The Effects of Micro-Osteoperforations on Osteoclastic and Osteoblastic Activities in Young and Adult Rats: A Split-Mouth Study

Background The aim of our study was to elucidate the bone metabolism and age-dependent effects in micro-osteoperforation (MOP)-assisted accelerated tooth movement during active tooth movement and post-orthodontic period. Methods This in vivo study included 36 Wistar-Albino male rats, aged 6 and 36-40 weeks, respectively. Upper first molar teeth were moved mesially with 25g force. Five MOPs were performed on the left side around the first molars, whereas the right side served as the control. After 7, 14, and 21 days, groups of animals were sacrificed, tooth movement was measured, samples underwent micro-CT and histologic analyses. Results MOPs effect was, especially in young rats, shortening the delay phase of tooth movement and initiation of osteoclastic activity earlier than adults. The young-MOP side exhibited a 1.46-fold increase on day 7 and a 1.23-fold increase on day 14 in tooth movement rate compared with the control side. The amount of tooth movement on the MOP side in the young group compared to the adult group on days 7 and 14, were 1.91 and 1.3 times faster, respectively. 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 and bone mineral density. Conclusions Although osteoblastic activity was higher in young MOP and control sides during the post-orthodontic phase, the levels of osteoclastic markers such as TRAP and RANK were also higher than adults. Therefore, orthodontic retention for both age groups should take longer to prevent relapse.