Several growth factors have been used in tissue regeneration therapy. Here we describe the use of an autologous blood clot combined with gelatin for teeth affected by severe periodontitis and vertical root fracture treated using three oral surgical procedures: periodontal flap surgery, intentional tooth replantation (IR), and tooth autotransplantation. Treatment with a blood clot improved the condition of the periodontal tissue, including reduction of pocket depth. Radiographical images demonstrated no evidence of ankylosis, and revealed the presence of alveolar bone regeneration. Our successful clinical outcome suggests that use of an autologous blood clot combined with gelatin is clinically effective for regeneration of lost periodontal tissue.