Kanekawa M, Shimizu N
Nihon University School of Dentistry at Matsudo, Matsudo City, Chiba, 271, Japan.
Am J Orthod Dentofacial Orthop. 1998 Dec;114(6):646-53. doi: 10.1016/s0889-5406(98)70196-9.
The purpose of the present study was to investigate age-related changes in bone regeneration during expansion of a midpalatal suture in rats. When the midpalatal suture was expanded for 7 days in rats of four different ages (6, 15, 24, and 52 weeks), it was found to have significantly widened in all groups by the analysis of a histomorphometric method. The expansion-induced widening of the suture was similar in 6, 15, and 24-week-old rats but was significantly less in 52-week-old rats. When the newly mineralized bone area and the osteoid area along the suture in all groups were quantified, newly mineralized bone area in all expansion groups significantly increased compared with corresponding controls, but expansion-induced newly mineralized bone area decreased in an age-dependent manner. Osteoid area also significantly increased by expansion, but expansion-induced osteoid area unexpectedly increased with age up to the 24-week-old rats. In the expansion-induced total bone area (expansion-induced newly mineralized bone area plus osteoid area), there was no significant difference among 6, 15, and 24-week-old rats, but it was markedly decreased in 52-week-old rats. Alkaline phosphatase activity in the suture strongly increased in all expansion groups, whereas increase in the rate of alkaline phosphatase activity clearly was less in 24 and 52-week-old rats. These results suggested that the difficulty of rapid-palatal expansion in 52-week-old rats and age-related decrease in bone regeneration after expansion of the suture within 24-week-old rats may be caused by decrease in mineralization of the bone matrix. Therefore, midpalatal suture can expand even in the cases exceeding the pubertal growth period, but more time may be necessary for mineralized bone to regenerate in the suture.
本研究的目的是调查大鼠腭中缝扩展过程中与年龄相关的骨再生变化。当在四种不同年龄（6周、15周、24周和52周）的大鼠中对腭中缝进行7天的扩展时，通过组织形态计量学方法分析发现所有组的腭中缝均显著增宽。6周、15周和24周龄大鼠中，扩展诱导的腭中缝增宽情况相似，但52周龄大鼠的增宽明显较少。当对所有组中沿着腭中缝的新矿化骨面积和类骨质面积进行定量时，所有扩展组的新矿化骨面积与相应对照组相比均显著增加，但扩展诱导的新矿化骨面积以年龄依赖性方式减少。类骨质面积也因扩展而显著增加，但扩展诱导的类骨质面积在24周龄大鼠之前随年龄意外增加。在扩展诱导的总骨面积（扩展诱导的新矿化骨面积加类骨质面积）方面，6周、15周和24周龄大鼠之间无显著差异，但52周龄大鼠明显减少。所有扩展组中腭中缝的碱性磷酸酶活性均显著增加，而24周和52周龄大鼠中碱性磷酸酶活性增加的速率明显较低。这些结果表明，52周龄大鼠快速腭扩展困难以及24周龄大鼠内腭中缝扩展后与年龄相关的骨再生减少可能是由于骨基质矿化减少所致。因此，即使在超过青春期生长阶段的情况下，腭中缝仍可扩展，但缝线中矿化骨再生可能需要更多时间。
