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Impression Materials www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Impression Materials Non-elastic Elastic Aqueous hydrocolloids Agar Alginate Non-aqueous elastomers Polysulfide Silicones Condensation Addition Polyether www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Indications Diagnostic casts preliminary opposing Indirect reconstruction fixed removable Bite registration www.rxdentistry.blogspot.com Giordano, Gen Dent 2000 www.dentalmatrix.blogspot.com Elastomeric Impression Materials Viscoelastic physical properties vary rate of loading Rapidly remove decreases permanent deformation chains recoil from a recoverable distance increases tear strength www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com Plaster Non-elastic Compound Waxes Impression Materials ZnO - Eugenol Aqueous Hydrocolloids Elastic Non-aqueous Elastomers Agar (reversible) Alginate (irreversible) Polysulfide Silicones Polyether Addition Condensation www.rxdentistry.blogspot.com O’Brien, Dental Materials & their Selection 1997 www.dentalmatrix.blogspot.com Aqueous Hydrocolloids Colloidal suspensions chains align to form fibrils traps water in interstices Two forms sol viscous liquid elastic solid gel Placed intra-orally as sol converts to gel thermal or chemical process www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com Aqueous Hydrocolloids Semi-permeable membranes poor dimensional stability Evaporation Syneresis fibril cross linking continues contracts with time exudes water Imbibition water absorption swells www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com O’Brien, Dental Materials & their Selection 1997 www.dentalmatrix.blogspot.com Reversible Hydrocolloid (Agar) Indications crown and bridge high accuracy Example Slate Hydrocolloid (Van R) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Agar Composition Potassium sulfate complex polysaccharide seaweed improves gypsum surface gelling agent strength Borax Water (85%) cool to 43ºC agar hydrocolloid (hot) agar hydrocolloid (cold) (sol) www.rxdentistry.blogspot.com heat to 100ºC (gel) O’Brien, Dental Materials & their Selection 1997 www.dentalmatrix.blogspot.com Manipulation Gel in tubes syringe and tray material www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com 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 gel www.rxdentistry.blogspot.com O’Brien, Dental Materials & their Selection 1997 www.dentalmatrix.blogspot.com Advantages Dimensionally accurate Hydrophilic displaces moisture, blood, fluids Inexpensive after initial equipment No custom tray or adhesives Pleasant flavor No mixing required www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com 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 disinfect www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com O’Brien, Dental Materials & their Selection 1997 www.dentalmatrix.blogspot.com Irreversible Hydrocolloid (Alginate) Most widely used impression material Indications study models removable fixed partial dentures framework Examples Jeltrate (Dentsply/Caulk) Coe Alginate (GC America) www.rxdentistry.blogspot.com Phillip’s Science of Dental Materials 1996 www.dentalmatrix.blogspot.com Composition Sodium alginate Sodium phosphate salt of alginic acid retarder mucous extraction of seaweed (algae) Filler Potassium fluoride Calcium sulfate reactor improves gypsum surface 2 Na3PO4 + 3 CaSO4 Ca3(PO4)2 + 3 Na2SO4 H2O Na alginate + CaSO4 (powder) www.rxdentistry.blogspot.com Ca alginate + Na2SO4 (gel) www.dentalmatrix.blogspot.com O’Brien 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) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Caswell JADA 1986 Advantages Inexpensive Easy to use Hydrophilic displace moisture, blood, fluids Stock trays www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s 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 disinfect www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s 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 monophasic www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien 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) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Composition Base polysulfide polymers fillers plasticizers Catalyst lead dioxide (or copper) fillers By-product water www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Polysulfide Reaction --SH HS---------------------SH HS--S-S---------------S-S- O = Pb = O S H O = Pb = O O Pb = O = S + 3PbO + H O 2 S H S mercaptan + lead dioxide polysulfide rubber + lead oxide + water www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien 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 hour www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Advantages Lower cost compared to silicones and polyethers Long working time High tear strength High flexibility Good detail reproduction www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 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 time www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Condensation Silicone Indications complete dentures crown and bridge Examples Speedex (Coltene/Whaledent) Primasil (TISS Dental) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Composition Base poly(dimethylsiloxane) tetraethylorthosilicate filler Catalyst metal organic ester By-product ethyl alcohol Phillip’s 1996 www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 CH3 CH3 C2H5O OC2H5 Condensation Silicone Reaction HO – Si – O – Si - O - H CH3 CH3 CH3 CH3 n Si HO – Si – O – Si - O - H CH3 CH3 n C2H5O OC2H5 metal organic ester CH3 CH3 OC2H5 n Si HO – Si – O – Si - O CH3 CH3 + 2C2H5OH ethanol CH3 CH3 OC2H5 n HO – Si – O – Si - O CH3 www.rxdentistry.blogspot.com CH3 www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Mix thoroughly paste - paste paste - liquid Manipulation Putty-wash technique reduces effect of polymerization shrinkage stock tray putty placed thin plastic sheet spacer preliminary impression intraoral custom tray inject wash material www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Advantages Better elastic properties Clean, pleasant Stock tray putty-wash Good working and setting time www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Disadvantages Poor dimensional stability high shrinkage polymerization evaporation of ethanol pour immediately within 30 minutes Hydrophobic poor wettability www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Addition Silicones AKA: Vinyl polysiloxane Indications crown and bridge denture bite registration Examples Extrude (Kerr) Express (3M/ESPE) Aquasil (Dentsply Caulk) Genie (Sultan Chemists) Virtual (Ivoclar Vivadent) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Composition Improvement over condensation silicones no by-product First paste vinyl poly(dimethylsiloxane) prepolymer Second paste siloxane prepolymer Catalyst chloroplatinic acid www.rxdentistry.blogspot.com Phillip’s 1996 www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 CH3 ---O – Si – CH = CH2 O H - Si – CH3 O CH3 CH = CH2 – Si – O --- Addition Silicone Reaction CH3 CH3 CH3 - Si - H O CH3 O Chloroplatinic Acid Catalyst ---O – Si – CH2 - CH2 - Si – CH3 CH3 O CH3 CH3 - Si - CH2 - CH2 – Si – O --O www.rxdentistry.blogspot.com CH3 www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Manipulation Adhesive to tray Double mix custom tray heavy-body light-body to prep Putty-wash stock tray www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Craig Adv Dent Res 1988 Advantages Highly accurate High dimensional stability pour up to one week Stock or custom trays Multiple casts Easy to mix Pleasant odor www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Expensive Sulfur inhibits set latex gloves ferric and Al sulfate retraction solution Pumice teeth before Disadvantages impressing Short working time Lower tear strength Possible hydrogen gas release bubbles on die palladium added to absorb www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Manikos Aust Dent J 1998 Addition Silicones Surfactants added reduce contact angle improved castability gypsum wettability?? still need dry field clinically www.rxdentistry.blogspot.com Pratten J Dent Res 1987 www.dentalmatrix.blogspot.com Mandikos Aust Dent J 1998 Agar (reversible) Aqueous Hydrocolloids Elastic Alginate (irreversible) Polysulfide Condensation Non-aqueous Elastomers Silicones Addition Polyether www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Polyether Indications crown and bridge bite registration Examples Impregum F (3M/ESPE) Permadyne (3M/ESPE) Pentamix (3M/ESPE) P2 (Heraeus Kulzer) Polygel (Dentsply Caulk) www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Composition Base difunctional epimine-terminated prepolymer fillers plasticizers Catalyst aromatic sulfonic acid ester fillers Cationic polymerization ring opening and chain extension www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Polyether Reaction R R base CH3 – CH – CH2 – CO2 – CH – (CH2)n – O – CH – (CH2)n – CO2 –CH2 – CH –CH3 m N H2C CH2 + R+ H2C N CH2 catalyst SO3- R– N+ H2C CH2 + H2C N CH2 R – N – CH2 – CH2 – N + ring opening H2C CH2 www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Manipulation Adhesive to tray stock or custom tray very stiff Paste-paste mix Auto-mixing hand-held low viscosity high viscosity mechanical dispenser www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Advantages Highly accurate Good dimensional stability Stock or dual-arch trays Good surface detail Pour within one week kept dry Multiple casts Good wettability www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Disadvantages Expensive Short working time Rigid difficult to remove from undercuts Bitter taste Low tear strength Absorbs water changes dimension www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Phillip’s Science of Dental Materials 1996 Impression Material Usage* Civilian General Dentists Crown & Bridge vinylpolysiloxane alginate polyether Inlays and Onlays vinylpolysiloxane polyether alginate 81% 38% 28% 71% 22% 20% *Multiple responses www.rxdentistry.blogspot.com DPR 2001 www.dentalmatrix.blogspot.com Impression Material Usage* Civilian General Dentists Complete dentures alginate vinylpolysiloxane polyether Partial dentures alginate vinylpolysiloxane polyether 58% 55% 27% 78% 43% 15% *Multiple responses www.rxdentistry.blogspot.com DPR 2002 www.dentalmatrix.blogspot.com Handling Properties Agar Preparation Boil, temper, store Technique sensitive Alginate Polysulfide Powder, water Good Pleasant, clean Very easy Poor 2 pastes Condensation Silicone 2 pastes or paste/liquid Fair Pleasant, clean Moderate Addition Silicone 2 pastes Polyether 2 pastes Ease of Use Patient Reaction Ease of removal Disinfection Fair Unpleasant, stains Easy Excellent Good Unpleasant clean Moderate to difficult Fair Thermal Shock Very easy Poor Pleasant Moderate Fair Fair Excellent www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Handling Properties Agar Working Time (min) Setting Time (min) Stability Wettability and castability Cost 7 – 15 5 1 hour 100% RH Alginate 2.5 3.5 Immediate pour Polysulfide 5–7 8 – 12 1 hour Condensation Addition Silicone Silicone 3 6–8 Immediate pour 2 –4.5 3–7 1 week Fair to good High to very high Polyether 2.5 4.5 1 week kept dry Excellent Excellent Fair Fair Good Low Very low Low Moderate Very high www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Properties Agar Elastic Recovery (%) 98.8 Alginate Polysulfide 97.3 94.5 – 96.9 Condensation Silicone 98.2 – 99.6 Addition Silicone 99 – 99.9 Polyether 98.3 – 99.0 Flexibility (%) Flow (%) Shrinkage, 24 hours (%) Tear Strength (g/cm) 11 -- 12 -Extreme 8.5 – 20.0 0.4 – 1.9 0.4 – 0.5 3.5 – 7.8 < 0.10 0.2 – 1.0 1.3 – 5.6 < 0.05 0.01 – 0.2 1640 – 5260 1.9 – 3.3 < 0.05 0.2 – 0.3 1700 4800 Extreme 700 380 – 700 2240 – 7410 2280 – 4370 www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Comparison of Properties Working time longest to shortest agar > polysulfide > silicones > alginate = polyether Setting time shortest to longest alginate < polyether < agar < silicones < polysulfide www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Comparison of Properties Stiffness most to least polyether > addition silicone > condensation silicone > polysulfide = hydrocolloids Tear strength greatest to least polysulfide > addition silicone > polyether > condensation silicone >> hydrocolloids www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Comparison Cost lowest to highest of Properties alginate < agar = polysulfide <condensation silicone < addition silicone < polyether Dimensional stability best to worst addition silicone > polyether > polysulfide > condensation silicone > hydrocolloid Phillip’s 1996 www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Comparison of Properties Wettability best to worst hydrocolloids > polyether > hydrophilic addition silicone > polysulfide > hydrophobic addition silicone = condensation silicone Castability best to worst hydrocolloids > hydrophilic addition silicone > polyether > polysulfide > hydrophobic addition silicone = condensation silicone www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com O’Brien Dental Materials & their Selection 1997 Regularly-Used Impression Materials* Alginate Polyether Other Civilian Practitioners 88% 85% 6% 27% Polyvinyl Siloxane *Multiple Responses www.rxdentistry.blogspot.com DPR 2005 www.dentalmatrix.blogspot.com Summary Study models Alginate most widely used inexpensive displaces moisture lower detail reproduction dimensionally unstable www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com Summary Prosthodontics Addition silicones most popular accurate dimensionally stable user friendly expensive www.rxdentistry.blogspot.com www.dentalmatrix.blogspot.com
