Biomedical Engineering Reference
In-Depth Information
100 nm and in dentin up to 50 nm. The acid-related destruction of the dental hard substance as a
biocomposite is initiated on the nanolevel. Due to its nonregenerative nature, enamel is unable to
heal and repair itself after surface alterations. Accordingly, modern prophylactic strategies intend
to substitute mineral loss with artificial or biomimetic nanoscopic mineral components or HA parti-
cles fitting to the initial tooth surface nanosized defects. Thereby, it is has to be kept in mind that
from a theoretical point of view, remineralization is the process of transferring anions and cations
to nucleation sites, where the lattices leading to mineralized structures are generated.
8.3
Main strategies for implementation of nanosized materials in
dental prophylaxis
Basically, there are two potential mechanisms for size-dependent effects of nanomaterials in pre-
ventive dentistry: (i) the interaction with bacterial adherence and oral biofilm formation and (ii) the
impact on de- and remineralization. As the process of demineralization starts at the nanolevel
caused by either caries or erosion-induced acidic challenges, it makes sense to supply small nano-
sized building units for optimized remineralization. This applies also for particle-size-related inter-
actions with bacteria and the bacterial membrane, where nanoparticles are much more effective
than microparticles. Many preparations considering these deliberations were developed; most of
them are in the experimental state and few are already available for the consumers
[11,33
36]
.
Pure inorganic nanomaterials applied in preventive dentistry are mostly HA or its derivatives
modified with zinc, fluoride, or carbonate, respectively. Also mineral nanotubes, nanorods, or other
geometric forms are tested, but represent rather a minority
[9,14,37
42]
.
Another group is represented by organic/inorganic compound materials. Nanosized organic
structures are components of several beverages and foodstuffs and contribute considerably to their
characteristic properties. A typical example is milk containing casein micelles and lipid vesicles.
Casein micelles are quite similar to micelle-like salivary structures involved in the formation of the
pellicle layer. These natural structures may be processed to serve as tailored carriers with high
affinity to the pellicle in order to accumulate minerals and protective proteins at the tooth surface.
All the promising options of caseins have not been exploited in full until now, but there is already
a widespread preparation based on casein phosphopeptide (CPP)
stabilized amorphous calcium
phosphate (ACP) nanocomplexes with a diameter of 2.12 nm
[11,34,35]
. Other unexplored nano-
sized components of foodstuffs or animals such as chitin skeletons of diatoms could serve as
carriers
[36,43
45]
.
Besides these biomimetic or even biological approaches, silver nanoparticles or nanosized syn-
thetic glass structures also have been described for possible application in preventive dentistry
[46
49]
. However, though these materials might be efficient, their side effects are not foreseeable.
Thus, the present overview will focus on biological or biomimetic strategies.
8.4
Modulation of bioadhesion and biofilm management
In principle, there are two general approaches to modulate and to minimize bacterial biofilm forma-
tion on the tooth surface or on the surface of dental materials. It is either possible to establish a
