In vitro reduction of Streptococcus mutans biofilm on silver nanoparticle-modified composite resin

Resumo

Currently, new methods to reduce biofilm formation on
biomaterials are very studied, for example the use of silver nanoparticles,
which were bactericidal. However, there are few studies investigating the
benefits of these particles in dental restorative materials. Objective:
This study aimed to compare in vitro the Streptococcus mutans
biofilm formation on conventional light-cured composite resin with
that on experimental light-cured composite resin, modified with silver
nanoparticles. Material and methods: Discs were produced with
either conventional resin (control group) and resin modified with
different concentrations of silver nanoparticles, 0.1%, 0.3% and 0.6
% wt. (groups 1, 2 and 3, respectively). The samples were incubated
in bacterial suspension (S. mutans) enriched with 20% sucrose to
promote biofilm growth on the surfaces. Incubation times were 1, 4
and 7 days. After each period, adherent biofilms were disaggregated
by ultrasound. Then, the numbers of viable cells recovered from
the biofilms were counted through the serial dilution method. A
morphological analysis of biofilm was also performed by Scanning
Electron Microscopy. The data were subjected to Anova and Tukey’s
test (α = 0.05). Results: The number of viable cells was statistically
lower in groups 2 and 3 than in group 1 and control group, after the
three incubation periods, without statistical difference between groups
2 and 3. The number of viable cells was statistically lower in group 1
than in control group, after 4 and 7 days of incubation. Conclusion:
Resins modified with silver presented reduction of S. mutans biofilm
on their surfaces, according to the conditions of this study.