title: Effects of static magnetic fields on bone regeneration of implants in the rabbit: micro-CT, histologic, microarray, and real-time PCR analyses.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of static magnetic fields (SMFs) on bone regeneration around titanium implants by μCT, histologic analysis, microarrays, and quantitative real-time PCR (qRT-PCR).
  
  
  METHODS
  Neodymium magnets provided the source of SMFs, the specimens were grade 5 titanium implants, and the animals were twenty-seven adult male New Zealand white rabbits. These implants were divided into six groups according to the presence of a magnet and predetermined healing period (1, 4, and 8 weeks). Each group comprised six specimens for μCT (n = 6) and histologic examination, and three specimens (n = 3) for microarrays and qRT-PCR, yielding a total of 54 specimens.
  
  
  RESULTS
  The μCT data showed that SMFs increased bone volume fraction (bone volume/total volume, BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th). Histologic observation indicated that SMFs promoted new bone formation and direct bony contact with implants. Microarray analysis identified 293 genes upregulated (>twofold) in response to SMFs. The upregulated genes included extracellular matrix (ECM)-related genes (COL10A1, COL9A1, and COL12A1) and growth factor (GF)-related genes (CTGF and PDGFD), and the upregulation was confirmed by qRT-PCR. Gene Ontology (GO) and pathway analysis revealed the involvement of the mitogen-activated protein kinase (MAPK), Wnt, and PPAR-gamma signaling pathways in implant healing.
  
  
  CONCLUSIONS
  μCT, histology, microarrays, and real-time PCR indicate that SMFs could be an effective approach to improving bone regeneration around dental implants.
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry and Institute of Oral Biology, Kyung Hee University, Seoul, Korea.
authors.forename: Eun-Cheol
authors.initials: EC
authors.lastname: Kim
authors.affiliation: Department of Biomaterials & Prosthodontics, School of Dentistry, Kyung Hee University, Gangdong, Korea.
authors.forename: Richard
authors.initials: R
authors.lastname: Leesungbok
authors.affiliation: Department of Biomaterials & Prosthodontics, School of Dentistry, Kyung Hee University, Gangdong, Korea.
authors.forename: Suk-Won
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Periodontology, School of Dentistry, Kyung Hee University, Seoul, Korea.
authors.forename: Ji-Youn
authors.initials: JY
authors.lastname: Hong
authors.affiliation: Department of Biomaterials & Prosthodontics, School of Dentistry, Kyung Hee University, Gangdong, Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Ko
authors.affiliation: Department of Biomaterials & Prosthodontics, School of Dentistry, Kyung Hee University, Gangdong, Korea.
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Ahn
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology*; D015921:Dental Implants; D055909:Magnetic Field Therapy / Q000379:methods*; D008297:Male; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D046888:Tissue Array Analysis; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: D015921:Dental Implants; D014025:Titanium
keywords: bone regeneration; implant; micro-computed tomography; microarray; static magnetic fields