title: Low-intensity low-frequency ultrasound promotes proliferation and differentiation of odontoblast-like cells.
abstract: BACKGROUND
  Ultrasound is a potential therapeutic tool for dental tissue repair, but its biological effects on odontoblasts have not been well characterized. In this study, the effects of low-intensity low-frequency ultrasound on the viability, proliferation, and differentiation of odontoblast-like cells were investigated.
  
  
  METHODS
  Cell viability and proliferation were assessed after the treatment of adherent clonal MDPC-23 odontoblast-like cells with a 25-mW/cm(2) 45-kHz ultrasound. An in vitro scratch wound healing assay was used to investigate the ultrasound effects on cell migration. Long-term cultures were used to study odontogenic differentiation and extracellular mineralization.
  
  
  RESULTS
  Ultrasound exposure for up to 30 minutes did not significantly affect odontoblast-like cell viability but significantly increased cell numbers after 2 days in culture. Ultrasound did not influence the scratch wound closure rate in the absence or presence of the mitogen inhibitor mitomycin C, indicating that ultrasound did not influence cellular migration. Single and consecutive exposures to ultrasound resulted in the enhancement of in vitro mineralization after 14 days in culture with an osteogenic differentiation medium. This coincided with the up-regulation of gene expression of collagen type I, osteoadherin, dentine matrix protein 1, and osteocalcin as well as the expression of cell markers alkaline phosphatase and nestin.
  
  
  CONCLUSIONS
  These findings indicate that low-frequency ultrasound is able to influence proliferation and differentiation of odontoblast-like cells and may potentially be considered as a therapeutic tool for dental pulp and dentine repair.
authors.affiliation: Oral Biology, School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Man
authors.forename: Richard M
authors.initials: RM
authors.lastname: Shelton
authors.forename: Paul R
authors.initials: PR
authors.lastname: Cooper
authors.forename: Ben A
authors.initials: BA
authors.lastname: Scheven
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D002113:Calcification, Physiologic / Q000502:physiology; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000502:physiology; D024042:Collagen Type I / Q000032:analysis; D003470:Culture Media; D016326:Extracellular Matrix Proteins / Q000032:analysis; D006801:Humans; D007381:Intermediate Filament Proteins / Q000032:analysis; D016685:Mitomycin / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000032:analysis; D064231:Nestin; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009804:Odontoblasts / Q000187:drug effects / Q000502:physiology*; D015675:Osteocalcin / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis; D011509:Proteoglycans / Q000032:analysis; D013997:Time Factors; D014465:Ultrasonics / Q000379:methods*; D015854:Up-Regulation
chemical_list: D024042:Collagen Type I; D003470:Culture Media; C513309:DMP1 protein, human; D016326:Extracellular Matrix Proteins; D007381:Intermediate Filament Proteins; C577484:NES protein, human; D009419:Nerve Tissue Proteins; D064231:Nestin; D019384:Nucleic Acid Synthesis Inhibitors; D010750:Phosphoproteins; D011509:Proteoglycans; C113360:osteoadherin; D015675:Osteocalcin; D016685:Mitomycin; D000469:Alkaline Phosphatase