Antiplatelet agents have conventionally been used in patients with cardiovascular diseases. Aspirin, a cyclooxygenase (COX) inhibitor, was the first antiplatelet drug. Since then, various antiplatelet agents have been developed, such as P2Y12 inhibitors including drugs like clopidogrel, prasugrel, and ticagrelor¹⁾. Dual antiplatelet therapy (DAPT) is a combination therapy of aspirin and P2Y12 inhibitors, which is used to prevent thrombosis in patients with coronary artery diseases, including individuals who have undergone percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) after acute coronary syndrome²⁾. The duration of DAPT depends on the patient's ischemic and bleeding risk. Short DAPT duration of six months is suitable for patients with low ischemic and high bleeding risk; however, a prolonged DAPT duration up to 30 months is recommended for patients with continued ischemic and low bleeding risk³⁾. The risk of perioperative bleeding may increase during invasive dental procedures in patients receiving dual antiplatelet agents. Temporary discontinuation of dual antiplatelet agents may lower the risk of bleeding, but increases the risk of thrombosis; therefore, discontinuation of dual antiplatelet agents prior to invasive dental procedure is controversial⁴⁾. This report describes a case of immediate implant placement after tooth extraction and maxillary sinus graft without discontinuation of dual antiplatelet agents.

A 48-year-old man visited our hospital with complaint of mobility of teeth 21, 25, 27, and 28 (Fig. 1). The patient had undergone PCI three months ago for chest pain due to unstable angina and was on DAPT with aspirin and clopidogrel. As a result of the medical consultation, it had been only three months since PCI, so aggressive treatment should be performed after six months or more if possible. And in case of emergency treatment, it was recommended to be performed while maintaining two antiplatelet drugs. Accordingly, the timing of surgical treatment such as tooth extraction was postponed to six months after the procedure. However, at four months after PCI, only extraction of teeth 25, 27 and 28 were performed while maintaining the drug due to severe pain which did not respond to drug and increased mobility (Fig. 2). Four months after extraction of the maxillary left molars, immediate implant placement was done after extraction of tooth 21 (Osstem TS III SA, 4.0D/11.5L, Osstem Implant Co., Seoul, Korea) and the insertion torque value was 40Ncm. In addition, maxillary sinus graft was performed in the left maxillary sinus, and implants were placed in the edentulous region of teeth 25 and 26 (Osstem SS III SA, 4.5D/8.5L, Osstem Implant Co., Seoul, Korea) (Fig. 3). The insertion torque values were 20Ncm and 55Ncm, respectively. Lateral window approach was used for bone graft, and an allograft was used as the graft material (Do bone, Renew medical, Bucheon, Korea). All these treatments were performed while maintaining DAPT in consideration of the medical history. There was no severe bleeding during surgery. The preoperative prothrombin time was 12.9, the activated partial thromboplastin time was 33.6, and the INR was 0.97, which were within the normal range. Flap manipulation and suturing were meticulously performed to prevent perioperative bleeding. The prosthesis was completed 10 weeks after immediate implant placement of tooth 21 and 26 weeks after implantation of 25, 26 where the maxillary sinus graft was performed (Fig. 4).

Figure 1. Preoperative panoramic radiography. Alveolar bone resorption was observed in the maxillary left posterior region.

Figure 2. Four months after extraction of left upper molars. (A) Panoramic radiography, (B) Tooth 21 is extruded due to the loss of alveolar bone, (C) The soft tissue at the extraction site healed well.

Figure 3. (A) Immediate implant placement was performed after the extraction of tooth 21, (B) Lateral approach of maxillary sinus graft with implant placement, (C) Postoperative panoramic radiography.

Figure 4. Two months after placement of the upper prosthesis.

DAPT has been used for secondary prevention of thrombosis in patients with coronary artery disease²⁾. Aspirin inhibits the enzyme COX-1 irreversibly, which in turn inhibits the synthesis of thromboxane. P2Y12 inhibitors act as antagonists of platelet adenosine diphosphate receptor, and inhibit platelet aggregation. Aspirin and P2Y12 inhibitors, two drugs with different mechanisms of action when used in combination showed synergistic effect. Aspirin and clopidogrel were the main therapeutic agents used in patients with acute coronary syndrome, but potent drugs, such as prasugrel and ticagrelor, have been developed for patients who exhibited poor platelet inhibition with clopidogrel. However, with the increase in potency, more adverse effects were reported. Although these drugs have clinical utility, various adverse effects, such as perioperative bleeding, are observed, especially in the elderly^5,6).

Surgeons manage a variety of patients in dental clinics, including those on antiplatelet drug therapy due to the risk of thrombosis. Several dental procedures are associated with the risk of bleeding, and care should be taken when treating patients on antiplatelet drug regimen. Studies have reported that maintenance of antiplatelet agents did not significantly increase the risk of bleeding during invasive dental procedures, including tooth extraction and dental implant placement, when local hemostatic measures were taken^4,6-8). It has been reported that patients on DAPT are at a higher risk of bleeding than patients on single antiplatelet therapy (SAPT). Additionally, patients in whom DAPT was not discontinued were reported to have an increased risk of perioperative bleeding compared to patients in whom DAPT was discontinued. Perioperative bleeding can be sufficiently controlled with sutures and other local hemostatic treatment in patients on antiplatelet drug therapy^4,9). In our case, we did not use local hemostatic agents because the perioperative bleeding was not severe. Since tooth extraction and minor surgeries, including dental implant placement, do not have high bleeding risk compared to other surgeries, it is advantageous not to discontinue antiplatelet agents in consideration of cardiac risk factors⁸⁾. Clopidogrel can be temporarily discontinued one year after the drug-eluding stent, if necessary. However, in patients who have been using antiplatelet agents for a prolonged period of time, abrupt discontinuation of the drug may increase the occurrence of thrombosis due to increased platelet response and rebound effect¹⁰⁾. Therefore, it is recommended not to discontinue the drug, if possible.

Although there have been several studies on tooth extraction or dental implant placement without drug discontinuation in DAPT patients, there is a paucity of data on immediate implant placement or maxillary sinus graft in these individuals. However, if careful approach is taken, as in this case, we can benefit from both bleeding and cardiac risks without discontinuing the drug. In particular, special care should be taken to prevent vascular damage when lateral approach is used for sinus graft, due to the presence of intraosseous and extraosseous anastomoses of the infraorbital and posterior superior alveolar arteries in the maxillary sinus, especially the lateral wall¹¹⁾. With the increase in resorption of the alveolar bone, the artery moves closer to the alveolar ridge. Thus, it is better to evaluate the risk in advance through computed tomography (CT) and approach the surgery with caution. If preliminary evaluation shows close proximity of the anastomosis, it is advisable to make a small bony window to avoid vessel injuries when the lateral approach is used (Fig. 5).

Figure 5. Preoperative cone-beam computed tomography. Preoperative radiographic examination identifies the location of major anatomical structures and proceeds with surgery with caution.

The number of patients undergoing procedures such as PCI and DAPT has increased with the increase in prevalence of acute coronary syndrome. With proper care and use of adequate techniques, treatment can be rendered without discontinuation of dual antiplatelet drug therapy, even immediate implant placement or sinus graft via lateral approach. If treatment is performed for these patients without discontinuing the drug, the surgeon would have to thoroughly manage the bleeding risk and take adequate measures to deal with it.