generated bone/bone marrow in the newly generated tissue at the test sites was higher than for the control sites after one month and three months. These results suggest that IP affects the quality of bone augmentation at an early stage. (J. Oral Sci.

No abstract

: This study investigated the effects of ipriflavone (IP) on augmented bone using a guided bone regeneration (GBR) procedure. In 15 rabbits, two titanium caps were placed into calvarial bone for GBR. The animals were divided into three groups: the No-IP (no intake of IP), Post-IP (IP orally, 10 mg/kg/day after GBR), and Pre-IP (IP intake beginning before GBR) groups. One cap was removed from each rabbit after 3 months, and the remaining site was a control. One month after one cap removal, all the animals were euthanized, and histologic and histomorphometric analyses were performed. In all of the groups, the newly generated tissue was of varying size, and it consisted of thin pieces of mineralized bone and large marrow spaces with fat cells and some hematopoietic cells. In all of the control sites, the newly generated tissue was noted and almost filled the space under the cap. There was a significant difference between groups No-IP and Pre-IP (93.8+/-4.6% vs. 98.5+/-0.8%, P<0.05). The tissue generated at the test sites in all of the groups was resorbed, and its original shape and volume were not maintained 1 month after one cap removal. In particular, the greatest percentage, approximately 20% of the newly generated tissue, was resorbed in the No-IP group (93.8+/-4.6% vs. 73.9+/-3.7%, P<0.05), and approximately 11% and 15% in groups Post-IP and Pre-IP, respectively. The relative amount of mineralized bone generated at the control and test sites was significantly larger in groups Post-IP and Pre-IP when compared with group No-IP, except for the test site between groups No-IP and Post-IP (P<0.05). Therefore, the amount of mineralized tissue generated appeared to increase with an increase in the total IP dose. Within the limitations of this rabbit experimental model, we conclude that the daily intake of IP before or after GBR inhibits the resorption of augmented tissue and would be useful for improving the quality of newly generated bone beyond the skeletal envelope.

We investigated the effect of ipriflavone (IP) on osteoblasts and osteoclasts during guided bone augmentation (GBA). Each of ten rabbits had two titanium caps placed into its calvarium for GBA. The animals were divided into two groups: No-IP and IP (IP orally, 10 mg/kg daily after GBA). One cap was removed from each rabbit after 3 months, and the remaining cap served as a control. One month after the removal, all of the animals were euthanized, and histologic and histomorphometric analyses were performed. The tissue generated at the test site in the two groups was resorbed, and its original shape and volume were not maintained 1 month after cap removal. In particular, roughly 20% of the newly generated tissue in the No-IP group was resorbed (72.9 ±2.6% vs. 92.4 ±3.3%, p < 0.05), while approximately 8% was resorbed in the IP group. Furthermore, more osteoblast-like cells were present in the IP group than in the No-IP group (44.4 ± 3.05 vs. 30.2 ± 3.11, p < 0.05), and the proportion of osteoclast-like cells was reduced in the IP group compared to the No-IP group (0.59±0.02 vs. 0.76±0.06, p < 0.05). Therefore, the amount of mineralized tissue generated appeared to increase as the total IP dose increased. Within the limitations of this experimental model, we conclude that daily intake of IP after GBA inhibits the resorption of the augmented tissue and may be useful for improving the quality of newly generated bone beyond the skeletal envelope.