Biomedical Engineering Reference
In-Depth Information
permanent modification/coating of the substrate's surface providing antiadhesive or easy-to-clean
characteristics, or to adopt dentifrices and mouthwashes, that will be applied frequently. For both
approaches, there are examples based on nanomaterials
[9,14]
. If mouthwashes or dentifrices are
adopted, the principal idea is that nanosized particles could interact more effectively with the struc-
tures of the bacterial membrane and the bacterial receptors than microparticles
[9,14]
. This might
apply for microscaled HA which has been a component of oral care products without appreciable
efficacy. HA does not exhibit cytotoxic effects and shows excellent biocompatibility. However,
previous approaches using microsized HA in toothpastes were not successful. This is different for
nanoscaled particles
[9,50]
. Various types of bioinspired nanosized apatites have been synthesized
during the last few years in order to develop and create innovative toothpastes, mouth rinsing solu-
tions, and remineralizing pastes (fluids) for use in preventive dentistry
[9,33,40,50,51]
. On the one
hand, apatite nanoparticles could become integrated in the pellicle layer at the enamel surface under
oral conditions, thereby changing the chemical composition and tenacity of the pellicle, and thus
modifying the subsequent bacterial adherence and the pattern of biofilm formation. On the other
hand, the nanosized apatite particles could also be adsorbed to the surface of planktonic bacteria as
well as to the surface of bacteria adherent at the tooth surface.
Venegas et al. (2006)
[52]
investigated the interaction of nanosized HA with bacterial cells in
aqueous solution and in human saliva under in vitro conditions. Crystallized HA nanoparticles
(average size 100
m), were used
in these experiments. Electron microscopic investigation of the bacteria cells and HA in saliva
revealed adsorption of nonaggregated and clustered apatite particles at the bacterial surface
[52]
.
The nanosized apatite particles adsorbed to the bacterial surface might interfere with the bacterial
adhesins, which are important for irreversible binding of bacteria to the tooth surface.
Interestingly, at the same time Lu et al.
[53,54]
reported that needle-like or spheroidal nano-HA
(with dimensions of less than 100 nm) not only has the potential to improve the remineralization of
artificial caries lesions but also could modify bacterial colonization of the tooth surface in a rat ani-
mal model, thus revealing a certain anticaries potential. The capability of nano-HA (spherical HA
with diameters of less than 100 nm) to reduce bacterial adherence and subsequent biofilm accumu-
lation was confirmed by a laboratory experiment using a four-organism bacterial consortium
(Streptococci mutans, S. sanguis, Actinomyces viscosus, Lactobacillus rhamnosus) for biofilm for-
mation over 48 h under in vitro conditions
[55]
. In addition, treatment of bovine enamel slabs with
an experimental dentifrice containing 15% nano-HA reduced bacterial adherence and colonization
in vitro compared to a test dentifrice without nanoapatite particles
[56]
. Pretreatment of rough
enamel surfaces with a 10% HA spherulite (particle diameter size of 0.02
10
5 nm), distinctly smaller than the bacteria (diameter of 1
μ
3
3
m) watery suspen-
sion significantly decreases adherence of S. mutans to the enamel surface under in vitro conditions,
probably due to a reduction of enamel surface roughness
[57]
. Furthermore, in vivo application
of an experimental dentifrice containing 38% nanosized HA spherulites (particle diameter size of
0.02
1.00
μ
m) using an individual tray one time daily over 7 days decreased the number of
S. mutans in saliva over a 4-week post-treatment evaluation period, whereas application of a denti-
frice containing 38% of dicalcium phosphate dihydrate placebo beads did not decrease S. mutans
levels
[57]
.
An already widespread biological nanomaterial based on derivatives of milk components is a
preparation containing CPP
1.00
μ
ACP nanocomplexes with a diameter of 2.12 nm
[58]
. The effect of
CPP
ACP (GC Tooth-Mousse) nanocomplexes on 24-h S. mutans biofilm formation has been
