Dr. Richard L. Wynn is Professor of Pharmacology at the University of Maryland Dental School. He holds a BS degree in Pharmacy and a PhD degree in Pharmacology. More »He chaired the Department of Pharmacology at the University of Maryland Dental School from 1980 to 1995. He is the lead author of the Drug Information Handbook for Dentistry, a co-author on many other dental drug publications, an author of over 300 refereed scientific journal articles, a consultant to the Academy of General Dentistry, a featured columnist, and a featured speaker presenting more than 500 courses in continuing dental education. One of his primary interests continues to be keeping dental professionals informed of all aspects of drug use in dental practice.
The aim of the warfarin study was to compare the bleeding patterns of dental extraction with or without altering the warfarin regimen in patients with a prosthetic heart valve and an international normalized ratio (INR) from 1 to 4. This study, out of Çukurova University, Adana, Turkey, showed that continuing warfarin in patients with INR levels below 4.0 did not result in significantly increased postoperative bleeding after single tooth extraction.
The study was conducted in 40 adult patients requiring dental extractions admitted to the oral surgery clinic at an academic setting. Three study groups and one control group were established: patients on warfarin treatment without interruption of warfarin therapy periopratively, patients on warfarin treatment and warfarin bridged with low molecular weight heparin perioperatively, patients on warfarin treatment and warfarin bridged with standard heparin perioperatively, and healthy individuals receiving no medication (control group).
A preoperative INR was measured for all patients taking warfarin. If INR was greater than 4, extraction was postponed until levels came below 4. Patients were hospitalized for at least one day for perioperative medical management.
Extractions were performed under local anesthesia using 3% prilocaine without vasoconstrictor (the 3% strength of prilocaine anesthetic is not available in the US). Extractions that were complicated during the operation were excluded from the study. A dry environment was created by isolating all salivary gland orifices and continuous meticulous suctioning during the measurement period. After each extraction, tamponades were used to staunch the bleeding from the sockets and changed for gauze swabs for 20 minutes. Each gauze swab was pressed gently over the extraction socket and changed for a new swab once it absorbed a sufficient amount of blood. The weights of the gauze swabs used before and after tamponade were measured using a sensitive electronic balance. Weights were determined in milligrams and the amount of bleeding interpreted as milligrams of blood loss. Weight differences before and after tamponade gauzes were interpreted as the amount of bleeding. After 20 minutes of tamponade, each extraction socket was packed with oxycellulose (Surgicel®) dressing and sutured. A new gauze swab was placed over the surgical area and the patient instructed to bite on it for one hour. Patients were given additional gauze swabs to be used if bleeding continued and advised to come to the emergency department for severe bleeding. They were asked to count the number of extra gauze swabs used for bleeding control during the first 48 hours. The sutures were removed 48 hours after extractions.
For the patients on warfarin therapy without interruption of therapy, the mean amount of bleeding in milligrams was 2,486 +/- 1,408, compared to control (healthy individuals receiving no medication) which was 1,736 +/- 876. This increase in the amount of bleeding values in the warfarin group compared to no warfarin group is not significant at the 95% level. Also, there were no significant differences among groups in the use of extra gauze swabs. The mean INR values in the warfarin group were 2.6 +/- 0.7. Hemostasis was successfully established locally by packing the extraction sockets with oxidized cellulose (Surgicel) and suturing with 3.0 silk sutures.
The study authors indicated that previous studies have determined bleeding outcomes and complications by subjective measurement methods, based on patient's feedback and clinician's observations. This study used quantitative data to measure bleeding in order to evaluate the outcomes of dental extraction in patients on warfarin therapy. Also, previous studies have shown that continuing warfarin in patients does not confer an increased risk of bleeding for dental extractions if a patient's INR is below 4.0 and local hemostatic measures are undertaken. This present study confirmed that continuing warfarin in patients with INR levels below 4.0 did not result in significantly increased postoperative bleeding.
The study authors concluded that, with regard to patients on warfarin when the INR values are below 4.0, warfarin therapy should not be discontinued for simple tooth extractions. Efficient hemostasis can be provided with local measures by packing the extraction socket with oxycellulose and 3.0 silk sutures.
The full report of that study can be found at Karsh ED, et al. Comparison of the effects of warfarin and heparin on bleeding caused by dental extraction: a clinical study. J Oral Maxillofac Surg 2011; 69:2500-2507.
The aim of the aspirin study was to evaluate the amount of bleeding that occurs during the intra-operative period of tooth extraction procedures in patients with coronary artery disease (CAD) who are either undergoing aspirin therapy or who have been instructed to discontinue aspirin one week prior to the surgery. This study, out of the University of São Paulo, Brazil, showed that there was no significant difference in the amount of bleeding that occurred during single tooth extraction between the patients that remained on aspirin and the patients that discontinued aspirin.
Eighty-three patients with CAD who were undergoing aspirin therapy were selected. Each needed at least one molar extraction and their CAD was being treated with aspirin 100 mg daily. They were randomly divided into two groups. Group one (no aspirin) had their aspirin therapy discontinued for 7 days before tooth extraction and were restarted on aspirin therapy the day following the surgical procedure. Group two (aspirin) remained on aspirin therapy. Extractions were performed by a single dentist who was unaware of whether or not the patient's aspirin therapy had been discontinued.
To gain information on the antiplatelet effectiveness of aspirin, patients were advised to undergo the platelet aggregation test on the morning of the day of the dental surgery. Blood samples were collected and the platelet reactivity index test was carried out on the same day of sample collection to verify the extent of platelet aggregation. The surgery was performed with 3% mepivacaine without vasoconstrictor. A 3.0 nylon suture was used after the procedure and a biological adhesive was then applied over the suture in cases of more intense bleeding episodes.
The amount of bleeding that occurred during the intra-operative period was measured by means of aspirated blood collection. The amount of bleeding was calculated by subtracting the final amount of removed blood during tooth extraction from the amount of 0.9% physiologic saline solution that was used during the irrigation period. A vacuum pump was used for quantification and and a dental aspirator was used to remove the secreted saliva.
Patients were advised to return a week later for suture removal and, in cases of hemorrhage complications, patients were advised to return to the dental department for further evaluation.
The mean volume of bleeding for the patients who discontinued aspirin was 12.10 ml (+/- 9.37 ml). The mean volume of bleeding for patients remaining on aspirin was 16.38 ml (+/- 13.54 ml). Although the greatest amount of bleeding occurred in the aspirin group, there was no statistical difference between the two groups at the 95% confidence level. Local hemostatic measures were sufficient to control bleeding and there were no reported episodes of hemorrhaging during intra- and postoperative episodes.
The platelet reactivity index values exhibited statistically significant differences between the two groups. The group remaining on aspirin had significantly greater inhibition of platelet aggregation than the group that discontinued aspirin.
The effect of aspirin on the amount of bleeding that occurs during tooth extraction procedures is controversial and current guidelines recommend that aspirin administration should not be altered for such procedures. Some may suggest that there is a significant threat of hemorrhaging for patients who are receiving aspirin and who undergo surgical procedures. However, some studies have suggested that most of these patients can be operated on safely, with no need for a discontinuation of aspirin therapy. The goal of this study was to evaluate the amount of bleeding that occurs during the intra-operative period of tooth extraction procedures in patients with CAD who are being administered 100 mg daily of aspirin for the prevention of thromboembolic events. These results were compared with patients who have had their ASA treatment temporarily discontinued.
There was no significant difference in the amount of bleeding that occurred during single tooth extraction between the patients that remained on aspirin and the patients that discontinued aspirin. This study reinforces other reports demonstrating no justification for suspending aspirin therapy for a single tooth extraction. The authors indicated that additional studies are required to evaluate more complex dental procedures to measure the amount of bleeding in CAD patients.
The full report can be found at Medeiros FB, et al. Bleeding evaluation during single tooth extraction in patients with coronary artery disease and acetylsalicylic acid therapy suspension: a prospective, double-blinded, and randomized study. J Oral Maxillofac Surg 2011; 69:2949-2955.