The risk factors associated with postoperative hemorrhage after tooth extraction: a multi-center retrospective study of patients receiving oral antithrombotic therapy. 
The purpose of this study was to retrospectively investigate the multivariate relationships between specific risk factors and postoperative hemorrhage after tooth extraction in patients who were prescribed oral antithrombotic therapy.  Risk factors for postoperative hemorrhage after tooth extraction were evaluated using univariate and multivariate analyses.  Patient characteristics such as age and gender; the presence or absence of known comorbidities such as diabetes mellitus, hypertension, cerebral infarction, and alcohol consumption; and perioperative diarrhea were assessed.  The drug used for antithrombotic therapy, preoperative blood test results, the presence or absence of preoperative antibiotics or nonsteroidal anti-inflammatory drug (NSAID) administration, the total number of extracted teeth, and the type of surgical procedures were also evaluated.  We found that the preoperative administration of antibiotics (odds ratio (OR) = 2.52), an increased prothrombin time international normalized ratio (PT-INR) value (OR = 1.94), and the extraction of multiple teeth (OR = 2.10) were significantly associated with postoperative hemorrhage.  There was no significant association between postoperative hemorrhage and any other demographic factors or comorbidities, including concomitant alcohol use.  We demonstrated the multivariate relationship between the risk factors and postoperative hemorrhage after tooth extraction in patients receiving oral antithrombotic therapy.  Surgeons should be aware of these risks and monitor the PT-INR of anticoagulated patients.