Biomedical Engineering Reference
In-Depth Information
investigated under in vitro conditions [35,59] . This investigation indicates a decrease in the total
number of adherent bacteria and a reduction in the viability of S. mutans as compared to the con-
trols, when HA-disks specimens had been pretreated with CPP
ACP in combination with acidu-
lated phosphate fluoride [59] .
ACP can be
incorporated into supragingival dental plaque by binding to the surfaces of bacterial cells, to
components of the intercellular plaque matrix, and to adsorbed proteins on the tooth surfaces,
thereby influencing the process of biofilm formation [9,60] . In addition, CPP
Immunolocalization studies
showed that CPP
ACP might become
incorporated into the pellicle layer in exchange for the streptococci-related receptors, thus inhibit-
ing or modifying the bacterial adherence [61] . The effects of CPP
ACP on intraoral biofilm have
been also reported by an in situ study using germanium surfaces as substrate for the investigation
of bacterial biofilm formation [61] . This study demonstrated that
treatment with CPP
ACP
resulted in strongly reduced biofilm formation within the 7-days observation period [62] .
Since a few years, there are oral health-care products on the market containing clustered zinc
carbonate
HA nanoparticles [33,63] . Actually, we could prove the applicability of a mouth rinsing
solution that contains (besides other components) zinc carbonate
HA nanoparticle clusters
(Biorepair Zahn- und Mundsp¨ lung, Dr. Wolff, Bielefeld, Germany) for decreasing bacterial
adherence and reducing initial biofilm formation [64] . Interestingly, pure zinc carbonate
HA
nanoparticle clusters in saline solution also reduced initial bacterial adherence over 12 h considerably
as shown with different fluorescence microscopic techniques such as DAPI (diaminophenolindol)-
staining or BacLight live-dead staining [64] .
Furthermore, a new bifunctional system (either as paste or rinsing solution) containing calcium
phosphate nanoparticles (with a diameter of 150
200 nm), functionalized by the antibacterial agent
chlorhexidine and modified by carboxymethyl cellulose to increase the adhesion properties, has
been described for dental maintenance treatment providing both mineralizing and antibacterial
properties [65] . In vitro results indicate that this material sticks to tooth surfaces and closes dentin
tubules and also provides efficient inhibition of bacterial growth under in vitro conditions.
However, much more extensive studies are necessary to prove the activity against bacterial adher-
ence and biofilm formation occurring in the mouth [65] .
Besides the application of HA or calcium phosphate nanoparticles for biofilm management, the
nanotechnological modification of microbicide/antimicrobial agents also could provide new routes
in dental prophylaxis. A nanoemulsion composed of 25% soybean oil, 65% water, 10% Triton
X-100, and 1% cetylpyridinium chloride has been tested recently, regarding its effects on in vitro
biofilm formation and related anticariogenic effects. Antimicrobial nanoemulsions are surfactant-
containing oil and water emulsions (droplet size 100
300 nm) which provide antibacterial effects
[66] . Indeed, the data from Lee et al. [66] indicate that the cetylpyridinium-containing nanoemul-
sion causes strong inhibition of bacterial growth under in vitro conditions. Although the mechanism
of antibacterial action of nanoemulsion has not been clarified in detail yet, it has been supposed
that the nanodroplets could fuse with the outer bacterial membrane, thereby destabilizing the bacte-
ria's lipid envelope and initiating its disruption [66] .
Another way for biofilm management could be the use of activated carbon as an adsorbent;
hence it is used in a wide range of oral care products such as toothpastes and mouth rinses. Carbon
nanotubes can adsorb bacteria [67] and exhibit strong antimicrobial activity. Carbon nanotubes
binding oral pathogens might be useful tools at the nanolevel for capturing oral pathogens [67] .
Thereby, carbon nanotubes of different diameters provide significantly different effects on the
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