Science Of Dental Materials Flashcards
(41 cards)
Characteristics of the ideal dental material
Biocompatible Mechanically stable Resistant to tarnish Dimensionally stable Minimally conductive Esthetic Easy to manipulate Adherent to tissues Cleanable/repairable Cost effective
Classes of materials
Metals
Ceramics
Polymers
Composites
Metal dental materials
Have high thermal/electrical conductivity
Can bend without breaking - conducive to restore teeth
Opaque
High luster
High melting temperatures
Ceramics (white/tooth colored)
Very esthetic results
Former by Union of metal and non-metal
Very brittle, cannot bend
High melting point
Low thermal/electric conductivity
Inert— body may see it as natural bone
Class ceramics/ Polymers
Newest
Used for reinforcing agents or fillers for composites
In many dental cements and temporary restorative materials
Used to make dentures, temp crowns, bridges
Bonding
A primary bond holds two solids together
Secondary holds liquids together
Atomic arrangements
Has an effect on how the materials behave
Rubber can stretch, another may be brittle
Solubility
All materials soluble to a point. The least so are ceramics and porcelains
Loss of small organic molecules in the oral cavity
Sorption
Uptake of fluids
May cause discoloration of materials
May cause expansion to the material and even enhance the seal at the margin closing area to microorganisms
OR
can cause failure of restorations
Adhesion
The force of attraction btw molecules of atoms on two different (dissimilar) surfaces as they are brought in contact
Cohesion
Force of attraction btw the molecules or atoms within a given material (not on surface), sticking together
Being mutually attractive
Factors that will determine effectiveness of adhesion/cohesion
Wetting
Viscosity
Wetting
The extent which the adhesive will spread onto a solid surface
Will help a material spread more easily
Good wetting is needed for materials to stick
Poor wetting is due to…
Contamination of material, instruments etc
Plaque
Pellicle
Pellicle
Thin layer of organic mix on the tooth deposited from saliva
Surface tension
The attraction that the atoms and molecules have for one another
High ST would cause materials to ball up instead of spread out. Ex: Mercury
Hue
Refers to the dominant color of the object
Value
Refers to the lightness of color
Scale 1-10
1= black
10= white
Chroma
Refers to intensity of the color
Scale 1-10
10= saturated. Is it rich in color or pale?
Natural teeth are around 1-3
Translucency
Refers to the fact that light enters the tooth
Light can be transmitted, reflected or scattered
Tarnish
Discoloration
It is reversible
Corrosion
The deterioration of metal by chemical or electro chemical reaction
Causes the restoration to break down or fail
Not reversible
Crevice corrosion
A gap, groove or slot exists next to or on a metal
Example: Margin around an amalgam
Is an issue because of secondary decay/recurring decay forming around the margin
Types of forces seen in oral cavity
Tensile
Compressive
Shear
