Kim T W, Yoshida Y, Yokoya K, Sasaki T
Departments of Orthodontics and Anatomy, School of Dentistry, Showa University, Tokyo, Japan.
Am J Orthod Dentofacial Orthop. 1999 Jun;115(6):645-53. doi: 10.1016/s0889-5406(99)70290-8.
This study was designed to clarify the effects of systemic administration of bisphosphonate, pamidronate, on the bone resorbing activity of osteoclasts during relapse of rat molars, after experimental movement. An elastic band was inserted between the upper first and second molars of 7-week-old rats and removed 21 days later. At 1 day before elastic band removal, bisphosphonate was administered via a tail vein. After elastic band removal, the rats were further maintained for 0, 5, or 10 days. The relapse of the first molars was studied by means of light and scanning-electron and transmission-electron microscopy. When an elastic band was removed, the mean interdental distance between the first and second molars in all rats was approximately 435 micrometer. In the control rats, it had decreased to 108 micrometer by day 5 and 57 micrometer by day 10. In these control rats, numerous osteoclasts appeared along the alveolar bone surface in the compressed side of the periodontal ligament of first molars. Administration of bisphosphonate significantly inhibited the prominent decrease in interdental distance. In these rats, it averaged 313 micrometer at day 5 and 115 micrometer at day 10. In bisphosphonate-treated rats, osteoclasts aggregated mainly in vascular canals of alveolar bone but were occasionally observed along the alveolar bone surfaces facing the periodontal ligament. Administration of bisphosphonate also induced structural changes, such as disappearance of ruffled borders and cytoplasmic polarity, in osteoclasts. A degenerated osteoclast was also observed in a bisphosphonate-treated rat. However, bisphosphonate induced no structural changes in osteoblasts, osteocytes, or periodontal ligament fibroblasts. These results suggest that a single systemic administration of bisphosphonate decreases the extent of initial relapse in experimentally moved rat molars via a mechanism involving impairment of the structure and resorptive functions of osteoclasts.
本研究旨在阐明全身给予双膦酸盐帕米膦酸二钠对实验性移动后大鼠磨牙复发期间破骨细胞骨吸收活性的影响。在7周龄大鼠的上颌第一和第二磨牙之间插入一根弹性带，并在21天后移除。在移除弹性带前1天，通过尾静脉给予双膦酸盐。移除弹性带后，将大鼠再饲养0、5或10天。通过光学显微镜、扫描电子显微镜和透射电子显微镜研究第一磨牙的复发情况。当移除弹性带时，所有大鼠第一和第二磨牙之间的平均牙间隙约为435微米。在对照大鼠中，到第5天时已降至108微米，到第10天时降至57微米。在这些对照大鼠中，在第一磨牙牙周膜压缩侧的牙槽骨表面出现了大量破骨细胞。给予双膦酸盐显著抑制了牙间隙的明显减小。在这些大鼠中，第5天时平均为313微米，第10天时为115微米。在双膦酸盐处理的大鼠中，破骨细胞主要聚集在牙槽骨的血管通道中，但偶尔也会在面向牙周膜的牙槽骨表面观察到。给予双膦酸盐还诱导破骨细胞出现结构变化，如皱褶缘和细胞质极性消失。在一只双膦酸盐处理的大鼠中还观察到一个退化的破骨细胞。然而，双膦酸盐对成骨细胞、骨细胞或牙周膜成纤维细胞未诱导结构变化。这些结果表明，单次全身给予双膦酸盐可通过涉及破骨细胞结构和吸收功能受损的机制降低实验性移动大鼠磨牙的初始复发程度。
