INTRODUCTION TO DENTURES, REMOVABLE PROSTHODONTICS, COMPLETE DENTURES, SHAMMASM

2. COMPLETE DENTURE WAX-
UP AND FLASKING
PROCEDURE

4. Learning outcomes
1. Explain the importance of wax-
up procedure.
2. Explain the procedure of
flasking the dentures.
3. Describe the wax elimination
procedure.
4. Explain the steps in packing
acrylic resin.

5. Patient Visit #3
Visit 3
Clinical
procedure
Lab.
procedure
Jaw relations Face bow record
Transferring Jaw
Relations to the
Articulator
Anterior teeth
Arrangement
Horizontal
relations
Posterior teeth
Arrangement
Waxing & carving
Teeth arrangement
Vertical
relations
Orientation
relations Teeth selection

6.  Waxing: the contouring of the
wax base of a trial denture into
the desired form.

7.  Festoon: carvings in the denture
base material of a denture that
simulate the contours of the natural
tissues that are being replaced by
the denture.

10. President George
Washington’s dentures (1795)

12. Criteria for waxing up

13. Upper denture:
 1. The wax at the
periphery must be:
extended to full
depth
Fully rounded and
polished

15.  2. The labial waxing may be thickened
in order to restore lost facial contour.

16. 3.The buccal surface should
face downwards and outwards.

17.  4.Festooning
and cuspid
eminence should
be provided.
 Gingival crests
should be
trimmed exactly
to the finished
line.

18. 5. Stippling of the facial surface.
Stippling

19. Stippling

20. 6. The palatal
surface will face
inwards and
downwards.
The palate should
have an even
thickness of 2.5
mm.

21. Lower denture
 1. The labial
surface is
concave.
 The
peripheries:
 Fully
rounded and
polished.

22. 2. In the premolar region the
buccal surface is flat and thin.
3. In the molar region the is
wax thick.

23.  3. The lingual surface must be
concave.

24. Importance
 The form of the polished surfaces and
the proper location of the artificial
teeth plays a major role in:
 Stability of the dentures.
 Influences its retentive quality.
 Influences the esthetics of the
denture.
 Support the cheeks, lips and tongue.

31. Patient Visit #4
Visit 4
Clinical
procedure
Lab.
procedure
Try-in
Appointment
Flasking Deflasking
Laboratory
Remount
Finishing and
polishing the
denture

33. Try-in procedure

34. FLASKING

35.  flask: a metal case or tube
used in investing procedures.
 flask closure: the procedure of
bringing two halves, or parts,
of a flask together.
 flasking: the act of investing in
a flask.

36. Heat-activated denture base
resins are polymerized by:
1. Compression molding
technique
2. Injection molding technique
3. By microwave energy

37. Injection molding technique

38. By microwave energy

39. Compression molding technique

40. Parts of a flask
1. The cap
(thin top)
2. The cope
(middle)
3. The drag
(bottom)

41. Split mold
Denture flask (ejector-type, three
piece)
1. The drag (bottom)
2. The cope (middle)
3. The cap (thin top)
1 2
3
1
2 & 3
1
2
3

42. When festooning is completed . . .
. . . Seal the periphery
of the denture flange
to the inner edge of
the land of the cast.
Flasking

43. After soaking the master casts and mountings in water for a few
minutes, gently remove the casts from the mountings.
Both dentures
are sealed
onto their
respective
casts
Flasking

45. Removing from articulator

46. Neither the master cast nor the
mounting has been damaged.
Following processing into heat cured
acrylic resin the denture and casts
can be precisely reattached to the
mountings .

48. Invest the trial dentures in the
lower half of the flask with
dental plaster

50. Smoothen
the dental
stone

51. Apply separating media to the
dental stone

52. Pour dental stone till the incisal
and occlusal surfaces

53. EXPOSE THE TEETH

54. • Separating medium is painted on the dental
stone.
• Dental stone is used to fill the remainder of
the flask. The lid of the flask is pressed into
place while the investing stone is still soft.

55. COMPLETED FLASKING.
STONE CAP
UPPER
HALF STONE
STONE CAST
LOWER HALF STONE

56. COMPLETED FLASKING FOR
THE MANDIBULAR
COMPLETE DENTURE.
STONECAP
UPPER
HALF STONE
STONECAST
LOWER HALF STONE

57. Clamp

58.  After the stone has hardened (30-45
min), the record base and wax must
be removed from the mold. To do
this task, the denture flask is put in
boiling water for 4 minutes.

59. Wax elimination: the removal of
wax from a mold, usually by heat

61. • Open the flask. The
softened wax is
removed from the
mold. Remaining wax
is flushed from the
mold with a stream of
boiling water. The
mold is then cleaned
with a soft brush.
Placed in boiling water for 4 mins
to soften the wax

63. Remove wax completely

64. Teeth locked in stone

65. Apply separating media while
the casts are still warm

66.  Failure to place an separating
medium can lead to two major
difficulties:
 (1) If water is permitted to diffuse
from the mold surface into the
denture base resin, it can affect the
polymerization rate as well as the
optical and physical properties of the
resultant denture base.

67.  (2) If dissolved polymer or free
monomer is permitted to soak
into the mold surface, portions of
the investing medium can
become fused to the denture
base. These difficulties often
produce compromises in the
physical and esthetic properties
of processed denture bases.

68. Mixing heat cure acrylic
A polymer-to-monomer ratio of
approximately 3 : 1 by volume. This
ratio provides sufficient monomer to
thoroughly wet the polymer
particles but does not contribute
excess monomer that would
produce increased polymerization
shrinkage.

69. Mixing acrylic

70. Packing Acrylic Resin
 The placement
and adaptation of
denture base
resin within the
mold cavity are
termed packing.

71.  The placement of too much
material produces a denture
base that has excessive
thickness and resultant
malpositioning of teeth.
 On the other hand, the use of
too little material leads to
denture base voids or porosity.

72. Steps in resin packing
(compression
molding technique)
 Properly mixed resin is placed
into the mold cavity.

73. Thin polyethylene separator
sheet

74.  Trial flask closure: any preliminary
closure made for the purpose of
eliminating excess material and
making sure that the mold is
completely filled.

75.  The flask assembly is placed into
a flask press, and pressure is
applied.

76.  Excess material is carefully
removed from the flask (flash).

77.  The flask is transferred to a flask
carrier, which maintains pressure on
the flasks during processing.

78. A cross-sectional representation of
the denture flask and
its contents.

79. POLYMERIZATION CYCLE
 The heating process used to
control polymerization is termed
the polymerization cycle or curing
cycle.

80.  One technique involves
processing the denture base resin
in a constant-temperature water
bath at 74 °C (165 °F) for 8 hours
or longer, with no terminal boiling
treatment.

81.  A second technique consists of
processing in a 74 °C water bath for 8
hours and then increasing the
temperature to 100 °C for 1 hour.
 A third technique involves processing
the resin at 74 °C for approximately 2
hours and increasing the temperature
of the water bath to 100 °C and
processing for 1 hour.

82.  Following completion of the
chosen polymerization cycle, the
denture flask should be cooled
slowly to room temperature.
Rapid cooling can result in
distortion of the denture base.

83.  The flask should be removed from
the water and bench cooled for 30
min. Then the flask should be
immersed in cool tap water for 15
min. The denture base can then
be deflasked and prepared for
delivery.

85. Questions