Biomedical Engineering Reference
In-Depth Information
polyethylmethacrylate (PEMA) and polybutylmethacrylate (PBMA)
have found uses as soft denture liners [141].
Acrylic resins are available in several shades to match tooth
shading (esthetics). They have a low thermal conductivity. These resins
are not easily washed out by the acids of the oral cavity (low solubility).
Acrylic resins are also resilient, which allows them to be used in stress-
bearing areas. Acrylic resins exhibit a moderate shrinkage from 3 to 8
percent. Acrylic resins have a low resistance to wear.
3 . 4 . 2 CompositeResins
Composite resins are the most commonly used material for all
permanent anterior restorations [14, 44, 80]. These resins make
excellent restorative materials because of their good resistance
to wear and their excellent esthetics. Different illers (glass, silica,
borosilicates, and fused quartz), binders and processing techniques
(rods, ibers, and matte) are being experimented to develop the
ideal denture polymer, suiting clinical requirements [3]. Several
technological solutions have been proposed and are under testing.
Polyethylene woven ibers, braided ibers and unidirectional ibers
are under experimentation [28, 39, 122]. Fiberlex based on Kevlar,
developed by Dupont, is under consideration as a unidirectional
iber reinforced denture material.
Composite resins have excellent esthetic properties and good
resistance to wear because of the iller. They also have an acceptable
compressive strength. Thermal expansion is at a minimum — the
manufacturer claims that the thermal expansion is close to the normal
expansion of tooth structure. Solubility and shrinkage are low.
A new luoride-containing, methacrylate-based denture lining
material has been introduced [48]. Because of the luoride content,
this material is expected to demonstrate low water sorption and
solubility and high stain resistance, but these attributes remain
untested.
Composite resins are widely used today instead of amalgams for
restorative dental practice. The mechanical properties of the cured
composite resins are shown to be dependent on the curing process
[78]. It is thus highly desirable to monitor the curing status of the
resin in real time as to achieve the optimum performance.
Synthetic polymer poly-L-lactide (PLLA) is often used as
polymeric material and has some features, which make it useful
 
Search WWH ::




Custom Search