Die materials/ orthodontics workshop


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Die materials/ orthodontics workshop

  1. 1. SEMINAR ON; DIE MATERIALS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. CONTENTS  Introduction  Ideal requisites of die materials  Classification of die materials  Gypsum  Trimming dies  Variations in die techniques and materials  Altering die dimensions  Die stone-investment combination  Types of die materials  Conclusion  References www.indiandentalacademy.com
  3. 3. DEFINITION DIE: A Positive replica of a prepared tooth or teeth in a suitable hard substance usually in metal or specially prepared stone or resin on which inlays , crowns and other restorations are made. www.indiandentalacademy.com
  4. 4. INTRODUCTION Indirect fabrication of patterns for extracoronal restorations in the mouth is inconvenient, difficult, time consuming, and virtually impossible, practically all wax patterns are made in the laboratory with the indirect technique. www.indiandentalacademy.com
  5. 5. Ideal requirements:  Accuracy of surface reproduction,  Dimensional accuracy and stability,  High strength  Abrasion resistance,  Compatibility with impression materials,  Good color contrast,  Economical,  Easy to use. www.indiandentalacademy.com
  6. 6. CLASSIFICATION Inorganic materials Die stone, based on calcium sulfate hemihydrate Dental cement – zinc silicophosphate Ceramic materials Metallic materials Dental amalgam Metal sprayed dies Electroplated dies Copper plated Silver plated Polymeric materials Auto-polymerizing acrylic Other resins which polymerize at room temperature. www.indiandentalacademy.com
  7. 7.  Casts and dies are frequently prepared from dental stone, which has calcium sulfate hemihydrate CaSO4. ½ H2O as their main constituent, prepared by heating calcium sulfate dihydrate.  Dental gypsum products are available in 5 forms (ADA Types I to V) 1) Type I – Impression plaster 2) Type II – Model plaster 3) Type III – Dental stone 4) Type IV – High-strength dental stone 5) Type V – High strength, high expansion stone www.indiandentalacademy.com
  8. 8. PROPERTIES :  W/P ratio: 0.22-0.24 ml,  Setting time: 12(+/-)4 min,  Setting expansion: 0.1%  Compressive strength: 5000(psi),  W/p ratio:0.18-0.22 ml,  Setting time:12(+/-)4 min,  Setting expansion:0.3%,  Compressive strength:7000psi . Type IV stone Type V stone www.indiandentalacademy.com
  9. 9. IMPRESSION SURFACE  Clean  Dry  Immersed in 3% potassium sulphate solution www.indiandentalacademy.com
  10. 10. PROPORTIONING  Measuring by weight  Thin mix  Thick mix www.indiandentalacademy.com
  11. 11. www.indiandentalacademy.com
  12. 12. TRIMMING DIES www.indiandentalacademy.com
  13. 13. www.indiandentalacademy.com
  14. 14. VARIATION IN DIE TECHNIQUE  Sevaral means are used to increase resistance to abrasion:  Gypsum hardners-aqueous colloidal silica.  Treating surface with epoxy resin or cyanoacrylate - dilution with acetone.  Incorporation of wetting agents such as lignosulphonates. www.indiandentalacademy.com
  15. 15. METHODS OF ALTERING DIE DIMENSIONS  To reduce setting expansion and therefore to reduce diameter of die (0.1 % to 0.01 %) :  pottasium sulfate ( accelerator )  borax ( retarder ) o To increase setting expansion:  Colloidal silica added to guaging liquid www.indiandentalacademy.com
  16. 16. DIE SPACER  To produce relief space for cement it is common to use a die spacer with a stone die.  Most commonly used die spacer are resins.  Other die spacers used are:  Model paint  Color nail polish  Spacers are applied in sevaral coats to with in 0.5 mm of preparation finish line www.indiandentalacademy.com
  17. 17.  Advantages of gypsum die materials:  Good strength  Easy manipulation  Excellent working time  Sets quickly  Compatible with impression materials  Have smooth hard surface  Can be easily trimmed  Have good color contrast  Is economical. www.indiandentalacademy.com
  18. 18.  Disadvantages:  Brittle  Susceptibility to abrasion during carving of wax pattern. www.indiandentalacademy.com
  19. 19. DIE STONE-INVESTMENT COMBINATION ( DIVESTMENT ):  This the combination of die material and investing medium.  The gypsum bonded material called divestment is mixed with colloidal silica liquid.  The setting expansion is 0.9% and thermal expansion is 0.6% when heated to 677c.  it is accurate technique for gold alloys. www.indiandentalacademy.com
  20. 20. Phosphate-bonded investment ( divestment phosphate )  Used in same manner as divestment.  Used for metal ceramic restorations ( high fusing alloys ) www.indiandentalacademy.com
  21. 21. ELECTROFORMED DIES  Electroforming refers to electrodeposition of the metal on a metallic or non metallic object by passage of electrical current through the electrolyte  The art of electroforming is called galvanoplasty.  1934 Jacob first used it.  1937 Wajna applied in dentistry. www.indiandentalacademy.com
  22. 22.  Metalizing:  The impression surface is made conductive so that it can conduct electric current.  Metalizing agents are:  Bronzing powder  Aqueous suspension of silver powder.  Powdered graphite.  They are placed with camel hair brush. www.indiandentalacademy.com
  23. 23. METALS USED FOR ELECTROFORMING  Copper sulfate crystals 200 gms,  Conc sulfuric acid 30 ml,  Phenol 2ml,  Distilled water 1000ml.  Silver cyanide 36gms,  Potassium cyanide 60gms,  Potassium carbonate 45gms,  Distilled water 1000ml. Copper bath: Silver bath: www.indiandentalacademy.com
  24. 24. Anode (+) Copper or silver plate Cathode ( _ ) Impression ammeter Electrolyte solution External circuit www.indiandentalacademy.com
  25. 25. www.indiandentalacademy.com
  26. 26. PROBLEMS IN METAL FORMING  Faulty conduction  Exhausted solution  Overconcentrated solution  Metal anode too small  Friable metal deposit www.indiandentalacademy.com
  27. 27. ADVANTAGES: 1.Superior surface reproduction,dimensional accuracy. 2.Hard,abrasion resistant. 3.Imparts a smooth surface to wax pattern. 3.Not very expensive. 4.Better marginal definition. 5.Does not absorb oil or water. 6. Allows satisfactory finishing and polishing. www.indiandentalacademy.com
  28. 28. DISADVANTAGES:  1.Difficult to trim.  2.Silver bath health hazard ( death chamber gas )  3.Not compatible with all impression materials.  4.Colour contrast not as good as die stone.  5.Adaptaion of wax pattern is not good,it tends to lift. www.indiandentalacademy.com
  29. 29. EPOXY RESIN DIES:  They are either self curing acrylic materials, e.g epoxy resins, poly esters, and polymeric materials with metallic or ceramic fillers. www.indiandentalacademy.com
  30. 30. COMPOSITION: They are two component systems that include resin and hardener. mix ratio: 10 parts resin to 1 part activator by weight.  The hardener is a polyamine , when mixed with a resin for about a minute causes polymerization  Dimensional changes occuar between 0.1 % to 0.2 % and may continue to occur up to 3 days  Auto mixing device  Compatibility with impresssion materials . www.indiandentalacademy.com
  31. 31.  Advantages:  Excellent surface detail  Adequate surface hardness and abrasion resistance.  Less brittle than die stone.  Can be cured at room temperature.  Disadvantages:  Dimensional inaccuracy.  Expensive. www.indiandentalacademy.com
  32. 32. AMALGAM DIES:  They are made by packing amalgam in to impression made of impression compound.  Dies exhibit superior strength and reproduce fine details.  Limitations:  It can be packed only in to a rigid impression material.  It is technique sensitive  It requires 24hrs for hardening.  It has high thermal conductivity and can cool wax pattern rapidly  Residual mercury presents a health hazard.  Dimensional changes due to delayed expansion. www.indiandentalacademy.com
  33. 33. SILICATE CEMENT DIES:  It is similar to the filling cement material.  Advantages:  Initial strength and surface hardness is superior to that of die stone.  Used with all impression materials  Disadvantages:  the cement contracts during setting and may be dimensionally in accurate.  There is loss of water on standing, causing a rough and dehydrated surface. www.indiandentalacademy.com
  34. 34. METAL SPRAYED DIES  A bismuth-tin alloy, which melts at 138c is sprayed directly on to an impression to form a shell. Which can be filled by die stone.  Disadvantage is that the alloy is soft and does not fulfill mechanical requirements of the die material. www.indiandentalacademy.com
  35. 35. CERAMIC DIE MATERIALS  Ceramic material supplied as a power and liquid and mixed to a putty like consistency.  After 1hr material is recovered from the impression and fired at 600c for 8 min to produce a hard strong die.  Advantages:  Accuracy is good.  Can be obtain rapidly from elastomeric impression materials.  disadvantages:  Less abrasion resistant.  Special equipment necessary. www.indiandentalacademy.com
  36. 36. Compatibility of impression materials Cast or die material Impression material Gypsum product Compound Zinc oxide eugenol Agar or Alginate, Plaster, if coated with separator Elastomeric impression materials Electroplated copper Compound Silicone (all types) rubber base. Electroplated silver Elastomeric impression materials Epoxy resin Elastomeric impression materials www.indiandentalacademy.com
  37. 37. REVIEW OF LITERATURE: 1. James c. ragain etal: Detail reproduction, contact angle and die hardness of elastomeric impression and gypsum die material combination. Int J PROSTHODONT 2000; Vol 13; No. 3; pp 214-20. i. Adequate detail reproduction of prepared teeth may be achieved with the combination of any of the elastomeric impression materials with any of the die stone materials tested. ii. When using polyvinyl siloxane or polyether impression material, type IV- resin reinforced die stone may produce dies that are less scratch resistant on the surface than the type IV die stone used in this study. iii. No overall combination of die and impression materials was identified as superior to another for all of the surface properties studied. www.indiandentalacademy.com
  38. 38. 2. Reza h. heshmati etal: Delayed linear expansion of improved dental stone J Prosthet Dent 2002 Jul Vol 88 No. 1 pp: 26-31. The objective of this invitro study were to measure the linear setting expansion of 6 ADA types IV and V dental stones To compare their expansion at 2 hours to 120 Hrs. All stones showed higher mean linear expansion values at 120 hrs than at 2 hrs. The amount of expansion varied significantly among the materials with 22% - 71% of the expansion occurring after 2hrs. www.indiandentalacademy.com
  39. 39. 3. Philip duke etal : Study of the physical properties of type IV gypsum, resin-containing and epoxy die materials J Prosthet Dent 2000 Apr; 83 (4): 466-73. i. All gypsum products expanded, whereas the epoxy resin material contracted during setting. ii. The epoxy resin exhibited much better detail reproduction, abrasion resistance and transverse strength than the gypsum materials. iii. A conventional type IV gypsum exhibited the highest surface hardness whereas the epoxy resin had the lowest value. iv. The resin-modified gypsum products were not significantly superior to the conventional type IV gypsum die materials. www.indiandentalacademy.com
  40. 40. 4. Tadanori , shane n. white: Dimensional accuracy of an epoxy resin die material using 2 setting methods J Prosthet Dent 2000 Mar; 83 (3): 301-5. Retarding the setting reaction of an epoxy resin die material improved its accuracy of the materials tested. The retarded set epoxy dies had the least mean dimensional change from the metal master. Epoxy resin die materials had a net shrinkage, but the gypsum-based materials had a net expansion. The epoxy resin materials exhibited more variability than the gypsum-based materials www.indiandentalacademy.com
  41. 41. 5.Johnson etal : Dimensional accuracy of 7 die materials. J Prosthodont 2005;14;25-31. i. Type 1V resin impregnated dental stone and copper plate dies most closely approximates the master die. ii. Conventional type 1V and V - setting expansion iii. Epoxy resin - shrinkage iv. Polyurethane-combination of expansion and shrinkage v. Bis-acryl composite dies – excessive shrinkage www.indiandentalacademy.com
  42. 42. 6. E ricardo etal : Fracture strength of type iv and type v die stone as function of time J Prosthet Dent 1997 ;vol 78; no 6; pp 554-559 The study evaluated the fracture resistance of four die stone materials at different time intervals ½, 1, 12, 24 hours and recommended to wait atleast 12-24 hours when separating casts from impressions to avoid fracturing casts. Residual moisture content in a stone cast may contribute to fracture. www.indiandentalacademy.com
  43. 43. 7. Paul E. harris and etal : Alterations of surface hardness with gypsum die hardners J Prosthet Dent 2004; vol 92; pp 35-38 The purpose of this study was to compare the surface microhardness of 4 contemporary gypsum materials with and without surface die hardner. Die stones evaluated in this study did not differ significantly in surface microhardness. Die hardner coatings reduced the surface hardness of the gypsum material. www.indiandentalacademy.com
  44. 44. 8. Gerard derrien etal : Compatibility of type IV dental stone with Polysulfide impression materials J Prosthodont 1992 Sep, Vol, No.1 pp:32-6. This study evaluated the compatibility of 6 polysulfide impression materials and 11modified type IV dental stone. The compatibility was determined by the presence of a reproduce line on the dental stone. The study showed that many combinations of polysulfide impression materials and modified type IV dental stones did not reproduce the 20 microns line, therefore not every polysulfide is compatible with every type IV dental stone. www.indiandentalacademy.com
  45. 45. 9. Smith D.C etal : Comtpatibility of impressions and die stone material Oper Dent 1990 May-Jun Vol 15 No. 3 Pp: 82-5. The purpose of this pilot study is to test the compatibility of four light- bodied polysiloxane impression materials with 11 different die stones. The ADA Spec No. 19 states that in order for an elastomeric impression material to be considered compatible with gypsum materials, it must reproduce a 20 µm wide line in stone. All 11 die stones and polysiloxane impression combinations performed within the 20µm ADA standard. www.indiandentalacademy.com
  46. 46. 10. Jack D. gerrow : Compatibility of a new epoxy resin with impression materials : Am J Dent 1990 Aug Vol 3 No.4 pp: 171-4. This study evaluated the compatibility of 5 Polyvinyl siloxanes, one Polysulfide and one Polyether impression materials with the new epoxy resin (Alpha die 87). Only the polysulfide and polyether were prepared with the super sepator. Detail reproduction of the line or compatibility was determined by the presence of the reproduced line on the epoxy specimen. The line was reproduced in only 71.4% of the epoxy specimens. The epoxy specimens reproduced the line in all the polyvinyl siloxane specimens. www.indiandentalacademy.com
  47. 47. CONCLUSION : The ease with which a restoration is fabricated and the accuracy with which it will fit the mouth is materially affected by the casts and dies. So a die material should be selected that has good dimensional accuracy, abrasion resistance and ability to reproduce fine detail and sharp margins. www.indiandentalacademy.com
  48. 48. REFERENCES : 1. Anusavice - Phillips Sciences of Dental materials, 10th Edition. 2. Contemporary fixed prosthodontics – Stephen F. Rosenstiel – 3rd Edition. 3. Dental materials- Properties and manipulation – Craig, Obrein, Powers, 5th Edition. 4. E.C. Combe-Notes on Dental Materials, 6th Edition. 5. John N.Andreson – Applied dental materials, 5th Edition. 6. John F. McCabe- applied dental materials, 7th edition 7. Restorative dental materials – Robert, G. Craig and John H. Powers, 11th Edition. 8. The clinical hadling of Dental materials – Bernard G.N, Smith, Paul S.Wright and David Brown 2nd Edition. www.indiandentalacademy.com
  49. 49. 1. James c. ragain etal: Detail reproduction, contact angle and die hardness of elastomeric impression and gypsum die material combination. Int J PROSTHODONT 2000; Vol 13; No. 3; pp 214-20 2. Reza h. heshmati etal: Delayed linear expansion of improved dental stone J Prosthet Dent 2002 Jul Vol 88 No. 1 pp: 26-31. 3. Philip duke etal : Study of the physical properties of type IV gypsum, resin-containing and epoxy die materials. J Prosthet Dent 2000 Apr; 83 (4): 466-73. 4. Tadanori , shane n. white: Dimensional accuracy of an epoxy resin die material using 2 setting methods .J Prosthet Dent 2000 Mar; 83 (3): 301- 5. www.indiandentalacademy.com
  50. 50. 5.Johnson etal : Dimensional accuracy of 7 die materials. J Prosthodont 2005;14;25-31. 6. E ricardo, xavier lepe : Fracture srrength of type iv and type v die stone as function of time. J Prosthet Dent 1997 ;vol 78; no 6; pp 554-559 7. Paul E. harris, scott hayer, clark m. stanford : Alterations of surface hardness with gypsum die hardner. J Prosthet Dent 2004; vol 92; pp 35- 38 www.indiandentalacademy.com
  51. 51. 8. Gerard derrien, georges sturtz : Compatibility of type IV dental stone with Polysulfide impression materials: J Prosthodont 1992 Sep, Vol, No.1 pp:32-6. 9. Smith D.C, price C.ACompatibility of impressions and die stone materials: Oper Dent 1990 May-Jun Vol 15 No. 3 Pp: 82-5. 10. Jack D. gerrow : Compatibility of a new epoxy resin with impression materials : Am J Dent 1990 Aug Vol 3 No.4 pp: 171-4. www.indiandentalacademy.com
  52. 52. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com