Study on the Osteogenic Effects of Yuliang Collagen Implantation Without Bone Grafting at 6–9 mm from the Maxillary Sinus Floor: A Prospective Cohort Study

Abstract

Objective: To evaluate the osteogenic effect and implant survival rate in the peri-implant region following simultaneous maxillary sinus floor elevation via the crestal approach and Yuliang collagen (a high-purity type I collagen matrix) implantation, without additional bone grafting, in patients with residual alveolar bone height (RBH) of 6–9 mm in the maxillary posterior region. Methods: A prospective cohort study design was employed, enrolling 42 patients (50 implants) requiring maxillary posterior implant restoration with RBH of 6–9 mm. All patients underwent bone-free transalveolar sinus floor elevation, with Yuli'an collagen implanted in the elevated space during surgery. Immediate postoperative and 6-month/12-month postoperative cone-beam computed tomography (CBCT) scans were performed to measure new bone height (NBH) above the implant apex and bone density changes (gray-scale analysis). Surgical complications and implant survival were recorded. Results: We followed up on 50 implants in 42 patients for an average of 14.3 months. One case involved minor periosteal perforation during the maxillary sinus lift, which did not affect final healing. No implant infections or failures occurred. The implant survival rate was 98% (49/50). At 12 months postoperatively, CBCT measurements revealed new bone formation above the implant apexes. Compared to the preoperative RBH (7.2 ± 0.8) mm, the mean height of newly formed bone was (3.8 ± 0.9) mm, with an average increase of approximately 3.4 mm in sinus floor bone height. For assessing the density of newly formed bone, we used the density of the contralateral normal maxillary bone as a reference. The mean bone density in the newly formed bone area reached (65.2 ± 7.1)% and (88.7 ± 5.3)% of the contralateral normal maxillary bone density at 6 and 12 months postoperatively, respectively, indicating good maturity of the newly formed bone. Conclusion: For maxillary posterior regions with a ridge height (RBH) of 6–9 mm, sinus floor elevation via the crestal approach using Yuliang collagen protein alone (without bone grafting) can guide the formation of sufficient quantities of high-quality new bone. This approach achieves clinical osteogenic outcomes and high implant survival rates comparable to traditional bone grafting methods. YuLiAn collagen, serving as a space-maintaining and guiding matrix, demonstrated excellent biocompatibility and osteogenic potential in this procedure, offering a reliable option for simplifying surgical steps, reducing patient costs, and minimizing trauma.