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Evaluation of postextraction bleeding incidence to compare patients receiving and not receiving warfarin therapy: a cross-sectional, multicentre, observational study
  1. Hiroshi Iwabuchi1,
  2. Yutaka Imai2,
  3. Soichiro Asanami3,
  4. Masayori Shirakawa4,
  5. Gen-yuki Yamane5,
  6. Hideki Ogiuchi6,
  7. Kenji Kurashina7,
  8. Masaru Miyata8,
  9. Hiroyuki Nakao9,
  10. Hirohisa Imai9
  1. 1Department of Oral and Maxillofacial Surgery, Kanagawa Dental University, Yokosuka, Kanagawa, Japan
  2. 2Department of Oral & Maxillofacial Surgery, Dokkyo Medical University School of Medicine, Shimotsuga-gun, Tochigi, Japan
  3. 3Department of Dentistry and Implant Center, Sanno Hospital, Minato-ku, Tokyo, Japan
  4. 4Nippon Dental University, Chiyoda-ku, Tokyo, Japan
  5. 5Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
  6. 6Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
  7. 7Oral & Dental Center, Aizawa Hospital, Matsumoto, Nagano, Japan
  8. 8Department of Dentistry and Oral Surgery, Ishikawa Prefectural Central Hospital, Kanazawa, Ishikawa, Japan
  9. 9Department of Epidemiology, National Institute of Public Health of Japan, Wako, Saitama, Japan
  1. Correspondence to Dr Hiroshi Iwabuchi; iwabuchi{at}


Objectives We investigated incidence and risk factors for postextraction bleeding in patients receiving warfarin and those not receiving anticoagulation therapy.

Design Cross-sectional, multicentre, observational study.

Setting 26 hospitals where an oral surgeon is available.

Participants Data on 2817 teeth (from 496 patients receiving warfarin, 2321 patients not receiving warfarin; mean age (SD): 62.2 (17.6)) extracted between 1 November 2008 and 31 March 2010, were collected. Warfarin-receiving patients were eligible when prothrombin time–international normalised ratio (PT-INR) measured within 7 days prior to the extraction was less than 3.0.

Interventions Simple dental extraction was performed, and incidence of postextraction bleeding and comorbidities were recorded.

Primary and secondary outcome measures Postextraction bleeding not controlled by basic haemostasis procedure was clinically significant.

Results Bleeding events were reported for 35 (7.1%) and 49 (2.1%) teeth, of which 18 (3.6%) and 9 (0.4%) teeth were considered clinically significant, in warfarin and non-warfarin groups, respectively, the difference between which was 3.24% (CI 1.58% to 4.90%). The incidence rates by patients were 2.77% and 0.39%, in warfarin and non-warfarin groups, respectively (incidence difference 2.38%, CI 0.65% to 4/10%). Univariate analyses showed that age (OR 0.197, p=0.001), PT-INR (OR 3.635, p=0.003), mandibular foramen conduction anaesthesia (OR 4.854, p=0.050) and formation of abnormal granulation tissue in extraction socket (OR 2.900, p=0.031) significantly correlate with bleeding incidence. Multivariate analysis revealed that age (OR 0.126, p=0.001), antiplatelet drugs (OR 0.100, p=0.049), PT-INR (OR 7.797, p=0.001) and history of acute inflammation at extraction site (OR 3.722, p=0.037) were significant risk factors for postextraction bleeding.

Conclusions Our results suggest that there is slight but significant increase in the incidences of postextraction bleeding in patients receiving warfarin. Although absolute incidence was low in both groups, the bleeding risk is not negligible.


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