Akira Okamura | PubMed Health

PubMed2004

Effect of the difference of bone turnover on peri-titanium implant osteogenesis in ovariectomized rats.

High and low bone turnover situations, both of which are typically observed as postmenopausal and senile osteoporosis, were created by ovariectomy (OVX), and then an investigation of whether or not the difference of bone turnover affected peri-titanium (Ti) implant osteogenesis in rats was conducted. Female rats were divided into four groups. The experimental and control groups underwent OVX or sham operations at 15 or 27 weeks of age, as high or low bone turnover groups, respectively. Ti implants were inserted into the tibiae at 30 weeks, then fluorochromes were injected 10 or 20 days after the implantation for histometry. The implants were retained for 30 days and then ground sections were prepared. Afterward, the cortical bone growth rate, bone contact ratio (BCR) of the implant in both the cortical bone area and medullary canal area, and the average trabecular bone thickness around the implant were evaluated. Biochemical markers of bone turnover were also measured. Biochemical measurements indicated both increasing osteocalcin production in OVX rats and decreasing tartrate-resistant acid phosphatase activity in the low-turnover group. Histometrical measurements showed decreasing cortical growth and low BCR in the medullary canal of the low-turnover group. The high-turnover group demonstrated BCR as high as that of the control group. There was no significant difference in the average trabecular bone thickness around the implant among the groups. As a result, two types of osteoporotic situations were confirmed and it was shown that the difference of bone turnover was clearly due to the diverse osteogenesis around the Ti implant.

Acid Phosphatase↗

PubMed2004

Simvastatin promotes osteogenesis around titanium implants.

OBJECTIVES: Hydroxymethylglutaryl-coenzyme A reductase inhibitors, the so-called statins, have been widely used for hyperlipidemic patients, and it was recently reported that it promoted bone formation. In the present study, we examined the effect of simvastatin on the promotion of osteogenesis around titanium implants. MATERIALS AND METHODS: Ten 30-week-old rats received pure titanium implants in both tibiae, and were then divided into experimental and control groups. The experimental group was administered simvastatin daily. Thirty days later, all animals were killed and then specimens were prepared. The bone contact ratio (BCR) to the implant and bone density (BD) around the implant, as well as histological findings, were obtained. RESULTS: In the control group, newly formed bone could be seen around the implants. It was seen to be in direct contact with the implant surface, but otherwise unmineralized connective tissue was occasionally interposed. In the medullary canal, a scanty amount of bone trabeculae was observed. In the experimental group, in contrast, thicker bone trabeculae were abundantly seen in the medullary canal and showed a mesh-like structure. In the histometrical observations, both BCR and BD of the experimental group were significantly greater than those of the control group. CONCLUSION: The administration of simvastatin increases the value of both BCR and BD. This drug may have the potential to improve the nature of osseointegration.

Animals↗