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Patient Safety Tip of the Week

January 25, 2022

More on Dental Patient Safety Issues



It’s been a while since we did a column on dental patient safety. In today’s column we have some old issues and some new ones.


We thought we had covered just about every conceivable problem in our March 15, 2016 Patient Safety Tip of the Week “Dental Patient Safety”. But here’s a new one on us: amaurosis following injection of inferior alveolar nerve! Yes, blindness following just that injection! Fortunately, it was temporary, though it was very disturbing. A 37-year-old patient was administered an inferior alveolar nerve block for a root canal procedure (Pandey 2018, Murphy 2018). Immediately after the administration of local anesthesia, the patient reported complete loss of vision. The patient recovered completely after 15 minutes.


The dentist used a 30-mm-long, 28-gauge aspirating syringe to administer anesthesia (1.8-mL lidocaine with 1:100,000 adrenaline) targeting the right inferior alveolar nerve. Aspiration was negative. Immediately after receiving the anesthesia, the patient reported blurred vision in his right eye. About 30 seconds later, he said that his vision was completely gone. Attempting to read a nearby letter chart, his vision was normal in his left eye, but he had no vision in his right eye. Other than this, the patient showed no physical symptoms or changes in speech or mental acuity.


Actually, there have been a handful of similar cases reported in the literature. The blindness usually resolved in about 20-30 minutes. Only two case reports have described permanent vision loss. The theory is that the local anesthetic is accidentally injected under pressure into the inferior alveolar artery, which lies adjacent to the inferior alveolar nerve, and backflow carries it into the maxillary artery and middle meningeal artery, where it’s eventually delivered into the central artery of the retina, resulting in vision and/or temporary vision loss. And needle size may be important. A smaller-gauge needle is more likely to be deflected when passing through the tissues.


Here's another new one – a swallowed dental needle. A 29-year-old woman presented with throat pain that had lasted 12 days (Mohammed 2020). She attributed onset of the pain to a meal containing duck, assuming she had swallowed a duck bone. A primary health care center prescribed painkillers and antibiotics for pharyngitis, but no imaging was performed. Her pain persisted over the following few days and now a soft tissue neck x-ray was taken, which revealed a foreign body. Referral to an ENT department was made. X-ray showed a long, thin, smooth, and impinged foreign body at the C5–C6 level, lying lateral to the esophagus, confirmed by computed tomography to be 3 cm in length. Neck exploration and removal of foreign body under general anesthesia was performed. The foreign body was identified as an injection needle with a bore and a pinged proximal end suggesting that it had broken from its base.


When the needle was shown to the patient, she recalled having a dental procedure in which she was given an intraoral local anesthesia, the same day she had consumed the duck meal. No official records of the denial procedure were able to be reviewed. Although there is no definitive evidence that the foreign body originated from this dental procedure, it appears to be the most logical explanation. The authors performed a simulation, using a 23-gauge needle and bending it as if preparing for an intraoral injection. The removed foreign body was almost identical to the needle that was used in the simulation.


The authors cite a prior publication of a case series of 16 patients with broken local anesthetic needles (Pogrel 2009). Of the 16 needle fractures, 15 occurred in connection with an inferior alveolar nerve block, and one occurred in connection with a posterior superior alveolar block. Of the 16 fractures, 13 involved a 30-gauge needle. Five of the patients involved were younger than 10 years, who often moved suddenly and violently as the dentist gave the injection. Porgrel concluded that dentists should avoid burying any needle up to the hub (so as to ensure the possibility of immediately retrieving the needle intraorally), avoid using 30-gauge needles to administer inferior alveolar nerve blocks and avoid bending the needle before inserting it.


Likewise, Mohammed et al. conclude that “the majority of intraoral needle breakages occur during the administration of inferior alveolar nerve blocks or a root canal wash, and in patients who suddenly move as the injection is being administered. Needles should not be bent prior to injections being administered. Additionally, needles should not be inserted up to their base to help facilitate their retrieval if an accidental breakage occurs intraorally. Clinicians performing intraoral procedures should also use larger-gauge needles when possible, as smaller needles are more susceptible to accidental breakages.”


Another intraoral injection incident raises an old issue – misidentification of injected solutions.  Hiremath et al. (Hiremath 2016) reported a case where 2% chlorhexidine gluconate was mistaken for an anesthetic solution and infiltrated into the buccal vestibule during routine root canal treatment. The patient experienced pain and a burning sensation over the injected area shortly after injection and developed swelling with extraoral redness over the right cheek area. The patient was immediately administered dexamethasone intramuscularly, and was prescribed antibiotics, analgesics, and antihistamines. The patient complained of a loss of sensation over the right cheek by the 15th day. The swelling reduced gradually over a period of 15 days and reversal of sensation was attained after 35 days. This incident brings to mind the devastating incidents where chlorhexidine antiseptic solution was mistaken for radiographic contrast media and injected intra-arterially (see our June 23, 2015 Patient Safety Tip of the Week “Again! Mistaking Antiseptic Solution for Radiographic Contrast”). Hiremath et al. note other reports of unintended injection of formalin, hydrogen peroxide, and sodium hypochlorite instead of local anesthetic, citing various reasons such as the widespread practice of using local anesthetic in bottles, reuse of local anesthetic bottles in dental operatory, nonavailability of professionally trained or educated dental assistants, and improper handling techniques.


In our June 23, 2015 Patient Safety Tip of the Week “Again! Mistaking Antiseptic Solution for Radiographic Contrast” we noted that incidents involving injection of the wrong substance when two look-alike substances are in proximity and are unlabeled have occurred in multiple venues (angiography suites, cath labs, dialysis units, hospital OR’s, ambulatory surgery centers, and others). Most hospitals have really focused on enforcing the “no unlabeled syringes” and “no unlabeled solutions in basins” in the OR. But it may be that those other areas (radiology suites, cath labs, dialysis units, etc.) may be even more vulnerable to such incidents. Add the dental office to that list. And don’t forget bedside procedures. They are probably even more prone to such mistakes. Clear, colorless skin antiseptics might be easily confused with substances intended for spinal injection or injection into other body cavity.


There’s always that tendency to think “I know what’s in that basin” and “there will only be one basin”. Then another basin shows up with a substance similar in appearance, often unbeknownst to the person who will actually be injecting. There’s also a tendency to keep the skin antiseptics around “just in case we might need them”. Once you’ve prepped the skin, the antiseptic agent should be removed from the sterile field (and even adjacent stands). There is usually easy access to these in most venues if you really do need them again so there is little reason to “keep them around just in case you might need them again”. And remember that the alcohol-based antiseptics are also flammable so you especially don’t want them sitting around where they might get ignited by a heat source during a procedure.


In our experience, dental offices have been very good at complying with recommendations once they reopened during the COVID-19 pandemic. But the dental community continues to look for ways to further improve COVID-19 safety. A recent study (Roy 2021) suggests that adding a small amount of hydrogen peroxide to the water in ultrasonic scalers used to clean teeth might help mitigate the risk of spreading airborne diseases, including COVID-19, in dental environments. The study did not test droplets that actually contained virus but looked at droplet size and the spread of droplets after the addition of low-dose hydrogen peroxide. Further research is necessary to determine whether this has practical application in dental practice.


Incidents like the swallowed needle and the incorrect injections would be examples of events we think should never occur. We have lists of never events for The Joint Commission and most state health departments. What about dental never events? An expert panel used the Delphi method to come up with candidate items for a dental never event list (Ensaldo-Carrasco 2018). They identified candidate events in several categories:

During routine assessment:

During the preoperative stage:

During the intraoperative stage:

During the postoperative stage:


One of our best tools for avoiding never events or other adverse events is use of checklists. We’ve done multiple columns on the WHO surgical safety checklist. So why not one for dental procedures? Using the Delphi technique, another expert panel assessed and adapted the WHO Surgical Safety Checklist to develop “The WHO Dental Safe Surgery Checklist” (Wright 2018). See the article itself for a sample of the checklist. Another surgical safety checklist was developed for dental implants (Bidra 2017). Use of that checklist 8 prosthodontic residents was assessed in 120 dental implant surgeries encompassing 262 implants over an academic year cycle (Remiszewski 2019). There was a 100% compliance rate for surgical safety checklist completion by all 8 prosthodontic residents. Within the checklists, the rate of incomplete responses or omissions was 2.4%.



Now back to an old issue – safety of sedation/anesthesia for dental procedures. In 2019 the American Academy of Pediatrics (AAP) published a joint statement with the American Academy of Pediatric Dentistry (AAPD) updating the AAP sedation guideline (Cote 2019). We discussed the updated guideline in our September 2019 What's New in the Patient Safety World column “New Guidelines for Pediatric Dental Sedation”. Perhaps the most important item in the guideline is a requirement that such procedures be done in the presence of two qualified individuals. That means that the dentist or oral surgeon performing the dental or oral surgery procedure cannot be the individual administering and monitoring the sedation. This ensures that individuals are attending to one primary task and not involved in two different tasks simultaneously. The guideline also clarifies that deep sedation or general anesthesia must be administered by a qualified anesthesia provider (a physician anesthesiologist, certified registered nurse anesthetist, dentist anesthesiologist or second oral surgeon). Because children commonly pass from an intended sedation level to an unintended deeper level of sedation, practitioners of sedation must have the skills to rescue the patient from a deeper level than that intended for the procedure. The ability to rescue means that practitioners must be able to recognize the various levels of sedation and have the skills and age- and size-appropriate equipment necessary to provide appropriate cardiopulmonary support if needed.


Cote et al. (Cote 2021), in a letter to the editor of the APSF Newsletter, raise concerns about some subsequent actions. They note that, in response to the 2016 joint AAP/AAPD guideline on sedation, the oral surgery community developed a Dental Anesthesia Assistant National Certification Examination (DAANCE) with no pre-examination educational requirements. It consists of 36 hours of internet study. A person with no practical or clinical experience could be certified to be the independent observer based on just 36 hours of internet reading. It would not require hands-on medical training to deal with a life-threatening emergency. Cote et al. note that the 2019 sedation guideline now states explicitly that deep sedation/anesthesia must be provided by an anesthesia-trained provider and the operating dentist must be currently PALS-certified to assist the anesthesia provider with an adverse event. This provides a ready-to-respond sedation team on site. The single-provider-operator-anesthetist oral surgery model must be replaced with the multiple-provider-sedation-care team AAP/AAPD model.


Persistent disagreements over safety of dental anesthesia and the single provider issue were also discussed in Anesthesiology News (Vlessides 2020), with comments on laws passed in California. One solution would be to do all cases requiring sedation/anesthesia in a hospital-based setting. But another option raised is using mobile anesthesiologists for dental procedures (Seidman 2021).


Issues related to training and qualifications pertinent to pediatric dental sedation were front and center in a 2018 trial about the tragic 2014 death of a 3-year-old during a dental procedure. Though the dentist was ultimately found not guilty of criminal manslaughter in the case, there were some striking revelations (KHON News 2018). The three sedating medications were administered by the receptionist, who was not licensed in any way, and the dentist was not present at the time they were administered. The dentist testified that she “was unable to force a pipe down Finley’s throat to provide her with necessary oxygen as the toddler’s muscles had contracted” (Schladebeck 2018).


We think the 2019 updated AAP/AAPD sedation guideline (Cote 2019) has all the safety requirements we would want in place if one of our own grandchildren were having sedation for a dental procedure. We’d want one person focusing on the procedure and another focusing on monitoring the sedation/anesthesia. And we’d certainly want to know that one or both are certified in PALS (note that most states that certify dentists for sedation in the office include a requirement for certification in PALS or equivalent).


Our July 2019 What's New in the Patient Safety World column “Dental Prescribing Called Into Question” discussed possible overprescribing of opioid analgesics and antibiotics by dentists. Regarding antibiotics, the major issue is whether prophylactic antibiotics should be given prior to invasive dental procedures in patients with prosthetic joints. Following a systematic review (Sollecito 2015), the ADA (American Dental Association) issued a guideline, last updated this January (ADA 2022). The guideline states “In general, for patients with prosthetic joint implants, prophylactic antibiotics are not recommended prior to dental procedures to prevent prosthetic joint infection.” Unfortunately, the orthopedic specialty societies have not endorsed that guideline and have largely left decisions up to individual orthopedic surgeons. As a result, some patients with prosthetic joints get prophylactic antibiotics prior to invasive dental procedures, while others don’t. (Note that f”or patients with a history of complications associated with their joint replacement surgery who are undergoing dental procedures that include gingival manipulation or mucosal incision, prophylactic antibiotics should only be considered after consultation with the patient and orthopedic surgeon; in cases where antibiotics are deemed necessary, it is most appropriate that the orthopedic surgeon recommend the appropriate antibiotic regimen and, when reasonable, write the prescription.”). Now a study just published in JAMA Open Network (Thornhill 2022) analyzed late prosthetic joint infections in England (where prophylactic antibiotics are not recommended). The researchers found no temporal association between late prosthetic joint infections and invasive dental procedures. The authors conclude that their findings suggest that there is no rationale to administer antibiotic prophylaxis before invasive dental procedures in patients with prosthetic joints. They state “The continuing use of antibiotic prophylaxis represents a large and unnecessary financial burden on individuals and the health care system as well as an unnecessary risk to patients, from adverse drug reactions, and society, owing to the potential development of antibiotic resistant bacteria, and should cease.” It remains to be seen whether this additional research finding changes current practices.


Lastly, what do dentists do when there is an adverse event to one (or more) of their patients? Our regular readers know we have long been strong advocates for disclosure and apology. The American Dental Association, and its ADA Council on Advocacy for Access and Prevention, is offering a free webinar "Communicating With Patients When Things Go Wrong In Dentistry" on two separate dates: January 19, 2022 at noon CST and February 1, 2022 at 6:30 p.m. CST (ADA 2022). The webinar highlights the importance of transparency and focuses on best practices for communicating with patients who have been involved in a “near miss” or adverse incident, while being able to describe how these skills reinforce the key behaviors needed to support patients and drive learning in dentistry. Since an incident in a dental practice could conceivably affect multiple patients (for example, exposure to contaminated instruments), you may also want to go back to our June 16, 2009 Patient Safety Tip of the Week “Disclosing Errors That Affect Multiple Patients”.



We’re delighted to see that our dental colleagues have taken a serious interest in patient safety.



Some of our previous columns on dental patient safety issues:


March 15, 2016 “Dental Patient Safety

August 2016 “Guideline Update for Pediatric Sedation

March 28, 2017 “More Issues with Dental Sedation/Anesthesia

August 8, 2017 “Sedation for Pediatric MRI Rising

November 28, 2017 “More on Dental Sedation/Anesthesia Safety

July 2019 “Dental Prescribing Called Into Question

September 2019 “New Guidelines for Pediatric Dental Sedation

May 5, 2020 “COVID-19 and the Dental Office






Pandey R, Dixit, N, Kixit KK, et al. Amaurosis, an Unusual Complication Secondary to Inferior Alveolar Nerve Anesthesia: A Case Report and Literature Review. Journal of Endodontics 2018; 44(9): 1442-1444



Murphy J. Rare complication causes temporary blindness during routine procedure. MDLinx 2018; October 30, 2018



Mohammed H, Shallik N, Barsoum M, et al. Dental needle foreign body in the neck: a case report. J Dent Anesth Pain Med 2020; 20(2): 83-87



Pogrel MA. Broken local anesthetic needles: a case series of 16patients, with recommendations. J Am Dent Assoc 2009; 140: 1517-1522



Hiremath H, Agarwal RS, Patni P, Chauhan S. Accidental injection of 2% chlorhexidine gluconate instead of an anesthetic agent: A case report. J Conserv Dent 2016; 19(1): 106-108



Roy T, Damoulakis G, Komperda J, et al. Effect of H2O2 Antiseptic on Dispersal of Cavitation-Induced Microdroplets. J Dent Res. 2021; 100(11): 1258-1264



Ensaldo-Carrasco E, Carson-Stevens A, Cresswell K, et al. Developing agreement on never events in primary care dentistry: an international eDelphi study, BDJ 2018; 224: 733-740



Wright S. Ucer TC, Crofts G. The adaption and implementation of the WHO surgical safety checklist for dental procedures. British Dental Journal 2018; 225(8), 727-729



Bidra AS. Surgical safety checklist for dental implant and related surgeries. J Prosthet Dent 2017; 118: 442-444



Remiszewski DP, Bidra AS. Implementation of a surgical safety checklist for dental implant surgeries in a prosthodontics residency program. J Prosthet Dent. 2019; 122(4): 371-375



Coté CJ, Wilson S. Guidelines for monitoring and management of pediatric patients before, during, and after sedation. Pediatrics 2019; 143: 6 e1-31



Cote CJ, Brown R, Kaplan A. The Single-Provider-Operator-Anesthetist Model for Dental Deep Sedation/Anesthesia: A Major Safety Issue for Children. APSF Newsletter 2021; 36(1): 33 February 2021



Vlessides M. Disagreements Persist Over Safety of Dental Anesthesia. Anesthesiology News 2020; September 28, 2020 (and Moore LJ. A Response to the Single Provider Issue in Dental Anesthesia)



Seidman P. How Mobile Anesthesiologists Can Help Provide Hospital-Grade Care for Dental Procedures. Anesthesiology News 2021; May 19, 2021



KHON News. Receptionist who administered drugs that killed Finley Boyle testifies . KHON News 2018; November 7, 2018



Schladebeck J. Former dentist accused of causing death of 3-year-old patient breaks down on the stand. New York Daily News 2018; November 17, 2018



Sollecito TP, Abt E, Lockhart PB, et al. The use of prophylactic antibiotics prior to dental procedures in patients with prosthetic joints. The Journal of the American Dental Association 2015; 146(1): 11-16.e8



ADA (American Dental Association). Antibiotic Prophylaxis Prior to Dental Procedures.

Last uupdated January 5, 2022



Thornhill MH, Crum A, Rex S, et al. Analysis of Prosthetic Joint Infections Following Invasive Dental Procedures in England. JAMA Netw Open 2022; 5(1): e2142987



ADA (American Dental Association). Communicating with patients when things go wrong in dentistry. Free webinar to highlight importance of transparency. ADA 2022; January 7, 2022






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