Impressionmaterials/ implant dentistry course

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Indian Dental Academy: will be one of the most relevant and exciting training

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professionals who wish to advance in their dental practice,Offers certified

courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry,

Prosthetic Dentistry, Periodontics and General Dentistry.

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Impressionmaterials/ implant dentistry course

  1. 1. Impression MaterialsImpression Materials INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Impression Materials Non-elastic Elastic Aqueous Hydrocolloids Non-aqueous Elastomers Polysulfide Silicones Polyether Condensation Addition Agar (reversible) Alginate (irreversible) Plaster Compound ZnO - Eugenol Waxes O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  3. 3. Elastic Aqueous Hydrocolloids Non-aqueous Elastomers Polysulfide Silicones Polyether Condensation Addition Agar (reversible) Alginate (irreversible) O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  4. 4. Impression Materials • Non-elastic • Elastic – Aqueous hydrocolloids • Agar • Alginate – Non-aqueous elastomers • Polysulfide • Silicones – Condensation – Addition • Polyether www.indiandentalacademy.com
  5. 5. Indications • Diagnostic casts – preliminary – opposing • Indirect reconstruction – fixed – removable • Bite registration Giordano Gen Dent 2000 www.indiandentalacademy.com
  6. 6. Elastomeric Impression Materials • Viscoelastic – physical properties vary • rate of loading • Rapidly remove – decreases permanent deformation • chains recoil from a recoverable distance – increases tear strength Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  7. 7. 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 gel • thermal or chemical process Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  8. 8. Aqueous Hydrocolloids • Semi-permeable membranes – poor dimensional stability • Evaporation • Syneresis – fibril cross linking continues • contracts with time • exudes water • Imbibition – water absorption • swells Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  9. 9. Reversible Hydrocolloid (Agar) • Indications – crown and bridge • high accuracy • Example – Slate Hydrocolloid (Van R) www.indiandentalacademy.com
  10. 10. Composition • Agar – complex polysaccharide • seaweed – gelling agent • Borax – strength • Potassium sulfate – improves gypsum surface • Water (85%) agar hydrocolloid (hot) agar hydrocolloid (cold) (sol) (gel) cool to 43 C heat to 100 C O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  11. 11. Manipulation • Gel in tubes – syringe and tray material www.indiandentalacademy.com
  12. 12. Manipulation • 3 chamber conditioning unit – (1) liquefy at 100°C for 10 minutes • converts gel to sol – (2) store at 65°C – place in tray – (3) temper at 46°C for 3 minutes – seat tray – cool with water at 13°C for 3 minutes • converts sol to gel O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  13. 13. Advantages • Dimensionally accurate • Hydrophilic – displace moisture, blood, fluids • Inexpensive – after initial equipment • No custom tray or adhesives • Pleasant • No mixing required Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  14. 14. Disadvantages • Initial expense – special equipment • Material prepared in advanced • Tears easily • Dimensionally unstable – immediate pour – single cast • Difficult to disinfect Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  15. 15. Irreversible Hydrocolloid (Alginate) • Most widely used impression material • Indications – study models – removable fixed partial dentures • framework • Examples – Jeltrate (Dentsply/Caulk) – Coe Alginate (GC America) Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  16. 16. Composition • Sodium alginate – salt of alginic acid • mucous extraction of seaweed (algae) • Calcium sulfate – reactor • Sodium phosphate – retarder • Filler • Potassium fluoride – improves gypsum surface 2 Na3PO4 + 3 CaSO4 Ca3(PO4)2 + 3 Na2SO4 Na alginate + CaSO4 Ca alginate + Na2SO4 (powder) (gel) H2O O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  17. 17. 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) Caswell JADA 1986 www.indiandentalacademy.com
  18. 18. Advantages • Inexpensive • Easy to use • Hydrophilic – displace moisture, blood, fluids • Stock trays Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  19. 19. Disadvantages • Tears easily • Dimensionally unstable – immediate pour – single cast • Lower detail reproduction – unacceptable for fixed pros • High permanent deformation • Difficult to disinfect Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  20. 20. 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 Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  21. 21. Elastic Aqueous Hydrocolloids Non-aqueous Elastomers Polysulfide Silicones Polyether Condensation Addition Agar (reversible) Alginate (irreversible) O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  22. 22. Polysulfide • First dental elastomers • Indications – complete denture – removable fixed partial denture • tissue – crown and bridge • Examples – Permlastic (Kerr) – Omni-Flex (GC America) www.indiandentalacademy.com
  23. 23. Composition • Base – polysulfide polymers – fillers – plasticizers • Catalyst – lead dioxide (or copper) – fillers • By-product – water Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  24. 24. --SH HS---------------------SH HS-- S H O = Pb = O O = Pb = OO = Pb = O H S -S-S---------------S-S- S S + 3PbO + H2O mercaptan + lead dioxide polysulfide rubber + lead oxide + water Polysulfide Reaction O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  25. 25. 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.indiandentalacademy.com
  26. 26. Advantages • Lower cost – compared to silicones and polyethers • Long working time • High tear strength • High flexibility • Good detail reproduction Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  27. 27. 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 Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  28. 28. Condensation Silicone • Indications – complete dentures – crown and bridge • Examples – Speedex (Coltene/Whaledent) – Primasil (TISS Dental) www.indiandentalacademy.com
  29. 29. Composition • Base – poly(dimethylsiloxane) – tetraethylorthosilicate – filler • Catalyst – metal organic ester • By-product – ethyl alcohol Phillip’s 1996 Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  30. 30. HO – Si – O – Si - O - H CH3 CH3 CH3 CH3 n HO – Si – O – Si - O - H CH3 CH3 CH3 CH3 n C2H5O OC2H5 Si C2H5O OC2H5 HO – Si – O – Si - O - CH3 CH3 CH3 CH3 n HO – Si – O – Si - O - CH3 CH3 CH3 CH3 n OC2H5 Si OC2H5 + 2C2H5OH Condensation Silicone Reaction metal organic ester ethanol Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  31. 31. Manipulation • Mix thoroughly – paste - paste – paste - liquid • Putty-wash technique – reduces effect of polymerization shrinkage – stock tray • putty placed • thin plastic sheet spacer • preliminary impression – intraoral custom tray • inject wash materialwww.indiandentalacademy.com
  32. 32. Advantages • Better elastic properties • Clean, pleasant • Stock tray – putty-wash • Good working and setting time Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  33. 33. Disadvantages • Poor dimensional stability – high shrinkage • polymerization • evaporation of ethanol – pour immediately • within 30 minutes • Hydrophobic – poor wettability Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  34. 34. 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) Click here for DIS evaluations of VPS impression materialswww.indiandentalacademy.com
  35. 35. Composition • Improvement over condensation silicones – no by-product • First paste – vinyl poly(dimethylsiloxane) prepolymer • Second paste – siloxane prepolymer • Catalyst – chloroplatinic acid Phillip’s 1996 Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  36. 36. O H - Si – CH3 O CH3 - Si - H O ---O – Si – CH = CH2 CH3 CH3 CH = CH2 – Si – O --- CH3 CH3 O - Si – CH3 O CH3 - Si - O ---O – Si – CH2 - CH2 CH3 CH3 CH2 - CH2 – Si – O --- CH3 CH3 Chloroplatinic Acid Catalyst Addition Silicone Reaction Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  37. 37. Manipulation • Adhesive to tray • Double mix – custom tray • heavy-body – light-body to prep • Putty-wash – stock tray Craig Adv Dent Res 1988 www.indiandentalacademy.com
  38. 38. Advantages • Highly accurate • High dimensional stability – pour up to one week • Stock or custom trays • Multiple casts • Easy to mix • Pleasant odor Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  39. 39. Disadvantages • Expensive • Sulfur inhibits set – latex gloves – ferric and Al sulfate retraction solution • Pumice teeth before impressing • Short working time • Lower tear strength • Possible hydrogen gas release – bubbles on die – palladium added to absorb Manikos Aust Dent J 1998 www.indiandentalacademy.com
  40. 40. Addition Silicones • Surfactants added – reduce contact angle – improved • castability – gypsum • wettability?? – still need dry field clinically Pratten J Dent Res 1987 Mandikos Aust Dent J 1998 www.indiandentalacademy.com
  41. 41. 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.indiandentalacademy.com
  42. 42. • Base – difunctional epimine-terminated prepolymer – fillers – plasticizers • Catalyst – aromatic sulfonic acid ester – fillers • Cationic polymerization – ring opening and chain extension Composition Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  43. 43. SO3 - + R+ CH3 – CH – CH2 – CO2 – CH – (CH2)n – O – CH – (CH2)n – CO2 –CH2 – CH –CH3 N H2C CH2 R R m N H2C CH2 N H2C CH2 R – N – CH2 – CH2 – + N H2C CH2 N H2C CH2 R – + + Polyether Reaction catalyst base ring opening Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  44. 44. Manipulation • Adhesive to tray – stock or custom tray • very stiff • Paste-paste mix • Auto-mixing – hand-held • low viscosity – mechanical dispenser • high viscosity www.indiandentalacademy.com
  45. 45. Advantages • Highly accurate • Good dimensional stability • Stock or dual-arch trays • Good surface detail • Pour within one week – kept dry • Multiple casts • Good wettability Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  46. 46. Disadvantages • Expensive • Short working time • Rigid – difficult to remove from undercuts • Bitter taste • Low tear strength • Absorbs water – changes dimension Phillip’s Science of Dental Materials 1996 www.indiandentalacademy.com
  47. 47. Handling Properties Agar Alginate Polysulfide Condensation Silicone Addition Silicone Polyether Preparation Boil, temper, store Powder, water 2 pastes 2 pastes or paste/liquid 2 pastes 2 pastes Ease of Use Technique sensitive Good Fair Fair Excellent Good Patient Reaction Thermal Shock Pleasant, clean Unpleasant, stains Pleasant, clean Pleasant Unpleasant clean Ease of removal Very easy Very easy Easy Moderate Moderate Moderate to difficult Disinfection Poor Poor Fair Fair Excellent Fair O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  48. 48. Handling Properties Agar Alginate Polysulfide Condensation Silicone Addition Silicone Polyether Working Time (min) 7 – 15 2.5 5 – 7 3 2 –4.5 2.5 Setting Time (min) 5 3.5 8 – 12 6 – 8 3 – 7 4.5 Stability 1 hour 100% RH Immediate pour 1 hour Immediate pour 1 week 1 week kept dry Wettability and castability Excellent Excellent Fair Fair Fair to good Good Cost Low Very low Low Moderate High to very high Very high O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  49. 49. Properties Agar Alginate Polysulfide Condensation Silicone Addition Silicone Polyether Elastic Recovery (%) 98.8 97.3 94.5 – 96.9 98.2 – 99.6 99 – 99.9 98.3 – 99.0 Flexibility (%) 11 12 8.5 – 20.0 3.5 – 7.8 1.3 – 5.6 1.9 – 3.3 Flow (%) -- -- 0.4 – 1.9 < 0.10 < 0.05 < 0.05 Shrinkage, 24 hours (%) Extreme Extreme 0.4 – 0.5 0.2 – 1.0 0.01 – 0.2 0.2 – 0.3 Tear Strength (g/cm) 700 380 – 700 2240 – 7410 2280 – 4370 1640 – 5260 1700 - 4800 O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  50. 50. Comparison of Properties • Working time – longest to shortest • agar > polysulfide > silicones > alginate = polyether • Setting time – shortest to longest • alginate < polyether < agar < silicones < polysulfide O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  51. 51. 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 O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  52. 52. Comparison of Properties • Cost – lowest to highest • alginate < agar = polysulfide <condensation silicone < addition silicone < polyether • Dimensional stability – best to worst • addition silicone > polyether > polysulfide > condensation silicone > hydrocolloid Phillip’s 1996 O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  53. 53. 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 O’Brien Dental Materials & their Selection 1997 www.indiandentalacademy.com
  54. 54. Summary • Study models – Alginate most widely used • inexpensive • displaces moisture • lower detail reproduction • dimensionally unstable www.indiandentalacademy.com
  55. 55. Summary • Prosthodontics – Addition silicones most popular • accurate • dimensionally stable • user friendly • expensive www.indiandentalacademy.com
  56. 56. • A good Impression must aid to fulfill M.M. Devan’s dictum: “It is the perpetual preservation of what already exists and not the meticulous replacement of what is missing.” www.indiandentalacademy.com
  57. 57. • DEFINITION • A COMPLETE DENTURE IMPRESSION is the negative registration of the entire denture bearing, stabilizing and border seal areas, of either the maxillas or mandible in a plastic material that becomes relatively hard or set while in contact with these tissues. www.indiandentalacademy.com
  58. 58. A PRELIMINARY IMPRESSION is made for the purpose of diagnostic treatment planning and the construction of a custom tray while a FINAL IMPRESSION is used for making the master cast over which the denture bases are fabricated. www.indiandentalacademy.com
  59. 59. • According to GPT, 7th Edition, 1999 Impression is defined as a negative likeness or copy in reverse of the surface of an object; an imprint of the teeth and adjacent structures for use in dentistry www.indiandentalacademy.com
  60. 60. • The five objectives of an impression as stated by Carl.D. Boucher in 1944 are • 1) PRESERVATION OF THE ALVEOLAR RIDGES. This is achieved by using impression techniques which cover maximum supporting areas as possible and using pressure within physiologic limit of the tissue. • (2) RETENTION - The factors of retention are (1) adhesion (2) cohesion (3) interfacial surface tension (4) mechanical locking into undercuts (5) peripheral seal and atmospheric pressure and (6) oral and facial musculature. Henry A. Collet in 1965 stated that primary retention depends upon close adaptation to the tissues and is proportionate to the area covered. www.indiandentalacademy.com
  61. 61. • . (3) STABII.ITY - It is the relationship of the denture base to the underlying bone. • Samuel Friedman in 1957, stated that stability is developed in the impression technique through more intimate contact of the labial and buccal flanges with the labial and buccal slopes and of the lingual flanges with the lingual slopes of the ridges. Boucher stated that stability requires maximum use of all bony foundations where the tissues are firmly and closely attached to bone. www.indiandentalacademy.com
  62. 62. • . (4) SUPPORT - Support is provided by the maxillary and the mandibular bones and their covering of mucosal tissue. It is enhanced by selective placement of pressures that are in harmony with the resiliency of the tissues that make up the basal seat. • (5) ESTHETICS - Role of esthetics in impression making refers to the development of the labial and buccal borders, so that they are not only retentive but also support the lips and cheeks properly. www.indiandentalacademy.com
  63. 63. • Fisher R.D. in 1951 laid down six fundamental rules for making full denture impressions – • (1) Roentgenographics, visual and digital examination of the oral cavity • (2) Surgical removal of such abnormal formations as would prevent successful completion of impressions. • (3) the require extension outlines. • (4) the location and position for area of variable tissue displaceability ( • 5) the required retention outline and • (6) the required adaptation.www.indiandentalacademy.com
  64. 64. • IMPRESSION TECHNIQUES may be classified depending on, [A] Amount of pressure used (Based on the theories of impression). • Pressure technique based on pressure theory • Minimal pressure technique - based on mucostatic theory. • Selective pressure technique -based on selective pressure theory. www.indiandentalacademy.com
  65. 65. • [B] 1. Open or • 2. Closed mouth • [C] 1. Hand-manipulation or • 2. Functional movements www.indiandentalacademy.com
  66. 66. • [D] Type of tray • 1. Stock tray : 1. Caulks Edentulous Rimlock Trays. • 2. McGowen Winkler Trays (mandibular) • 3. STO-K Trays. (Square, round or Tapering shapes of ridges). • 2. Custom or special tray • 1. Shellac • 2. Acrylic • 3. Wax. www.indiandentalacademy.com
  67. 67. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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