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Dental Impression Material, Dyandra Wirahana Hasna, 2106717682 - Coggle…
Dental Impression Material
Definition of dental impression
Dental impression material is a material that are use to make an impression. the tools are impression tray and dental impression material
Functions
it its use to make the exact replica
The replica are used to evaluate the dentition when orthodontic, occlusal, or other problems are involved, also it is used for restorations and prostheses
used to duplicate models or cast that has been formed
Dental impression: is a construction of intraoral and extraoral tissue Structure. it produce the form and relationship of the teeth and oral tissue. The impression may be taken from portions of the tooth, multiple tooth, or even an arch.
Gypsum
Gypsum is a mineral that is mined all over the world, but it is also made as a by-product of flue gas desulfurization in coal-fired power plants. principal constituent of gypsum-based products is calcium sulfate hemihydrate [(CaSO4)2•H2O or CaSO4• 12 H2O].
Types of Gypsum
MODEL PLASTER (TYPE II) for example Snow White Plaster No. 1 (Kerr/Sybron)
DENTAL STONE (TYPE III) For example Microstone (Whip Mix)
IMPRESSION PLASTER (TYPE I) For example Impression plaster (modern materials manufacturing)
DENTAL STONE, HIGH STRENGTH (TYPE IV) For Example Vel Mix Stone (Kerr/Sybron)
DENTAL STONE, HIGH STRENGTH, HIGH EXPANSION (TYPE V) For example Suprastone (Kerr/Sybron)
Properties
quality, fluidity at pouring time, setting time, linear setting expansion, compressive strength, hardness and abrasion resistance, and reproduction of detail.
Functions
as auxiliary material
used to form models and casts on which wax dental prostheses and restorations are constructed
For making study model
When a gypsum is mixed with refractory fillers, such as different crystalline forms of silica (gypsum-based investment) it becomes more heat resistant, which makes it useful to form molds for the casting of molten metal in an anatomic form for dental restorations.
Characteristic
Stone
has a crystal characteristic but more dense
Found in type 3
often called α-hemihydrate
stronger and harder dihydrate structure than β-hemihydrate (plaster)
Improve Stone
often called modified α-hemihydrate or die stone
the hemihydrate crystals characteristic will be shorter and thicker than those produced in a closed container
If the calcination process happen under pressure in a 30% calcium chloride solution or in the presence of more than 1% of sodium succinate, thus creating the Improved Stone
Found in type 4 and 5
Plaster
often called the β-hemihydrate
has a crystal characteristic and sponginess
weaker because of the irregular crystal character and require more water
Found in type 1 and 2
How to manipulate
measure the measurement and combination of powder and liquid
Spatulation or mix by hand or mechanically
pouring the model into the mold
disinfection
Advantages and disadvantages
advantage
cheap
They are able to reproduce fine detail from the impression
good accuracy and stability
disadvantage
The mechanical properties are not ideal and the brittle nature of gypsum
Problems occasionally arise when gypsum model and die materials are used in conjunction with alginate impression.
Alloy Casting
Dental alloy casting refers to alloys that are used in clinical settings in their natural state.
High-noble alloys
Characteristic: easy to cast, expensive, low corrosion, high densities
sub-classes
Au-Pt
Au-Pd
Au-Cu-Ag
consist 40% of gold and 60% noble metal
Noble alloys
consist at least 25% of noble metal
Sub-classes
Pd-Cu
Ag-Pd
Au-Ag-Cu
Characteristic: it has low melting point, cant be used for ceramic alloy restoration
Predominantely Base-metal Alloys
consist less than 25% noble metal
complex, contain 6-8 element, low densities, the cheapest.
Classification of dental impression materials
Setting mechanism
reverseable
irreverseable
Mechanical Properties
elastic
inelastic
Composition
Applications
Dental Wax
wax is a mixture of various component that can be made of natural or synthetic materials. it also has low-molecular weight.
classification and Functions
Pattern wax
boxing, utility, and sticky
Processing wax
Bite registration and correction
Impression wax
inlay, casting, and base plate
Properties
Thermal Properties
poor thermal conductor
dimensional changes
Solid-solid transition
Mechanical properties
flow value
Brittleness
Characteristic
thermoplastic material
normally solid at room temperature but melt, without decomposition to form mobile liquids
when to use wax
inlay pattern wax
base plate wax
boxing wac
casting wax
utility wax
sticky wax
corrective impression wax
bite registration wax
Reference:
Sakaguchi RL and Powers JM. Craig’s Restorative Dental Materials,13th ed. Mosby Elsevier, 2012
Anusavice, Shen, Rawls. Phillips’ Science of Dental Materials, 12th ed. Elsevier Science, 2013
O’Brien WJ. Dental Materials and Their Selection, 4th ed. Quintessence Publishing Co, Inc, 200
Dyandra Wirahana Hasna
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