Time- and concentration-dependent cytotoxicity of antibiotics used in endodontic therapy.
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.
Ferreira
Marina Beloti
MB
Department of Restorative Dentistry, Dental School, University of São Paulo, São Paulo, Brazil. marinabeloti@uol.com.br
Myiagi
Suely
S
Nogales
Carlos Goes
CG
Campos
Marcia Sampaio
MS
Lage-Marques
José Luiz
JL
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
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