This document discusses the flasking process for fabricating complete dentures. It describes the materials and techniques used, including the compression molding process of investing the master cast and wax denture set-up in dental stone inside a denture flask. It also briefly covers microwave and injection molding processing techniques. The key steps of boil out, packing of acrylic, curing, deflasking, and remounting are outlined. Remounting allows correction of any occlusal errors from the processing.

1. Flasking
D.SIRAG AL-HAMADI
CLINICAL DEMONSTARATOR
PROSTODONTIC DEPARTMENT
TRIPOLI UNIVERSITY
DENTAL FACUALTY

2. Processing
 Ideal denture base material:
 No trial packing needed
 Good shade match with surrounding tissues
 Dimensionally stable
 Complete polymerization
 Easily polished

3. Processing
 Note: Master cast must be recovered from
flasking for laboratory remount.
 Techniques
 Compression
 Microwave
 Injection

4. Processing Technique
 Compression molding
 Conventional method
 More than 60 years
 Time consuming

8. Master cast
Mounting (with casts already
indexed on the bases)
* Trim base of cast to the dimension
that will fit in the processing flask
prior to indexing

9. 2
1 3
Split mold
Denture flask (ejector-type, three piece)
1. The drag (bottom)
2. The cope (middle)
3. The cap (thin top)

10. Split mold

11. STIPLE WAX ON FLANGES.
TINFOIL
BASE OF
CAST.
CHECK CLEARANCE
WITH FLASK.

12. CHECK PERIPHERAL
CLEARANCE.
LOWER HALF
OF FLASK
POURED.
POURING STONE FOR
THE UPPER HALF.

14.  Maxillary denture with the index in place
and embedded in the flask Soap, or a
gypsum separator, is used between the two
pours of dental stone in the lower and
upper portions of the flask.

15. CLEAR THE
LINGUAL TROUGH.
CLEAR THE TEETH.

16. •The surface of the third layer is left slightly rough to hold the fourth investment layer in
position.
•Tinfoil separating medium is painted on the third layer.
•The fourth investment layer 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. The flask is set aside for
min. 1 hr. before the wax elimination.

17. Second pour (upper half of flask)

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

19. STONE CAP
UPPER
HALF STONE
STONE CAST
LOWER HALF STONE
COMPLETED FLASKING FOR
THE MANDIBULAR
COMPLETE DENTURE.

23. Boil-out
When the wax and shellac record base are
completely warmed, the flasks can be opened.
The teeth remain in the lower portion of the flask
(left).
The record base is soft and can be easily removed in
one piece, along with any remaining wax (right).
Both flask halves are thoroughly cleaned by rinsing
with boiling water. The teeth are removed and
also cleaned with boiling water. Ensure that the
wax is completely removed by using a detergent.

25. Placed in boiling water for 5 mins
to soften the wax
• Stiff, bladed instrument is used to open the flask. Upper portion of the flask is lifted as
vertically as possible to avoid fracturing the investment layers.
• 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 and a
powdered detergent. Detergent is removed by flushing the mold with clean boiling water.

28. Smooth all sharp edges and create an escape
groove
Feathered stone edges must be removed because
they break off easily and can become embedded
in the acrylic resin base material. A groove is
made completely around the master cast for the
purpose of allowing excess acrylic resin to escape
(right).
The surface of the dental stone in both halves of the
flask is coated with a gypsum separating medium.
Each tooth is carefully placed in its original
position. Make under cuts in the acrylic resin
teeth similar to the diatorics in porcelain teeth.

32. Packing
Mixing the acrylic resin I and packing the dough
The autopolymerizing acrylic resin is mixed to a
kneadable dough according to the manufacturer’s
instructions (powder to liquid volume ratio usually
3:1) and placed in the cold flask halves in which the
denture teeth are positioned.

36. •Trial packing (3000-4500 lbs over the entire flask area)
•Use two sheets of cellophane between
two layers of resin dough to allow
opening of the flask without pulling
acrylic resin.
•Trim excess acrylic and flash
•Repeat until no excess is visible
•Final closure of the flask halves is
accomplished without the intervening
sheets of cellophane
•Heat cure in water bath with temp. set at
160-165°F for at least 8 hrs. with constant
pressure

38. 8 hrs 160-165 F

39. Occlusal correction
Laboratory Remount
to eliminate the processing error
depends on
Jaw relation technique
instrumentation

40. Processing Technique
 Microwave System
 (GC America Inc.3737 W. 127th Street, Alsip, IL 60803)
 Use the split mold technique to form molds
 ACRON MC microwave cured acrylic
 Need special flask
(resin + small metal screws)
 One minute microwaved to soften wax
 Eliminate wax from mold
 Three minute curing in microwave
 Leave 15-20 mins before opening flask
 Less VDO increase??
 Easy to use
 Low water absorption

41. Microwave system
 Three minute curing in microwave
 Fast, easy to use
 Allows more efficient use of time
 Produces denture in short processing time
 Denture repair
 Interim partial

42. Processing Technique
3. Injection
3.1 Ivocap injection system, Ivoclar, Vivadent, Inc, Amherst, NY)
 In Mid 1970
 VDO is more stable compare with conventional
 Flask is closed during the procedure

43. Processing Technique
3. Injection
3.2 Success System (Dentsply, International, Inc, York, PA)
 PMMA Lucitone 199
 90 PSI, use heat-polymerized resin

44. Success
Flasking or Investing
After Boil out
Divesting
Flask is closed

45. Insert plastic nozzle Flask in injecting unit
De-flasking Master cast Recovery

46. Master cast removed from invest material
Finished denture

47. Eclipse™ Prosthetic Resin System
(Dentsply)
•Light-cured composite resin
•New indirect build-up method for making dentures
•Flask-free and monomer-free
•Conditioning Oven to warm models and materials
•Melting Pot to prepare and melt Contour Resin
•Electric Spatula to apply Contour Resin
•Hot Air Gun to replace flaming
•Eclipse Processing Unit to polymerize materials
•Resin materials and supplies
•Eclipse Bonding Agent

48. Dimensional change in CD fabricated by injected molding and microwave processing.
Keenan, Radford, and Clark. J Prosthet Dent 2003;89:37-44.
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Compression Success Acron MC Microbase
VDO After storage

49. Deflasking
Remove the flasking stone
The denture can be deflasked as shown
without damage. The silicone index can
be easily removed.
Denture after deflasking
Because the denture was carefully waxed
and a silicone index was used, finishing
around the teeth can be readily
accomplished.

51. Remounting and Occlusal Equilibration
After the dentures have been deflasked they are
mount ed in the articulator without removing
them from their casts. Small errors can now be
seen that occurred during the flasking and
polymerization procedures. Although there is
very little shrinkage during autopolymerization,
occlusal contacts may have been slightly
altered. For this reason, the first occlusal
equilibration is performed so that a clear cusp-
to-fossa relation can be obtained

52. After all centric contacts are established,
the eccentric excursions are equilibrated
and the protrusive and retrusive
movements are ground free from
interferences. The occlusion is then
refined with carborundum paste. Only
now should the dentures be separated
from the casts.
Post-processing remount
The dentures are not yet separated.
Dentures and master casts are remounted
in the articulator.

54. Checking the condylar guidances
The condylar guidances are still set at the
patient’s individual condylar path angle.

55. Equilibrating the occlusion in centric relation
Premature centric contacts
Polymerization shrinkage has caused a slight shift in the original
cusp-to-fossa relations. Initial contacts are now premature or
deflective, and must be selectively eliminated in order to
restore proper intercuspation.
Below left: The occlusion is corrected with a round diamond
stone. Avoid grinding the centric supporting cusps, which in
complete dentures are primarily the maxillary palatal cusps
and the mandibular buccal cusps.