[Two-stage closed sinus lift for severe bone deficiency in the posterior maxilla imrpoves long-term clinical outcomes].

To evaluate the long-term clinical outcomes of two-stage closed sinus lift for the maxillary sinus with residual bone height (RBH) of 1-3 mm in the posterior maxillary.Seventy-eight patients with maxillary posterior tooth loss (1 mm≤RBH≤3 mm and alveolar ridge width ≥5 mm) were treated with two-stage closed sinus lift at the Dental Implantation Center of our hospital between March, 2012 and December, 2014. Coral hydroxyapatite powder and 148 implants were implanted. The superstructure was fixed within 6 months after the operation and the patients were followed up for 1-5 years for assessing the patients' satisfaction, postoperative response, stability and survival rates of the implant, soft tissue condition, bone height of maxillary sinus floor elevation and the marginal bone loss.

Perforation of the maxillary sinus floor occurred in 3 (3.85%) of the cases. Twenty-three (30.67%) patients complained of mild pain, and 52 (69.33%) did not experience headache or fever or reported obvious pain or swelling after the operation. The overall response to the operation was favorable. The ISQ value was 58.39±1.39 immediately after the operation, and increased significantly to 81.88±1.22 at 6 months (P < 0.05). During the healing period and the follow-up, none of the implants fell off, and the implant survival rate was 100%. The peri-implant probing depth and modified sulcus bleeding index at 1 year after sinus lifting were similar to those at 5 years after the operation (P > 0.05), but the sinus floor elevation and marginal bone resorption at the two time points differed significantly (P < 0.05).

Compared with lateral wall lifting, two-stage close lifting of the maxillary sinus floor is associated with less trauma and less discomfort, and effectively solves the problem of severe alveolar bone height deficiency in the maxillary posterior region to achieve favorable long-term clinical outcomes.