Hemostatics are agents used in surgery to control the bleeding. To make the right choice is a challenge to the dentist because he should weigh the benefits of these agents against its effect on bone healing. These agents act by different mechanism of action which effect wound healing. It is important to compare these mechanisms to make the right choice when we select these agents during surgery. Objectives: To evaluate the effects of topical hemostatic agents on healing of bone after endodontic microsurgical procedures using experimental animals model. Materials and method: The study was involving 300 patients (160) male, (140) female (10-45y) come to the Department of maxillofacial surgery/College of dentistry/University of Anbar (2000-2018) endodontic microsurgery. Local anesthesia was used (2% Lidocaine with 1:80.000 adrenalines). Alustat, Collagen sponge and adrenalin were tested for their hemostatic effect and tissue reactions, and were compared with untreated control. 60 New Zealand white rabbits were involved in the study, used for examination the tissue reaction to these agents. The animal were anesthetized by i.p ketamine 10mg with XYL-M2 xylazine 20mg.The bone defects were made using standardized aseptic technique. Three sided flap were made in the anterior mandible of the rabbits using scalpel. The bone defects (5 mm) were made using straight surgical hand piece and burs with constant irrigation by normal saline. The effect of the above agents (bleeding time and tissue reaction) was examined visually then compared with control. The biopsy were taken after 3 and 4 weeks then sent for histopathological examination. Results: Statistical analysis in Table 1 & Figure 5 indicate that the highest healing % was in collagen group (81.000%). While the lowest healing % was in Alustat group (72.2500%). The healing % for Adrenalin was (75.000%). The mean difference in healing % is significant at 0.01 &0.05 level. Conclusion: Hemostasis in experimental bone defects is most effectively accomplished by using collagen. Understanding such mechanism is important for successful results.

collagen, adrenalin, alustat, bone healing, hemostasis, endodontic surgery, topical hemostatics, bone necrosis, resorbable hemostatic agents, osteoid