This document discusses the process of duplicating dental casts and wax patterns. It describes how duplicating materials like agar and silicones are used to make refractory casts from a master cast. Then, various dental waxes are used to form the pattern for a metallic dental framework on the refractory cast. Different gauges and shapes of wax are used for components like the lingual bar, connectors, saddles, and external finish lines. The completed wax pattern can then be invested and cast into metal.

1. Purpose
Procedure
Material
What is duplicating ?

2. Duplicating & wax-up

3. Advantages
 Preserve the original cast
 Eliminating the danger of fracture or
abrading the surface of the original master
cast
 Forming the wax or plastic pattern
 The metal framework is cast against the
surface of refractory cast

4. Duplicating materials & flasks

5. Duplicating materials & flasks

6. Duplicating materials & flasks

7. Duplicating materials & flasks

8. Duplicating
 Materials used for duplicating :
 Duplicating gels
 Silicones

9. Agar
 Composition
Agar 12-25 %
Borax 0.2 %
Potassium sulfate 1-2 %
Alkyl benzoate 0.1 %
Water 85 %
Plasticizer glycerin
Filler silica , wax , rubber
Bactericidal Agent Thymol , Quaternary ammonium
Coloring / flavoring agent

10. Hysteresis
70-100 °
Gel Sol
37-50 °
Agar

11. Agar
liquefaction 100 ° 8-12 min
Storage 65 ° 7 days
Chilling 18-21 ° 3-5 min

12. Duplicating procedure

13. Duplicating procedure

14. Duplicating procedure

15. Duplicating procedure

16. Duplicating procedure

17. Duplicating procedure

18. Duplicating procedure

19. Duplicating procedure

20. Duplicating procedure

21. Duplicating procedure

22. Investment
 Select investments that is compatible
alloys

23. Investment
Wax pattern shrinkage
Metal shrinkage
(~ 1.5-2%)
Wax pattern expansion
Investment expansion
• Setting
• Hygroscopic
• Thermal

24. Expansion
 Setting Expansion
Hygroscopic setting expansion
 Thermal Expansion.

25. “Ideal” Investment:
 Expaned to compensate metal shrinkage
 not decompose at high temperature
 Strengthed at various temperature
 Porous to allow the escape of gases
 Consistent casting temperatures

26. “Ideal” Investment
 Easy to manipulate.
 Smooth castings.
 Easy to break out.
 Inexpensive.

27. TYPES OF INVESTMENTS
Based on the type of binder:
 Gypsum-bonded or Calcium-sulfate bonded
 Phosphate-bonded

28. Gypsum-bonded or Calcium-sulfate bonded
Composition
 Binder: a-hemihydrate form of gypsum (25-45%)
Ca SO4 ½+3/2 h2o= Ca So4.2H2o
 Not to be heated above 700oC  decomposition

29. Phosphate-bonded investment
Composition:
 Filler (refractory) = quartz or cristobalite or both (80%)
 Binder = magnesium oxide and acid phosphate
 Liquid = colloidal silica suspension

30. Factor
Setting hygroscopic
expansion
Thermal expansion
Water/powder ratio
increased
Decreased Decreased
Time of spatulation
increased
Increased No effect
Rate spatulation
increased
Increased No effect
Age of investment
increased
Decreased No effect
Delay before
immersion increased
Decreased
Water bath temperature
patterns
Increased

31. Duplicating

32. Duplicating

33. Duplicating procedure

34. Refractory cast

35. 1
2
3
1-Master cast
2. Refractory cast
3. Master cast

36. Waxing the framework

37. Dental waxes

38. Pattern waxes
1.Inlay waxes
2.Casting waxes 3.Baseplate waxes

39. Casting wax
The pattern for the metallic framework of RPD.

40. Casting wax

41. Casting wax : Composition
The ingredients are similar to inlay waxes

42. Casting wax : Properties
Flow
Breaking point : no fracture

43. Working properties
Pilable and readily adaptable
Adapt accurately to surface against which it pressed
not be brittle on cooling
Vapporize, leaving no film rather than carbon

44. Lingual bar waxing
Half-pear-shaped , 6- gauge
+
24-gauge sheet wax

45. Minor connector (guiding plate)
Half round 8-gauge

46. Minor connector
Round wax 10-gauge

47. Metal base
24-gauge sheet wax
24-gauge sheet wax

48. Rest
Half round 8-gauge

49. Reciprocal arm
Half-round 12
gauge
Half-round
8- gauge

50. External finish line
14-gauge round wax

51. Saddle waxing
Longitudinal pieces
12-gauge half round

52. Saddle waxing
Buccal loop 18-gauge round wax

53. External finish line
14-gauge round wax

54. Nailhead configurations
Round wax 14-gauge

55. Wrought wire joining

56. Completed wax pattern

57. any questions ?