Effects of BMP-2 and LIPUS on Bone Formation at Palatal Sites in Aged Rats

Objectives: Bone Morphogenetic Protein-2 (BMP-2) has been demonstrated to enhance bone formation and Low-intensity pulsed Ultrasound (LIPUS) has been shown to cause rapid maturation of ossification and promote bone and cartilage healing. Many people suffering from periodontitis or bone resorption are aged. The aim of this study was to evaluate the effects of BMP-2 and LIPUS on bone formation at palatal sites in aged rats.
Methods: Eighteen Wistar rats of each 10-week-old and 70-week-old were used and divided into three experimental sites (n=6). In the first group, BMP-2 (1.0 μg/μl) contained in alginate gel was implanted at palatal subperiosteal sites (BMP site). In the second, LIPUS (1 MHz, 160 mW, 5 min) was performed every three days after implantation of BMP-2 (LI-BMP site). The others, neither implantation of BMP-2 nor LIPUS was done (Control site). The animals were euthanized three weeks after surgery.
Results: The new bone volume (NBV) was significantly higher in the both BMP and LI-BMP sites than in the Control site (P < 0.05) and new bone was almost integrated with original bone in the LI-BMP site in 10-week-old and 70-week-old rats.
Moreover, NBV of each site in 10-week-old rats was significantly higher than that of the same experimental sites in 70-week-old rats.
Conclusions: These results suggested that the combination of BMP-2 and LIPUS enhanced the maturation of bone formation in aged rats, although new bone volume declined with aging in the case of palatal subperiosteal sites.