title: Time- and concentration-dependent cytotoxicity of antibiotics used in endodontic therapy.
abstract: OBJECTIVE
  New drugs have to be assessed in endodontic therapy due to the presence of microorganisms resistant to therapeutic procedures. Thus, this study evaluated the time- and concentration-dependent cytotoxicity of different antibiotics used in endodontic therapy.
  
  
  METHODS
  Human gingival fibroblasts were treated and divided into the following experimental groups: Group I - control; Group II - ciprofloxacin hydrochloride; Group III - clyndamicin hydrochloride; and Group IV - metronidazole. Each drug was used at concentrations of 5, 50, 150, and 300 mg/L for 24, 48, 72, and 96 h. Cytotoxicity was evaluated by the MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and spectrophotometric reading of ELISA plates. The results were analyzed by BioEstat 4.0 software using Kruskal-Wallis and Dunn's tests at a significance level of 5%. Cell viability was assessed for the different concentrations and times.
  
  
  RESULTS
  All drugs presented dose-dependent cytotoxicity. Concentrations of 5 and 50 mg/L produced viable fibroblasts at all experimental times in all groups.
  
  
  CONCLUSIONS
  Cell viability at 24 h was greater than in the other experimental times. Comparison between the same concentrations of antibiotics at different times showed that metronidazole presented the highest cell viability at 72 and 96 h compared to the other antibiotics, whereas clyndamicin hydrochloride showed higher cell viability at 72 h than ciprofloxacin hydrochloride.
authors.affiliation: Department of Restorative Dentistry, Dental School, University of São Paulo, São Paulo, Brazil. marinabeloti@uol.com.br
authors.forename: Marina Beloti
authors.initials: MB
authors.lastname: Ferreira
authors.forename: Suely
authors.initials: S
authors.lastname: Myiagi
authors.forename: Carlos Goes
authors.initials: CG
authors.lastname: Nogales
authors.forename: Marcia Sampaio
authors.initials: MS
authors.lastname: Campos
authors.forename: José Luiz
authors.initials: JL
authors.lastname: Lage-Marques
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000633:toxicity*; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000633:toxicity; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000633:toxicity; D002981:Clindamycin / Q000008:administration & dosage / Q000633:toxicity; D004396:Coloring Agents; D003593:Cytoplasm / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects*; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008795:Metronidazole / Q000008:administration & dosage / Q000633:toxicity; D012390:Root Canal Therapy; D013053:Spectrophotometry; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004396:Coloring Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D008795:Metronidazole; D002981:Clindamycin; D002939:Ciprofloxacin; C022616:thiazolyl blue