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ALTERED CAST
TECHNIQUE
By
Dr. Saili Chandavarkar
MDS II
1
CONTENTS
• Introduction
• Support of distal extension based
partial denture
• Concept of functional impression
• Need of f...
CONTENTS
• Factors influencing support of distal
extension base
• Materials used for functional impression
• Impression me...
SUPPORT OF DISTAL EXTENSION BASED
PARTIAL DENTURE
•
•
•

A minor support comes from the abutment teeth
The major support c...
ACCORDING TO THE METHOD OF
IMPRESSION MAKING
RESIDUAL
RIDGE

Anatomic
form

Functional
form

5
ANATOMIC FORM
• The surface of the residual ridge at rest.
• It is the shape of the ridge before functional load is
applie...
FUNCTIONAL FORM
• It means the shape of the residual ridge tissue when it is
functioning to support the denture base.
• It...
Anatomic or Resting form

Supporting or Functional form

McCracken’s Removable Partial Prosthodontics 3rd edition

8
CONCEPT OF FUNCTIONAL
IMPRESSION
The term functional impression means
recording the functional form of the
residual ridge ...
HISTORY
• Applegate used impression wax to load functionally
the residual ridge
• Hindel felt that free –end denture base ...
HISTORY
• Kramer & Singer used a double impression technique
based on load distribution by Hindel
• McCracken concluded th...
NEED OF FUNCTIONAL IMPRESSION

• The displaceability of the mucosa of residual ridge is
not uniform.
• The need of functio...
INDICATIONS FOR FUNCTIONAL IMPRESSION
• Mandibular distal extension partial dentures –
Only a limited ridge area can be us...
OBJECTIVES OF FUNCTIONAL IMPRESSION
(O.C. Applegate)
•
•
•
•

To obtain the maximum area of coverage
Traumatic impact on a...
Factors influencing the support of
distal extension base
• Contour & Quality of residual ridge

McCracken’s Removable Part...
•Extent of residual ridge coverage by the denture base

McCracken’s Removable Partial Prosthodontics

16
•Type & Accuracy of impression registration

McCracken’s Removable Partial Prosthodontics

17
•Accuracy of fit of denture base

McCracken’s Removable Partial Prosthodontics

18
•Design of partial denture framework

McCracken’s Removable Partial Prosthodontics

19
•Total Occlusal load applied

McCracken’s Removable Partial Prosthodontics

20
IMPRESSION MATERIALS
ANATOMIC IMPRESSIONS

FUNCTIONAL IMPRESSIONS

• IRREVERSIBLE
HYDROCOLLOID
• ELASTOMERIC IMPRESSION
MA...
METHODS OF FUNCTIONAL IMPRESSION
SELECTED PRESSURE
IMPRESSION TECHNIQUE

PHYSIOLOGIC OR
FUNCTIONAL IMPRESSION

McLean's me...
The master cast may be altered to
accommodate the new ridge impression it is
referred as Altered Cast Technique Or
Correct...
McLean’s Physiologic Method

Clinical Removable Partial Prosthodontics – Stewart. 3rd edition
24
Custom tray over a preliminary cast

25
Custom tray over a preliminary cast

26
Occlusal rim over a distal extension base is made

27
Functional impression of extension area under
occlusal load

28
Hydrocolloid impression over the first impression made
under finger pressure.

29
McLean’s Physiologic Method
Disadvantages• Finger pressure not equal to biting pressure
• Alginate between stock tray and ...
Hindel’s Modification
• First anatomic impression in alginate is made
• Acrylic resin tray over saddle area is prepared

•...
Hindel’s special tray with holes to apply
pressure

32
HINDLE’S FINGER LOADING

33
HINDLE’S FINGER LOADING
Disadvantage
• Tissues are in constant
stage of compression

• Ischemia and bone
resorption
• Prem...
Functional Reline Method

Clinical Removable Partial Prosthodontics – Stewart. 3rd edition
35
Layer of relief given

36
The denture is processed & fitted in the mouth in
customary manner, except that the relief metal is
left in place.

It sho...
The relief metal is stripped off from the acrylic.

38
low fusing modeling compound is added in increments

39
Border molding done.

40
1 mm Modeling plastic is removed from the intaglio
surface.

41
Impression made using one of the corrective
materials : fluid wax, Zinc-oxide Eugenol pastes or
any elastomeric impression...
Functional Reline Method
• Disadvantage –
a) Occlusion may be altered slightly by reline
procedures & may require adjustme...
FLUID WAX TECHNIQUE

44
Clinical Removable Partial Prosthodontics – Stewart. 3rd edition
FLUID WAX TECHNIQUE
• The most frequently used waxes are –
Korrecta wax no. 4 - Dr. O.C.& S.G. Applegate at University of
...
The armantarium for fluid wax technique. (51- 54
degree Celsius)

46
Undercuts eliminated using baseplate wax

47
Separating medium applied to the cast.

48
Framework seated on the cast.

49
Tray material adapted 12 mm relief between
residual ridge and
intaglio surface of tray.

Excess material removed.

Tray bo...
Fluid wax painted onto the intaglio surface of tray (1 -2 mm)
Assembly seated in patients mouth.(5 -7 mins)

51
Completed impression.
Check for proper tissue contact.(final insertion for 12
mins)

52
FLUID WAX TECHNIQUE
• The finished impression must be handled
carefully & the new cast poured as soon as the
wax is fragil...
SELECTIVE TISSUE PLACEMENT
IMPRESSION METHOD

54
SELECTIVE TISSUE PLACEMENT
IMPRESSION METHOD
• The technique attempts to direct more force to
those portions of ridge able...
Framework tried on the cast

McCracken’s Removable Partial Prosthodontics 56

Tray outline marked for
extension
Framework with tray fabricated on it with
holes on its ridge.

McCracken’s Removable Partial Prosthodontics

57
Areas in which relief is to
be provided is marked

Tray is being relieved
before the final
impression is made

58
Clinical...
Acrylic resin
impression trays
with holes

Framework with
tray tried in
patient’s mouth

Functional
impression made

59
ALTERED CAST TECHNIQUE
Altered cast oˆ l#terd ka˘ st: a final cast that is revised in
part before processing a denture bas...
ALTERED CAST TECHNIQUE
• Also known as Corrected cast or Split cast Technique.
• It is mainly a modification of functional...
Functional impression
made

Final impression

McCracken’s Removable Partial Prosthodontics 12thedition

62
Edentulous area cut from the master
cast

63
Framework with attached impression seated on
the master cast

It is imperative that all the rests occupy their proper
posi...
Assembly from underside
of the cast

Peripheral borders of the
impression are protected with
utility wax & the assembly
wr...
The newly obtained altered cast with newly added
stone

66
Alternate
techniques

67
Alternate technique to separate the
edentulous cast

68
Boxed elastomeric final impression in which edentulous
ridges have been separated with contoured baseplate
wax (A arrows) ...
Mix of properly proportioned dental stone vibrated into three
compartments of impression. Impression must be overfilled to...
Master east ready for duplication.
Three to 5 mm thick base (line
shown by arrow) below level of
separating wax to prevent...
Base of the cast has been
trimmed to line shown by arrows in previous dgm
and cast is ready for immersion in boiling slurr...
View from bottom of master cast after base has been trimmed
to expose separating
wax and wax dovetails.

Izharul Haque Ans...
Edentulous portions separated from rest of master cast when removed
from boiling clear slurry water. Appearance of dovetai...
Alternate boxing technique

Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing
impressi...
Replacement of impression and
framework on master cast after
removal of edentulous distal
extension areas of cast.

Framew...
Protection of teeth in master cast
with irreversible hydrocolloid.

Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis...
Immersion of master cast and
frame assembly within
supporting base.

Framework with corrected
impression
is seated into a ...
• Make a support base mix with an Accu-Dent (Buellton, Calif.)
water measure. Mix 2 parts (26 mL) cornstarch (Argo Cornsta...
• Mix 50% cornstarch (Argo Cornstarch, Best Foods Div. C.P.C.
International Inc., Englewood Cliffs, N.J.) and 50% white mo...
Boxing wax placed around plaster
base and cast leaving at least 20 mm
from top of wax to highest point on
impression.

Lei...
• Completed altered cast.

Completed altered cast.

Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple techn...
Alternative to altered cast technique

Ming-Sheh Chen, W.A. Eichhold, Chao-Chin Chien and D.A. Curtis : An altered-cast im...
Tissue surface of final impression.
Note excess rubber base
impression material has been
trimmed to internal finish line
(...
Tissue surface of distal-extension
irreversible hydrocolloid pickup
impression. Irreversible
hydrocolloid is purposely
ove...
Irreversible hydrocolloid pickup
impression after trimming is
completed. Note a land of
irreversible hydrocolloid
impressi...
Tissue surface of final impression is
surrounded
by a uniform land of irreversible
hydrocolloid.

87
Tissue surface of pickup
impression. Note wax
blockout (arrows) of all undesirable
mechanical undercuts.
There is no block...
Master cast obtained by this
method. Note uniform
stone land transition in distalextension regions.

89
Alternative to altered cast technique

Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression...
Aluminum foil and two sheets of
baseplate wax over
diagnostic cast before tray
fabrication.

Herman B. Dumbrigue and Josep...
Custom tray fabricated with
extensions reduced 2 mm
short of vestibule.

Herman B. Dumbrigue and Josephine F. Esquivel: Se...
Custom tray with softened
modeling compound
reseated on diagnostic cast.
Modeling compound over
residual ridges shaped
app...
Border molding procedure completed.

Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression
p...
Trial of metal framework,altered cast
technique and interocclusal record in
one appointment

95
Technique 1
• Richard Bauman and James DeBoer :A modification
of the altered cast technique. J Prosthet Dent
1982;47:212-2...
Border molding is completed.

Final impression is
completed in
material of choice

Richard Bauman and James DeBoer :A modi...
Interocclusal record is made by placing low fusing modelling compound
over the wax rim to record the interocclusal relatio...
An over impression of the
entire assembly in
irreversible hydrocolloid
Richard Bauman and James DeBoer :A modification of ...
Technique 2
• Lih-Shou Lay,Wing-Hong Lai and Chen-Tsye Wu
:Making the framework try-in, altered-cast
impression, andocclus...
Wax used to block out undercuts around framework over edentulous
portion of cast. Autopolymerizing acrylic resin tray mate...
Index grooves on occlusal surface of trays. Jaw relation record (yellow)
made in mouth with framework and record base in p...
Technique 3
• U. Santana-Penín and J. Gil Lozano: An accurate
method for occlusal registration and altered-cast
impression...
Light-cured acrylic resin tray formed over edentulous
ridge portion of framework. Holes are made in tray to allow
resin co...
Acrylic resin trays (with holes for
resin columns)
detached from framework

Framework in mouth showing 1
inch resin column...
Framework in mouth showing 1
resin column built up
as jaw relation index.

Acrylic resin tray in position on
framework aft...
Completed impression seated on
cast from which
edentulous ridges have been
removed.

Impression is boxed, in this case
wit...
Finished altered master cast, with
impression and jaw
relation indexes (arrows) in place.

Resin columns are used to relat...
Richard P. Frank et al :Clinical Outcome Of Altered
Cast Impression Procedure Compared With Use Of A
One Piece Cast
J Pros...
REFERENCES
• Essential of Removable partial denture –
Applegate
• Removable Partial Prosthodontics – Miller
• Partial dent...
REFERENCES
• Treatment of partially edentulous
patients – Louis Boucher
• J.Pros.Dent. July,2004 :volume
24;number1
• J.Pr...
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Altered casts technique

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dentistry: functional impressions in cast partial dentures

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Altered casts technique

  1. 1. ALTERED CAST TECHNIQUE By Dr. Saili Chandavarkar MDS II 1
  2. 2. CONTENTS • Introduction • Support of distal extension based partial denture • Concept of functional impression • Need of functional impression • Indication for functional impression • Objectives of functional impression 2
  3. 3. CONTENTS • Factors influencing support of distal extension base • Materials used for functional impression • Impression methods • Altered Cast Technique • Modifications of altered cast technique 3
  4. 4. SUPPORT OF DISTAL EXTENSION BASED PARTIAL DENTURE • • • A minor support comes from the abutment teeth The major support comes from elastic fibrous connective tissue pad overlying the alveolar process Residual ridge: It is the remnant of the alveolar process together with the fibrous connective tissue covering (& included structures) in an edentulous area of the dental arch. 4
  5. 5. ACCORDING TO THE METHOD OF IMPRESSION MAKING RESIDUAL RIDGE Anatomic form Functional form 5
  6. 6. ANATOMIC FORM • The surface of the residual ridge at rest. • It is the shape of the ridge before functional load is applied. 6
  7. 7. FUNCTIONAL FORM • It means the shape of the residual ridge tissue when it is functioning to support the denture base. • It is the shape of the ridge after functional load is applied. 7
  8. 8. Anatomic or Resting form Supporting or Functional form McCracken’s Removable Partial Prosthodontics 3rd edition 8
  9. 9. CONCEPT OF FUNCTIONAL IMPRESSION The term functional impression means recording the functional form of the residual ridge tissue & to obtain uniformity of support when the functional load is applied. 9
  10. 10. HISTORY • Applegate used impression wax to load functionally the residual ridge • Hindel felt that free –end denture base under masticatory load should be related to metal framework when it is seated • Holmes used four different materials with altered cast technique • Leupold & Kratochvil used Zinc-oxide Eugenol paste to record the shape of residual ridges 10
  11. 11. HISTORY • Kramer & Singer used a double impression technique based on load distribution by Hindel • McCracken concluded that a functional technique should be used when constructing mandibular distal extension based partial denture 11
  12. 12. NEED OF FUNCTIONAL IMPRESSION • The displaceability of the mucosa of residual ridge is not uniform. • The need of functional impression arises in cases of distal extension based partial denture. • Some mouth does not exhibit significant difference in anatomical and functional form of ridge. • Short span distal extension bases. 12
  13. 13. INDICATIONS FOR FUNCTIONAL IMPRESSION • Mandibular distal extension partial dentures – Only a limited ridge area can be used as a stress bearing site. • Mainly Kennedy’s class I & II edentulous arches. 13
  14. 14. OBJECTIVES OF FUNCTIONAL IMPRESSION (O.C. Applegate) • • • • To obtain the maximum area of coverage Traumatic impact on any area must be avoided At rest there must be no islands of ischemia Under work loads all areas must receive massage stimuli. 14
  15. 15. Factors influencing the support of distal extension base • Contour & Quality of residual ridge McCracken’s Removable Partial Prosthodontics15
  16. 16. •Extent of residual ridge coverage by the denture base McCracken’s Removable Partial Prosthodontics 16
  17. 17. •Type & Accuracy of impression registration McCracken’s Removable Partial Prosthodontics 17
  18. 18. •Accuracy of fit of denture base McCracken’s Removable Partial Prosthodontics 18
  19. 19. •Design of partial denture framework McCracken’s Removable Partial Prosthodontics 19
  20. 20. •Total Occlusal load applied McCracken’s Removable Partial Prosthodontics 20
  21. 21. IMPRESSION MATERIALS ANATOMIC IMPRESSIONS FUNCTIONAL IMPRESSIONS • IRREVERSIBLE HYDROCOLLOID • ELASTOMERIC IMPRESSION MATERIALS • REVERSIBLE HYDROCOLLOID • FLUID WAXES • METALLIC PASTES • ELASTOMERIC IMPRESSION MATERIALS • SOFT RELINERS 21
  22. 22. METHODS OF FUNCTIONAL IMPRESSION SELECTED PRESSURE IMPRESSION TECHNIQUE PHYSIOLOGIC OR FUNCTIONAL IMPRESSION McLean's method Hindel’s modification for McLean's method Functional relining method The Fluid wax technique 22
  23. 23. The master cast may be altered to accommodate the new ridge impression it is referred as Altered Cast Technique Or Corrected Cast Impression Technique 23
  24. 24. McLean’s Physiologic Method Clinical Removable Partial Prosthodontics – Stewart. 3rd edition 24
  25. 25. Custom tray over a preliminary cast 25
  26. 26. Custom tray over a preliminary cast 26
  27. 27. Occlusal rim over a distal extension base is made 27
  28. 28. Functional impression of extension area under occlusal load 28
  29. 29. Hydrocolloid impression over the first impression made under finger pressure. 29
  30. 30. McLean’s Physiologic Method Disadvantages• Finger pressure not equal to biting pressure • Alginate between stock tray and occlusal rim acts as buffer. May not transfer entire load to special tray. 30
  31. 31. Hindel’s Modification • First anatomic impression in alginate is made • Acrylic resin tray over saddle area is prepared • Impression of saddle area is made in zinc oxide eugenol paste without pressure • Super impression is made with a modified tray applying finger pressure. Clinical Removable Partial Prosthodontics – Stewart. 3rd edition 31
  32. 32. Hindel’s special tray with holes to apply pressure 32
  33. 33. HINDLE’S FINGER LOADING 33
  34. 34. HINDLE’S FINGER LOADING Disadvantage • Tissues are in constant stage of compression • Ischemia and bone resorption • Premature contacts at rest. 34
  35. 35. Functional Reline Method Clinical Removable Partial Prosthodontics – Stewart. 3rd edition 35
  36. 36. Layer of relief given 36
  37. 37. The denture is processed & fitted in the mouth in customary manner, except that the relief metal is left in place. It should be worn for a trial period of a week & all needed adjustments are done 37
  38. 38. The relief metal is stripped off from the acrylic. 38
  39. 39. low fusing modeling compound is added in increments 39
  40. 40. Border molding done. 40
  41. 41. 1 mm Modeling plastic is removed from the intaglio surface. 41
  42. 42. Impression made using one of the corrective materials : fluid wax, Zinc-oxide Eugenol pastes or any elastomeric impression material. 42
  43. 43. Functional Reline Method • Disadvantage – a) Occlusion may be altered slightly by reline procedures & may require adjustments b) There remains a fine line of demarcation between the newly added & old resin of the denture 43
  44. 44. FLUID WAX TECHNIQUE 44 Clinical Removable Partial Prosthodontics – Stewart. 3rd edition
  45. 45. FLUID WAX TECHNIQUE • The most frequently used waxes are – Korrecta wax no. 4 - Dr. O.C.& S.G. Applegate at University of Michigan IOWA wax -Developed by Dr.Smith at University of IOWA • Korrecta wax no. 4 is slightly more fluid than IOWA wax 45
  46. 46. The armantarium for fluid wax technique. (51- 54 degree Celsius) 46
  47. 47. Undercuts eliminated using baseplate wax 47
  48. 48. Separating medium applied to the cast. 48
  49. 49. Framework seated on the cast. 49
  50. 50. Tray material adapted 12 mm relief between residual ridge and intaglio surface of tray. Excess material removed. Tray border smoothed using laboratory bur. Should be 2 mm short of border extension required. 50
  51. 51. Fluid wax painted onto the intaglio surface of tray (1 -2 mm) Assembly seated in patients mouth.(5 -7 mins) 51
  52. 52. Completed impression. Check for proper tissue contact.(final insertion for 12 mins) 52
  53. 53. FLUID WAX TECHNIQUE • The finished impression must be handled carefully & the new cast poured as soon as the wax is fragile & subject to distortion 53
  54. 54. SELECTIVE TISSUE PLACEMENT IMPRESSION METHOD 54
  55. 55. SELECTIVE TISSUE PLACEMENT IMPRESSION METHOD • The technique attempts to direct more force to those portions of ridge able to absorb stress without adverse response & to protect the areas of ridge which are least able to absorb forces. 55
  56. 56. Framework tried on the cast McCracken’s Removable Partial Prosthodontics 56 Tray outline marked for extension
  57. 57. Framework with tray fabricated on it with holes on its ridge. McCracken’s Removable Partial Prosthodontics 57
  58. 58. Areas in which relief is to be provided is marked Tray is being relieved before the final impression is made 58 Clinical Removable Partial Prosthodontics – Stewart. 3rd edition
  59. 59. Acrylic resin impression trays with holes Framework with tray tried in patient’s mouth Functional impression made 59
  60. 60. ALTERED CAST TECHNIQUE Altered cast oˆ l#terd ka˘ st: a final cast that is revised in part before processing a denture base—called also corrected cast, modified cast Altered cast partial denture impression oˆ l#terd ka˘ st pa¨r#shal de˘n#cher ı˘m-pre˘sh#an: a negative likeness of a portion or portions of the edentulous denture bearing area(s) made independent of and after the initial impression of the natural teeth. This technique employs an impression tray(s) attached to the removable dental prosthesis framework or its likeness 60
  61. 61. ALTERED CAST TECHNIQUE • Also known as Corrected cast or Split cast Technique. • It is mainly a modification of functional impression through laboratory procedure. • Functional impression for this technique can be made using any of the above mentioned materials and techniques. Robert J. Leupold And Frank J. Kratochvil:An Altered-cast Procedure To Improve Tissue Support For Removable Partial Dentures .J Prosthet Dent61 1965:672-679
  62. 62. Functional impression made Final impression McCracken’s Removable Partial Prosthodontics 12thedition 62
  63. 63. Edentulous area cut from the master cast 63
  64. 64. Framework with attached impression seated on the master cast It is imperative that all the rests occupy their proper position on the cast 64
  65. 65. Assembly from underside of the cast Peripheral borders of the impression are protected with utility wax & the assembly wrapped with boxing wax 65
  66. 66. The newly obtained altered cast with newly added stone 66
  67. 67. Alternate techniques 67
  68. 68. Alternate technique to separate the edentulous cast 68
  69. 69. Boxed elastomeric final impression in which edentulous ridges have been separated with contoured baseplate wax (A arrows) and sealed to anatomic contour of impression at base. Triangular wax bars (B arrows) are attached to make dovetails (three separate compartments of impression). Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 69 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  70. 70. Mix of properly proportioned dental stone vibrated into three compartments of impression. Impression must be overfilled to make solid base to prevent premature separation Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 70 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  71. 71. Master east ready for duplication. Three to 5 mm thick base (line shown by arrow) below level of separating wax to prevent premature separation while cast is handled to make the framework. Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 71 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  72. 72. Base of the cast has been trimmed to line shown by arrows in previous dgm and cast is ready for immersion in boiling slurry water. Portions of old cast may require trimming (arrow) before new impression is poured Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 72 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  73. 73. View from bottom of master cast after base has been trimmed to expose separating wax and wax dovetails. Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 73 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  74. 74. Edentulous portions separated from rest of master cast when removed from boiling clear slurry water. Appearance of dovetails for additional retention for dental stone. Izharul Haque Ansari: A new procedure for separating the edentulous distal extension portion 74 from the master cast when an altered cast is made. J Prosthet Dent 1994;72:666-9.
  75. 75. Alternate boxing technique Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 75
  76. 76. Replacement of impression and framework on master cast after removal of edentulous distal extension areas of cast. Framework is luted to master cast with sticky wax. Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 76
  77. 77. Protection of teeth in master cast with irreversible hydrocolloid. Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 77
  78. 78. Immersion of master cast and frame assembly within supporting base. Framework with corrected impression is seated into a plaster mix contained bv wax boxing sheet. Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 78
  79. 79. • Make a support base mix with an Accu-Dent (Buellton, Calif.) water measure. Mix 2 parts (26 mL) cornstarch (Argo Cornstarch, Best Foods Div, CPC International Inc, Englewood Cliffs, N.J.), 1 part (13 mL) fine pumice, and 1 part (13 mL) plaster. Mix the dry powders and add to 115 mL water. Pour the material into a denture flask. • Let set for 15 minutes. Pour a base with a compatible stone to that of the master cast, filling up the denture flask. Once set, remove from flask. • Separate master cast from the supporting base and irreversible hydrocolloid (this supporting base is easy to remove with one’s fingers). Trim the cast to the desired dimensions Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 79
  80. 80. • Mix 50% cornstarch (Argo Cornstarch, Best Foods Div. C.P.C. International Inc., Englewood Cliffs, N.J.) and 50% white modeling plaster by volume with water to a creamy consistency. Pour this into the boxing wax form. Place the impression in the mixture. • Allow the mixture to set for 10 minutes. Remove and save the boxing wax. • Seal the previously used boxing wax to the trimmed base leaving at least 20 mm from the top of the boxing wax to the highest point on the impression. • Soak the master cast in slurry water for 5 minutes. Pour the cast using the same stone as the original master cast. No separating medium is needed • When the stone is set, remove the boxing wax and place the cast in a water bath of 110” F to facilitate removal of the plaster/cornstarch mixture and the Framework. Separate the plaster/cornstarch mixture with plaster pliers and your fingers. Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 80
  81. 81. Boxing wax placed around plaster base and cast leaving at least 20 mm from top of wax to highest point on impression. Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 81
  82. 82. • Completed altered cast. Completed altered cast. Leila Jahangiri, Patrick Mascarenhas and Donald Kitzis: A simple technique for boxing impressions for fabrication of altered casts. J Prosthet Dent 2001;85:519-20 Kevin D. Plummer:Technique for boxing an altered cast impression. J Prosthet Dent 1982;47:573-575 82
  83. 83. Alternative to altered cast technique Ming-Sheh Chen, W.A. Eichhold, Chao-Chin Chien and D.A. Curtis : An altered-cast impression technique that eliminates conventional cast dissecting and impression boxing. J Prosthet Dent 83 1987;57:471-474
  84. 84. Tissue surface of final impression. Note excess rubber base impression material has been trimmed to internal finish line (arrows) of metal framework. Lingual surface of custom tray. Most of excess final impression material has been trimmed. Only 3 mm of impression material is left over and above border flange. This residual final impression material is later used as a guide to develop ledge of an irreversible hydrocolloid land. Ming-Sheh Chen, W.A. Eichhold, Chao-Chin Chien and D.A. Curtis : An altered-cast impression technique that eliminates conventional cast dissecting and impression boxing. J Prosthet Dent 84 1987;57:471-474
  85. 85. Tissue surface of distal-extension irreversible hydrocolloid pickup impression. Irreversible hydrocolloid is purposely overextended 3 to 5 mm around distal-extension region. 85
  86. 86. Irreversible hydrocolloid pickup impression after trimming is completed. Note a land of irreversible hydrocolloid impression material that is 3 mm in width and 3 mm below crest of border flange. It shows relationship between final impression, irreversible hydrocolloid land, and stock metal tray. 86
  87. 87. Tissue surface of final impression is surrounded by a uniform land of irreversible hydrocolloid. 87
  88. 88. Tissue surface of pickup impression. Note wax blockout (arrows) of all undesirable mechanical undercuts. There is no blockout of major connectors, rests, and reciprocal clasp arms 88
  89. 89. Master cast obtained by this method. Note uniform stone land transition in distalextension regions. 89
  90. 90. Alternative to altered cast technique Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression procedure for tooth-mucosa–supported removable partial dentures. J Prosthet Dent 1998;80:259-61 90
  91. 91. Aluminum foil and two sheets of baseplate wax over diagnostic cast before tray fabrication. Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression procedure for tooth-mucosa–supported removable partial dentures. J Prosthet Dent 1998;80:259-61 91
  92. 92. Custom tray fabricated with extensions reduced 2 mm short of vestibule. Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression procedure for tooth-mucosa–supported removable partial dentures. J Prosthet Dent 1998;80:259-61 92
  93. 93. Custom tray with softened modeling compound reseated on diagnostic cast. Modeling compound over residual ridges shaped appropriately before intraoral placement. Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression procedure for tooth-mucosa–supported removable partial dentures. J Prosthet Dent 1998;80:259-61 93
  94. 94. Border molding procedure completed. Herman B. Dumbrigue and Josephine F. Esquivel: Selective-pressure single impression procedure for tooth-mucosa–supported removable partial dentures. J Prosthet Dent 1998;80:259-61 94
  95. 95. Trial of metal framework,altered cast technique and interocclusal record in one appointment 95
  96. 96. Technique 1 • Richard Bauman and James DeBoer :A modification of the altered cast technique. J Prosthet Dent 1982;47:212-213 A custom tray was fabricated over the metal framework in the edentulous portion. A wax occlusal rim was fabricated over the custom tray 96
  97. 97. Border molding is completed. Final impression is completed in material of choice Richard Bauman and James DeBoer :A modification of the altered cast technique. J Prosthet 97 Dent 1982;47:212-213
  98. 98. Interocclusal record is made by placing low fusing modelling compound over the wax rim to record the interocclusal relationship Richard Bauman and James DeBoer :A modification of the altered cast technique. J Prosthet 98 Dent 1982;47:212-213
  99. 99. An over impression of the entire assembly in irreversible hydrocolloid Richard Bauman and James DeBoer :A modification of the altered cast technique. J Prosthet 99 Dent 1982;47:212-213
  100. 100. Technique 2 • Lih-Shou Lay,Wing-Hong Lai and Chen-Tsye Wu :Making the framework try-in, altered-cast impression, andocclusal registration in one appointment. J Prosthet Dent 1996;75:446-8. 100
  101. 101. Wax used to block out undercuts around framework over edentulous portion of cast. Autopolymerizing acrylic resin tray material formed over edentulous ridge portion of framework. Trays detached from framework. Custom-made trays attached to framework with acrylic 101 resin.
  102. 102. Index grooves on occlusal surface of trays. Jaw relation record (yellow) made in mouth with framework and record base in place. Altered cast poured without removal of jaw registration material. 102
  103. 103. Technique 3 • U. Santana-Penín and J. Gil Lozano: An accurate method for occlusal registration and altered-cast impression for removable partial dentures during the same visit as the framework try-in. J Prosthet Dent 1998;80:615-8. 103
  104. 104. Light-cured acrylic resin tray formed over edentulous ridge portion of framework. Holes are made in tray to allow resin columns to be built up through it. Position of holes can be marked with pencil so that it is clear where to locate bases of columns (arrows). U. Santana-Penín and J. Gil Lozano: An accurate method for occlusal registration and alteredcast impression for removable partial dentures during the same visit as the framework try-in. 104 J Prosthet Dent 1998;80:615-8.
  105. 105. Acrylic resin trays (with holes for resin columns) detached from framework Framework in mouth showing 1 inch resin column built up as jaw relation index. 105
  106. 106. Framework in mouth showing 1 resin column built up as jaw relation index. Acrylic resin tray in position on framework after building up resin column (a) that acts as jaw relation index. In addition, stone index beneath major connector (b) will facilitate accurate repositioning of framework on altered cast. 106
  107. 107. Completed impression seated on cast from which edentulous ridges have been removed. Impression is boxed, in this case with plasticine. 107
  108. 108. Finished altered master cast, with impression and jaw relation indexes (arrows) in place. Resin columns are used to relate mandibular cast to previously mounted maxillary cast, and are attached to lower arm of articulator with stone. 108
  109. 109. Richard P. Frank et al :Clinical Outcome Of Altered Cast Impression Procedure Compared With Use Of A One Piece Cast J Prosthet dent 2004;91:468-76 Altered cast procedure does not offer significant advantages over one piece cast if the following standards are met : • Complete extension of impression • Use of magnification to adjust and ensure complete seating of the framework. • Coverage of retromolar pad and buccal shelf area by the base 92 109
  110. 110. REFERENCES • Essential of Removable partial denture – Applegate • Removable Partial Prosthodontics – Miller • Partial dentures – Osborne & Lamiae • Advanced removable partial dentures – Brudvik • Clinical dental prosthetics –Fenn ,Liddelow and Gimson’s 110
  111. 111. REFERENCES • Treatment of partially edentulous patients – Louis Boucher • J.Pros.Dent. July,2004 :volume 24;number1 • J.Pros.Dent May – June 1992 : Volume 15;number 3 111

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