title: Effect of curing regime on the cytotoxicity of resin-modified glass-ionomer lining cements applied to an odontoblast-cell line.
abstract: OBJECTIVE
  The aim of this in vitro study was to evaluate the cytotoxicity of resin-modified glass-ionomer lining cements submitted to different curing regimes and applied to an immortalized odontoblast-cell line (MDPC-23).
  
  
  METHODS
  Forty round-shaped specimens of each experimental material (Fuji Lining LC and Vitrebond) were prepared. They were light-cured for the manufacturers' recommended time (MRT = 30 s), under-cured (0.5 MRT = 15 s), over-cured (1.5 MRT = 45 s) or allowed to dark cure (0 MRT). Sterilized filter papers soaked with either 5 microL of PBS or HEMA were used as negative and positive control, respectively. After placing the specimens individually in wells of 24-well dishes, odontoblast-like cells MDPC-23 (30,000 cells/cm2) were plated in each well and incubated for 72 h in a humidified incubator at 37 degrees C with 5% CO2 and 95% air. The cytotoxicity was evaluated by the cell metabolism (MTT assay) and cell morphology (SEM).
  
  
  RESULTS
  Fuji Lining LC was less cytotoxic than Vitrebond (p < 0.05) in all the experimental conditions. However, the cytotoxicity of Fuji Lining LC was noticeably increased in the absence of light-curing while the same was not observed for Vitrebond. The length of light-curing (15, 30 or 45 s) did not influence the toxicity of both lining materials when they were applied on the odontoblast-cell line MDPC-23.
  
  
  CONCLUSIONS
  The light-activation plays an important role in reducing the cytotoxicity of Fuji Lining LC. Following the manufacturer' recommendation regarding the light-curing regime may prevent toxic effect to the pulp cells.
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of São Paulo State-UNESP, Araraquara, São Paulo, Brazil.
authors.forename: Andreza M F
authors.initials: AM
authors.lastname: Aranha
authors.forename: Elisa M A
authors.initials: EM
authors.lastname: Giro
authors.forename: Pedro P C
authors.initials: PP
authors.lastname: Souza
authors.forename: Josimeri
authors.initials: J
authors.lastname: Hebling
authors.forename: Carlos A
authors.initials: CA
authors.lastname: de Souza Costa
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D048430:Cell Shape / Q000187:drug effects; D004396:Coloring Agents / Q000378:metabolism; D003736:Dental Cavity Lining; D017220:Dentin-Bonding Agents / Q000528:radiation effects / Q000633:toxicity*; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000528:radiation effects / Q000633:toxicity*; D008027:Light; D008689:Methacrylates / Q000633:toxicity; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009804:Odontoblasts / Q000187:drug effects*; D044367:Phase Transition; D012117:Resins, Synthetic / Q000528:radiation effects / Q000633:toxicity*; D013778:Tetrazolium Salts / Q000378:metabolism
chemical_list: D004396:Coloring Agents; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D008689:Methacrylates; D012117:Resins, Synthetic; D013778:Tetrazolium Salts; C042207:4-anisyltetrazolium blue; C067790:Vitrabond; C084541:Fuji glass-ionomer lining cement; C005044:hydroxyethyl methacrylate