title: The effects of Er:YAG laser treatment on titanium surface profile and osteoblastic cell activity: an in vitro study.
abstract: BACKGROUND
  Laser light has been proposed as a tool to decontaminate the surface of endosseous implants. The effects of this maneuver on the interactions between cells and surface, however, are poorly known. The goal of the present study is to investigate osteoblast growth and differentiation on three commercially available surfaces untreated or after irradiation by erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser at two levels: 150 and 200 mJ/pulse at 10 Hz.
  
  
  METHODS
  Human osteoblastic Saos-2 cells were plated on machined, sandblasted and acid-etched titanium, or titanium plasma-sprayed disks. The effects of lasing were observed with a scanning electronic microscope, and cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Moreover, we measured the production of the osteoblast-specific protein osteocalcin and of osteoprotegerin in the supernatants by immunoenzymatic assays.
  
  
  RESULTS
  Although no visible changes were observed on machined or titanium plasma-sprayed disk samples at the tested levels, titanium peaks on sandblasted and acid-etched titanium disks appeared fused as a consequence of laser irradiation. Interestingly, cell proliferation was slower on irradiated titanium at both intensities on all the surfaces. Cell differentiation, as assessed by osteocalcin production, was generally unaffected by laser treatment, whereas the production of osteoprotegerin was decreased on all the surfaces irradiated at the intensity of 200 mJ/10Hz.
  
  
  CONCLUSIONS
  These results indicate that Er:YAG laser at energy levels used in this study can alter the surface profile of titanium implants and these changes may negatively affect the viability and the activity of osteoblastic cells. Therefore, Er:YAG lasers should be used with caution on titanium surfaces.
authors.affiliation: Unit of Periodontology, University of Parma, Parma, Italy. carlo.galli@unipr.it
authors.forename: Carlo
authors.initials: C
authors.lastname: Galli
authors.forename: Guido M
authors.initials: GM
authors.lastname: Macaluso
authors.forename: Erida
authors.initials: E
authors.lastname: Elezi
authors.forename: Francesca
authors.initials: F
authors.lastname: Ravanetti
authors.forename: Antonio
authors.initials: A
authors.lastname: Cacchioli
authors.forename: Giacomo
authors.initials: G
authors.lastname: Gualini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Passeri
mesh_terms: D002460:Cell Line; D049109:Cell Proliferation; D003666:Decontamination / Q000295:instrumentation / Q000379:methods; D045662:Dental Etching / Q000379:methods*; D015921:Dental Implants; D006801:Humans; D053844:Lasers, Solid-State; D016348:Osseointegration / Q000528:radiation effects; D010006:Osteoblasts / Q000528:radiation effects / Q000648:ultrastructure*; D013499:Surface Properties / Q000528:radiation effects; D014025:Titanium / Q000528:radiation effects*
chemical_list: D015921:Dental Implants; D014025:Titanium