Abstract: This article reports a case of spontaneous bone formation on the maxillary sinus floor. This patient was scheduled to undergo dental implant surgery after extraction of maxillary left first premolar. The preoperative CBCT showed that bone density of extraction socket was low and the bottom of extraction socket was close to maxillary sinus floor. After tooth extraction and cleaning of granulation tissue, the socket was filled with bone graft material and covered with resorbable collagen membrane, and gingival flap was tightly sutured. Six months later, CBCT showed that new bone formed under the membrane of maxillary sinus floor. The vertical bone height was increased from approximately 6 mm to 10 mm.

Key words: maxillary sinus, CBCT, bone formation