title: [Effect of ultrasound on osteoprotegerin and receptor activator nuclear factor kappaB ligand expression during root resorption in rats].
abstract: OBJECTIVE
  To evaluate the effect of pulsed ultrasound on the expressions of osteoprotegerin (OPG) and receptor activator nuclear factor kappaB ligand (RANKL) during root resorption in a mouse model of orthodontic tooth movement.
  
  
  METHODS
  Thirty-two male Wistar rats (6-8 weeks old) were randomly assigned into 4 equal groups, including the blank control group, two ultrasound exposure groups with daily local LIPUS stimulation (100 and 150 MW/cm(2)) for 10 days during mechanical loading, and the control group with mechanical loading but not LIPUS exposure. Nickel-titanium closed-coil springs were used to generate 100 g mesial force for 10 days to move the maxillary right first molars. The expression of OPG and RANKL proteins at the compression sites was detected by immunohistochemistry.
  
  
  RESULTS
  Ultrasound stimulation significantly up-regulated the expression of OPG and down-regulated RANKL expression (P<0.05). The expressions of OPG and RANKL showed significant differences between the two ultrasound exposure groups (P<0.05).
  
  
  CONCLUSIONS
  Ultrasound stimulation might be useful to protect against root resorption and accelerate its repair by regulating the expressions of OPG and RANKL.
authors: Department of Stomatology, General Hospital of PLA, Beijing 100853, China.
authors: Zhi-feng
authors: ZF
authors: Liu
authors: Juan
authors: J
authors: Xu
authors: Ling-ling
authors: LL
authors: E
authors: Dong-sheng
authors: DS
authors: Wang
authors: Dan-dan
authors: DD
authors: Bei