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Are You Concerned About Mandibular Blocks In Patients Taking Anticoagulants?

Hand holding vacuum venipuncture test tube

This question was submitted to us by a general dentist: Are you concerned about mandibular blocks and possible injury to blood vessels (Inferior Alveolar Artery/Vein) in patients continuing anti-coagulant therapy (Warfarin)? Potential Hematomas? Management?

Dr. Jason Goodchild provided this quick initial response:

For patients on anticoagulant therapy, a careful review of the medical history including consultation with the patient’s physician is warranted.  This consultation should include information on the patient’s INR (International Normalized Ratio).  Ideally, a recent INR (with 24-48 hrs) is needed in order to ascertain the patient’s bleeding risk during surgery.  

The literature is consistent on this issue:

  • If the patient’s INR is within the therapeutic range (i.e., less than 3.5), they can receive most dental treatments and should not discontinue anticoagulant therapy.  
  • If the patient’s INR is less than 3.5, inferior alveolar nerve blocks (IANB) are not contraindicated, but should be done with caution; alternating cycles of administration and aspiration should be used to minimize intravascular injection and potential bleeding.  

The best way to avoid complications with anticoagulant patients is proper planning and knowledge of INR status.  Invasive dental treatments, including IANB, must only proceed once the INR status of the patient is known and the dentist is prepared to manage potential complications.  

Hematomas are a known potential complication of IANB injections.  With good technique and knowledge of anticoagulant status, the risk can be minimized.  Management strategies include warm compresses, and pain control (trismus).  Immediate follow-up is needed, if submandibular swelling occurs or airway patency is compromised, although these should be considered extremely rare with good anticoagulant control.  

Follow-up: What further information would you like on this topic? Email us at jcdaoasis@cda-adc.ca

Readers are invited to comment on this initial response and provide further insights by posting in the comment box which you will find by clicking on “Leave a reply“ below. You are welcome to remain anonymous and your email address will not be posted .


  1. Gary McRae March 21, 2013

    The second paragraph reads ambiguous to me. Is it correct as written? Thankyou.My INR is kept between 2.0 and 2.5.

    1. JCDA Oasis March 22, 2013

      Hello Gary, Thank you for your comment and for pointing out the confusion. I have reordered the statement. I hope this clarifies it a bit. JCDA Oasis Team.

  2. Peter Haslam March 23, 2013

    Following best practices for hems tasis , what INR would you consider safe to do simple surgeries?
    Also ,nowadays with the conversion by many Md’s to the new wave of anticoagulants eg . Pradax, Xarelto with no INR measurements and no known antidote, how do we know what procedures are safe to perform and when?

    1. JCDA Oasis March 26, 2013

      Hello Peter, we are seeking a response to your question. We will notify you as soon as we have it. Thanks,

    2. dr m.galanter-mosielski March 26, 2013

      also with Plavix there is no test ,so how do we know if is safe to treat?

      1. Mark Donaldson March 26, 2013

        Again, these are great questions and very topical. I want to avoid any confusion, however, and be clear that there are two topics being queried here: anticoagulants and antiplatelet agents.

        The original post refers to anticoagulant agents, specifically warfarin (Coumadin). Warfarin inhibits the vitamin K-dependent clotting factors II, VII, IX and X. Because of this non-specific interaction, it is difficult to assign a true half-life to warfarin and instead we use the half-life of the longest acting clotting factor as a surrogate. In this case, factor II has a half-life of about 40 hours, so the half-life of warfarin is probably close to this. The reason we do not stop warfarin prior to surgery is because of this non-specific action, relatively long half-life, drug- and dietary-interactions and interpatient variability: we cannot be sure that stopping the drug 24, 48 or even 72 hours ahead of surgery will be effective in mitigating bleeding risk in all patients. More importantly, what is the risk versus benefit? If we cannot definitively determine when to stop the drug (and consequently, when to restart the medication), are we safer to simply keep patients on the drug (in which case 1% of patients may not achieve optimal hemostasis postoperatively) or should we consider interrupting the therapy (in which case about 1% of patients could suffer a venous-thrombolic event (VTE) such as a stroke or heart attack). We have great strategies and medicines to manage the 1% of patients who do not get good hemostasis initially; we cannot reverse the 1% who may face mortality.

        The ability to test and get an accurate INR in order to avoid operating on the patient who may be a high VTE risk (INR less than 2) or a high bleeding risk (INR greater than 3.5), not only keeps your patient, but also you and your team, safe. The INR is a composite measurement of the patients fibrinogen, factor II (thrombin), factors V, VII, and X.

        In contrast to warfarin, there are three new oral anticoagulants on the market: dabigatran (Pradax, Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis). Each of these new drugs has a specific mechanism of action (they target just one clotting factor), and they all have short half-lives (less than 12 hours). Dabigatran is a factor II (thrombin) inhibitor; the other two agents are factor Xa inhibitors. For these reasons we can safely stop and start the medications without putting our patients at risk of becoming too under-anticoagulated or too over-anticoagulated. There is no concern for an antidote given the short half lines and also since the risks of bleeding or VTE are much less than with warfarin. Also, the dosing of these agents is much more universal and less dependent on the patient’s habitus, diet and even concurrent medications. Please see past e-Bulletins (March 12, 2013) for a more in depth discussion on these new agents. There is a growing body of evidence suggesting that the measurement of factor Xa levels or TCT (thrombin clotting time), may help guide the dosing of these new therapies, however, additional coagulation tests are not indicated at this time given the safety, reproducibility and reliability of standard doses being effective in most patients.

        Dr. Galanter-Mosielski was asking about antiplatelet agents. Historically we have ASA (aspirin; acetylsalicylic acid) and more recently clopidogrel (Plavix). There was an agent ticlopidine (Ticlid) available in the 1980s and 1990s but it has since been removed from the market. More recently we have two new additions: prasugrel (effient) and ticagrelor (Brilinta).

        Unlike the anticoagulants which affect clotting factors in the blood, the antiplatelet agents inhibit platelet aggregation. Different from aspirin which inhibits cyclooxygenase-1 and 2, all of these new agents block adenosine diphosphate (ADP) receptors of subtype P2Y12. Ticagrelor is the only one that does this in a reversible manner.

        If a patient is taking 100mg or less a day of aspirin, there is no need to stop the aspirin prior to dental treatment. In fact minor dental treatment can take place without stopping the aspirin in most patients regardless of dose. If the procedure is to be more invasive, however, many sources still suggest stopping the aspirin 7-10 days PRIOR to surgery and reinstituting treatment 24 hours AFTER surgery when adequate hemostasis achieved.

        There is no scientific evidence to warrant the discontinuance of clopidogrel, prasugrel or ticagrelor prior to dental surgery. Patients requiring dental surgery who are taking any of these agents in combination with aspirin should be given special consideration in consultation with their healthcare provider, however, as these are our highest risk cardiac patients. Typically though, these medications are used in conjunction with aspirin at doses ≤100 mg/day.

    3. Alison Dougall April 8, 2013

      When patients are in the therapeutic range which renders them sufficiently anti-coagulated to prevent a stroke , (but not so much that bleeding is a risk to them) – then all minor surgeries can be performed safely, so long as meticulous local measures are used to promote primary haemostats. e.g. scafolding agent such as surgical, local pressure post-operatively, LA with adrenaline, opst op soft diet etc.
      The advantage of pradaxa, and the anti-platelet medications such as plavix and persantin etc is that they are easier to regulate and have less interactions than warfarin so are more reliable to administer. Therefore patients on these drugs do not usually suffer the extra-ordinay changes in anticoagulation levels which require the pre-operative checking which is required with warfarin and cannot be checked via an INR in any case.
      It is important not to stop the anti-platelet drugs or other anticoagulants to ‘be on the safe side’ as there is a true risk of rebound thrombsis which puts the patient at risk of stroke – far wore than the consequences of a slightly increased bleeding time, which can be appropriately managed with local measures.

  3. Alastair Nicoll March 26, 2013

    I worry about engaging the patient’s physician for routine medical management such as this. All to often the advice will be to discontinue anticagulation which practise can be dangerous. Surely if, even after physician consultation, the patient has a rebound thrombosis after unnessisary dicontinuation of anticoagulation the dentist will bear the primary responsibility. Unless there are other co-morbidities we review the patients INR trend and most recent results and then decide if we need to order an INR (possibly same day) or coordinate the pateints appointment with a routine INR.

    1. Timothy Winlow March 26, 2013

      I couldn’t agree more with you. The difficulty I have encountered as a general dentist in Québec is that (unless I am mistaken) I am unable to order a INR test. Clarification here would be appreciated.


      1. Mark Donaldson March 26, 2013

        This is a great conversation and many excellent points are being raised. I am not sure why a dentist cannot order and INR. The order is simply written on a prescription pad which the patient then takes to the laboratory. Let’s make this even easier, however. Take a look at http://www.coaguchek.com/ca/. While I am not advocating or promoting any particular product on this clinical forum, Point-Of-Care (POC) machines have been around for many years and are certainly becoming more commonplace in both clinics and in patients’ own homes.

        If you are seeing more patients on Coumadin in your practice it may be in your best interest to have a machine in your own office. In much the same way that a diabetic takes a drop of blood and places it on a test strip in order to get an accurate blood glucose reading within a minute, the same can be done with a point of care machine that is calibrated to measure INR. Furthermore, dentists have access to patient’s blood in the mouth so it may not even be necessary to lance a finger. Now imagine if these results were at least as accurate as the reference laboratories findings without having to send the patient for a venipuncture. This too has been proven (Donaldson M, Sullivan JW, Norbeck AO. A comparison of international normalized ratio values attained by two point of care methodologies and laboratory-based venipuncture in a pharmacist-managed anticoagulation clinic. Am J Health Syst Pharm 2010 67: 1616-1622). I know in the United States this is even a billable service.

        To Dr. Nicoll’s point above too, here now is your opportunity to get excellent, and immediate clinical information that will help you treat patients even more safely. You make a great point about the dentists’ responsibility should the patient suffer an unexpected VTE event secondary to they or their physician deciding to stop the coumadin several days ahead of a dental appointment in order to mitigate the potential for poor post-operative hemostasis. Current guidelines do not support this practice for obvious reasons (in fact this suggestion was first made over 50 years ago [NEJM 1957;256(8):351-3] so the guidelines have really not changed in over 50 years). The ability to test and get an accurate INR at chairside in order to avoid operating on the patient who may be a high VTE risk (INR less than 2) or a high bleeding risk (INR greater than 3.5), not only keeps your patient, but also you and your team, safe. After all, the oath that we took upon graduation was to, “first, do no harm.”

        1. M Champney April 8, 2013

          I have always ordered my own INR 24 hours prior to surgery for patients anticoagulated with warfarin. The lab requisitions come from the hospital or community lab and are easily filled out. All too often asking for an INR req from the MD yields red tape because lab results can only be released to the MD and then must be relayed to the dentist.

  4. Sandy Pirie March 26, 2013

    I believe it would be ice and not heat that would be applied if bleeding was a concern and the risk of hematomas was to be minimized. If the goal is to increase blood flow to help speed the resorption of the hematoma after bleeding is no longer a risk, then heat could be applied.

    1. Jason Goodchild March 26, 2013

      Hi Sandy,

      If there is a concern about active bleeding then ice/cold would be preferred but in my experience most hematomas present later as pain, swelling, trismus, or bruising. In this case warm compresses would be appropriate.

      In general, the literature agrees that if a patient has an INR less than 3.5 most dental treatment can be performed without interruption of coumadin. This would include: prophy, simple operative, intracoronal root canal therapy, one quadrant of scaling, and up to 5 simple extractions. For more invasive treatments or where a risk for increased perioperative bleeding exists, consultation with the patient’s physician is warranted. In these cases modification of the coumadin dose, bridging, or hospitalization may be required.

  5. Geoff Smith March 26, 2013

    A possible alternative to IANB would be an intraligamentary injection, as reported by Melamed. THis technique ir reported to have a higher success rate as measured by pulpal anaesthesia and is indicated for patients with bleeding disorders

    1. Alison Dougall April 8, 2013

      In patients with bleeding disorders – more important is preventing a muscular bleeding – from small barbs on the needles where bone has been engaged to locate the ID block. Most of the bleeding is historic, and many guidelines for patients with even severe haemophilia are not absolutely contra-indicated – even in patients with severe haemophilia – although this is not universally accepted.
      Current recommendations are as follows, to use a fine guage needle and inject very slowly after aspirating, to avoid hitting bone to locate the IDB if possible and not to re-use needle if a second IDB is required – so as toinimise the micro-barbs that may tear muscle tissue.

  6. Lance Rucker March 26, 2013

    “The best way to avoid complications with anticoagulant patients is proper planning and knowledge of INR status. Invasive dental treatments, including IANB, must only proceed once the INR status of the patient is known and the dentist is prepared to manage potential complications.

    “Hematomas are a known potential complication of IANB injections. With good technique and knowledge of anticoagulant status, the risk can be minimized. Management strategies include warm compresses, and pain control (trismus). Immediate follow-up is needed, if submandibular swelling occurs or airway patency is compromised, although these should be considered extremely rare with good anticoagulant control. ”

    I am curious as to why warm compresses are advised rather than cold compresses (which one might logically apply in order to reduce blood flow into the area and thereby reduce exacerbation of the hematoma).

    1. Jason Goodchild March 26, 2013

      Below is a picture of a patient I saw. From past experience I knew she had a tough time after extractions. I referred her to my local oral surgeon, who I know does awesome work. She was not taking any anticoagulants or antiplatelets. Apparently the local and extraction went very smoothly, but yet this how the patient came back to me about a week later. She was experiencing soreness and trismus. I recommended warm compresses and OTC pain meds like Tylenol.

      1. alison dougall April 8, 2013

        This lady probably had an underlying von willerands disease, un detected despite her age – this is not uncommon and also typical of the late bleeding/bruising

  7. Michael Saso April 5, 2013

    If INR is less than 3.0 I find no issues most times.
    However, in patients taking Plavix and ASA, i have had significant bleeding, and for these patients, we have had them D/C the Plavix ahead of treatment but this is directed by their physician.

    1. alison dougall April 8, 2013

      I would disagree with dscontinuing plavix. There is a significant risk of rebound thrombosis and meticulous local measures with pressure and tranexamic acid moutwash if required due to a prolonged bleeding time, are a preferred option, despite what the GP say.

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