The effects of micro-osteoperforations on osteoclastic and osteoblastic activities in young and adult rats

The aim of our study is to elucidate the bone metabolism and age dependent effects in micro-osteoperforation assisted accelerated tooth movement during active tooth movement and post-orthodontic retention. This experimental in-vivo study included 36 Wistar-Albino male rats, aged 6 weeks and 36-40 weeks, respectively. Upper right and left first molar teeth were moved mesially with a 25 g force. 5 MOPs were performed on the left side around the first molar, whereas the right side served as the control group. After 7, 14 and 21 days, groups of animals were killed and tooth movement was measured, samples underwent Micro-CT and histologic analyses. With the effect of MOP, especially in young rats, the delay phase of tooth movement was shortened and osteoclastic activity initiated earlier than adults. The young-MOP side exhibited a 1.46 fold increase on day 7 and 1.23 fold increase on day 14 in the rate of tooth movement compared with the control side. Amount of tooth movement on the MOP side in young group compared to adult group on days 7 and 14, were 1.91 and 1.3 times faster, respectively. While the young-MOP group, which demonstrated the highest osteoclastic activity during the active treatment period, had the highest OPN levels in post-orthodontic retention, but also showed the lowest levels of bone volume/total volume (BV/TV) and bone mineral density (BMD). Although osteoblastic activity was higher in young MOP and control sides during the post-orthodontic retention, level of osteoclastic markers such as TRAP and RANK were also higher than adults. Therefore, orthodontic retention for both age groups should take longer in order to prevent relapse.