Modified internal sinus elevation for patients with low residual bone height: A retrospective clinical study

We have modified the internal sinus elevation by combining it with the sinus mucoperiosteum stripping procedure, which further increases the indications for the internal lift. Similar long-term clinical follow-up studies and three-dimensional finite element analyses are rare.This study aimed to investigate the feasibility of the modified internal sinus floor elevation method in patients with low residual bone height using a three-dimensional (3D) finite element model and report on the long-term outcomes.Overall, 99 implants were placed in 86 patients. All patients were followed-up for 3-24 months. The modified internal sinus floor elevation was dynamically simulated using a 3D finite element model, and the stress of the sinus membrane was measured.In trial group A (modified internal sinus floor elevation group), 57 implants were placed in 52 patients. The sinus floor height was lifted by 6.5 mm (95%confidence interval (CI): 6.2-6.8). The perforation rate was 8.8%, and the implant survival rate was 96.5%. In control group B (external sinus floor elevation group), 42 implants were placed in 34 patients. The sinus floor height was lifted by 8.8 mm (95%CI: 8.4-9.3). The perforation rate was 14.3%, and the implant survival rate was 100%. In trial group A, compared with the control group B, perforation decreased by 5.5% (odds ratio = 0.50 and 95%CI: 0.14-1.78; p = 0.282), and the sinus floor lift height was 2.3 mm lower (95%CI, 1.8-2.9; p < 0.001). The finite element analysis showed that the peak stress of the sinus membrane increased with an increase in height elevation and degree of membrane separation.Our findings indicate the positive clinical outcomes in patients with low RBH associated with the modified internal sinus elevation procedure.