Anticoagulants and dentistry
Exam practice

Anticoagulant drugs are mainly used to prevent blood clot formation in people with conditions that make it more likely for blood clots to develop, like those with artificial aortic heart valves or atrial fibrillation. They can also be used as treatment to dissolve existing blood clots, such as DVTs (Deep Vein Thrombosis). Additionally, they may be taken preventively by patients who are known to be at risk of developing a DVT.

Antiplatelet drugs play an important role in preventing recurrence or worsening of coronary artery disease, cerebrovascular accidents and peripheral arterial disease. These medications work by inhibiting platelet aggregation which is key factor in the development of these conditions. Commonly prescribed antiplatelets include aspirin and clopidogrel but newer agents such as prasugrel and ticagrelor have become available too. Patients with stents or metal heart valves usually take antiplatelets regularly.

Simple extractions are low risk for post-operative bleeding complications. Pocket probing, RSI/scaling, and subgingival preparation of teeth for restorations are also considered low risk.

When assessing a patient's medical history prior to dental treatment, any illnesses or medications mentioned should be checked for their potential effect on bleeding. This includes liver or kidney disorders, cancer treatments, NSAIDs such as ibuprofen and anticoagulant or antiplatelet drugs which can increase the likelihood of excessive bleeding during and after many dental procedures.

The general advice for high risk treatments is to do them early in the day and early in the week, as this gives subsequent time to manage any emergencies. Additionally, consider doing high risk treatments over multiple stages rather than one big visit. If a patient is on multiple anticoagulant drugs or has a medical condition that complicates bleeding, it may be necessary to discuss with their GP or specialist.

When treating patients who are taking Vitamin K Antagonists such as Warfarin, Phenindione or Acenocoumarol, dentists should treat early in the day and check the INR ideally 24 hours before the procedure. If it's below 4 then no changes need to be made; however if it's above 4 then delay treatment until it drops back down again and inform their GP of this change.

Oxidised cellulose gauze and collagen sponge are used to treat a bleeding socket by accelerating platelet aggregation and helping the blood clotting process. The fibres in the gauze can absorb up to seven times their own volume in blood, swelling into a gelatinous mass which creates an acidic environment that triggers clotting. This helps stop the bleeding quickly and prevents infection.

Suturing should be strongly considered when treating patients on anticoagulants/antiplatelets with surgery, particularly with high risk procedures where there is a chance of restarting bleeding after they leave. It can also be used as a preventative measure if gingival bleeding will not stop or if there is concern about potential problems due to medical history or medications.

Atrial fibrillation (AF) is a very common heart condition in older people. It occurs when the “initial” signal comes not just from the sino-atrial node (SA), but from multiple other areas of the atria that have developed the ability to fire similar electrical signals. These cause the atrial muscles to quiver erratically, like a bag of worms. The erratic signals reach the AV node at irregular intervals, causing the heart’s ventricles to beat irregularly and quickly - from 100 to 200 beats per minute.

People with AF are 4-8 times more likely than normal individuals to have a stroke, and their strokes are twice as likely to cause death or serious brain injury. Life-long anticoagulant drugs are used to prevent blood clots forming in AF patients, and often reduce their risk of stroke back down to normal levels.

Risk factors for developing a DVT include being over 60, being overweight, smoking, taking the contraceptive pill or HRT, having cancer or heart failure and having varicose veins.

Treatment of a DVT usually involves an anticoagulant injection of heparin initially while waiting for ultrasound scan results. After diagnosis, oral anticoagulant tablets are prescribed for at least 3 months to help dissolve the clot. In some cases, newer treatments such as breaking up and sucking out the clot through a small tube in the affected vein may be used instead. If anticoagulants are not suitable then placement of a filter in the vena cava may be necessary to trap and stop clots travelling to other parts of the body. For pregnant women with DVTs treatment usually involves anticoagulant injections until 6 weeks after birth.

Laminar flow is the normal, smooth movement of blood through the body. It occurs when there are no irregularities in blood flow, such as pooling or eddying. This type of steady and consistent motion helps to prevent abnormal clot formation inside the heart or major blood vessels.

Anticoagulants interfere with the clotting process and make it difficult for clots to form. By preventing abnormal clot formation, they can save lives by reducing the risk of stroke or pulmonary embolism caused by transported internal clots.

Anticoagulants are drugs that reduce blood clotting by interrupting the clotting pathway. Different anticoagulant drugs block different parts of the cascade, such as Vitamin K antagonists which reduce the action of vitamin K, and DOACs (Direct Oral Anticoagulants) which inhibit Factor Xa from working. Heparin and LMWH’s activate an inactive protein called Antithrombin III to prevent other clotting factors like thrombin and Factor Xa from forming. The overall effect is to prevent fibrinogen from being converted into fibrin strands, thus preventing clot formation.

Vitamin K antagonists are a group of substances that reduce blood clotting by reducing the action of vitamin K. Vitamin K is required for proper production of certain proteins involved in the blood clotting process, such as prothrombin which needs vitamin K to be changed into thrombin - a crucial step in creating a clot. By blocking this reaction with Vitamin K antagonists, it prevents clots from forming or growing larger.

Platelets are a type of blood cell that play an important role in preventing bleeding. They stick to damaged blood vessel surfaces and then to each other, forming a clot with the help of a protein called Fibrin. This helps to stop any further bleeding from occurring.

Aspirin works by irreversibly blocking COX-1 inside the platelets, which is an enzyme necessary for generating thromboxane A2 - a potent platelet activator. By blocking this enzyme, it prevents new platelets being activated and reduces platelet aggregation, thus acting as an antiplatelet agent.