title: The effect of nicotine and cotinine on human gingival fibroblasts attachment to root surfaces.
abstract: BACKGROUND
  Different compounds of smoking (e.g., nicotine and cotinine) are risk factors for various diseases such as oral cancer and periodontal diseases. Some studies reported the negative effects of nicotine on cell proliferation and differentiation. The present in vitro study assessed the effects of nicotine and cotinine (long-acting metabolite of nicotine) on the attachment and viability of human gingival fibroblast (HGF) cells to tooth root surfaces.
  
  
  METHODS
  A total of 70 teeth specimens were placed into 48-well culture plates and covered with HGF cell suspension, in complete Dulbecco's modified Eagle's medium culture medium containing 1 nM, 1 μm, 1 mM, and 5 mM of nicotine and cotinine concentrations. Cellular attachment and viability measured using an MTT assay and a scanning electron microscope were used for cell morphological evaluation.
  
  
  RESULTS
  After 24 h, low (nanomolar and micromolar) and high concentrations (millimolar) of nicotine and cotinine caused a significant reduction in the initial cell adhesion in comparison with the control group, but no significant difference was observed between the nicotine and the cotinine groups (p<0.05). Dentally attached cells with low concentrations of nicotine and cotinine proliferated 48 h after exposure, the same as the control group. However, dentally attached cells with high concentrations of nicotine and cotinine (especially 5 mM) did not proliferate 24 h after exposure (p<0.05).
  
  
  CONCLUSIONS
  Low concentrations of nicotine and cotinine caused a reduction in the initial cell adhesion. However, no significant adverse effects on the proliferation of attached cells were seen in the longer period. High concentrations of nicotine and cotinine have adverse effects on the cell adhesion and proliferation of HGF cells.
authors.forename: Zeinab Rezaei
authors.initials: ZR
authors.lastname: Esfahrood
authors.forename: Amirhosein
authors.initials: A
authors.lastname: Zamanian
authors.forename: Maryam
authors.initials: M
authors.lastname: Torshabi
authors.forename: Maryam
authors.initials: M
authors.lastname: Abrishami
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003367:Cotinine / Q000009:adverse effects*; D005347:Fibroblasts / Q000187:drug effects*; D005881:Gingiva / Q000187:drug effects*; D006801:Humans; D009538:Nicotine / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects; D014092:Tooth Root / Q000187:drug effects*
chemical_list: D009538:Nicotine; D003367:Cotinine