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Evaluation of Space-Maintaining Sinus Membrane Using the Absorbable Screws in Sinus Lifting Bone Augmentation

Purpose: We investigated whether it was possible to perform a sinus lift maintaining absorbable screw material with biological activity. Materials and Methods: Thirty rabbits were used. The screws used in this study were unsintered hydroxyapatite/poly-L-lactic acid (uHA/PLLA) (uHA/PLLA group) and titanium alloy (Ti group). Some uHA/PLLA screws were treated with ultraviolet light (UV-uHA/PLLA group). Each group consisted of 10 rabbits, and 2 screws were implanted for 1 rabbit. The screws were implanted into the frontal bone. Rabbits were euthanized at 3 days, 1, 2, 3, and 4 weeks postoperatively and prepared for histological examination, BMP-2 cell staining, and micro-computed tomography (micro-CT) assessment. Results: At 1, 2, and 3 weeks, the UV uHA/PLLA group had significantly more bone contact and new bone ratio on histological assessment than the other 2 groups. At 1, 2, 3, and 4 weeks, micro-CT assessment revealed significant differences between the UV uHA/PLLA group and the other 2 groups. Conclusions: Sinus lift surgery using absorbable screw allowed bone formation. The UV-treated hydroxyapatite/poly-L-lactic acid (uHA/PLLA) was superior for sinus lift bone augmentation using a screw.