This document discusses impression procedures for removable partial dentures. It defines partial denture impressions and differentiates them from complete denture impressions. Various impression techniques are described including anatomic form impressions, functional impression techniques like McLean's method and the functional reline method. The document reviews literature on modified techniques like the altered cast technique and selective tissue placement impressions. It emphasizes the importance of functional impressions to distribute load and maximize longevity of remaining structures. In summary, the choice of impression technique impacts the support, function and longevity of the resulting removable partial denture.

1. Impression Procedures in Removable Partial
Denture
Guided by:
Dr. U.M. Radke Dr. N.A. Pande Dr. S Deshmukh
HOD & Guide Professor Reader
Dr. T.K. Mowade Dr. R. Banerjee DR. A. Chandak
Reader Reader READER
Presented by:-
Dr. Richa Sahai
II MDS

2. Contents • Introduction
• Definitions
• Rpd impression vs Complete denture impression
• Impression techniques
• Anatomic form impression
• Functional impression techniques
• Review of literature
• Recent Advances
• Summary and Conclusion
• References

3. • A widely accepted axiom of removable partial prosthodontics holds that
it is fully as important that  the denture be designed and constructed
in such a way as best to preserve the oral structures as it is to restore
function.
• The principle of functional basing is employed to create conditions which
favor maximum longevity of the remaining structures.
INTRODUCTION

4. Impression
A negative likeness or copy in reverse of the surface of an object ; imprint of
teeth and adjacent structures for use in dentistry. GPT – 9
Partial Denture Impression
A negative likeness of a part or all of a partially edentulous arch. GPT – 9

5. Impression trays
A receptacle in to which suitable impression material is placed to make
negative likeness
OR
A device that is used to carry, confine and control impression material while
making an impression.

6. Impression trays can be classified broadly into :
Stock trays and Custom trays

7. 1. By the manner in which they Harden or Set :
• Impression plaster
• ZOE
• Alginate
• Elastomers
Chemical / Irreversible
• Thermoplastic
• Impression compound
• Waxes
• Non-thermoplastic
• Agar
Reversible
Phillips-science of dental material,11th edition
Classification of impression materials

8. Non-elastic
Elastic
Aqueous
Hydrocolloid
Non-aqueous
Elastomers
Polysulfide
Silicones
Polyether
Condensation
Addition
Agar
(reversible)
Alginate
(irreversible)
Plaster
Compound
ZnO - Eugenol
Waxes
2. According to elasticity :

9. 3.According to the use of the materials in dentistry :
A) Materials used for obtaining impression of Dentulous mouth
• Alginate
• Agar
• Non-aqueous Elastomers
B) Materials used for obtaining Impression of Edentulous mouth:
• Impression Compound
• Impression Plaster
• Zinc Oxide eugenol
• Wax

10. • Impression plaster
• Agar
• Alginate
Mucostatic
• Impression Compound
• Putty elastomersMuco-compressive
4. According to the viscosity or tissue displacement:

11. RPD IMPRESSION
• Records not only relative
soft yielding tissues as
well as a hard unyielding
substance .
CD Impression
• Records the edentulous
mucosa with underlying
bone only.

12. To Start :
1. PRIMARY IMPRESSION; Study casts
2. Checking Maxillary Tray and Mandibular tray For Correct Size.
3. Control of Gagging
4. Control of Saliva

13. 1. Bubbles or voids
in and around rest
preparations.
2. Contact of
cusp with the
tray.
3. Show through
between teeth and
modeling plastic or
modeling plastic and
hard palate
4. Voids or
bubbles in
palatal vault.
5.Peripheral under
extension.
6. Interproximal
tearing of the
impression
material.
7. Lack of detail on
the impression
surface.
8. Any doubt as
to the accuracy
of the
impression.

14. Types of Impression
Techniques
Anatomic form Functional form

15. • The proponents of functional impression put great emphasis on the tissue
compression to get a registration of “Functional ridge form” in order to place
load properly on ridge and there by minimize cantilever action on abutment
teeth.
• Two requirements must be satisfied:
– That it records and relates the supporting soft tissue under some loading.
– It distributes load over a maximum area and establish precisely accurate
functional borders for the denture.

16. FUNCTIONAL IMPRESSION METHODS
• Mc.Leans
• Hindel’s method
• Functional reline method
• Fluid wax method
PHYSIOLOGIC
IMPRESSION
TECHNIQUE
• Equalizes the support between the
abutment teeth and the soft tissue.SELECTIVE PRESSURE
IMPRESSION METHOD

17. McLean’s Physiologic Impression

18. 1. Fabrication of the custom-made impression tray
over the edentulous areas of the preliminary cast.
2. Making of the occlusal rim on the custom tray.
3. Impression material loaded on the tray is inserted
into the patient’s mouth.
4. An alginate over-impression is made by using a
large stock tray.
• The functional master impression will come along when the over-impression is
removed and it is called as ‘pick up’ impression.

19. McLean’s Physiologic Impression

20. Disadvantage:
• The finger pressure had to be applied on the hydrocolloid impression tray
during the ‘over-impression’.
• This finger pressure could only be approximated to the occlusal load applied
earlier.

21. McLean-Hindels Impression Technique
• These trays had large holes in posterior segment so that the operator could
apply finger pressure to functional impression as the hydrocolloid impression
was being made.

22. 1. Fabrication of the occlusal rim in a special tray using the
primary cast.
2. The supporting tissues under rest – anatomical
impression is recorded by special tray.
3. Large holes with over impression is made by a special
stock tray.
4. A pseudo-functional stress is gave by pushes the
edentulous ridge by using the finger pressure on the
special tray.

24. The chief modifications were:
Impression of the
edentulous ridge was
made in the anatomic
form made with zinc
oxide eugenol and
not under finger
pressure.
However, when the
over impression was
being made with the
hydrocolloid, finger
pressure was applied
through the modified
tray to the anatomic
impression.
The pressure had to
be maintained till the
alginate sets.
The finished
impression was a
reproduction of the
anatomic surface of
ridge and the surfaces
of teeth but the two
were related to each
other as if the
masticating forces
were taking place on
the denture base.

25. Disadvantages:-
• If the action of the retentive clasps of RPD is sufficient in order to maintain
the denture base in soft tissue displace, blood vessels interruption will occur
with worst soft tissue destruction and bone resorption.
• If the action of the retentive clasps of RPD is not sufficient in order to
maintain the denture base in soft tissue displace, it will result in artificial
teeth premature contact.

26. Functional Reline Method
• It consists of adding of a new surface to the tissue side of the denture base.
• The procedures of this technique should be done before the insertion of
RPD.
• It also can be done later in future if the denture base having loose or no
longer fits to the ridge due to bone resorption. (Steffel, 1954)

27. Procedure :
1. Partial denture frame work is constructed on cast made from single
impression. (anatomic form)
2. To allow room for impression material between the denture base and the
ridge, a uniform space is provided by adapting a metal spacer over ridge of
cast before processing the denture base.

28. 3. After processing the denture base, metal spacer is removed and uniform
space is achieved.
4. Low fusing modeling plastic is applied onto the tissue surface of denture
base, tampered and placed in patient’s mouth.

29. • To provide space for impression material 1mm of modeling plastic is
removed and impression is made with free flowing zinc oxide- euqenol
paste or light bodied polysulfide rubber base.

30. Advantages:
• The amount of soft tissue
displacement can be controlled
by the amount of relief given to
the modeling plastic before the
final impression is being made.
Disadvantages:
• Failures to maintain correct
relationship between framework
and abutment teeth, during
impression procedure
• Failure to achieve correct
occlusal contact following reline.
• The patient must keep the mouth
partially open because the
border tissues, cheek and tongue
are thus best controlled
• The relationship between partial
denture framework and teeth
must be observed

31. Fluid Wax Functional Technique
• Objective  Obtaining maximum denture base peripheral borders extension
which it will not interfered with the movable border tissues function.
 It also used in ridge stress-bearing areas recording for functional
form and recording of non pressure- bearing areas in anatomic form.
• The borders made should be short for all movable tissues which is not more
than 2 mm short. This is due to the insufficient strength of fluid wax to support
itself beyond the distance.

32. OBJECTIVE
To obtain maximum
extension of
peripheral borders
while not interfering
with function of
movable border
tissues.
To record stress
bearing areas of
the ridge in their
functional form.
To record non
pressure bearing
areas in their
anatomic form.

33. 1. A container of wax is placed in water bath
maintained at 51°C-54°C.
2. Wax is painted onto impression surface with
brush.
3. The tray is then seated in the mouth and the patient
must hold his mouth half open for about 5 min; the
impression is left in the mouth for 12 min.
The new cast need to be poured as soon as possible after the impression is
completed. This due the wax fragile and might be distortion.

34. Disadvantages
1. Time consuming.
2. Accurately followed timing of procedures.
3. The excessive tissue displacement might result to the impression if the
timing period is not followed properly as mentioned.

35. Selective Tissue Placement Impression method
OBJECTIVES
1. This attempts to direct more force to those portions of the ridge that are able
to absorb stress without adverse response.
2. Protect the areas of the ridge which is least able to absorb force.
• Buccal shelf is primary stress bearing area, as a result only sight relief is
provided.
• The crest of the ridge is not stress bearing area and hence the surface of the
tray is relieved down to metal retention using laboratory bur.

36. 1. fabrication of the special tray on the master cast from
the anatomical impression.
2. Trimming of the special tray tissue surface by using
burs for adequate relief.
3. prepared special tray is loaded by impression
material, such as zinc oxide eugenol and inserted into
the patients’ mouth.

39. The framework is placed in the mouth and great care is to be taken ensuring that it is
seated on the teeth by pressure on the occlusal rests & indirect retainers only - no
finger pressure is applied to the base area. Once the framework is fully seated,
border moulding is carried out.

40. Altered Cast Technique
FIG 1 Fig 2
Contemp Clin Dent. 2010 Apr-Jun; 1(2): 103–1
Objective  To reduce the support differential for a free-end saddle by
obtaining a compressive impression of the edentulous area under conditions
which mimic functional loading.

41. FIG 3 FIG 4
Contemp Clin Dent. 2010 Apr-Jun; 1(2): 103–1

42. FIG 5 FIG 6
FIG 7 Fig 8

43. Fig 9

44. FIG 10 FIG 11

45. FIG 12 FIG 13

46. John B. Holmes* conducted a study to determine the “Influence of impression
procedures and occlusal loading on partial denture movement”
He concluded that:
1. The movement of partial dentures from occlusal loading is related to the
impression technique and material used.
2. The altered cast technique provided the least amount of movement from
occlusal loading at the time of insertion .
3. Partial dentures made with Korecta wax 4 (altered cast) resulted in least
amount of movement. *J PROSTHET. DENT. May 1965:15(3);474-481

47. REVIEW OF LITERATURE

48. Modification of Altered Cast Technique
Technique :
Richard Bauman & James- JPD 1982(47) 2,212-213

49. FIG 3 FIG 4
FIG 5
FIG 6
Richard Bauman & James- JPD 1982(47) 2,212-213

50. • Pour a completely new master cast into the combined impression.
• After the stone has set, remove the metal tray and irreversible hydrocolloid
impression material.
• Mount the new master cast on the articulator by means of the interocclusal
record.
• Arrange the teeth and process the denture base.
Richard Bauman & James- JPD 1982(47) 2,212-213

51. Technique for semi-precision
and precision partial dentures

52. *Louis Blatterfien et al. J Prosthet. Dent, 1980:43 (1);9-14
FIG 1 Fig 2
FIG 3 FIG 4

53. FIG 5 FIG 6
FIG 7 FIG 8*Louis Blatterfien et al. J Prosthet. Dent, 1980:43 (1);9-14

54. FIG 9
FIG 10
FIG 11
*Louis Blatterfien et al. J Prosthet. Dent, 1980:43 (1);9-14

55. Roberto von Krammer. J Prosthet. Dent, Aug 1988:60(1);199-201

56. FIG 1 FIG 2
FIG 3 FIG 4Roberto von Krammer. J Prosthet. Dent, Aug 1988:60(1);199-201

57. FIG 5 FIG 6
FIG 7 FIG 8
Roberto von Krammer. J Prosthet. Dent, Aug 1988:60(1);199-201

58. FIG 9 FIG 10
Roberto von Krammer. J Prosthet. Dent, Aug 1988:60(1);199-201

59. Impression technique for maxillary
removable partial dentures
- C D. LEACH & T E. DONOVAN JPD 1983 (50)2,283-285

60. Fig 1 Fig 2
Fig 3

61. Fig 4 Fig 5
Fig 6

62. Single tray dual impression for
distal extension partial dentures
JOSEPH A. R- JPD 1970(24,1,41-46)

63. Joseph A. Rapuano. J Prosthet Dent, July 1970:24(1);41-46
Fig 1 Fig 2
Fig 3 Fig 4

64. Fig 5 Fig 6
Fig 7
Fig 8
Joseph A. Rapuano. J Prosthet Dent, July 1970:24(1);41-46

65. Fig 9 Fig 10
Joseph A. Rapuano. J Prosthet Dent, July 1970:24(1);41-46

67. Summary and Conclusion
Impression procedures
Anatomic form Functional form
Physiologic impression
procedures
Selective tissue
placement impressions
The cast is altered to relate
the teeth in anatomic form to
the mucosa in functional form
Patient comfort, functional
application and longevity of the
prosthesis
Tooth supported
removable partial
dentures

68. “Unless a partial denture is made with adequate
abutment support, optimal base support and with
harmonious and functional occlusion, it should be
clear to all concerned that such a denture should
be considered only a temporary treatment”

69. 1. Glossary of Prosthodontic Terms -8 th Edn, 2005.
2. Stewart, Rudd, Kuebker : Clinical Removable Partial Prosthodontics.
3. McGivney GP, Alan B Carr David T Brown : McCracken’s Removable Partial
Dentures-11 th Edn.
4. Joseph E. Grasso, Ernest L. Miller : Removable Partial Prosthodontics.
5. Alan A. Grant, Wesley Johnson : Removable Partial Dentures.
6. APPLEGATE OC. An evaluation of the support for removable partial
denture. J PROSTHET DENT 1960; 10:112-23.
References

70. 7. HINDEL GW. Load distribution in extension saddle denture. J PROSTHET DENT
1952; 22:92-100.
8. HINDEL GW. Stress analysis in distal extension partial. J PROSTHET DENT
1957; 7:197-205.
9. HOLMES JB. Influence of impression procedures and occlusal loading on
partial denture movement. J PROSTHET DENT, 1965; 15:474-81.
10. F. James Kratochvil : Partial Removable Prosthodontics.
11. Robert P. Renner, Louis J. Boucher : Removable Partial Dentures.
12. Kenneth D Rudd, Morrow: Dental Lab, Procedure for Removable Partial
Dentures.