Oral Health Group

Putting the Risk in Context

February 20, 2018
by Alia El-Mowafy, BDS, MSc

Sedation and anesthesia for dentistry has come under scrutiny in the past few years due to a few tragic events where patients experienced harm. These events have raised several questions: are these just isolated incidents due to negligence in clinicians’ practices; did these patients pose unforeseeable challenges; and ultimately, what is the safety of dentistry under deep sedation or general anesthesia?

It is important to note that while these events are incredibly tragic for the victims, their families, and the personnel involved, taking sole incidents out of context can be misleading to the safety profile of a procedure. When estimating the prevalence of mortality or morbidity for any procedure in dentistry, we can only understand the total risk involved by knowing the total number of critical incidents that have occurred, and by comparing this number to the total number of procedures that have been administered without complications. This gives context to the level of risk inherent in a procedure.


For example, in order to investigate the risk of mandibular fracture following third molar extractions, Libersa et al1 retrospectively examined the experiences of one hundred and fifty oral and maxillofacial surgeons with intra-operative or late mandibular fracture during impacted third molar surgery.1 The survey inquired about the surgeons’ experiences over a ten-year period. Based on the survey responses, the authors found that there were 27 reported mandibular fractures in an estimated 750,000 surgeries that were administered during this time.1 According to this study, the prevalence of mandibular fracture occurring would be about 1 in 28,000 impacted third molar surgeries. Based on these results, the risk of mandibular fracture would be very low.2 This is likely not surprising to experienced clinicians. Understanding and putting these values into context, however, is important when communicating the level of risk associated with a procedure to patients especially when they may be familiar with a case of a rare complication.

The same holds true for severe injury or death associated with dentistry under deep sedation or general anesthesia. Media reports can be misleading to the public without providing context. Several studies have set out to determine the prevalence of severe injury and death for dental procedures under deep sedation or general anaesthesia. Reported dental anaesthesia mortality rates range from one to seven deaths per one million cases.3-7 The prevalence of severe injury has been reported in the range of one incident per 37,000 to 364,000 cases.3-7 These rates support the safety of the practice of dentistry under deep sedation or general anesthesia, and they provide evidence for the minimal risk of severe injury or death in relation to these procedures.

Regardless of how low the risk is, there is much to be learned from the reporting of critical incidents.8 The tragic events that have occurred in North America highlight the need for a surveillance system to be established in all of the Canadian provinces to monitor mortality and morbidity events for dentistry under sedation or general anaesthesia on a regular basis. These data should be readily available to the regulators (e.g. RCDSO), clinicians, and patients alike. It is essential to not only establish a surveillance system of incidents, but it is also essential to ensure that the professional community has the analytical capacity to review these incidents. This would allow professionals to speculate on the causes, themes, or patterns that led to injury or death of the patients in order to avoid similar outcomes in the future. Importantly, this would provide everyone with a readily available database to assist in communicating the risk to patients. OH

Oral Health welcomes this original article.


  1. Libersa, P., Roze, D., Cachart, T., & Libersa, J.-C. (2002). Immediate and Late Mandibular Fractures After Third Molar Removal.
    American Association of Oral and Maxillofacial Surgeons, 2, 163–165. http://doi.org/10.1053/joms.2002.29811
  2. Jenkins, K., & Baker, A. B. (2003). Consent and anaesthetic risk. Anaesthesia, 962–984.
  3. D’Eramo, Edward; Bookless, Steven Howard, J. B. (2003). Adverse Events With Outpatient-Anesthesia in Massachusetts. American Association of Oral and Maxillofacial Surgeons, 2391(3), 793–800. http://doi.org/10.1016/S078-2391(03)00238-6
  4. D’Eramo, E. M. D. (1999). Mortality and Morbidity with Anesthesia: The Massachusetts Outpatient Experience, 531–536.
  5. Deegan, A. E. (2001). Anesthesia morbidity and mortality, 1988-1999: claims statistics from AAOMS National Insurance Company. Anesthesia Progress, 48(3), 89–92. Retrieved from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2007373&tool=pmcentrez&rendertype=abstract
  6. Nkansah, P. J., Haas, D. a, & Saso, M. a. (1997). Mortality incidence in outpatient anesthesia for dentistry in Ontario. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics, 83(6), 646–651.
  7. Bennett, J. D., Kramer, K. J., & Bosack, R. C. (2015). How safe is deep sedation or general anesthesia while providing dental care? The Journal of the American Dental Association, 146(9), 705–708. http://doi.org/10.1016/j.adaj.2015.04.005
  8. Bosack, R. C. (2015). Anesthetic complications-How Bad Things Happen. Scientific American. http://doi.org/10.1038/scientificamerican0602-26

Alia El-Mowafy attended the Bachelor of Science programme at York University majoring in Psychology and Kinesiology. She went on to complete her degree in dentistry at Future University in Egypt. She completed her masters degree in Dental Anaesthesiology at the University of Toronto.

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