Radiographic and histopathologic study on morphologic changes of mandibular condyle in ovariectomized cynomolgus monkey

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15592042
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 補綴理工系歯学
• Research Institution: Tohoku University
• Principal Investigator: KOMAI Shinya TOHOKU University, Hospital, assistant, 病院, 助手 (90234864)
• Co-Investigator(Kenkyū-buntansha): MORI Shiro TOHOKU University, Hospital, Lecturer, 病院・講師 (80230069) ; SAKAMOTO Maya TOHOKU University, Hospital, Lecturer, 病院・講師 (90157686) ; SASANO Takashi TOHOKU University, Department of dentistry, Professor, 大学院・歯学研究科, 教授 (10125560)
• Project Period (FY): 2003 – 2005
• Keywords: osteoporosis / mandibular condyle / μ-CT / Ovariectomy / cynomolgus monkey / 下顎頭 / 卵巣摘出

Research Abstract

This study carried out to investigate the micro structural and histomorphometrical changes in mandibular condyles in ovariectomized cynomolgus monkeys. The experimental animals were female cynomolgus monkeys (n=24) with a mean age of 10 years, range 9-15 years. They were divided into 2 groups : an experimental group to be ovariectomized (OVX group) and a control sham operated group (Sham group). The bone mineral content (BMC) of the mandibular condyle was determined by densitometric analysis of lateral oblique transcranial projection radiograph. Bone X-ray microanalysis on the mandibular condyle was performed using μ-computed tomography (μ-CT). The condyles were immersed in Prankricro solution for demineralization, embedded in paraffin, and used for standard light microscopical observation.
The result was as followed. Densitometric analysis of lateral oblique transcranial projection radiograph showed that BMD of the mandibular condyle did not significantly decrease in OVX group in comparison with Sham group. However, micro-CT analysis did show that bone volume (BV/TV) of the cancellous bone, trabecular thickness and number, number of node strut, and total strut length of tissue volume in OVX group were significantly lower than those found in Sham group. Further, trabecular separation in OVX group was significantly higher than in Sham group. On the other hand, the cortical bone volumes were similar in those two groups. Histomorphometrical analysis on condylar cartilage showed that both thickness of the hypertrophy stratum and unit number of hypertrophic cartilage cells were lower in OVX group than those in Sham group.
The conclusion is that bone loss and trabecular fragmentation in the monkey condyle could be induced with ovariectomy and the changes occurred only in cancellous bone, but not in cortical bone.