MARGINALIZATION (Different learners in Marginalized Group
SILICON RUBBER IMPRESSION MATERIALS
1. SILICON RUBBER IMPRESSION MATERIAL
BY
PHILIP SHAIBILA
BWALYA CHILESHE
DENTAL TRAINING SCHOOOL, TECHNOLOGY STUDENTS
2. DEFINATION
• A dental impression is defined as the negative record of
the tissues of the mouth . It is used to reproduce the
form of the teeth and surrounding tissues.
Impression material: Is any substance or combination of
substances used for making an impression or negative
reproduction.
6. • There are two types of silicon rubber impression
material, namely addition and Condensation
7. Condensation silicones
• Condensation silicone was the first type of silicone
impression material.
• Also known as conventional silicones.
• Setting occurs at room temperature , and so are
also called RTV silicones.
8. PROPERTIES
• Sets time 8-9 min
• Mixing time 45 sec
• Excellent detail product
• Hydrophobic
• Shelf life 2 yrs
12. ADDITION SILICONE
• Also called as polyvinyl siloxanes
• Has better properties than condensation silicones
• It has an excellent recovery of 99.93%
• Addition polysilicones are the most stable of all the
existing materials
• It exhibits pseudoplastic properties.it can be used both
as syringe and tray materials
• Extremely hydrophilic
13. PROPERTIES
• Setting time 5-9 min
• Mixing time 45 sec
• Excellent surface detail
• Low curing shrinkage
• Low flexibility
• Shelf life 1-2 years
14. Composition
Base
• Poly(methyl hydrogen siloxane)
• Other siloxane prepolymers
• Fillers
Accelerator :
• Divinyl polysiloxane
• Other siloxane prepolymers
• Platinum salt : Catalyst (chloroplatinic acid)
• Palladium (Hydrogen absorber)
• Retarders
• Fillers
15. ADVANTAGES
• Accurate impressions, very low shrinkage
• Very good surface detail
• Highly elastic
• Perfect elastic recovery.
• Dimensionally stable
• Non-toxic and non-irritant
16. DISADVANTAGES
• Hydrophobic – necessary to add a surfactant
• Setting inhibited by latex gloves or some
adstringents (sulfur, heavy metals)
• Hydrogen release – surface bubbles – pouring time
1 h after removal from the mouth
• High price
17. FACTORS INFLUENCING WORKING
AND SETTING TIME
• Decrease in temperature
(Cooling of glass slab and storing materials at room
temperature can help in prolonging the working and
setting time)
• Decrease in viscosity
• Increase in temperature
( Rise in temperature accelerates the curing rate )
• Increase in viscosity
(Changing the proportions of base/catalyst can alter the
setting reaction)
19. Manipulation
• Mixing:
• 1. Using paper pad (Glass slab) and Spatula; Light,
medium and heavy consistencies
• 2. Hand Kneading; Heavy or putty consistency
• 3. Automixer and Dispenser; Cartridge form only (Light,
medium, heavy)
• 4. Automatic mixing; All consistencies, special electric
mixer + special material form