Impression Materials
6/9/2012
Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist
1
Official Disclaimer The opinions expressed in this presentation are those of the author and do not necessarily reflect the official position of the US Air Force or the Department of Defense (DoD). Devices or materials appearing in this presentation are used as examples of currently available products/technologies and do not imply an endorsement by the author and/or the USAF/DoD.6/9/2012 Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist 2
Impression Materials Non-elastic Elastic Aqueous hydrocolloids Agar Alginate
Non-aqueous elastomers Polysulfide Silicones Condensation Addition6/9/2012
Polyether
Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist
3
Indications Diagnostic casts preliminary opposing
Indirect reconstruction fixed removable
Bite registration6/9/2012 Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist 4 Giordano, Gen Dent 2000
Elastomeric Impression Materials Viscoelastic physical properties vary rate of loading
Rapidly remove decreases permanent deformation chains recoil from a recoverable distance
increases tear strength6/9/2012 Dr Nabeel Safwat Al Nahass 5 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Plaster Non-elastic Compound Waxes Impression Materials
ZnO - Eugenol
Aqueous Hydrocolloids Elastic
Agar (reversible) Alginate (irreversible) Polysulfide
Non-aqueous Elastomers
Condensation Addition
Silicones Polyether
6/9/2012
Dr Nabeel Safwat Al Nahass 6 OBrien, Dental Materials & their Selection 1997 Prosthodontist and Implant Specialist
Aqueous Hydrocolloids Colloidal suspensions chains align to form fibrils traps water in interstices
Two forms sol viscous liquid
gel elastic solid
Placed intra-orally as sol converts to gel6/9/2012
thermal or chemicalSafwat Al Nahass Dr Nabeel process
7 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Aqueous Hydrocolloids Semi-permeable membranes poor dimensional stability
Evaporation Syneresis fibril cross linking continues contracts with time exudes water
Imbibition water absorption swells6/9/2012 Dr Nabeel Safwat Al Nahass 8 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Agar (reversible)
Aqueous HydrocolloidsElastic
Alginate (irreversible)Polysulfide Condensation
Non-aqueous Elastomers
Silicones Addition Polyether
6/9/2012
Dr Nabeel Safwat Al Nahass 9 OBrien, Dental Materials & their Selection 1997 Prosthodontist and Implant Specialist
Reversible Hydrocolloid (Agar) Indications crown and bridge high accuracy
Example Slate Hydrocolloid (Van R)
6/9/2012
Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist
10
Composition Agar complex polysaccharide seaweed
Potassium sulfate improves gypsum surface
gelling agent
Borax strength
Water (85%)
cool to 43C
agar hydrocolloid (hot)(sol)6/9/2012
agar hydrocolloid (cold)(gel)
heat to 100C
Dr Nabeel Safwat Al Nahass 11 OBrien, Dental Materials & their Selection 1997 Prosthodontist and Implant Specialist
Manipulation Gel in tubes syringe and tray material
6/9/2012
Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist
12
Manipulation 3-chamber conditioning unit (1) liquefy at 100C for 10 minutes converts gel to sol
(2) store at 65C place in tray (3) temper at 46C for 3 minutes seat tray cool with water at 13C for 3 minutes converts sol to gelDr Nabeel Safwat Al Nahass 13 OBrien, Dental Materials & their Selection 1997 Prosthodontist and Implant Specialist
6/9/2012
Advantages Dimensionally accurate Hydrophilic displaces moisture, blood, fluids
Inexpensive after initial equipment
No custom tray or adhesives Pleasant flavor No mixing required6/9/2012 Dr Nabeel Safwat Al Nahass 14 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Disadvantages Initial expense special equipment
Material must be prepared in advanced Tears easily Dimensionally unstable Must be poured immediately Can only be used for a single cast
Difficult to disinfect6/9/2012 Dr Nabeel Safwat Al Nahass 15 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Agar (reversible)
Aqueous HydrocolloidsElastic
Alginate (irreversible)Polysulfide Condensation
Non-aqueous Elastomers
Silicones Addition Polyether
6/9/2012
Dr Nabeel Safwat Al Nahass 16 OBrien, Dental Materials & their Selection 1997 Prosthodontist and Implant Specialist
Irreversible Hydrocolloid (Alginate) Most widely used impression material Indications study models removable fixed partial dentures framework
Examples Jeltrate (Dentsply/Caulk) Coe Alginate (GC America)6/9/2012 Dr Nabeel Safwat Al Nahass 17 Phillips Science of Dental Materials 1996 Prosthodontist and Implant Specialist
Composition Sodium alginate salt of alginic acid mucous extraction of seaweed (algae)
Sodium phosphate retarder
Calcium sulfate reactor
Filler Potassium fluoride improves gypsum surface
2 Na3PO4 + 3 CaSO4 Na alginate + CaSO4(powder)6/9/2012
Ca3(PO4)2 + 3 Na2SO4H2O
Ca alginate + Na2SO4(gel)
Dr Nabeel Safwat Al Nahass 18 Prosthodontist and Implant Specialist OBrien Dental Materials & their Selection 1997
Manipulation Weigh powder Powder added to water rubber bowl vacuum mixer
Mixed for 45 sec to 1 min Place tray Remove 2 to 3 minutes after gelation (loss of tackiness)6/9/2012 Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist 19 Caswell JADA 1986
Advantages Inexpensive Easy to use Hydrophilic displace moisture, blood, fluids
Stock trays
6/9/2012
Dr Nabeel Safwat Al Nahass 20 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
Disadvantages Tears easily Dimensionally unstable immediate pour single cast
Lower detail reproduction unacceptable for fixed pros
High permanent deformation Difficult to disinfect6/9/2012 Dr Nabeel Safwat Al Nahass 21 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
Non-Aqueous Elastomers Synthetic rubbers mimic natural rubber scarce during World War II
Large polymers some chain lengthening primarily cross-linking
Viscosity classes low, medium, high, putty monophasic6/9/2012 Dr Nabeel Safwat Al Nahass 22 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
Agar (reversible)
Aqueous HydrocolloidsElastic
Alginate (irreversible)Polysulfide Condensation
Non-aqueous Elastomers
Silicones Addition Polyether
6/9/2012
Dr Nabeel Safwat Al Nahass 23 Prosthodontist and Implant Specialist OBrien Dental Materials & their Selection 1997
Polysulfide First dental elastomers Indications complete denture removable fixed partial denture tissue
crown and bridge
Examples Permlastic (Kerr) Omni-Flex (GC America)6/9/2012 Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist 24
Composition Base polysulfide polymers fillers plasticizers
Catalyst lead dioxide (or copper) fillers
By-product water 6/9/2012Dr Nabeel Safwat Al Nahass 25 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
Polysulfide Reaction--SH O = Pb = O H S mercaptan + lead dioxide polysulfide rubber + lead oxide + water S H O = Pb = O HS---------------------SH O Pb = O = S + 3PbO + H O 2 S HS--S-S---------------S-S-
6/9/2012
Dr Nabeel Safwat Al Nahass 26 Prosthodontist and Implant Specialist OBrien Dental Materials & their Selection 1997
Manipulation Adhesive to tray Uniform layer custom tray
Equal lengths of pastes Mix thoroughly within one minute
Setting time 8 12 minutes Pour within 1 hour6/9/2012 Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist 27
Advantages Lower cost compared to silicones and polyethers
Long working time High tear strength High flexibility Good detail reproductionDr Nabeel Safwat Al Nahass 28 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
6/9/2012
Disadvantages Poor dimensional stability water by-product pour within one hour single pour
Custom trays Messy paste-paste mix bad odor may stain clothing
Long setting time6/9/2012 Dr Nabeel Safwat Al Nahass 29 Prosthodontist and Implant Specialist Phillips Science of Dental Materials 1996
Agar (reversible)
Aqueous HydrocolloidsElastic
Alginate (irreversible)Polysulfide Condensation
Non-aqueous Elastomers
Silicones Addition Polyether
6/9/2012
Dr Nabeel Safwat Al Nahass 30 Prosthodontist and Implant Specialist OBrien Dental Materials & their Selection 1997
Condensation Silicone Indications complete dentures crown and bridge
Examples Speedex (Coltene/Whaledent) Primasil (TISS Dental)
6/9/2012
Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist
31
Composition Base poly(dimethylsiloxane) tetraethylorthosilicate filler
Catalyst metal organic ester
By-product ethyl alcohol6/9/2012 Phillips 1996 Dr
