Biomedical Engineering Reference
In-Depth Information
Sucrose
Glucose
Bacteria
Lactate
Pellicle
Enamel
2
−
Ca
2+
+ HPO
4
White
area
lesion
H
+
+ L
−
Demineralization
FIGURE 2.2
Early stages of tooth decay caused by bacterial biofilm. Bacteria metabolize sugar and other carbohydrates to
produce lactate (HL) and other acids that, in turn, dissociate to form H
1
ions that demineralize the enamel
beneath the surface of the tooth; calcium and phosphate are dissolved in the process. This is known as a
white-spot lesion. Owing to reprecipitation, a pseudointact surface layer is observed on top of the body of the
carious lesion in this early stage of tooth decay. This pseudointact layer is permeable to ions
[36]
.
and it is thought that the metabolic interactions between different bacterial species play a key role
in the maturation process of the biofilm
[35]
. Therefore, the number of streptococci and lactobacilli
bacteria that cause caries can increase, especially in the presence of dietary sugars
[31]
. These bac-
terial species produce acids as by-products from the metabolism of fermentable carbohydrates and
cause demineralization below the surface of the tooth
[32,33]
(
Figure 2.2
).
Further to conventional oral hygiene, antiadhesive surface coatings can be used to control the
formation of dental biofilms because nanostructured surface topography and surface chemistry can
both determine initial bioadhesion
[37]
. The classic lotus effect in ultrahydrophobic surfaces is an
example of a self-cleaning surface
[38,39]
. However, such nanostructured surfaces are not
suitable for application in the oral cavity because of surface wear and equilibration of the surface
nanotopography by the ubiquitous pellicle layer
[34]
. To prevent the pathogenic consequences of
tenacious intraoral biofilm formation over a longer interval, wear-resistant nanocomposite surface
