Using in vivo microfocus computed tomography (micro-CT) and tissue sections, we evaluated bone regeneration in non-critical-sized rat calvarial flat bone defects during systemic administration of lactoferrin (LF). Ten 11-week-old male Fischer rats were used. Non-critical-sized calvarial bone defects (diameter, 2.7 mm) were trephined into the dorsal parietal bone on both sides of the midsagittal suture, and a collagen sponge soaked in saline was placed on each side. LF was injected intraperitoneally every day, starting on the day of the operation (day 0; groups: control, 10 mg/kg LF, 100 mg/kg LF). Micro-CT imaging was performed repeatedly from 1 to 4 weeks after surgery. The defect sites were then removed, along with surrounding bone and soft tissues, and stained with hematoxylin and eosin. During weeks 1-4, micro-CT showed a significant difference in reossification ratio between the controls and the 100 mg/ kg LF group. Histological analysis revealed that there were more osteoblast-like cells around the bony rim in the 100 mg/kg group than in the control group. In summary, micro-CT and histological analyses showed that systemic administration of LF accelerated bone regeneration in non-critical-sized rat calvarial bone defects. (J Oral Sci 55, 343-348, 2013) Keywords: lactoferrin; bone regeneration; non-criticalsized rat calvarial flat bone defect.

We evaluated the ability of platelet-derived growth factor (PDGF) to promote bone augmentation beyond the skeletal envelope in rat calvarium. The calvaria of 14 rats were exposed and two plastic caps were placed with 0.03% or 0.01% PDGF with a collagen sponge (ACS) or ACS alone in the calvarium. Micro-CT and histological sections were used to obtain amount of bone augmentation within the plastic caps. Bone volume (BV) was calculated using BV-measuring software. The BV and amount of bone augmentation were significantly increased in the PDGF groups compared to the control groups after 4 weeks. However, there was no significant difference between the 0.03% and 0.01% PDGF groups. These results indicate that 0.03% and 0.01% PDGF in ACS enhance bone formation beyond the skeletal envelope in rat calvarium.

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