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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

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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

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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

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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)

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Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist

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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

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Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist

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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

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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

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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-

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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)

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Dr Nabeel Safwat Al Nahass Prosthodontist and Implant Specialist

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Composition Base poly(dimethylsiloxane) tetraethylorthosilicate filler

Catalyst metal organic ester

By-product ethyl alcohol6/9/2012 Phillips 1996 Dr

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