Die materials
- 1. Die materials Presented by: Dr. Hileri Mori (Part 1)
- 2. Content Introduction Ideal requirements of die materials Types of die materials Gypsum products Refractory die materials Electroformed dies Resin die material Flexible die materials Silicophophate die material Amalgam die materials Metal spread dies Working cast and die system Conclusion References
- 4. Die A positive reproduction of the form of the prepared tooth in any suitable substance. GPT 9 Cast A working model or master cast is the positive replica on which restorations or appliances are fabricated, eg. Complete denture, removable partial denture orthodontic appliances.
- 5. Ideal requirements of die material Be dimensionally accurate Have good abrasion resistance, strength and toughness Setting expansion and contraction, variations in response to change in temperature need to be minimum. Have a smooth surface Be able to reproduce all fine details in the impression Be compatible with all impression materials. Be easy to manipulate Have a color contrast with wax, porcelain and alloys Be non injurious to health by touch or inhalation Be economical
- 6. Types of die material gypsum Metal and metal coated dies polymers cements Type 4 dental stone : high strength, high expansion electroformed Metal or inorganic filled resins Silicophosphate or polyacrylic acid bonded cements Type 5 dental stone, high strength, high expansion Sprayed metals polyurethane (no longer used) amalgam Epoxy resin
- 7. Non metallic Metallic Gypsum dies Electroplated dies Resin dies Low fusing alloys Silicophosphate dies Amalgam dies Ceramic dies Metal sprayed dies Flexible dies
- 8. Die material Impression material 1. Dental stone Impression compound Alginate ZOE Agar Rubber base material 2. Electroplated (copper) Impression compound 3. Electroplated (silver) Polysulphide Polyether a.silicon 4. Polymer epoxy resin Polysulphide Polyether A. silicone
- 9. Type 4 – dental stone, high strength (die stone) • AKA densite, class 2 stone, improved stone • Gypsum is calcined by boiling it in 30 % calcium chloride solution. The chlorides are then washed away or autoclaved in presence of sodium succinate 0.5%. These particles are the densest of all three types. • They are cuboidal in shape Gypsum products (ADA sp no. 25)
- 10. Gypsum products (ADA sp no. 25) W/P ratio 0.22-0.24 Setting time 12 (+ or – )4 min 2hrs. Setting expansion 0.10% 1hr. Compressive strength 34.5 mega pascal Final compressive strength 5000psi Rockwell hardness no. 92
- 11. Comparison of the effect of different setting conditions on the pore size and the abrasion resistance of three different commercially available type 4 dental stone Kalabhai Synarock eliterock
- 12. Positive air pressure is found to decrease the pore size and increases the abrasion resistance of all three types of type 4 dental stone compare to normal setting conditions. Kalabhai type 4 dental stone is highly resistant to abrasion under both setting conditions with synarock whereas eliterock type 4 dental stone is least resistant to abrasion under both setting conditions.
- 13. Type 5 – dental stone, high strength & high expansion Type 5 – dental stone, high strength & high expansion the setting expansion has been increased from 0.01 to 0.3%. This higher setting expansion is required in the stone used for the die to aid in compensation for the base metal alloy solidification shrinkage. W/P ratio 0.18-0.22 Setting time 12 (+ or – )4 min 2hrs. Setting expansion 0.30% 1hr. CompressiveType 5 – dental stone, high strength & high expansion strength 48.3 mega pascal Final compressive strength 7000psi Rockwell hardness no. ?
- 14. Surface detail reproduction is acceptable with type 4 and 5 gypsum products. These materials are capable of reproducing a 20micrometer wide line (ADA sp no. 19) Ref: die and die materials : overview; ACTA scientific dental sciences; sunny sharma,lucky Jindal,abhishek kumar er al, 2020
- 15. Die hardener Abrasion is the major concern when gypsum products are used as dies. Application of surface hardeners to gypsum material improves abrasion resistance. Most commonly used die hardner : colloidal silica, cyanoacrylate or epoxy resin (by impregnation) A solution of 10% polystyrene in amyl acetate can be painted on the surface of die and then excess blown off. Incorporation of wetting agents such as lignosulphonates has also been employed.
- 16. Refractory materials This includes investments and divestments. Investment casts are used to make patterns for RPD frames. Divestment dies are used in indirect baking of porcelain crowns or preparation of wax patterns. The regular gypsum cast cannot withstand the high temprature involved in the casting of metal and would disintegrate under these conditions.
- 17. Gypsum bonded die material (ADA sp no 2) When gypsum is heated to a high temperature, it shrinks and fractures. They can withstand temperature upto 700 degree celcius Why??? The proven standard for the Hygroscopic Technique. Also excellent for the High Heat Technique. Used for- Low Fusing Crown and Bridge Alloys Dentalcompare.com
- 18. Composition: Silica ( 60-65%) Alpha hemihydrate (dental stone) 30-35% Chemical modifiers (5%) Acts as a refractory during heating. Regulates thermal expansion. Increases setting expansion of stone It binds and holds the silica particles together
- 19. Phosphate bonded die materials Supplied as powder in packets of varying weight with special liquid Withstand tempratures more than 900 degree celcius This phosphate investment contains carbon for bright, gold-colored castings. Expansion can be controlled to fit your needs -- yet technic is easy to follow. Even extremely thin sections will be cast with sharp, clean margins just like lower-fusing golds. Accurately fitting castings with smooth and clean surfaces -- without grinding. Uniform results time after time. Dentalcompare.com
- 20. CERA-FINA is a carbon-free phosphate investment developed for professionals who demand a more finely grained investment. It is designed for use with all classes of casting alloys: precious, semiprecious, and non-precious. Dentalcompare.com
- 21. Composition: Silica (80%) Ammonium diacid phosphate Liquid Acts as a refractory during heating. In the form of quartz or cristobalite It gives strength at room temperature. Soluble in water and provides phosphate ions. It reacts with silica at high temp. to increase strength at casting tempratures. Liquid is a form of silica sol in water, which gives higher thermal expansion.
- 22. Silica bonded die materials ( declined use) Silica Silica gel Modifiers Acts as a refractory during heating. Binder Magnesium oxide (strengthens the gel) Ammonium chloride (accelerator) Can withstand temperature more than 1150 degree Celsius but not used due to complex manipulation
- 23. Divestment ( die material +investment) Gypsum bonded material + colloidal silica liquid Die is prepared from the mix and a wax pattern together with die is invested in divestment. The setting expansion of divestment is 0.9% and thermal expansion 0.6% when heated to 677 degree celcius. As it is gypsum bonded material, not indicated for high fusing alloys eg. Metal ceramic alloys Divestment phosphate or DVP is a phosphate bonded investment that is similar to the divestment and is suitable for use with high fusing alloys. Highly accurate technique. Removal of wax pattern from the die is not required. Thus, possibility of distortion of wax pattern during removal from the die or during setting of the investment is minimized. www.indiandentalacademy.com
- 24. Divestment cast vs. Refractory investment cast Investment cast are not as strong and abrasion resistant as the divestment cast. They are quite fragile and disintegrate easily. Divestment is used generally for smaller castings, whereas investment refractory casts are used during the fabrication of larger structures such as CPDs and Complete dentures.
- 25. Advantage disadvantage Has smooth, hard surface Brittle Easily trimmed Not as abrasion resistant as the epoxy and electroformed dies. Edges and occlusal surface may be rubbed off. Good color contrast economical
- 26. Electroformed dies (electroplating/electrodeposition) It is a process by which a thin coating of metal is deposited on the impression, after which a gypsum cast is poured. The cast thus formed will have a metallic surface layer. Metals used : copper, silver Plating is done for: impression compound (copper plated), polysulfide impression (silver plated), silicone impression Other impression materials show dimensional changes when plated.
- 27. Advantage disadvantage Dimensional accuracy Difficult to trim Hard and abrasion resistant, does not absorb oil and water. Silver bath is a potential health hazard. Better marginal definition Not compatible with all impression materials, economical Color contrast not as good as die stone
- 28. Components of an electroplating apparatus. Cathode : the impression to be coated is made the cathode Anode: is the metal to be deposited : coper,silver Anode holder, cathode holder Electrolyte Ions are deposited from anode to cathode e.g. silver cyanide or copper sulfate. Ammeter : 10mA per tooth area for 12 hours Plating tank is made of glass or hard rubber with a well fitting cover to prevent evaporation Temperature : 25 degree room temperature
- 29. Procedure Wash and dry the impression Metallizing agents: bronzing powder suspended in almond oil, aqueous solution of silver powder, powder graphite Surface of impression tray is covered with wax 2mm beyond the margin of the impression, this protects the tray and prevent its plating With a dropper tray is filled with electrolyte, avoiding air bubbles The impression is attached to the cathode holder with an insulated wire. Distance b/w the cathode and anode should be at least 4 inches.
- 30. Composition of electroplating bath For copper plating baths For silver plating baths Copper sulphate crystals 200g Silver cyanide 36g Sulfuric acid (conc.) 30ml Potassium cyanide 60g Phenol sulfonic acid 2ml Potassium carbonate 45g Water 1000ml Water 1000ml
- 31. Resin die material : epoxy resin Effective with rubber impression materials. Care should be taken that activator should not come in contact with the skin, as it is toxic Supplied by manufacturer in 2 or 3parts that are mixed before insertion into impression 1st part (activator) : 50-60% epoxy polymer, 30-40% vinyl cyclo hexane dipoxide 2nd part : hydrolysed benzophene tetra carboxylic acid 3rd part: tertiary amine catalyst Material is mixed in vaccum and then poured in impression Indian journal of dental research; Influence of polyurethane resin dies on the fit and adaptation of full veneer crowns Graeme R R Lillywhite, Fahim Vohra
- 32. Properties W.T 15 min. S.T.1 to 12 hours depending on the manufacturer Compressive strength after 7 days 16000psi Abrasion resistance is superior to stone die Dimentional change due to shrinkage during polymerization is b/w 0.03% and continues to occur for upto 3 days Epoxy resin are very viscous when pored hence porosity can occur.
- 33. Advantage disadvantage Tougher Slight shrinkage (0.1%) More abrasion resistant than die stone Viscous, does not flow readily, requires centrifugal machine Setting may take up 24 hours Expensive Cannot be used with hydrochloride impression material as water retards polymerization.
- 34. Polyurethane Supplied in glass bottles containing: base material (200ml) hardener (100ml) filler (400g) It is favorable, accurate in detail and dimensionally stable. It has edge strength and abrasion resistance and is easy to trim. Indication : for use with elastomers. Die separator must be applied when casting polyether impression. Contraindication: not indicated for alginates and hydrocolloid impression materials.
- 35. Manipulation Briefly shake the bottles containing both the base material and hardener prior to mixing Close the glass bottles carefully immediately after use. Do not allow the material to come into contact with water Fill the required amount of base material in the dispensing and mixing container supplied. Then add the correct quantity of filler and thoroughly spatulate the mixture. Add the correct quantity of hardener and spatulate the mixture again thoroughly.
- 36. Mixing ratio base : hardener 2:1 Approx 15 grams filler is required for a full dental arch Mixing time 30 sec Pouring after mixing the resin is poured in a thin stream into the cleaned and dried impression. The material remains flowable for approx. 2 min. at 20 degree celcius The die is sufficiently hard after 1 hour to permit trimming and grinding.
- 37. Flexible die materials Similar to polyether and Polyvinyl siloxane impression materials. Uses: Flexible die materials have been introduced to facilitate the fabrication of indirect provisional or definitive restorations in 1 appointment Indirect composite restoration or chair side onlays. Impregum F die material with Extrude Light impression material produced better surface detail reproduction than the control dies. Impregum F impressions were incompatible with Blu-Mousse, Impregum F, or Imprint die materials. Polyvinyl siloxane impressions were incompatible with polyvinyl siloxane dies unless a separator was used. When a separator was used, the surface detail reproduction was not as good as the control die system or the Extrude Light impression material/Impregum F die material combination Gerrow JD, Price RB. Comparison of the surface detail reproduction of flexible die material systems. J Prosthet Dent. 1998 Oct;80(4):485-9. doi: 10.1016/s0022-3913(98)70016-2. PMID: 9791798.
- 38. Silicophosphate cement dies Used with impression compound mostly Advantage: harder die than dental stone Disadvantage: shrink on setting Cement has tendency to loose water making it friable. Precautions : should be stored in water or glycerine. No longer used
- 39. Amalgam dies These dies are made in impressions made with impression compound in the copper band procedure. Advantage: produces a hard die. Disadvantages: can only be picked into a rigid impression Time consuming process Can not be made in hydrocolloid impressions as they can not withstand condensation pressure.
- 40. Metal sprayed dies A bismuth tin alloy, which melts at 138degree Celsius can be sprayed directly on to an impression to form a metal shell, which can then be filled with dental stone. A metal sprayed die can be obtained rapidly from elastomeric impression materials Disadvantage: the alloy is rather soft, care is needed to prevent abrasion of the die.
- 41. Working cast and die system 1. working cast with a separate die : This is the simplest means of fabricating a working cast and die, since no other procedures are required other than making a sectional cast and a full arch cast 2. Working cast with a removable die: Dies that can be removed from the casts have become very popular. They are convenient to use because wax patterns or copings need not be removed from their respective dies when they are transferred to the casts. Lucky Jindal, et al. “die and die materials- An overview”. Acta scientific Dental Sciences 4.7(2020)
- 42. Working cast with a separate die Advantages 1. Ease of fabrication of wax patterns on separate dies. 2. The accuracy in development of proximal contacts. 3. The accuracy with which a fixed prosthesis can be assembled on an intact cast. Disadvantages a) The need to transfer a wax pattern between a die and a working cast particularly when there are inaccuracies in working cast and this can cause pattern fracture. b) Technique suited for non-aqueous elastomeric impression materials where multiple pours can be obtained with sufficient accuracy for polysulphide and condensation polysilicon all pours should be over in 2 hours. Addition polysilicon has long term dimensional stability, the procedure may be carried out over a long period (days). This technique cannot be followed for hydrocolloid impressions.
- 43. Working cast with a removable dies Systems included are: • Wet pinning system - Straight dowel pin , Curved dowel pin • Dry pinning system - Pindex system, Dilok system, DVA system, Zeiser system, Accutrac system. a) Straight dowel pin: This means of orienting dies has been in use for a number of years and most of the dowel systems are modifications of this. The brass dowel pin is one of the most accurate in terms of resisting horizontal displacement and the second lowest in vertical deviation among the mentioned die systems. b) Curved dowel pin: Curved dowels can be incorporated in a working cast by fixing the dowels to the impression before it is poured, or by cementing the dowels into holes drilled in a previously poured cast.
- 44. Pindex system The Pindex system was developed by Whaledent International. A similar system, developed by APM - Sterngold and named the Accudrill, is described as a dowel pin press. In the Pindex system, a reverse drill press is used to create a master cast with dies that can be removed and replaced repeatedly with great precision. Advantages of pindex system a) Only one impression pouring is required thus, it can be used with all types of impression materials including hydrocolloids whereas conventional methods are restricted to distortion free impression materials as it requires two pours. b) This system eliminates guess work as pins are accurately placed by mechanical instruments. c) Rotation of dies is minimized by placing pins bucally and lingually. Thus, the dies are more stable despite repeated insertions and removals as they are housed in a plastic sleeve c) Rotation of dies is minimized by placing pins bucally and lingually. Thus, the dies are more stable despite repeated insertions and removals as they are housed in a plastic sleeve
- 45. Dilok tray : A snap apart plastic tray with internal orienting grooves and notches can also be used to resemble the working cast and die. This system has been found to have the least vertical error. DVA and Zeiser model system : The DVA Model System and the Zeiser model system use a precision drill and special baseplates that are aligned and drilled to provide die removal. These systems offer the advantage of allowing for the expansion of stone, which is relieved by the saw cuts. Accutrac : This removable die system is a modification of plastic tray with internal orientation grooves and notches (e.g. Accutrac, JF Jelenko, Armonk, NY)
- 46. Dimensional accuracy of 7 die material Type 4 resin impregnated dental stone and copper plated dies were more dimensionally accurate than the other die materials tested. Journal of prosthodontics,Vol 4, No 1 ; dimentional accuracy of 7 die materials; brian J. Kenyon et al.
- 47. PROPERTIES OF DIE MATERIALS: A COMPARATIVE STUDY A comparative study of the pertinent properties of die materials used for the indirect materials has been made. Eight classes of materials were evaluated. No one material proved to be superior in all properties, The stones were superior from the standpoint of dimensional accuracy but their abrasion resistance was low. All of the dies, with the exception of those made from stone or low-fusing alloy, were undersize at the cervical margin of the simulated full cast crown preparation. The dies made from the ceramic material, silicophosphate cement, one of the resins and by electrodeposition were superior in abrasion resistance, The surface of the electroplated dies, the ceramic material, stones and silicophosphate cement provided excellent duplication of detail. Differences were observed in the compatibility of certain die materials and rubber impression products, as compared to the duplication produced when the die material was poured against an inert surface. PROPERTIES OF DIE MATERIALS: A COMPARATIVE STUDY ;SVICRKER TORESKOG at al, journal of prosthetic dentistry; 1996
- 48. Conclusion The choice of a specific technique relies on operator preference and after assessment of each methods advantages and disadvantages. If they are conducted carefully all methods achieve clinically acceptable accuracy. No single die material or fabrication technique possess all the ideal properties, for an indirect working model, gypsum products have gained general acceptance and popularity because they more closely approximate the critical properties of an ideal die materials and an ideal die-cast system.
- 49. References 1. Lucky Jindal, et al. “die and die materials- An overview”. Acta scientific Dental Sciences 4.7(2020) 2. Gerrow JD, Price RB. Comparison of the surface detail reproduction of flexible die material systems. J Prosthet Dent. 1998 Oct;80(4):485-9. 3. Phillips dental material sciences, edition 12th 4. Journal of prosthodontics, Vol 4, No 1 ; dimensional accuracy of 7 die materials; brian J. Kenyon et al. 5. SVICRKER TORESKOG at al, PROPERTIES OF DIE MATERIALS: A COMPARATIVE STUDY ;J Prosthet Dent. ; 1996 6. Glossary of prosthodontics 9 7. www.indiandentalacademy.com