Objectives
To delineate the dynamic micro‐architectures of bone induced by low‐dose bone morphogenetic protein (BMP)‐2/7 heterodimer in peri‐implant bone defects compared to BMP2 and BMP7 homodimer.
Material and Methods
Peri‐implant bone defects (8 mm in diameter, 4 mm in depth) were created surrounding SLA‐treated titanium implants (3.1 mm in diameter, 10 mm in length) in minipig's calvaria. We administrated collagen sponges with adsorbed low‐dose (30 ng/mm3) BMP2/7 to treat the defects using BMP2, BMP7 or no BMP as controls.2, 3 and 6 weeks after implantation, we adopted micro‐computer tomography to evaluate the micro‐architectures of new bone using the following parameters: relative bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), connectivity density, and structure mode index (SMI). Bone implant contact (BIC) was also revealed histologically.
Results
Consistent with 2 and 3 weeks, after 6 weeks post‐operation, BMP2/7 resulted in significantly higher BV/TV (63.033 ± 2.055%) and significantly lower SMI (−4.405 ± 0.500) than BMP2 (BV/TV: 43.133 ± 2.001%; SMI: −0.086 ± 0.041) and BMP7 (BV/TV: 41.467 ± 1.850%; SMI: −0.044 ± 0.016) respectively. Significant differences were also found in Tb.N, Tb.Th and Tb.Sp at all time points. At 2 weeks, BMP2/7 resulted in significantly higher BIC than the controls.
Conclusions
Low‐dose BMP2/7 heterodimer facilitated more rapid bone regeneration in better quality in peri‐implant bone defects than BMP2 and BMP7 homodimers.