title: Effects of Low-Intensity Pulsed Ultrasound on Implant Osseointegration in Ovariectomized Rats.
abstract: OBJECTIVE
  To investigate the effect of low-intensity pulsed ultrasound (US) on peri-implant bone healing and osseointegration under osteoporotic conditions.
  
  
  METHODS
  Seventy-two 12-week-old female Sprague Dawley rats received bilateral ovariectomies. Twelve weeks later, titanium implants were bilaterally placed in the proximal tibial metaphysis. The right tibia was exposed to low-intensity pulsed US (40 mW/cm2, spatial and temporal average) for 20 min/d starting the 2nd day after implantation, and the left tibia served as a control without stimulation. The rats were randomly assigned to 6 groups of 12 each according to the US duration (group 1: weeks 0-2, 280 minutes; group 2: weeks 0-4, 560 minutes; group 3: weeks 0-6, 840 minutes; group 4: weeks 0-8, 1120 minutes; group 5: weeks 0-10, 1400 minutes; group 6: weeks 0-12, 1680 minutes). At the end of the 2nd, 4th, 6th, 8th, 10th, and 12th weeks, the rats were euthanized, and bilateral tibias were harvested. Peri-implant bone volume and bone-implant contact were assessed by micro-computed tomography; the implant-bone interface was assessed histologically; and implant fixation strength was determined by a removal torque test.
  
  
  RESULTS
  Low-intensity pulsed US increased bone-implant contact at the 4th, 6th, 8th, 10th, and 12th weeks (P = .019, .017, <.001, <.001, and <.001, respectively) and peri-implant bone volume at all times (P = <.001, .002, .012, .007, .005, and .010). Removal torque on the US side was improved at the 6th, 8th, 10th, and 12th weeks (P= .012, <.001, .006, and .009). Ultrasound evoked a favorable bone response in the histologic study.
  
  
  CONCLUSIONS
  Low-intensity pulsed US might enhance new bone formation, especially at an early stage, and improve osseointegration in osteoporotic bone as an auxiliary method. However, further studies are needed to elucidate the mechanisms underlying its action.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, School of Stomatology, Central South University, Changsha, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Implantology, Hefei Dental Hospital, Hefei, China.
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, West China College of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Weixiong
authors.initials: W
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, West China College of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, West China College of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, West China College of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.|Department of Prosthodontics, West China College of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Wenchuan
authors.initials: W
authors.lastname: Chen
mesh_terms: D000818:Animals; D015921:Dental Implants; D005260:Female; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology*; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014464:Ultrasonic Therapy / Q000379:methods*; D000069453:Ultrasonic Waves
chemical_list: D015921:Dental Implants
keywords: animal model; micro-computed tomography; osseointegration; osteoporosis; torque; ultrasound