model_and_die.pptx .

PowerPoint for model and die in dentistry

1. WORKING CASTS AND DIES

2. Contents Introduction and definitions Requirements for good cast Requirements of die Requirements of die material Die materials Classification of model& die systems 1 _ definitive / solid cast 2 _virtual Cast and die system

3. INTRODUCTION . Working ( master or , definitive) cast ;; is the positive reproduction of the prepared teeth, ridge areas, and other parts of the dental arch. Die is the positive reproduction of the prepared tooth and consists of a suitable hard substance of sufficient accuracy For construction of indirect restoration ( inlay ,only ,crown & bridge ) model and die is made. The die must be hard and strong substance( usually made of improved stone “gypsum type IV&V” , resin or metal “amalgam or electroplated die” ) The model and die must be accurate Which is related to accurate ; As the model and die can’t be more accurate than the impression Which they reproduce .

4. Requirements for good casts : It must accurate reproduce details in the impression of the prepared ,unprepared tooth & All soft tissues (including all edentulous spaces and residual ridge contours )that will be involved in the fixed prosthesis. 1. All portions of the cast must be free of air bubbles and distortion , especially along the finish lines of the prepared teeth. All surfaces of any teeth involved in the anterior guidance and the occlusal surfaces of all unprepared teeth must allow for precise articulation of the opposing casts.

5. Opposing cast Working Master cast /model Trimmed Dei NB . The working cast # during mounting ; provide the most accurate articulation for accurate occlusion . # In the fabrication of the wax pattern , it is used to establish interproximal contacts, buccal and lingual contours, and occlusion with the opposing teeth. While, the margins of the wax pattern are finished on the die.

6. Ideal requirements of die: Exact reproduction of the prepared tooth. all surfaces must be accurately duplicated and no air bubbles or voids can be accepted. Finish line complete. Detection of the unprepared area tooth structure immediately cervical to the finish line, (0.5 to 1m m visible );;. To identify the contour of the tooth & allow margin adaptation .

7. Selection criteria (Requirements of die material ) Compatible with impression material and separating medium Reproduction of surface details accurately Dimensionally accurate and dimensionally stable High mechanical properties to resist distortion or fracture Easy to section and easy to trim Easily wetted by wax High hardness to resist scratching during wax pattern carving Color contrast

8. DIE MATERIALS: Amalgam (historical) Silver or copper Electroplated dies (historical) Acrylic or epoxy Resin Silicon or polyether “ Flexible die material ” Ceramic “ Refractory die “ Gypsum . ” Improved stone (type IV, type V) “

9. Amalgam die Impression material : only used with impression compound ; mustn’t used with rubber base " due to elastic properties " so it won’t withstand forces of condastion of amalgam . Used : only with copper bands with impression compound Advantages : Very strong and hard die . Disadvantages : setting expansion ) Dimensionally unstable ( Long setting t ime ) time consuming. ( HISTORICAL (NOT USED ANY MORE (

10. Silver or copper Electroplated dies Electrolytic deposition of a coat of pure silver or copper on the impression to produce the die. " Copper plating die and silver plating die " Impressions materials : s ilver electroplating ; with polysulphide rubber impression … ; silicone rubbers, Can electroplated by silver but not provide equal deposition of layers “ not compatible” Copper electroplating; with impression compound . _Polyether and hydrocolloides can’t be electroplated “liable to imbibe water= loss dimensions ” Use : All cermic crown • Advantages: High strength Good abrasion resistance High accuracy. stable for many years • Disadvantage: Special equipment is needed Time consuming Expensive

11. Resin die: Resin are used as a die material to overcome the low strength and abrasion resistance of die stone e.g : • Epoxy resin & • Polyurethan resin Impression from which dei obtained : by pour silicon and polyether impression materials Or by 3D printing technology Use : All ceramic crawn Advantages • High strength High abrasion resistance than the stone Disadvantages •Polymerization shrinkage of resin material so undersized die. Expensive Long setting time. Complex procedures

12. Flexible die: Are similar to heavy body silicon and polyether material in consistency. I mpression material : must be carefully selected for reproduction of good surface details Used for construction of ; : Interim " temporary " restoration indirect composite resin/ceramic inlay or onlays “ intra coronal restoration “ O nly at chairside Advantages Over astone die ; more rapid setting easy of remove of interim restoration or inlay

13. Ceramic (Refractory die) : Special type of ceramic " mainly quartz silica " supplied in powder and liquid, mixed and fired " fired after remove the mix from the impression " according to the manufacturer construction to form the die, Advantages : Can withstand very high temperatures without any distortion U se : Special for construction of allceramic restoration s ;" crown , inlay " because it allows porcelain to be built direct on the die.

14. GYPSUM ) stone die ): GYPSUM = calcium sulfate = naturally occurs as dihydrate ;Heat removes water and converts dihydrate to hemihydrate. [Gypsum Powder] + [H2O]  == [Gypsum] + [Heat] Calcium Sulfate GYPSUM PRODUCTS and their uses: • Type I : Impression Plaster. .only impression for complete denture • Type II : Model plaster …model fabrication “ study cast “ • Type III : Dental stone ... Model fabrication “ study cast” Type VI: High strength dental Stone ( hard but brittle , less expansion )… can used in most situations • Type V: Improved Stone , Die Stone(extra hard , but more expansion, low cost)…can used in most situations CAD/CAM stones: high reflective stones are available to fabricatesolid casts that may be scanned in the dental laboratory to generate subsequent virtual cast-and-die systems. ;It has high compressive strength, low expansion, and an extended working time, enabling the pouring of multiple impression. N.B; it can be done from copper band impression either with impression compound or rubber base Rubber base

15. Crystal expansion and interlocking Advantages 1• Inexpensive 2 • Compatible with most impression materials 3• Reproduce fine details in the impression. 4. Easy to use 5. Constant results Disadvantage 1) Poor resistance to abrasion ; . Overcome by: 1• Gypsum hardeners (colloidal silica) 2• Application of low viscosity resin (Cyanoacrylates). 3• Resin- strengthed gypsum product e.g Resin Rock 4• Gum arabic and calcium hydroxide mixture. 2)Setting expansion: Linear expansion occur during setting (0.06-0.9%). To Control setting expansion: Avoid : 1 . Decrease water/ powder. 2 . Increasing mixing time. 3 . Immersion of gypsum products in water during the setting process. 4 . Increasing temperature of mixing water from 23-30 ° … Follow the manufacturer’s instruction for the current water/powder ratio and manipulation.

16. Get some tea 🍵

17. Classification of cast & die systems: 1 _ definitive / solid cast -: A_The single die technique “ types according to materials ??“ B_Working cast with a separate die ( multiple-pour technique ) C_ Working cast with removable die, Dowel Pin Technique ” Pre -pour technique” Pindex System” Post pour technique” Di- Lok Tray Technique DVA model system Zeiser Model system. 2 _virtual Cast and die system

18. A_ single die technique Single copper band impression may be done using either: impressions compound rubber base. Classification of the single die according to the die materials: a . Stone die. b . Amalgam die. c . Acrylic or epoxy resins die. d . Refractory die (ceramic die). e . Electroplated die: 1 ) Sliver plated die. 2 ) Copper plated die f . Flexible die. Indication : • Impression for a single full metal crown preparation.

19. B_WORKINing cast with a separate die ) multiple-pour technique ). It is the simplest method of fabricating working cast &d This technique requires : a . Sectional cast (separate die) b . Full arch cast (working cast) Techniques Separate impression s " two impressions " Pouring full arch impression " one impression " twice ( double pour ) : First pour : The most accurate, is trimmed into a die with a handle of sufficient length. Second pour: The complete arch cast is mounted on an articulator N.B . double pour technique must only with rubber base impression, because hydrocolloids distort so Inaccurate .

20. WORKINing cast with a separate die . Advantages : Ease of fabrication Keep the relationship between abutments fixed and immovable which is necessary for fabricating bridges and minimizing casting adjustments. The gingival tissues around the prepared teeth left intact so that restoration contours are easier to reproduce in wax patterns. . Disadvantages : Fragile wax patterns are difficult to transfer between the two parts( from cast to die). So distortion of some of internal adaptation of the wax pattern . The second pour of the impression may be different (slightly larger) than the first, therefore, it may be necessary to relieve the stone slightly to seat the pattern

21. WORKINing cast with a separate die Impression Pouring:

22. WORKINing cast with a separate die

23. Write down your hints ; ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️ ✍️

24. C _ Working cast with removable die Die s Retained by pins in a base (stone or plastic) ; & pins are attached to the cast before or after pouring the impression One die used for proximal contacts, occlusion and margins Requirements of Removable Dies • The dies must return to their exact positions. Dies are stable even when inverted; and accurately related to adjacent and opposing teeth Dies are removable individually The cast containing the dies must be easy to mount on an articulator

25. C _ Working cast with removable die Advantages • Wax patterns or copings need not to be removed from their respective dies when they are transferred to the working cast • No discrepancy ; Disadvantage • The risk of introducing an error in the pattern if the die does not reseat accurately in the working cast. For stabilization of the die use flat pin from one end ..to prevent rotation Curved pin Two pines for one die Pin commen head with two ends

26. C _ Working cast with removable die Techniques of removable die: Dowel Pin Technique. Pindex System Di- Lok Tray Technique DVA model system Zeiser Model system. Positioning of a dowel pin in the working cast: Pre-poured technique : pin oriented in the impression before it is poured . e.g DOWEL PIN TECH. Post-poured technique : attached to the underside of a cast that has been already poured e.g PINDEX SYSTEM

27. C _ Working cast with removable die 1_Dowel Pin Technique” Pre-pour technique”: First pour Second pour dei sectioning die prepration Dei trimming Marking finish line Dei hardener Dei spacer

28. The first pour

29. Second pour

30. die sectioning “sewing “:

31. Dei trimming Remove most of excess stone with Arbor band. Use a pear shaped acrylic bur to trim the die apical to the finish line of the preparation. Then fine trimming and smoothening with scalpel or cleoid -discoid carver. Advantages of die trimming: Accentuate the finish line Resembling the normal contour of the natural root for proper cervical contouring of the wax pattern. Produce smooth area gingival to the finish line

32. The original contour of the tooth structure below the margin must be preserved. Over trimming (dotted line) will result in over contoured restoration

33. Finish line The F.L. is outlined with a red pencil ” marker” to define/ demarcate it. Graphite “carbon” pencils are contraindicated as carbon could attach to the wax and contaminate the future casting. ¾ crown onlay

34. Apply die hardener Cover die beyond finish lines Allow to set for 5 minutes Apply die spacer 40 micron thickness allows space for cement 2-3 coats placed Spacer 1 mm from finish line “ 1mm band at the margin is left unpainted.” Remove excess with die setting retardant Die is lubricated to reduce surface tension and allow free flow of wax.

35. C _ Working cast with removable die 2_Pindex System” Post pour technique ” Pindex system: Is a reverse drill press is used to create a master cast with dies that can be removed and replaced repeatedly with great precision. it is similar to a dowel pin system but create a working cast with dies with great precision.

36. Pouring the impression The impression is poured without positioning and attaching dowel pins

37. Cast trimming and pin channels creation Scan for video

38. Each segment must have at least 2 pins for stability and to prevent rotation Base of the cast is flat and smooth and parallel to the occlusal plane . Cast is 15-20 mm thick from gingival crest to the base • The cast should be poured in a U-shape with no stone in the center. A minimum height of 10 mm at edentulous ridge area is essential to avoid fracture of the cast.

39. Drilled holes opposite to laser beam

40. Index the Cast 1. Glue pins with cyanoacrylate cement – Long pin toward facial – Short pin toward lingual – Glue short pins first (better access) 2. Place sleeves on pins (stability of pins) 3. Box and seal cast 4. Apply separating solution (Super-Sep) 5. Pour second base with yellow stone

41. Die trimming and prepration Parallel pin channels at least 5 mm apart

42. C _ Working cast with removable die C. Di-lock tray technique Disadvantage • The oversize of the tray can make articulation and manipulation are difficult

43. C. Di-lock tray technique

44. Briefly

45. 2 _virtual Cast and die system 2 _virtual Cast and die system ✔️✔️ ✔️✔️ _ _ ✔️✔️ CAD/CAM ( C omputer- a ided D esign/ C omputer- a ided M anufacturing (

46. 2 _virtual Cast and die syste CAD/CAM ( C omputer- a ided D esign/ C omputer- a ided M anufacturing ( The recent nomination is: CAI / CAD / CAM ; CAI : Computer-Aided-Imaging ( Scanning ) CAD : Computer-Aided-Designing ( Designing ) CAM : Computer-Aided-Manufacturing ( Milling )

47. Scanning may be : Intraoral scanner Virtual casts can be created using data captured directly intraorally ( clinically ) Extra oral scanner a scan of a solid model " CAD/CAM stones " of the dentition obtained in the dental laboratory using a traditional impression technique and a special scanning device. 3D lesser scanner

48. N.B CAD/CAM stones: high reflective stones are available to fabricate solid casts that may be scanned in the dental laboratory to generate subsequent virtual cast-and-die systems. ;It has high compressive strength, low expansion, and an extended working time, enabling the pouring of multiple impression. Implementation OF CAD-CAM SYSTEMS Dentalrestoration : Crowns , Veneers , Bridges , Inlays , Onlays , Removable Denture , Orthodontic appliances

49. ADVANTAGES OF CAD-CAM SYSTEMS Application of new materials Introduction of high-strength ceramics could be used Reduced the lab cost and the chair side time Quality control (CAD better guarantees the durability and reduces the risk of fracture . Limitation OF CAD-CAM SYSTEMS I nitial High Cost of CAD/CAM Systems Time and Cost Investment to Master the technique Some are not user friendly and very complicated to operate on Massive waste of expensive materials, as most of the block is not being used.

50. CLASSIFICATION OF CAD/CAM SYSTEMS

51. Virtual articulator

52. Thank you Best of luck 💖 You can read in “ contemporary fixed prosthodontics “for more .