Comparison of bone morphogenetic protein-2 delivery systems to induce supracrestal bone guided by titanium implants in the rabbit mandible

Objective: To compare the ability of three non-glycosylated/rhBMP-2 (BMP-2) delivery systems to induce supracrestal bone. Material and methods: Thirty-six custom SLActive dental implants were partially embedded in transverse orientation into the posterior mandibles of 18 adult rabbits with the head of the implant located 3 mm supracrestal. Delivery of BMP-2 (30 mu g) from the following materials was studied: (1) Ti implant + BMP-2 with hydroxyapatite (HA)-coated collagen (Col/HA) scaffold, (2) Ti implant with Col/HA infused with PEG hydrogel + BMP-2, or (3) Ti implant with HA/beta-TCP/PEG hydrogel scaffold + BMP-2. Scaffolds were secured with a metal umbrella. Non-BMP-2 contralateral controls were included. MicroCT imaging and histological analysis was performed after 10 weeks to assess new supracrestal bone formation. in vitro BMP-2 release studies were conducted. Results: All treatment groups displayed new supracrestal bone formation. Ti + BMP-2 with Col/HA (3.0 +/- 0.2 mm) and Ti with Col/HA/PEG hydrogel I BMP-2 (2.7 +/- 0.4 mm) had significantly greater (P < 0.05) outcomes than without BMP-2. Maximum bone volume occurred in the Ti implant with HA/beta-TCP/PEG hydrogel scaffold BMP-2 group. Conclusions: The use of an implant system composed of a partially inserted Ti implant, adjacent scaffold and scaffold stabilizer resulted in the formation of new supracrestal bone across all test groups with and without BMP-2. Delivery of BMP-2 directly from the Ti implant increased bone height, BIC and bone volume as compared to no BMP-2 when a Col/HA was used, but did not improve performance of the HA/beta-TCP/PEG scaffold.