Module 3 - Impression Materials Flashcards
Used to record the impression of edentulous ridges and supporting tissues
Impression compound
Reversible, rigid, impression material
Impression compound
type 1 (low fusing) material for impression compound
green stick
Type 2 (medium fusing)
modelling compound
Type 3 (high fusing compound)
tray compound
(type of impression compound) - used for preliminary impression of edentulous mouths
True compound (type 1)
(type of impression compound) - this impression is known as secondary impression using zinc oxide eugenol pastes
tray compound (type 2)
the thin layer of plaster reproduces the fine detail of the denture referred as ________
corrective impression material
Considered as the first ingredient but it exhibits brittleness, lack of dimensional stability and tendency toward tackiness.
Beeswax
A filler agent, particles (core) and the surrounding ingredients as the matrix. It is usually added to improve workability and texture of the compound.
French chalk
Compositions of Impression compound that improve plasticity and workability (3)
1.) Burgundy Pitch
2.) Shellac
3.) Gutta Percha
T or F
smaller the size of the filler particles, it will be increasing the strength and hardness
true
Methods of cast construction (3)
- boxing method
- inversion method
- rubber base former
An irreversible rigid impression material used as secondary technique for edentulous patients (mucocompressive).
Zinc oxide-eugenol paste
characteristics of zinc oxide-eugenol paste
- Sets by chemical change
- High degree of accuracy and good surface reproduction of details.
Classification of zinc oxide-eugenol paste material
type 1 - hard
type 2 - soft
Available in paste form in 2 tubes
1.) Base paste (white)
2.) Accelerator/reactor paste (red)
Base paste composition
- zinc oxide (87%)
- olive oil (13%)
Accelerator paste
- gum or polymerized rosin
- filler
- oil of cloves
- resinous balsam
- accelerator soln
- Lanolin
- gum or polymerized rosin 50%
- filler 20%
- oil of cloves 12%
- resinious balsam 10%
- accelerator soln. 5%
- Lanolin 3%
setting reaction is an acid base reaction to form a chelate
chelation
the product of chelation
zinc eugenolate
Factors controlling the setting time of zinc oxide-eugenol paste
- decreasing setting time
- increasing the mixing time
- small drop of water mixed in the paste containing eugenol
- increasing accelerator paste while mixing
How to increase setting time of zinc oxide-eugenol paste?
- coolling the spatula & mixing slab
- addition of inert oils & waxes during mixing to reduce hardness like: olive oil
- increasing/add base paste while mixing
Biological considerations
- burning senation & tissue irritation in the mouth due to eugenol
use non eugenol paste
