title: Gene expression profile of osseointegration of a hydrophilic compared with a hydrophobic microrough implant surface.
abstract: OBJECTIVE
  To compare the gene expression profile of osseointegration associated with a moderately rough and a chemically modified hydrophilic moderately rough surface in a human model.
  
  
  METHODS
  Eighteen solid screw-type cylindrical titanium implants, 4 mm long and 2.8 mm wide, with either a moderately rough (SLA) or a chemically modified moderately rough (SLActive) surface were surgically inserted in the retromolar area of nine human volunteers. The devices were removed using a trephine following 4, 7 and 14 days of healing. The tissue surrounding the implant was harvested, total RNA was extracted and microarray analysis was carried out to identify the differences in the transcriptome between the SLA and SLActive surfaces at days 4, 7 and 14.
  
  
  RESULTS
  There were no functionally relevant gene ontology categories that were over-represented in the list of genes that were differentially expressed at day 4. However, by day 7, osteogenesis- and angiogenesis-associated gene expression were up-regulated on the SLActive surface. Osteogenesis and angiogenesis appeared to be regulated by BMP and VEGF signalling, respectively. By day 14, VEGF signalling remains up-regulated on the SLActive surface, while BMP signalling was up-regulated on the SLA surface in what appeared to be a delayed compensatory response. Furthermore, neurogenesis was a prominent biological process within the list of differentially expressed genes, and it was influenced by both surfaces.
  
  
  CONCLUSIONS
  Compared with SLA, SLActive exerts a pro-osteogenic and pro-angiogenic influence on gene expression at day 7 following implant insertion, which may be responsible for the superior osseointegrative properties of this surface.
authors.affiliation: UCL Eastman Dental Institute, Periodontology Unit, London, UK. n.donos@eastman.ucl.ac.uk
authors.forename: N
authors.initials: N
authors.lastname: Donos
authors.forename: S
authors.initials: S
authors.lastname: Hamlet
authors.forename: N P
authors.initials: NP
authors.lastname: Lang
authors.forename: G E
authors.initials: GE
authors.lastname: Salvi
authors.forename: G
authors.initials: G
authors.lastname: Huynh-Ba
authors.forename: D D
authors.initials: DD
authors.lastname: Bosshardt
authors.forename: S
authors.initials: S
authors.lastname: Ivanovski
mesh_terms: D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis / Q000235:genetics; D002448:Cell Adhesion / Q000235:genetics; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D005110:Extracellular Space; D020869:Gene Expression Profiling; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D020935:MAP Kinase Signaling System / Q000235:genetics; D018919:Neovascularization, Physiologic / Q000235:genetics; D055495:Neurogenesis / Q000235:genetics; D016348:Osseointegration / Q000235:genetics*; D010012:Osteogenesis / Q000235:genetics; D013499:Surface Properties; D013997:Time Factors; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
chemical_list: D019485:Bone Morphogenetic Proteins; D015921:Dental Implants; D042461:Vascular Endothelial Growth Factor A