矯正学的歯の移動後の歯槽骨再形成に対する低出力超音波パルスの効果

Low-intensity pulsed ultrasound (LIPUS)

北海道歯学会

北海道歯学雑誌

Low-intensity pulsed ultrasound (LIPUS) promotes bone formation and is widely used for fracture healing in clinical medicine. The purpose of this study was to evaluate the effects of LIPUS on alveolar bone reformation following orthodontic tooth movement. 　An elastic band was inserted between the upper first and second molars of 10-week-old rats. After 7 days, the band was removed and the molars were fixed by a retainer (super bond). 　Four experimental groups were included : 1) rat with 7 days-tooth　movement (Ret-0day group), 2) rat with subsequent observation (retention) for 7 days without LIPUS (control group), 3) rat with LIPUS( LIPUS group) ,and the untreated group. 　A low-intensity pulsed ultrasound (1.0 MHz, 240 mW, 20% duty cycle, 15 min per day, 6days) was used. Animals were euthanized after tooth movement or after following retention period. 　Bone volume of interalveolar septum between the first and second molars were determined using microfocus x-ray tomography and 3D-reconstruction technology. Histological evaluations were performed under a light microscope. 　The bone volume of the Ret-0 day group was significantly lower when compared with the untreated group, and increased after retention. Bone volume of the LIPUS group at around the middle portion of the root was higher than the control group. Histological analysis pointed out bone formation in the interalveolar septum advanced in the LIPUS group rather than the control group. LIPUS accelerated bone formation thereby a difference occurred in time between the LIPUS group and the control group. The present study demonstrates that LIPUS promotes alveolar bone reformation in retention period.