Abstract: Objective: To evaluate the long-term clinical outcomes of two-stage closed sinus lift for the maxillary sinus combined with CGF for severe bone deficiency in the posterior maxillary. Methods: Twenty-three patients with maxillary posterior tooth loss(1mm≤RBH≤2mm) were treated with two-stage closed sinus lift combined with CGF at the prosthodontics department of our hospital between February, 2014 and February, 2018, with 41 implants implanted. And implant-supported fixed prostheses were restored. According to the clinical observation and x-ray examination to assess the survival rates of the implant within 2 years. Results: Among the 41 implants placed, all implants showed well-osseointegrated to the alveolar bones, no implants were failed. The cervical alveolar bone surrounding the implants were stable at the end of the two years. The survival rate was 100%. Conclusions: In the 2-year follow up clinical study, favorable long-termclinical outcomes can be achieved by two-stage closed sinus lift for the maxillary sinus combined with CGF for severe bone deficiency in the posterior maxillary with less trauma and less clinical time, and provide a simpler and more convenient method to solve the problem of severe alveolar bone height deficiency in the maxillary posterior region, especially for the patients with severe limitation of mouth opening and thickening check muscle.

Key words: CGF(concentrate growth factors), closed maxillary sinus floor augmentation, dental implants