In Vitro and In Vivo Toxicity Evaluation of Colloidal Silver Nanoparticles Used in Endodontic Treatments.
BACKGROUND
Silver nanoparticles have been used for different purposes in dentistry, including endodontic treatments. The aim of this study was to determine the cytotoxicity of different types of silver nanoparticles on mouse fibroblast cell line L929 and the reaction of subcutaneous connective tissue of Wistar rats to these nanoparticles.


METHODS
Silver nanoparticles of an average size of 5 nm were synthesized with ammonia (SNA) or polyvinylpyrrolidone (SNP). L929 was exposed to SNA and SNP (0.1-100 μg/mL), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and enzyme-linked immunosorbent assays were performed after 6, 24, and 48 hours. Culture medium was used as the control. Sixteen rats received, individually, 3 polyethylene tubes filled with a fibrin sponge embedded in 100 μL SNA or SNP (1 μg/mL). A fibrin sponge with no embedding was the control. Tissue reaction was performed qualitatively and quantitatively after 7, 15, 30, and 90 days of implantation in the dorsal connective tissue of Wistar rats.


RESULTS
SNA and SNP were cytotoxic to L929 in higher concentrations, with SNA significantly more toxic than SNP. SNA and SNP did not induce significant interleukin-1β and interleukin-6 production. The release of stem cell factor by L929 increased 48 hours after the treatment with SNP at 5 μg/mL. Histologic examination showed that the inflammatory responses caused by SNA and SNP at 1 μg/mL were similar to the control in all experimental periods.


CONCLUSIONS
It was concluded that SNA and SNP were not cytotoxic at 25 μg/mL or lower concentrations. However, for safe clinical use, further studies establishing others points of its toxicologic profile are recommended.
Department of Pediatric Dentistry and Public Health Dental, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil. Electronic address: alinetakamiya@gmail.com.
Aline Satie
AS
Takamiya
Department of Pediatric Dentistry and Public Health Dental, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil.
Douglas Roberto
DR
Monteiro
Department of Pathology and Clinical Propedeutics, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil.
Daniel Galera
DG
Bernabé
Interdisciplinary Laboratory of Electrochemistry and Ceramics-Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
Luiz Fernando
LF
Gorup
Interdisciplinary Laboratory of Electrochemistry and Ceramics-Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
Emerson Rodrigues
ER
Camargo
Department of Basic Sciences, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil.
João Eduardo
JE
Gomes-Filho
Department of Endodontics, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil.
Sandra Helena Penha
SH
Oliveira
Department of Dental Materials and Prosthodontics, Araçatuba Dental School, Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil.
Debora Barros
DB
Barbosa
D000641:Ammonia / Q000737:chemistry; D000818:Animals; D002460:Cell Line / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003238:Connective Tissue / Q000187:drug effects; D003764:Dental Materials / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005337:Fibrin / Q000737:chemistry; D005347:Fibroblasts / Q000187:drug effects; D007249:Inflammation; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D008422:Materials Testing / Q000379:methods*; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000737:chemistry* / Q000633:toxicity*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D009504:Neutrophils / Q000187:drug effects / Q000473:pathology; D010316:Particle Size; D011161:Porifera; D011205:Povidone / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012834:Silver / Q000008:administration & dosage / Q000737:chemistry* / Q000633:toxicity*; D019089:Stem Cell Factor / Q000187:drug effects; D040521:Subcutaneous Tissue / Q000187:drug effects; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D018675:Toxicity Tests / Q000379:methods*
D003764:Dental Materials; D053583:Interleukin-1beta; D015850:Interleukin-6; D019089:Stem Cell Factor; D013778:Tetrazolium Salts; D013844:Thiazoles; C586932:colloidal silver; D012834:Silver; D000641:Ammonia; D005337:Fibrin; C022616:thiazolyl blue; D011205:Povidone
Biocompatibility; endodontic materials; inflammation; silver nanoparticles; toxicity