3 impression new 1

4. A complete denture impression is a negative
registration of the entire denture bearing,
stabilizing, and peripheral (border) seal areas
present in the edentulous mouth. from which
a positive likeness or a cast can be made
Definition:
It is one of the most important steps in denture
construction as all steps depend on it.

Making Or Taking ?

5. Maxillary arch
1. The labial frenum
2. The labial vestibule
3. The buccal frenum
4. The buccal vestibule
5. The residual ridge
6. Maxillary tuberosity
7. Posterior palatal seal
 The hamular notch
 The fovea palatina
 Vibrating lines
8. Hard palate
9. Median palatine suture
10. Rugae area
11. The incisive papilla
Mandibular arch
1. The labial frenum
2. The labial vestibule
3. The buccal frenum
4. The buccal vestibule
5. The residual ridge
6. The buccal shelf area
7. The external oblique ridge
8. The retromolar bade
9. The lingual pouch
(Retromylohyoid space)
10. The mylohyoid muscle
11. The sublingual fold
(Crescent area )
12. The lingual frenum

6. Maxillary arch

7. Mandibular arch

8. Maxillary landmarks Mandibular landmarks

9.  must attain maximum area coverage within
anatomico-physiological limits.
 develop a border seal without interference
with the functional movement of the border
tissue
 reproduce the foundation and border
tissues accurately. ( surface details)
 To equalize forces on the denture
foundation area.

11. 1. Preservation of the remaining
structure
2. Support
3. Stability
4. Retention
5. Esthetics

12.  Pressure in the impression technique is
reflected as pressure in the denture base and
results in soft tissue damage and bone
resorption.
 Patients with special cases need some
precautions during impression making to
prevent tissue damage.
 By maximizing denture base coverage within
the limit of health & function of the tissues
reduce the occlusal load per unit area

14.  the resistant to the vertical components of
the force of mastication
 Maximum coverage provide the snowshoe
effect, which distributes applied forces over
as wide an area as possible.

15.  The quality of a prosthesis to be firm, steady,
or constant to resist displacement by
functional horizontal or rotational stresses.
 Close adaptation to the undistorted mucosa
is most important to resist horizontal
movement.

16.  The ability of the denture to withstand
force of dislodgment in vertical direction
 Atmospheric pressure:
Depends on peripheral seal which ensured by
extension of denture borders to the length of
the vestibular fornix (movable tissue).
 Muscle control.

18.  An impression will act as a foundation for
improved appearance
 Border thickness was varied in each patient
in accordance to extent of residual ridge
resorption
 The vestibular fornix should be filled, but not
overfilled, to restore facial contour.

20. 1 – Preliminary impression
(primary impression)
2 – Final impression
(secondary impression)

21.  Preliminary impression is a negative likeness
of the denture bearing area made for the
purpose of diagnosis, treatment planning and
the fabrication of a custom tray.

22.  1. To provide the study cast.
 2. To provide a cast for the fabrication of a
final impression tray.
 3. In some techniques the impression itself
is modified for use as a final impression
tray.

23. An instrument which will carry the impression
material inside the mouth , hold it until hardens,
then help it's removal from the mouth.
Parts of the tray :
Body (floor& flange)
Handle
For completely edentulous patient the tray has
rounded floor ,short flange and L shaped handle
For dentulous patient the tray has flat floor, long
flange and handle in line with the floor

24. Types
Stock for 1ry imp.
Special or custom made
Metallic
Plastic
Perforated
Non Perforated
Aluminum
St. steel.
Autoclavable
Single use

26. Stock tray:
Should be oversize to provide about 3 mm of
space between the inner surface of the tray
and the tissue, and the flanges shouldn’t
impinge on the frenal and muscle
attachements
-Rigid
- Ease of modification
-Compatible with the impression mat.
-Smoothness and comfortable in the oral
cavity
-Ability to be sterilized or disposible

27. Adding
Bending
Cutting
Modification Of Stock Trays

28.  Irreversible hydrocolloid (alginate)
 Impression compound (modeling plastic,
modeling compound)

29.  Stock Tray Selection:
1. According to impression materials:
1. Compound
2. Alginate
2. According to patient mouth:
Based on size of the arch select the tray size which
must be large enough to cover all supporting
areas and seal areas with about 3-5 mm space
and shorter about 2mm from the full depth of
the sulcus.
Solid tray
Perforated

32.  Patient position:

33. -Elbow
-Position of the operator
for maxillary impression
-Shoulder
-Position of the operator for
mandibular impression

36. Sequence of making the
impression ?
The lower impression should be made
first
1- the upper may cause greater
discomfort and stimulation of reaching
reflex
2-increase rate of salivation may affect
lower impression

41. The impression should be
carefully examined immediately
after removal from the mouth
for…….. ??????
Common faults in impression
making (alginate or impression
compound)……….????? And its
causes ???

42. V. I.
Do not forget
cross infection
control

45. Final Impression
?

46. Final (2ry) Impression:
Is a negative registration of the entire
denture foundation and border seal areas
present in the edentulous mouth to ensure
maximum support, retention and
stability for the denture during use'.

47. According to Devan, the difficulty in making edentulous
impression is due to the fact that the mouth is lined with
tissue of varying displaceability.
The amount of tissue displacement varies according to
tissue’s thickness, its rigidity, the force applied to it, and
its anatomic location in the mouth
The forces directed to the tissues during impression
making is directly influenced by:
1- The viscosity and flow of the impression material used
2- type of the impression tray made
3- forces exerted upon the tray when the impression is
being made

48. CLASSIFICATION OF final
IMPRESSION MAKING TECHNIQUES
The Final Impression techniques have
been classified in different ways,
either depending on the degree of
mouth opening (closed or open
mouth impression techniques) or on
the amount of pressure exerted on
the tissue during impression making

49. 1. Minimal-pressure Impression Technique
(At rest or, Muco- static Impression Technique)
2. Muco- compression Impression Technique,
3. Selective- pressure Impression Technique,
4. Functional impression technique

50.  Definition:
This is a negative representation of the
denture supporting area under a static
condition of the mucous membrane. The
impression made under minimal pressure
and the oral tissues are recorded at
minimal displacement.
1. Minimal-pressure Impression Technique

51.  Requirements:
1. Fluid impression materials are used to record
the supporting area without distortion and
pressure.
2. Rigid special tray with perforation and, spaced
with definite stoppers.
3. The ideal impression material is plaster of
paris.
4. Used open mouth technique.

52.  Advantages:
1. By using open mouth impression technique;
The operator can see the proper border
molding and the various muscle movement
can be accomplished easily.
2. Applied minimal pressure lead to decreased
tissue distortion and bone resorption.
3. It’s the technique of choice in cases of flabby
ridges and in those patients liable to severe
bone resorption.

53.  Disadvantages:
1. The mucosal topography is not static over the
day.
2. The mucostatic principle neglect the value of
distributing masticatory forces over good
supporting areas and relief the sensitive
areas.
3. There is reduction in the length of the flange
4. doesn’t cover the maximum amount of
available tissue

54. Plaster of Paris impression

55. 2. Muco-compression Impression Technique
Definite- pressure impr.
 Definition:
This is a negative representation of the
denture supporting area under pressure
while the impression material set. This
impression is usually made under biting
force, the greater the biting force the more
the displacement of soft tissue and their
fluid content.

56.  Requirements:
1. Impression materials used should have a
relatively longer setting time and not be easy
flow, to allow functional movements of border
tissues.
2. Rigid, non-perforated special tray with closed
fit and occlusion rim may be used.
3. The ideal impression material is zinc-oxide
impression material.
4. Used closed mouth technique, or open mouth

57.  Advantages:
1. The main advantages is that it provide
excellent retention
2. Provide maximum area coverage by the
denture

58.  Disadvantages:
1. The denture did not fit well at rest, because
tissue rebound.
2. The impression made with closed mouth
technique don’t allow for adequate border
molding .
3. The muco-compression interfere with blood
supply and therefore accelerate resorption of
the alveolar ridge.

59. 3. Selective-pressure Impression Technique
 Definition:
This is a negative representation of the
different denture supporting areas with
different pressure applied. Based on; Some
supporting areas can withstand masticatory
force (1ry Sa), other can withstand less
force (2ed Sa), other can’t withstand forces
(sensitive areas), must be relifed.

60.  Requirements:
1. Compound impression used as a special tray.
2. Modification of the compound impression:
 Fitting surface; by scraping the compound in
different areas according to the type of support
gained ( 1ry, 2ed or relive area)
 Border moulding and refinement.
3. The final impression is completed by wash
impression materials (plaster, thin mix of
zinc oxide or alginate)

62. 4. Functional Impression Technique
Uses a complete denture that is delivered,
relieved on its internal aspect , and filled
with a slow setting imp. Material (tissue
conditioning material) the patient wears the
prosthesis for several days, allowing the
tissues to be recorded in function

63. Custom Trays:
 Strong
 Adjustable
 comfortable

64.  Try-in of the tray for refinement of it’s
borders and evaluation of fit and stability.
 Border molding of the impression tray.
 Registration of tissue detail with a suitable
impression materials: Zno/eug. , Rubber
base, Plaster , tissue cond. Mat.

66. Sequence-maxillary

67. Border Molding
Sequence- mandible

71. Final impressions may have to be remade for a
number of reasons such as:
1- Voids too large for accurate correction
2- incorrect consistency of the impression
material when the tray was placed in the
mouth
3- excessive pressure spots in critical areas
4-errors in border formation
5-incorrect placement of the tray in the pt
mouth
6-movement of the tray before the impression
mat. Has set

72. V. I.
Do not forget
cross infection
control

73. The final imp. Is
then poured to
get the master
cast & occlusion
blocks for jaw
relation record

75. References:
Hassaballa M, Clinical Complete Denture Prosthodontics, 2nd.
ed., King Saud University Academic Publishing and Press, 2010.
Chapter 6 pg:100-154
-Prosthodontic Treatment for Edentulous Patients. (Zarb,
Hobkirk, Eckert and Jacob) ( chapter 8) 13th ed.