Biomedical Engineering Reference
In-Depth Information
The actual contact zone developed depends on a combination of the above discussed
mechanisms and the tissue. The latter varies from a cellular-free high content apatite tissue
in the case of a dental enamel, via dentine to a bone structure with cellular and body liquid
contact. Also the material can be in contact with other implant materials as dental crowns,
dental screws or coatings on implants. In the tables 10 and 11 are summarized in which
applications and specific tissues the demonstrated mechanisms are predominant.
Tissue
Mech 1
Mech 2
Mech 3
Mech 4
Mech 5
Mech 6
Enamel
x
x
Dentine
x
x
X
x
(x)
Bone
x
x
X
x
x
x
Table 10. Type of tissue and possible mechanisms.
Application
Mech 1
Mech 2
Mech 3
Mech 4
Mech 5
Mech 6
Cementation
a. towards tissue
b. towards implant
x
x
x
(x)
X
x
x
Dental fillings
a. towards enamel
b. towards dentine
x
x
x
x
X
x
(x)
Endo fillings
a. orthograde
b. retrograde incl bone
x
x
x
x
X
x
x
Coatings and augmentation
towards implant
gap filling
x
x
(x)
x
X
x
x
x
Table 11. Applications and possible mechanisms.
Nanostructure and nano-porosity used in certain applications
The nanostructure including nanoporosity developed in the Ca-aluminate biomaterial
system when near complete hydration occurs, yields some unique properties related to how
bacteriostatic and antibacterial properties may develop in the biomaterial. The nano-
porosity can also be used to control release of drugs incorporated the biomaterial. The
background to this is that even if the total porosity is low, all porosity is open, thus allowing
transport of molecules in the nanoporosity channels. The nanostructure used in thin film
coatings will also be touched upon.
Antibacterial aspects
The surprising finding in studies recently performed (Doxa patent application 2010) shows
that the bacteriostatic and antibacterial properties of the Ca-aluminate biomaterial are not
primarily related to pH or specific ions and ion concentration or reducing agents, but to the
hydration procedure and the microstructure obtained. This also to some extent is an answer
why highly biocompatible and even bioactive biomaterials can combine apparently
contradictory features such as biocompatibility, bioactivity and apatite formation and
environmental friendliness with bacteriostatic and antibacterial properties.
