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DIE PREPARATION AND DIE SYSTEMS.pptx
- 1. DIE PREPARATION AND DIE SYSTEMS DR.SATVIKA PRASAD MDS DEPARTMENT OF PROSTHODONTICS
- 2. CONTENTS 1. Introduction 2. Definitions 3.Requirements of a die 4. Materials used for fabrication of die 5. Compatibility of die materials with impression materials 6. Die systems 7. Different types of dowel pins 8. Different systems for dowel preparations 9. Conclusion
- 3. INTRODUCTION • An accurateworking cast with removable dies is essential to make a well fitting restoration. • Detailed reproduction of die materials for fixed prostheses affects the accuracy of working casts and is related to the compatibility between the die and impression materials
- 4. Definitions Die - Itis the positive replication of the form of a prepared tooth in any suitable substance . - GPT 7 Working cast- it is a master cast that reproduces the entire arch including the prepared and unprepared teeth, relevant soft tissues, and edentulous areas. Die pin / dowel pin – a metal pin used in stone casts to remove die sections and replace them accurately in the original position –GPT 8
- 5. Requirements of adie • Reproduce the preparation exactly • All surface should be adequately duplicated • Avoid voids in the margins • Adequate access to margin is imperative • Adequately rigid • Compatibility with the impression materials • Mechanical properties- A) High strength to reduce the likelihood of accidental breakage B) Abrasion resistance so that the die can withstand the manipulative procedures during carving of wax pattern • Economical • Easy to use
- 6. Materials used forfabrication of die • Gypsum products- A) Type IV (High strength) dental stone B) Type V (High strength and expansion) dental stone • Electroformed dies- A) Electroplated Copper B) Electroplated silver • Epoxy resins • Silico-phosphate cement • Amalgam dies • Ceramic dies • Metal sprayed dies
- 7. Compatibility with impressionmaterials - Dental stone Impression compound Zinc oxide eugenol (ZOE) Alginate Impression plaster when used with separator Rubber base material Electroplated Cu Impression compound Electroplated Ag Polysulphide Rubber base material Epoxy resin Rubber base material Resin Polyether Polysulphide Addition silicone
- 8. Gypsum products 1. Theseare the most commonly used materials 2. 2 CaSO4 . 2H2O (CaSO4).H2O + 3H2O 1. Generally compatibly with all impression materials 2. Have the ability to reproduce fine detail and sharp margins 3. Dimensional accuracy and stability are good 4. Produces consistent results 5. Easy to use. 6. inexpensive Type IV is susceptible to abrasion during carving of wax pattern ADVANTAGES DISADVANTAGES Calcium sulphate dihydrate Calcium sulphate hemihydrate
- 9. Electroplated dies 1. Metaldies can be made by copper plating, compound impression or silver plating, rubber base impression, when a die is made in this manner the process is referred to as electroplating 2. The areas to be plated are first coated with finely powdered silver or graphite to make them conduct electricity, and the impression is then placed in an electroplating bath. A layer of pure metal is deposited on the impression and is supported with type IV stone or resin. 3. Polyether impressions, because of their hydrophilic nature, imbibe water and become distorted; they therefore cannot be plated accurately
- 10. 1. No expansionand contraction occur with these, unless the impression material shrinks before the initial plating is deposited 2. Electroformed dies have higher strength hardness and abrasion resistance 3. Allows satisfactory finishing and polishing of metal restoration on the die 1. Time consuming 2. Special equipment is needed 3. Not compatible with all impression materials 4. Expensive 5. Precaution needed ADVANTAGES DISADVANTAGES
- 11. Copper plating procedure 1.Copper plated dies – compound or addition silicone rubber impressions 2. Surface of the impression material is treated so that it conducts electricity, this process is called metallizing 3. Coated impression is made cathode and copper plate is made anode 4. Immersed in electrolytic solution of copper sulphate with alcohol / phenol and current of 15 amp is applied for 10 hrs.
- 12. Silver plating 1. Indicatedfor polysulphide polyether, silicone rubber impression material 2. Current applied is less than copper plating ~ 5mamp 3. Similar to Cu plating 4. Cathode- impression coated with Ag / graphite 5. Anode – silver plate 6. Electrolytic solution – alkaline solution of silver cyanide with potassium cyanide & potassium carbonate in distilled water Precaution:- • Care must be taken to avoid the addition of acids to the cyanide solution, which can cause release of cyanide vapour a death chamber gas. • Cu plating should not be done in the same area where Ag plating is done, because the risk of contamination of Ag plating solution with acidic Cu plating solution
- 13. Amalgam die 1. Theyare made by packing the amalgam into impression made of impression compound 2. Material of choice previously but replaced by electroplated dies 3. Resistant to abrasion ADVANTAGES 1. Dies made of amalgam exhibit superior strength, resistance to abrasion and reproduce fine details and sharp margins 2. Can be packed only to a rigid impression DISADVANTAGES 1.Dimensional accuracy may vary from one die to other 2. Time required for fabricating is lengthy (procedure=30min ;hardening of die = 12-24hrs) 3.High thermal conductivity so it can cool the pattern rapidly which may cause distortion of the pattern {so to overcome it the die should be warmed}
- 14. Silico - phosphatecement 1. Similar to the filling and cementing material 2. Powder is a mixture of silicate powder and zinc oxide liquid contains phosphoric acid Strength and surface hardness 1. It contracts during setting 2. May be dimensionally inaccurate 3. Loss of water on standing, since viscosity of these materials is high 4. Presence of surface voids can occur ADVANTAGES DISADVANTAGES
- 15. Epoxy resin (polymers) 1.Used with polyether, polysulphide or silicone 2. Hardener polyamine causes polymerization 3. Epoxy resin cannot be used with water containing agar and alginate materials because water retards the polymerization of the resin. 4. Viscous when poured, porosity can occur 1. Abrasion resistance 2. Less brittle than die stones 3. Can be carved at room temp. 1. Shrinkage on polymerization 2. Less dimensional stability 3. Expensive 4. Very viscous when poured hence cause porosity ADVANTAGES DISADVANTAGES
- 16. Metal sprayed dies •Bismuth- tin alloy which melts at 138 ̊C can be sprayed directly on to an impression to form a metal shell which can be filled with dental stone & solidify at 30 pounds of pressure ADVANTAGE a metal coated die can be obtained rapidly from elastomeric impression materials DISADVANTAGE the alloy is soft, care is taken to prevent abrasion of the die
- 17. POLYURETHANE It isthe most accurate, strongest and cleanest die material than die stone and epoxy Silicone impression material is used Properties- • No noticeable shrinkage or expansion • More accurate than epoxy • Water resistant • Superior mechanical properties Uses- • Long span bridges, inlay, onlay • Excellent for scanning • Fabricating CAD/CAM models • Shoulder and partial crown preparations
- 18. Ceramic die materials Recent advance in die materials Porcelain inlays, onlays, veeners Manipulation- • Supplied as powder and liquid system • Mixed into paste and vibrated into the impression and allowed to set for an hour and then fired at 600 ̊C for 8 min to produce a strong die
- 19. Working cast with separatedie 01 Working cast with a removable die 02 Die Systems - Two basic die systems
- 20. Working cast withseparate die Advantages 1. Simple to fabricate a cast and die 2. Maintains fixed and immovable relationship between the abutments 3. Easier to obtain physiologically harmonious restoration contours when fabricating wax pattern Disadvantages 1. Wax pattern should be transferred from one to the other 2. Can be used only with elastomeric impression Obtained from – • Separate impressions • Pouring an elastomeric full arch impression twice first cast is used for the fabrication of die This technique can be used only with elastomeric impression, since hydrocolloid is torn and distorted too much for the 2nd pour
- 21. 8 Stone is addedto the impression in small increments above the preparation Tray is tilted to fill the impression Stone is added to the impression so that base of the set stone will be 1” 1”
- 22. The die issmoothened below the finish line with discoid end of a tanner carver Shaping of the handle near the finish line is completed with a scalpel The prepared finish line on the die should be outlined with a red pencil
- 23. Working cast withremovable die Requirements of removable die system – 1. Dies must return to their exact original positions 2. Die must remain stable, even inverted 3. Cast containg the dies must be easy to mount on an articulator
- 24. Advantages 1. Die canbe removed from the working cast 2. Convenient to use. 3. Eliminates discrepancies between separate die and working cast 4. Eliminates discrepancies of relief application 5. Wax pattern need not be removed from die and transferred to the working cast Disadvantage 1. Risk of an error in the pattern if the die does not reseat accurately in the working cast.
- 25. Method of repositioningthe die- 1. Pre pour technique – devices are oriented into the impression before pouring the stone 2. Post pour technique – devices are oriented into the impression after pouring the stone 1. Methods of repositioning die in its working cast 2. Systems using pre formed plastic trays without die pins 1 2
- 26. Different types ofdowel pins 1. Tapered, flat sided brass dowel pin 2. Flat sided, stainless steel dowel pin 3. Curved, single dowel pin 4. Single dowels 5. Double dowels 6. Two separate dowels 7. Horizontal contact tracks and vertical ribs Flat sided single dowel Single curved dowel Double straight dowel with common head Two separate parallel dowel Keyed plastic out tray
- 27. Systems for diepreparations 1. Straight dowel pin 2. Curved dowel pin 3. PINDEX system 4. DI-LOK system 5. ACCUTRAC (veeners) 6. ZEISER system 7. MONOTRAC ARTICULATION
- 28. Straight dowel pin 1.Commonly used for many years 2. Brass dowel pin is used 1. Resists horizontal displacement 2. Removable die facilitates wax up and ceramic build up 3. No special equipment required Technical skill is needed ADVANTAGES DISADVANTAGE
- 29. Sticky wax isused to stabilize the whole assembly Dowel pins are placed over the preparation in the impression using bobby pins 1. Type IV (high strength) or type V (high strength and expansion) dental stone is used. 2. Water and stone are first hand mixed till powder gets wet and then vacuum mixing is done for 15 sec. 3. First small amount of stone is placed on the side of the preparation and is vibrated till the stone reaches the occlusal surface. 4. Add stone in small increments and build stone to a height of 1” or 2.5 cm to have adequate bulk. Pouring impression Paper clips Bobby pins 1 2 3 4 5
- 31. Curved dowel pin Incorporateinto the impression before or after the stone is poured
- 32. Procedure for prepour technique • Curved dowel is placed in the impression using finger pressure, through a positioning bar • The bar is oriented facio-lingually and the head of the dowel extends 1-2 mm into the impression • Straight pins are places through the positioning bar, on the facial and lingual aspects of the impression, these are used for stabilization. • Stone is poured into the impression • Straight pins and positioning bar are removed after the stone is set • Separating medium is applied and the cast is boxed • Base is poured • Dies are cut using a saw • Dies are separated by tapping at the protruding end of the curved dowel
- 33. 1 2 3 4 5 (Forindexing)
- 34. • Post pourtechnique is used • Reverse drill press is used to create a master cast • The machine accurately drills parallel holes from the under side of the trimmed cast PINDEX System
- 38. • Mark thefinish line with red pencil and be careful not to destroy the finish line • Prepare the die with tungeston and rose head burs and sand paper Die trim
- 39. ADVANTAGE Allows accurate placementof the die pins DISADVANATGE Special equipment is required COMPLETING THE DIE
- 40. DI – LOKTRAY ● A snap apart plastic tray with internal orienting grooves and notches is used
- 42. 1. Extremely accurate 2. Re-usabletrays 3. No pins are required 4. Impression is poured once 5. Good for FMR cases 1. Time consuming 2. Much cast trimming is required to accommodate wide arch 3. Indexing are small ADVANTAGES DISADVANTAGES
- 43. ACCUTRAC ● The modeland base are poured as one, eliminating the additional work when using pins and sleeves ● It is a modification of a plastic tray with internal orientation grooves and notches
- 45. • One pourtechnique • One universal tray size • Economical • Low base height Advantages
- 46. ZEISER SYSTEM ● Thedouble expansion of the base & in the teeth leads to undesirable heights and axial displacements of the whole model ● In Zeiser model, the original dimensions of the impression of on a dimensionally stable base plane transfer is done to avoid undesired discrepancies
- 51. MONOTRAC ARTICULATION ● Monotrac Articulationhas evolved as the first single- pour, cast-in-place, and pin-less articulation system. ● Vertical single pour base (VSP)
- 52. Trim the impressionSpray silicone spray on cones to separate the stone Map pins are used – act as guide for placement Retrieve the model by tapping SILICONE SPRAY
- 53. Section the models Becausethere are no natural vertical stops, this particular case will require full tripod vertical stabilization to hold solid centric location. A combination of plug-in vertical stop and Cast-In Place Stop Heads will be used
- 54. The model isclosed into the cup to dry fit check for clearance After the plaster has set up, remove the cup, rubber bands and break away the retainer tabs from the Stop Heads to allow the articulator to open up The Pic-Up Cup is poured with dental plaster
- 55. Advantages • Simple andfast • Eliminating labor intensive pinning and basing procedures • Easily removed and re-seated with solid stable precision. • Even lower anterior, the thinnest of dies, resist lateral movement. • The plug-in adjustable vertical stops are easy to place and eliminate the need for a metal articulator set up • Does not require stone basing, cross arch and linear secondary base expansion issues
- 56. • CEREC system •The ED4 (D4D TECH) • DCS PRECIDENT System • iTERO • LAVA Dies for CAD/ CAM system
- 57.
- 58. • Designed formetal copings for PFM • Conventional wax up required • Touch probe • Acceptable marginal adaptability • Concludes that manual adjustment significantly improves marginal accuracy of CAD / CAM system fabricated titanium copings. • The highest marginal accuracy was achieved with the DCS system, using a longer refinement time. DCS PRECIDENT System
- 59. • It usesa camera that takes several views (stills), and uses a strobe effect as well as a small probe that touches the tooth to give an optimal focal length. • NO use of powder iTERO
- 60. • Chair sideoral scanner, takes a completely different approach using a continuous video stream of the teeth • Crowns from intra oral scans revealed signs of better marginal fit than crowns from silicone impressions • These tend to show better interproximal contact area quality LAVA ADVANTAGES • Saves time and 1 visit in –office systems • Opportunity to view occlusion • Accurate restorations created • Wear and chip resitant • No casting / soldering errors • Cross infection control
- 61. • The choiceof a specific technique relies on operator preference and after assessment of each methods advantages and disadvantages. • A good impression and an accurate die are the first step towards the fabrication of an accurate restoration whether its inlay, onlay or crown. • Proper selection of the die material and its manipulation are paramount to achieve accuracy in the die. Conclusion
- 62. • Shillingburg HT,Hobo S, Whitsett LD, Jacobi R, Brackett SE. Fundamentals of fixed prosthodontics. Chicago, IL, USA: Quintessence Publishing Company; 1997 Jan. • Anusavice KJ, Shen C, Rawls HR, editors. Phillips' science of dental materials. Elsevier Health Sciences; 2012 Sep 27. • Rosenstiel SF, Land MF, Walter R, editors. Contemporary fixed prosthodontics-e- book. Elsevier Health Sciences; 2022 Jun 22. • Rudd KD, Morrow RM, Eissmann HF, editors. Dental Laboratory Procedures: Fixed partial dentures. Mosby; 1979. • Touchstone A, Nieting T, Ulmer N. Digital transition: the collaboration between dentists and laboratory technicians on CAD/CAM restorations. The journal of the American dental association. 2010 Jun 1;141:15S-9S. • Mansueto MA, Phoenix RD. A comprehensive approach to die trimming. Journal of Prosthodontics. 1994 Dec;3(4):251-5. • Thornton LJ. Simplified procedure for preparing removable dies. Journal of Prosthetic Dentistry. 2001 Mar 1;85(3):306-7. References