his expert was unable to point to a specific area of negligence in the performance of the injection itself, he discontinued the claim of a negligently performed block, but continued the case forward on the theory of lack of informed consent.

Dr. W testified at trial just as she had at deposition. The patient testified that, had she known of the undisclosed risk in advance of the procedure, she would have sooner had the filling replaced with no anesthesia at all, rather than accept the risk that this type of injection posed. Based upon the testimony of the parties, under oath and in front of the jury, the judge determined that this case fell within the realm of negligence per se, which is a legal concept that states that if a violation of a statute directly causes an injury, the defendant is liable, leaving to the jury the lone question of the monetary value of the injury. The judge determined that, in the court’s interpretation, a mandibular block was an invasive procedure about which the patient had not been properly advised, but which the statute required she should have been, thereby depriving her of the opportunity to undergo the procedure without anesthesia and, therefore, with no nerve injury risk. The court also held that this violation of a statute, which was the predicate for the injection having been given, was then, consequently, the direct cause of the injury, as the defendant dentist had admitted.

The jury was directed to presume liability and award the patient a measure of damages which its members believed would fairly and reasonably compensate the plaintiff. The jury did just that and made a substantial monetary award.


It is not the purpose of this case study to give dentists advice as to whether any particular dental procedure meets the requirements of the practice’s jurisdiction for the obtaining of a patient’s informed consent; nor does the study mean to suggest that any dentist must or should obtain a patient’s informed consent under given circumstances. It is for each dentist before each procedure to determine, both dentally and according to local laws, whether informed consent needs to be obtained and by what means.

“Informed consent” is not a form, even if signed by all parties involved, but rather a process during which a patient is provided with information by which an informed decision can be made. The process, by its very nature, must allow for a patient to ask questions and receive frank responses. A signed “consent form” does not substitute for the give-and-take needed to make a patient an educated consumer; it is merely a written memorialization that such a process took place, and it can serve as an extremely valuable tool in defending dental malpractice claims because it lessens the legitimate arguments by plaintiffs that they were not provided with the information needed for them to be informed.

By comparison, a chart entry, alone, written by the dentist, or worse yet, no entry on the issue at all, will inevitably lead to a litigation battle between dentist and patient as to whether the process took place, with the dentist contending that it did, and the patient asserting that it did not. Such disagreements are left for juries to decide, and realizing that all jurors are, themselves, patients, should serve as guidance as to what they might conclude in the face of no tangible evidence of the patient having been advised.

A patient’s stated willingness to have a procedure performed, with nothing more, cannot be viewed as the obtaining of informed consent. Although such willingness is clearly necessary, it is the end-product of a process, but not the process itself.

Finally, while it was not an issue in this case, it is a frequent issue in claims of paresthesia following block injections whether a 4% solution of a local anesthetic is appropriate for this purpose. There are anecdotal reports and even published papers on both sides of this debate, so without giving advice regarding which anesthetic solutions may be appropriate under a specific set of circumstances, we take this opportunity simply to alert dentists to this increasingly frequent source of malpractice actions, and to suggest that they update their knowledge bases in order to make the soundest patient decisions possible.

Note that this case presentation includes circumstances from several different closed cases, in order to demonstrate certain legal and risk management principles, and that identifying facts and personal characteristics were modified to protect identities. The content within is not the original work of MedPro Group but has been published with consent of the author. Nothing contained in this article should be construed as legal, medical, or dental advice. Because the facts applicable to your situation may vary, or the laws applicable in your jurisdiction may differ, please contact your personal or business attorney or other professional advisors if you have any questions related to your legal or medical obligations or rights, state or federal laws, contract interpretation, or other legal questions.

Additional Risk Tips content

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Patient refusal is an aspect of dental care dentists must navigate. In this article, a patient presents to her dentist with tooth decay but refuses x-rays. Later, the patient sues the dentist for negligence.

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In dentistry, documentation is an essential element of practice. In this case study, the lack of detail in a dentist’s chart entry impacts the outcome of a malpractice case against her.

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Dentists must strictly adhere to state guidelines about records retention. In this case study, a dentist neglects to maintain records for the required duration in the state in which he is sued.

This document does not constitute legal or medical advice and should not be construed as rules or establishing a standard of care. Because the facts applicable to your situation may vary, or the laws applicable in your jurisdiction may differ, please contact your attorney or other professional advisors if you have any questions related to your legal or medical obligations or rights, state or federal laws, contract interpretation, or other legal questions.

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