Dental Materials M2
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DENTAL MATERIALS M2
o
most patronized impression material among dentists
IRREVERSIBLE HYDROCOLLOID •
•
ALGINATE
•
Manner of hardening: THERMOSET
•
Elasticity: ELASTIC
•
Dispensing form: POWDER
•
Components:
WATER – POWDER RATIO o
o
o
o
o
Manipulation: o
Water first before powder
o
Horizontal figure 8 (mix briskly or under pressure)
Na/K ALGINATE
Main component
Soluble SOL from alginic acid
o
•
Rubber bowl is turned every now and then to have all the powder mixed
Mixing time: 45sec – 1min
CaSO4 FACTORS:
o
•
15 – 18g of powder per 40-50cc of water
Chief reactor
•
Na3PO4
Retarder
Allows proper manipulation
•
POTASSIUM TITANIUM FLUORIDE
Accelerator
Plaster hardener
Fluoride improves the strength of set plaster
•
W/P RATIO o
More water retards setting
o
More powder hastens setting
MIXING TIME o
Longer time faster setting
o
Shorter time slower setting
PRECOOLING o
Prolongs gelatination of alginate
ORGANIC GLYCOL 2 TYPES OF ALGINATE ACCORDING TO ADA
o
o
•
TYPE 1
FILLERS
ZnO, diatomaceous earth
Hardening agents to improve strength
•
COLORING & FLAVORING MATERIALS
•
Dust-free
helps ease in reading the impression
o
Fast set
o
1 – 2mins
TYPE 2 o
Normal/regular set
o
2 – 4.5mins
o
Commonly used
makes the impression material palatable to the patient’s mouth PROPERTIES OF ALGINATE
advantages: o
sets promptly inside the patient’s mouth
o
cheaper than agar and ZOE paste
•
Not dimensionally stable o
SYNERISIS
Shrinkage due to loss of water
o
IMBIBITION
Expansion due to gain of water
•
Good flow property
•
Viscoelasticity
•
Compressive strength: 49.8psi
•
Elasticity: 97.8%
•
Prone to bubble formation
*Mix should not readily drip down from the spatula *Perforations should be 2-3mm in diameter and 0.5cm apart when making individual trays
EQUATION: SOLUBLE SOL
INSOLUBLE GEL
CaSO4 + Na3PO4 → Ca3(PO4)2 + Na2SO4 Na/K alg. + CaSO4 → Na2/K2SO4 + Ca alg.
-Rosette Go 011309
o
most patronized impression material among dentists
IRREVERSIBLE HYDROCOLLOID •
•
ALGINATE
•
Manner of hardening: THERMOSET
•
Elasticity: ELASTIC
•
Dispensing form: POWDER
•
Components:
WATER – POWDER RATIO o
o
o
o
o
Manipulation: o
Water first before powder
o
Horizontal figure 8 (mix briskly or under pressure)
Na/K ALGINATE
Main component
Soluble SOL from alginic acid
o
•
Rubber bowl is turned every now and then to have all the powder mixed
Mixing time: 45sec – 1min
CaSO4 FACTORS:
o
•
15 – 18g of powder per 40-50cc of water
Chief reactor
•
Na3PO4
Retarder
Allows proper manipulation
•
POTASSIUM TITANIUM FLUORIDE
Accelerator
Plaster hardener
Fluoride improves the strength of set plaster
•
W/P RATIO o
More water retards setting
o
More powder hastens setting
MIXING TIME o
Longer time faster setting
o
Shorter time slower setting
PRECOOLING o
Prolongs gelatination of alginate
ORGANIC GLYCOL 2 TYPES OF ALGINATE ACCORDING TO ADA
o
o
•
TYPE 1
FILLERS
ZnO, diatomaceous earth
Hardening agents to improve strength
•
COLORING & FLAVORING MATERIALS
•
Dust-free
helps ease in reading the impression
o
Fast set
o
1 – 2mins
TYPE 2 o
Normal/regular set
o
2 – 4.5mins
o
Commonly used
makes the impression material palatable to the patient’s mouth PROPERTIES OF ALGINATE
advantages: o
sets promptly inside the patient’s mouth
o
cheaper than agar and ZOE paste
•
Not dimensionally stable o
SYNERISIS
Shrinkage due to loss of water
o
IMBIBITION
Expansion due to gain of water
•
Good flow property
•
Viscoelasticity
•
Compressive strength: 49.8psi
•
Elasticity: 97.8%
•
Prone to bubble formation
*Mix should not readily drip down from the spatula *Perforations should be 2-3mm in diameter and 0.5cm apart when making individual trays
EQUATION: SOLUBLE SOL
INSOLUBLE GEL
CaSO4 + Na3PO4 → Ca3(PO4)2 + Na2SO4 Na/K alg. + CaSO4 → Na2/K2SO4 + Ca alg.
-Rosette Go 011309
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