title: Effects of low-intensity pulsed ultrasound on bone formation after the expansion of the inter-premaxillary suture in rats: a histologic and immunohistochemical study.
abstract: BACKGROUND
  Orthodontic maxillary expansion is a commonly-performed treatment approach to correct transverse maxillary deficiencies by separating the mid-palatal suture. To obtain a successful treatment result and prevent relapse, the expanded maxillary sutures require maintenance by means of qualified bone reorganisation.
  
  
  OBJECTIVE
  To assess the effects of low-intensity pulsed ultrasound (LIPUS) on sutural bone formation after the expansion of the interpremaxillary suture in rats.
  
  
  METHODS
  Sixteen male Wistar rats, 6 to 8-week old, were used. The expansion appliance comprised a helical spring fabricated from 0.014 inch stainless steel wire (Dentaurum, Ispringen, Germany). The rats were divided into two equal groups and randomly assigned to the LIPUS treatment group or a sham-operation group. LIPUS was delivered via a 2.5 cm diameter ultrasound transducer (Exogen, Smith and Nephews, Inc., Memphis, TN, USA) for 20 minutes per day during 7 days of post-expansion retention. Following retention, the rats' maxillae were surgically removed and histologic and immunohistochemical specimens were prepared and examined.
  
  
  RESULTS
  The number of osteoblasts and blood vessel dimensions in the ultrasound group increased but was not significant, compared with the control group. A statistically significant difference in osteocalcin, VEGF and TGF-β immunoreactivities (p < 0.01) was found in the area of the mineralising tissue. Only VEGF immunoreactivity was significant between two groups (p < 0.01) in the fibrous tissue area.
  
  
  CONCLUSIONS
  The area of mineralising tissue in the LIPUS-applied group expressed activity markers for osteocalcin, VEGF and TGF-β compared with a surrounding area of fibrous tissue. Cellular activation in the LIPUS group was greater than that of controls. Therefore, LIPUS may be accepted as a useful approach to enhance sutural bone formation.
authors.affiliation: Department of Orthodontics, İnönü University, Malatya, Turkey.
authors.forename: Ebubekir
authors.initials: E
authors.lastname: Toy
authors.forename: Firat
authors.initials: F
authors.lastname: Oztürk
authors.forename: Sedat
authors.initials: S
authors.lastname: Altindiş
authors.forename: Sümeyye
authors.initials: S
authors.lastname: Kozacioğlu
authors.forename: Hatice
authors.initials: H
authors.lastname: Toy
mesh_terms: D000818:Animals; D002113:Calcification, Physiologic / Q000502:physiology; D003238:Connective Tissue / Q000033:anatomy & histology; D003393:Cranial Sutures / Q000033:anatomy & histology* / Q000502:physiology; D003722:Dental Alloys / Q000737:chemistry; D007150:Immunohistochemistry; D008297:Male; D008437:Maxilla / Q000033:anatomy & histology* / Q000502:physiology; D055806:Microvessels / Q000033:anatomy & histology; D009969:Orthodontic Wires; D010006:Osteoblasts / Q000166:cytology; D015675:Osteocalcin / Q000032:analysis; D010012:Osteogenesis / Q000502:physiology*; D010155:Palatal Expansion Technique / Q000295:instrumentation; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013193:Stainless Steel / Q000737:chemistry; D013997:Time Factors; D014159:Transducers; D016212:Transforming Growth Factor beta / Q000032:analysis; D014465:Ultrasonics / Q000295:instrumentation / Q000379:methods; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis
chemical_list: D003722:Dental Alloys; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D015675:Osteocalcin; D013193:Stainless Steel