title: Silver nanoparticles in resin luting cements: Antibacterial and physiochemical properties.
abstract: BACKGROUND
  Silver has a long history of use in medicine as an antimicrobial and anti-inflammatory agent. Silver nanoparticles (NAg) offer the possibility to control the formation oral biofilms through the use of nanoparticles with biocidal, anti-adhesive, and delivery abilities. This study aims to evaluate the antibacterial effect of resin luting cements with and without NAg, and their influence on color, sorption and solubility.
  
  
  METHODS
  NAg were incorporated to two dual-cured resin cements (RelyX ARC (RA) color A1 and RelyX U200 (RU) color A2) in two concentrations (0.05% and 0.07%, in weight), obtaining six experimental groups. Disc specimens (1x6mm) were obtained to verify the antibacterial effect againstStreptococcus mutansin BHI broth after immersion for 1min, 5min, 1h, 6h, and 24h (n=3), through optical density readings. Specimens were evaluated for color changes after addition of NAg with a spectrophotometer (n=10). Sorption and solubility tests were also performed, considering storage in water or 75% ethanol for 28 days (n=5), according to ISO 4049:2010. Data were subjected to statistical analysis with ANOVA and Tukey (p=0.05).
  
  
  RESULTS
  The optical density of the culture broths indicated bacterial growth, with and without NAg. NAg produced significant color change on the resin cements, especially in RA. Solubility values were very low for all groups, while sorption values raised with NAg. The cements with NAg did not show antibacterial activity againstS. mutans. They also showed perceptible color change and higher sorption than the materials without NAg.
  
  
  CONCLUSIONS
  The resin luting cements with NAg addition did not show antibacterial activity against SS. mutans. They also showed perceptible color change and higher sorption than the materials without NAg.Key words:Silver, resin cements, products with antimicrobial action, solubility, color perception tests.
authors.affiliation: DDS, MS, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Ana-Paula-Rodrigues
authors.initials: AP
authors.lastname: Magalhães
authors.affiliation: DDS, MS, PhD, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Francine-Couto-Lima
authors.initials: FC
authors.lastname: Moreira
authors.affiliation: DDS, MS, PhD, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Denise-Ramos-Silveira
authors.initials: DR
authors.lastname: Alves
authors.affiliation: DDS, MS, PhD, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Cyntia-Rodrigues-Araújo
authors.initials: CR
authors.lastname: Estrela
authors.affiliation: DDS, MS, PhD, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Estrela
authors.affiliation: Physicists, MS, PhD, Student, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Marcus-Santos
authors.initials: MS
authors.lastname: Carrião
authors.affiliation: Physicists, MS, PhD, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Andris-Figueiroa
authors.initials: AF
authors.lastname: Bakuzis
authors.affiliation: Physicists, MS, PhD, Department of Prevention and Oral Rehabilitation, Dentistry School, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Lawrence-Gonzaga
authors.initials: LG
authors.lastname: Lopes