Bone Metabolism in the Mandibular Edentulous Region of the Beagle Dogs

本研究旨在研究比格犬无牙骨代谢。13只雌性比格犬在3个月（n=3）、4个月（n=1）、5个月（n=3）、6个月（n=2）和9个月（n=4）后取出全部前磨牙，处死。分别在献祭前14天和7天用四环素和钙黄蛋白双标记狗。下颌骨解剖，双能x线吸收仪分析。测定无牙区骨密度（BMD）。随后，对第二前磨牙处无牙骨进行未钙化处理，进行骨组织形态学测定。在距骨内表面250 mm的松质骨区测量这些参数。测量了以下参数：骨小梁体积（BV/TV）， Feret X/Y和骨髓面积用于骨结构，矿化表面（MS）用于骨形成，破骨细胞表面（OS/BS）用于骨吸收。采用Spearman秩相关分析提取后3 ~ 9个月测量值的序列变化。采用Mann-Whitney U检验比较3个月、5个月、9个月两组间的差异。骨密度测量结果显示，实验期间骨密度呈连续下降趋势。组织形态学测量值显示BV/TV、Feret X/X和骨髓面积增加，MS和OS/BS下降。提示骨小梁结构的快速变化与牙齿脱落引起的力学状态的改变相对应。

This study was conducted to investigate the edentulous bone metabolism of beagle dogs. Thirteen female beagle dogs had all premolars extracted and were sacrificed after 3 months (n=3), 4 months (n=1), 5 months (n=3), 6 months (n=2) and 9 months (n=4). Dogs were double-labeled with tetracycline and calcein, 14 days and 7 days prior to sacrifice, respectively. Mandibles were dissected and analyzed with dual energy X-ray absorptiometry. Bone mineral density (BMD) was measured in the edentulous region. Subsequently, the edentulous bone located at the second premolar was processed undecalcified for bone histomorphometry. The parameters were measured in the cancellous bone area 250 mum from the endosteal surface. The following parameters were measured ; trabecular Bone Volume (BV/TV), Feret X/Y and Marrow Area for bone structure, Mineralizing Surface (MS) for bone formation and Osteoclast Surface (OS/BS) for bone resorption. The sequential changes of measured values from 3 months to 9 months after extraction were analyzed by the Spearman rank correlation. Additionally, the differences between two groups of 3 months, 5 month and 9 month group were evaluated by the Mann-Whitney U test. The results of the BMD measurements showed a successive decrease during the experimental period. The values of histomorphometric measurement exhibited an increase of BV/TV,Feret X/X and Marrow Area, and a decrease of MS and OS/BS.It may be suggested that structure of trabecular bone which changed repidly corresponded to the alteration of mechanical status caused by tooth loss.