Healing of extraction wounds was examined in an animal experiment model on Beagle dogs. After bilateral extraction of the premolars of 12 dogs the alveoli were filled up with a combination of beta-tricalcium phosphate (Cerasorb) graft and platelet rich plasma (PRP) on the experimental side, and with Cerasorb alone on the control side. Biopsy specimens were taken from the regenerating bone at 6, 12 and 24 weeks after surgery for histological study. Results of the histologic and histomorphometric examinations revealed that after 6 weeks the newly formed bone was significantly denser on the experimental side. After 12 weeks this difference became moderate, and after 24 weeks the bone forming activity was nearly equal on the two sides. These results suggest that local administration of Cerasorb and PRP results in more intense bone regeneration, especially in the early phase.