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Casts, dies and cast forming

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Casts, dies and cast forming

  1. 1. CASTS, DIES AND CAST FORMING Presented by: Apurva Thampi MDS 1st year
  2. 2. A Good Impression…  Requires time and effort  Ensures an accurate and detailed cast Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  3. 3. Definations  Cast : it is a life-size likeness of some desired form  Die : the positive reproduction of the form of a prepared tooth in any suitable substance Glossary of prosthodontic terms
  4. 4. Casts
  5. 5. Pre – requisites of casts  Void free  Distortion free  Reproduce both prepared and unprepared surfaces  Occlusal surface of all teeth must allow articulation  All relevant soft and hard tissue must be involved  The side walls should be vertical or slightly tapered outward Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  6. 6.  Peripheral roll : 3-4mm  Edge of the cast : 3-4mm  Base of the cast : 15-16mm at the thinnest point  Tongue space should be flat nad smooth Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  7. 7. Types of casts Diagnostic casts Working casts Refractory casts Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  8. 8.  Diagnostic casts : A life size production of a part or parts of the oral cavity and/or facial structures for the purpose of study and treatment planning  Working casts: A cast formed of a prosthesis for the purpose of mounting on an articulator  Refractory casts: A cast made of a material that will withstand high temperatures without disintegrating (investment cast) Glossary of Prosthodontic terms
  9. 9. CAST FORMING PRELIMINARY IMPRESSION FINAL IMPRESSION INVERSION METHOD INVERSIO N METHOD WAX BOXING METHOD DENTAL PLASTER & PUMICE METHOD CAULKING COMPOUN D & PADDLE BOXING METHOD Rudd an Morrow, dental laboratory procedures - complete dentures (volume I),
  10. 10. Preliminary impression materials  Alginate  Impression compound Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  11. 11. Alginate impressions  Used to make diagnostic cast and removable partial dentures  Impressions to be poured soon after taking the impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  12. 12.  Procedure  Examine the impression  Run cold tap water and clean it gently  Trim excess alginate  Weigh the stone and mix it with the recommended W/P ratio  Vibrate the tray gently and add the stone in increments  Create undercuts in the first pour Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  13. 13.  After initial set, soak in slurry water from 3-5 mins  Mix stone and place on glass slab, shape to approx. size and thickness  Invert the stone cast onto this  Remove excess, and shape until surface is flat Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  14. 14. PROBLEM CAUSE SOLUTION Voids in impression Voids in impression material during making of impression. Obtain another impression. Impression separated from tray Too much time between impression and pouring. Pour as soon as possible. Cast surface chalky and soft Impression not separated from cast within 1hr after pouring. Incorrect water powder ratio, making mix too thin. Separate within 1 hr. Weigh stone and mix with required amount of water. Voids on surface of cast Mechanical spatulator not used. Stone poured into impression too quickly Mix it in mechanical Spatulator. Pour slowly into only one distal corner. Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  15. 15. PROBLEM CAUSE SOLUTION Cast too thin or thick Cast trimmed improperly. First pour of stone not checked for thickness. Trim with care to prevent over trimming. If first pour stone is too thick trim it before pouring base. Critical areas of cast trimmed away Trimmed improperly. Check cast frequently when trimming. Cast broken easily Improper water powder ratio. Cast trimmed too thin. Use recommended water powder ratio. Do not over trim Rudd an Morrow, dental laboratory procedures - complete dentures (volume I),
  16. 16. Modelling plastic impressions  Thermoplastic material  Rigid, hydrocolloid – less subject to distortion Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  17. 17.  Procedure  Examine the impression  Place it in a holder and make a mix of stone  Gently tap while pouring mix  After initial set, pour base (inversion method)  After 45min – 1hr, dip in warm slurry water  Lift the modelling plastic off the cast  Examine the cast and trim Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  18. 18. PROBLEM CAUSES SOLUTION Cast broken during separation from impression. Modeling plastic not softened adequately before removal. Immerse poured impression in warm water to soften before separation Modeling plastic stuck to cast at time of separation. Modeling plastic overheated when placed in water that is too warm. Do not over soften modeling plastic, place in warm water only long enough to soften and remove. Cast too thin or thick. Cast poured or trimmed too thin. Thick base as a result of first pour being too thick. Pour cast to proper thickness do not trim too thin. Check thickness of first pour before pouring base , trim on cast trimmer if needed. Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  19. 19. Cast forming in final impression  Wax boxing method  Dental plaster and pumice boxing method  Caulking compound and paddle boxing method Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  20. 20. Wax boxing method Effective for zinc oxide paste impression Beading Grip wax, Orthodontic tray wax, and utility wax are used for beading an impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  21. 21.  Procedure  Place the impression such that ridge portion is parallel to the bench top  Fill the tongue space with wax and seal it 3- 4mm below the border  Adapt 4mm wide beading wax 3-4mm below the border Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  22. 22.  Warm boxing wax until flexible  Seal the ends to the underlying layer of wax  Check the boxing for adequate width, height, border and sealing  Check for leaks  Pour the impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  23. 23. Problem Cause SOLUTION 1. Borders of cast too narrow or wide Beading wax too narrow or wide Make beading wax approximately 3- 4mm wide. 2. Border of cast not high enough to preserve thickness of impression flange Beading wax placed too high Adapt beading wax 3 – 4mm below border of impression. 3. Border of cast too high Beading wax placed too low Place beading wax 3 – 4mm below border of impression. 4. Base of cast too thin Boxing strip not extended too high Extend boxing strip 13mm above highest area of impression. 5. Base of cast too thick Boxing strip extended too high Keep boxing strip approximately 13mm above impression.
  24. 24. Dental plaster and pumice boxing  Excellent for rubber based silicones Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  25. 25.  Procedure  Mix a 1:1 mix of dental plaster and pumice  Place a patty of it on a glass slab  Settle the impression into the patty till 3-4mm below border  Remove excess material  Border is 4mm wide  Adapt boxing wax ( height – 13mm above the highest point on the impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  26. 26.  Paint plaster surface with separating medium  Check for leaks  Pour the impression with stone  After setting place in warm water  Adjust the dimension on a cast trimmer Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  27. 27. PROBLEM CAUSE SOLUTION 1. Border of cast too high or low Plaster of paris and pumice not trimmed to proper level Trim it until 3 – 4mm below border of impression 2. Borders of cast too narrow or wide Plaster of paris and pumice border of wrong width Make border 4mm wide 3. Cast unable to be separated Separating medium not applied Apply separating medium 4. Base of cast too high on one side and low on another Impression not oriented properly before boxing Place the impression parallel to bench top 5. Base of cast too thick or too thin Height of boxing strip wrong Place boxing strip 13mm above highest point on impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  28. 28. Caulking compound and paddle boxing method  The impression is boxed on a paddle and wax and caulking compound is used for beading  The beading should be 4-5mm wide  Fold a metal boxing strip around the impression  Secure with rubber band Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  29. 29.  Procedure  Strips of caulking compound rope to bead impressions (3-4mm below border)  The beading should be 4-5mm wide  Fold a metal boxing strip around the impression (13mm above highest point on impression)  Secure with rubber band  Seal the caulking compound to the boxing strip  Pour the impression with stone Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  30. 30. PROBLEM CAUSE SOLUTION 1. Borders of cast too high / low Beading placed at wrong level Place it 3 – 4mm below border of impression 2. Borders of cast too narrow / wide Beading too narrow / wide. Cast over trimmed Beading approximately 4mm wide Exercise care when trimming 3. Base of cast too thick / thin Boxing wax at wrong height Place it 13mm above border of impression Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  31. 31. Pre-requisits of a Die  Void free  Distortion free  Trimmed to ensure access for carving wax pattern margins  Reproduce tooth exactly  Remaining unprepared tooth structure should be 0.5 – 1mm visible Rosenteil, contemporary fixed prosthodontics, 3rd edition
  32. 32. Material sciences Dimensional accuracy Resistance to abrasion Both these criteria are achieved by GYPSUM Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  33. 33. Gypsum (CaSO4.2H2O)  Available in 5 forms : type I – V  When subjected to a temperature of 110C – 120C, water of crystallisation is driven out and produces CaSO4.1/2H2O CALCINATION Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  34. 34.  Differences between various types of gypsum are attributed to Calcination • Beta form(Plaster) • Irregularly shaped and extremely porous crystals Calcination in open kettle • Alpha form (type I stone – Hydrocal) • Dense non-porous crystals, regularly shaped and cuboidal Under steam pressure in autoclave • Alpha form(Type II stone – Densite) • Crystals are dense and larger than in type I Boiling in 3-% solution of calcium chloride Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  35. 35. Physical properties of Dental stone Setting expansion Setting time Compressive strength Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  36. 36. Setting expansion of dental stone  Linear expansion occurs during conversion from hemihydrate to dihydrate due to the outward thrust of needle-like crystals  Expansion ranges from 0.06% - 0.5%  Can be controlled by:  Smaller w/p ratio  Longer mixing time  Hygroscopic expansion  Accelerators and retarders Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  37. 37. Setting time of dental stone  Manufacturers  Accelerator: 2% K2SO4 - decreases  Retarders : 2% Borax - increases  Powdered CaSO4.2H20 mixed with hemihydrate - increases  Operators  Increase amount of water - increases  Longer and faster mixing time - decreases  Exposure to high humidity - decreases Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  38. 38. Compressive strength of dental stone  Inversely proportional to the water powder ratio  Presence of accelerators and retarders decrease compressive strength  Increasing spatulation time increases strength  Compressive strength of:  Dental plaster : 1800 p.s.i  Type I stone (hydrocal) : 4500 p.s.i  Type II stone (Densite) : 5500 p.s.i Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  39. 39. Strength Wet strength Dry strength Gypsum product has excess Water than that required for the hydration of the hemihydrate Excess water present in the Gypsum Product is driven off • Dry strength is usually twice that of the wet strength • Accelerators and retarders decrease compressive strength • Increasing spatulation time increases compressive strength Rudd an Morrow, dental laboratory procedures – Fixed Partial dentures (volume II), 2nd edition
  40. 40. Alternative die and cast material  Resins  Electroplated die  Flexible die materials Rosensteil, Contemporary fixed prosthodontics,#rd edition
  41. 41. Resins (Epoxy resin)  Advantages  Overcomes low strength and abrasion of stone  Cures at room temperature without expensive equipment  Dimensionally stable  Abrasion resistant  Disadvantages  More expensive than gypsum  Undergoes shrinkage  Some impression materials are not compatible with resin Rosensteil, Contemporary fixed prosthodontics,3rd edition
  42. 42. Electroplated dies  Deposition of a coat of pure copper or silver on the impression  Insert cathode wire in the border of the impression in the metallised area  Fill the preparations with electrolytic material  Completely submerge the impression into the plating solution  Plate for initially 5mA per tooth for 1 hr. re- submerge and plate for12hrs at 10mA  Wash and dry, and use dental stone for the construction of working casts Rudd and Morrow, dental laboratory procedures –volume II, 2nd edition
  43. 43.  Advantages  Overcome poor abrasion resistance of gypsum  When done properly, it can be as accurate as a stone die  Disadvantages  Distortion commonly occurs  Time consuming  Time required to for a film is enough for the development of dimensional changes  All impression materials are not suitable due to low surface energies Rosensteil, Contemporary fixed prosthodontics,3rd edition
  44. 44. Flexible die material  It is similar to heavy bodies silicone or poly ether impression  Selection of compatible impression and die material is very important to achieve good surface details  It is more rapid setting  Easy to remove Rosensteil, Contemporary fixed prosthodontics,3rd edition
  45. 45. Rosensteil, Contemporary fixed prosthodontics,3rd edition
  46. 46. Die systems  Working cast with removable die  Straight dowel pin  Curved dowel pin  Pindex system  Di-lok tray  Working cast with separate die  DVA model system  Zeiser model system Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  47. 47. Working cast with removable die  Dies that can be removed from the working cast  Convenient to use  It should satisfy the following requirements  Must return to their exact positions  Must remain stable even if inverted  Should be easy to mount on an articulator Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  48. 48. Straight dowel pin  The brass dowel pin is one of the most accurate dowel types  It resists horizontal displacement and vertical deviation Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  49. 49.  Procedure  Dowel is positioned over each prepared tooth  Place it between the arms of a bobby pin  Push a straight pin between the arms of the bobby pin and into the impression  Pin should be placed parallel to the long axis of the prepared tooth  Pour die stone into the impression covering the knurled end of the dowel  Paperclips can be used to add retention to the base Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  50. 50.  Once the stone has set, remove the straight pins from the impression  Place a small ball of soft wax on the tip of each dowel  Cut a V-shaped bucco- lingual orientation groove or a round dimple on each die to aid in reseating the die completely  Lubricate around each dowel with separating medium for easy separation from working cast  Pour the base leaving peaks and curls to facilitate retention for the mounting Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  51. 51.  Once the stone is dry, use a saw with a thin blade to cut through the layer of die stone on the mesial and distal sides of he prepared tooth  The cuts should taper towards each other from occlusal to gingival  Trim the die with no.25 blade and mark the finish line with a red pencil Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  52. 52. Curved pin dowel  Procedure  To install pins before pouring the impression, use finger pressure to insert a curved dowel, tip first into an opening in the positioning bar  The dowel extends 1-2mm into the impression of the prepared tooth, and the tail points facially Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  53. 53.  Insert a straight pin into one of the three holes in the facial aspect of the bar onto the impression  It should not touch the impression and should be approx. parallel to the long axis of the tooth.  Vibrate a mix of die stone into the impression until it covers the heads of the dowels and 1- 2mm of the thicker hexagonal bodies.  After the stone has hardened, extract the straight pins and side the position bar off each dowel Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  54. 54.  Cut a 2mm deep hole on either side of the dowel with an acrylic bur  Paint the stone and the exposed parts of the dowel with petrolatum.  Box the impression with wax allowing the tails to extend slightly.  Fill the boxed impression with yellow stone Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  55. 55.  Remove boxing wax and make vertical saw cuts on either side of each die  Separate each segment from the working cast by tapping on the exposed end with a knife handle Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  56. 56. To place the dowels after the cast has been made:  Pour the impression with die stone to form a horse shoe shaped working cast  Trim the bottom to a height of 10mm from the necks of the teeth  Drill a 5mm deep hole on the bottom of the cast directly under the centre of each prepared tooth.( with a 2mm bur)  Clean the hole with a drill if necessary  Cement the dowels into the holes one at a time placing a drop of cyanoacrylate cement into each (tails of the dowel point facially) Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  57. 57.  Brush a thin layer of petrolatum on the flat surface of the cast  Box the cast, pour the base, and separate the dies Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  58. 58. Pindex system Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  59. 59.  Procedure  Pour the impression, adding approximately 20mm of stone.  Wet the cast prior to trimming  Use a model trimmer to flatten the heels of the cast  It should sit perfectly flat on a tabletop, and its thickness must be a minimum of 15mm. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  60. 60.  Trim the periphery of the cast  Remove any excess stone in the palate/tongue area with an arbor band on a lathe.  The lingual border of the cast should taper slightly toward the base to facilitate removal of the dies from the cast later.  The faciolingual width -20mm.  Use a pencil mark the desired location of the pins on the occlusal surfaces of the teeth or preparations. Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  61. 61.  Place the prepared cast on the worktable and align the first pencil mark with the illuminated dot from the light beam director.  Using both hands, exert firm downwards pressure on the cast with thumbs.  Raise the handle bar with slow, even pressure and the drill assembly moves upwards cutting the pinholes.  When proper depth is achieved, red light goes off.  Same procedure is repeated with each mark.  For better results, cast is made slightly damp to prevent dust formation. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  62. 62.  Compressed air and brush is used to remove debris from holes.  The pin holes are refined with hand reamer.  Cyanoacrylate cement is placed on the pins prior to cementing the pin tips.  Shorter pins are placed before the long pins in lingual or palatal holes and long pins in the facial holes. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  63. 63.  White sleeves are placed on the long pins and gray sleeves on the short pins.  The bottom of the cast is lightly coated with the petrolatum.  Gray sleeves are blocked with small amount of molten wax to prevent the sleeve from filling with stone when secondary base is added.  Strip of utility wax along the ends of the long pins to facilitate removal of the dies later. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  64. 64.  A palatal or tongue filler is made of boxing wax.  The filler is seated to the cast.  Boxing wax is applied around the cast.  Base is poured with the die stone. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  65. 65.  When stone becomes hard, the cast is seated in the base former.  Saw cuts are pre-marked with the pencil.  then dies are sectioned from the underside.  It may also be sectioned from the occlusal aspect. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  66. 66.  After the die are sectioned, trim them in a conventional manner.  Mark the finish line with red pencil.  Apply die hardener and die spacer.  Then place the completed cast on the articulator and then cast is ready for fabrication of the wax pattern. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  67. 67. Di-lok tray system  A snap apart plastic tray with internal orienting grooves and notches is used to reassemble working cast and dies.
  68. 68.  Procedure  The cast should be poured in a U shape, with no stone in the center building it up to 2.5cm. (1.0 inch)  A lingual side of the cast base is trimmed with an arbor band.  Horizontal grooves are cut in the base to for retention.  When stone has set for 1 hr, separate it from impression.  Cast is trimmed in horseshoe configuration to fit in Di-lok tray and the buccal border is tapered towards base with arbor band. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  69. 69.  Soak the base of cast with water for 5 min.  Pour the base in tray, until ¾ of its is filled  Seat the cast on tray; in such a way that cervical line of the prepared teeth should be approximately 4mm above the level of base.  Wipe off the excess stone.  Allow the stone to set until it is hard and dry .  To complete the dies, the cast must be removed from the tray. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  70. 70.  Disassemble the tray by lifting the back up, and then slide the buccal segment forward.  Then with a saw frame and a thin saw blade, cut between the prepared tooth and the adjacent tooth.  The saw cut should start in the interdental papilla area and extend downward on a very slight taper.  The occlusal saw cut should extend three-quarters of the way through the stone base.  use finger pressure to break the die and attached teeth from the cast. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  71. 71.  Remove excess stone gingival to the finish line with a pear-shaped acrylic bur.  Then cast and dies are reassembled in the tray.  cast and tray mounted on the articulator.  When the stone has set, the articulated cast in the Di-lok tray is ready for the fabrication of the wax pattern. Shillingburg, Fundamentals of fixedproshodontics, 3rd edition
  72. 72. Working casts with separate die  ADVANTAGES  Simple  Slightly more accurate.  Minimum trimming.  DISADVANTAGES  Difficult to transfer complex or fragile wax patterns from cast to die.  Seating the pattern on the cast may be problematic.  Technique can be used with elastomeric impression materials. Rosensteil, Contemporary prosthodontics, #rd edition
  73. 73.  Procedure  The area of preparation is poured with the stones in small increments.  When set, it is separated. A second pour is then made of the entire arch.  The first pour which is more accurate is trimmed into a die with a handle.  A properly trimmed die handle is slightly larger in diameter than the preparation Rosensteil, Contemporary prosthodontics, #rd edition
  74. 74.  Improperly trimmed die with a handle that meets the preparation at an angle  Handle should be 1 inch long  The die is trimmed with an acrylic bur  The die is smoothened below the finish line with the discoid end of a tanner carver  The prepared finish line on the die should be outlined with a red pencil.  Die relief agent is painted on the preparation-20 to 40mm Rosensteil, Contemporary prosthodontics, #rd edition
  75. 75. DVA system Trimmed figure on alignment fixture Marking dowel pin locations on a clear plate Rosensteil, Contemporary prosthodontics, #rd edition
  76. 76. Drilling holes for dowel pins as marked Inserting dowels in the base plate Impression Is poured, stone is placed Around the dowel pins and the alignment Fixture is placed over the poured impression Rosensteil, Contemporary prosthodontics, #rd edition Drilling holes for dowel pins as markedDrilling holes for dowel pins as markedDrilling holes for dowel pins as marked
  77. 77. Cast is removed Cast is trimmed Rudd an Morrow, dental laboratory procedures - complete dentures (volume I), 2nd edition
  78. 78. Cast is sectioned using a thin blade saw Trimmed working cast using the DVA model system Rosensteil, Contemporary prosthodontics, #rd edition
  79. 79. Zeiser model system The Zeiser model system The impression is leveled, blocked out’ With silicone putty and positioned over The base plate Rosensteil, Contemporary prosthodontics, #rd edition
  80. 80. The pin locations are determined Pinholes drilled in place Rosensteil, Contemporary prosthodontics, #rd edition
  81. 81. Pins are inserted into the base Impression is poured Base inverted into the stone Rosensteil, Contemporary prosthodontics, #rd edition
  82. 82. Cast is separated from the impression when set Rosensteil, Contemporary prosthodontics, #rd edition
  83. 83. Precision saw aids in sectioning The sectioned cast Rosensteil, Contemporary prosthodontics, #rd edition
  84. 84. Summary Accurate working casts and dies are essential to successful restorations. There are various techniques and materials that provide an extremely precise reproduction of the prepared tooth. The die of the prepared tooth can be made removable by the use of dowels or other more convenient system. Alternatively, a solid working cast and separate die can be used. Whatever system is chosen, it must articulate precisely with an accurately made opposing cast
  85. 85. Bibliography  Rudd and Morrow, dental laboratory procedures – Volume I, 2nd edition  Rudd and Morrow, Dental laboratory procedures – volume II, 2nd edition  Rosenteil, Contemporary fixed Prosthodontics, 3rd edition  Shillingburg, fundamentals of fixed prosthodontics, 3rd edition  Philips  Glossary of prosthodontic terms
  86. 86. Thank You!

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