The Pt. adaptation on his complete dentures are based on the ability of the dentures to restore the missed functions due to the loss of the teeth. Good impression is the first step in the success of the complete dentures. A trial to review all the basics necessary to have a good impression is exposed in this lecture.

1. IMPRESSIONS FOR
CONVENTIONAL COMPLETE
DENTURES.
Dr. Bahjat Abu Hamdan.
Consultant Prosthodontist.
DDS, CES, DSO .
Damascus – Syria, Paris – France.

2. 1. Introduction
2. Relevant anatomy and physiology.
3. Patient examination for impressions
4. Impression materials.
5. Classification of impressions
-primary impressions
-secondary impressions
1.compressive. 2. mucostatic . 3. selective.
Conclusion.

3. 1. Introduction.
 The purpose of the CD is to restore
function, aesthetic, phonation and
maintenance of remaining tissues.
 To be able to assume these functions,
dentures should enjoy the following
mechanical qualities:
 Retention
 Stability
 support

4. 1. Introduction
 The following anatomical factors play a
positive or negative mechanical role;
1.Bone size Height and width
2. Maxillo-mandibular relationship.
3. Position and orientation of the occlusal
Plane.
4.Muscle attachment and quality of mucous
tissue.
5.Presence of opposed natural teeth to
edentulous ridge.

5. 1.Introduction.
 Mechanical qualities are also related to all
the steps of complete denture construction
:
1. good impressions.
2. correct JRR
3. correct setting of the artificial teeth
4. well established static and dynamic
occlusion
5. Good processing
6. well formed and polished external surfaces
of the dentures.

6. Mechanical factors

7. Anatomical factors.

8. Practical procedures.

9. 2.Relevant anatomy and
physiology.
 Good knowledge of the anatomy,
physiology and histology of all the
elements in relation with the dentures is
mandatory;
 Bone and mucous tissues.
 Kinetics of the muscles of mastication,
facial expression, tongue and floor of the
mouth.

10. Intra oral drawing of the
maxillary arch.

11. Neutral zone (free of muscle
insertion and muscle action)

12. Intra oral drawing of the
mandibular arch.

13. The disto-lingual limits to the
denture flange

14. Glands in relation with the lower
denture.

15. palatoglossal arch muscles.

16. Lateral view of pharynx

17. Muscles of facial
expression.

18. 3.Patient examination
 Its so important to investigate all the
elements that may affect the procedure
and the quality of the impressions which
affect the quality of the dentures.
 Medical and dental past.
 Extra oral examination.
 Intra oral examination.
 X ray examination.
 Study models.

19. Extra oral examination.( Nilson
triad(

20. Intra oral Exam.
 1. Salivary flow.
 2. Alveolar ridge resorption chronology.
 3. Combination syndrome.
 4. Floor mouth posture and tongue
position.
 5. Neuromuscular control.
 6. Oral diseases and oral lesions.
 7. Existing dentures.
 8. Muscle tonicity.

21. Alveolar ridge resorption
classification.

22. Posterior palatal seal
Posterior palatine salivary
glands
Permits compression of •
tissues
Improves adaptation of •
denture to compensate for
shrinkage of resin
Glandular tissue
Posterior palatal seal

23. Different form of soft palate

24. Measures to slow
resorption.

25. Preventive measures.

26. Floor of the mouth and retruded
tongue.

27. shape of retro-mylohyoid area.

28. Combination syndrome

29. Combination syndrome

30. Severe resorbed lower ridge
due to combination syndrome.

31. Oral diseases and oral lesions.
 Long term insulin dependent (diabetes)
 Oral lichen planus.
 Pemphygoid.
 Chronic candidiasis.
 Inflammatory fibrous hyperplasia.
 Premalgnant lesions
leukoplakia,erythroplakia.
 Malignant lesion.

32. Surgical preparatory treatment.
 Augmentation with bone graft.
 -frenectomy
-tuberosity reduction
-tori removal
-surgical removal of redundant tissue
(epulus fissuratum)
-ridge recontouring e.g. flabby ridges
and -bony undercuts
-removal of remaining teeth and severe
undercut.

33. 4.Impression materials

34. Impression Material Usage*
Civilian General Dentists
 Complete dentures
 alginate 58%
 vinylpolysiloxane 55%
 polyether 27%
 Partial dentures
 alginate 78%
 vinylpolysiloxane 43%
 polyether 15%
DPR 2002

35. Handling Properties

36. Handling Properties

37. Comparison of Properties
 Wettability
 best to worst
○ hydrocolloids > polyether > hydrophilic
addition silicone > polysulfide > hydrophobic
addition silicone = condensation silicone
 Castability
 best to worst
○ hydrocolloids > hydrophilic addition silicone >
polyether > polysulfide > hydrophobic addition
silicone = condensation silicone

38. 5. Classification of impressions
in CD

39. Lower edentulous ridge.

40. Upper edentulous ridge.

41. Preliminary impression

42. Primary impression

43. Final impression.

44. Preliminary and primary
impression
 preliminary impression;
1. Anatomic.
2. Stock tray.
3. Alginate.
4. Surgical preparatory treatment.
5. Occlusal plane adjustment of the
remaining teeth.

45. Preliminary and primary
impression
 Primary impression
1. Anatomic.
2. Stock tray.
3. Alginate or plaster.
4. Indicate on the cast the flabby tissue,
new extraction area, sharp edge, mental
foramina and thin mucous tissue area.
5. Special tray; adapted, spaced or
partially spaced.

46. Preliminary and primary
impression
 In the practice;
 Choose a stock tray insuring 3-4 mm of
space away from the ridge.
 Tray should cover the retro-molar pad
area and extend to the palatoglosse
arch, hamular notch, palatal fovea use
the wax to adjust the extension of the
tray.
 With floating mouth bottom use thicker
consistence dental material.

47. Preliminary and primary
impression
 Stock trays.

48. Primary impression and
custom
tray.
 L to R plaster Imp. Alg. Imp. Anterior
flabby tissue tray and Occ. Rim handle.

49. Final impression
(compressive).
 Factors controlling the pressure applied by the
impression;
 Type of the custom tray adapted or spaced.
 Consistence of the dental material light,
regular or putty.
 Holes opposed to a concerned area means
less pressure.
 Border impression is always compressive in
functional impression and partially
compressive impression. If it is not, impression
is mucostatic (anatomic).

50. Final impression
(compressive).
 Custom tray… adapted or spaced.
 Borders are 2mm far from the labial and
buccal vestibule, 3mm space in the frenum
areas (lateral and median).
 Tray should cover the vibration line area
and hamular notch. Mandibular custom tray;
borders are 2mm far from the border in the
buccal shelf and anterior sublingual area.
Checking up the custom tray is done by pulling
the muscles horizontally in the concerned
area.

51. Final impression
(compressive).
 Border impression includes all the
borders of the maxillae.
 It includes just the buccal shelf and the
anterior sublingual area.
 Muscle M. are done functionally by the
Pt.( open widely, suction and lateral M.
Swallowing, tongue M. Grimace M.).
Muscle M. are done by the dentist in
case of low muscle tonicity.

52. Final impression
(compressive).
 Certain extreme muscle M. coincide with
the functional M.
 Muscle M. (during border impression
can be done by the dentist) but the Pt.
should functionally move his muscle in
the 2nd phase of final impression.
 Border impression is done gradually by
the thermoplastic green Kerr. Or one
using the regular elastic material.
Greene Brothers

53. Functional movements for
border impression.

54. Border impression.
Silicone medium
viscosity
Impregum
Thermoplastic
green Kerr

55. Final impression
(compressive).
 It is important to use occlusal rim as tray
holder ( which represent the missing
teeth) so that the functional M. are close
to the natural.
 The wash material can be ZnO eugenol
paste or light elastic material.
 Preferable silicone by addition.

56. Final impression 2nd phase.
 Silicone (medium)
 Zno eugenol paste
 Silicone light

57. Final impression (mucostatic).
 Advocates of this technique believe that
impression must be recorded in an anatomic
form of the tissues without distortion (resting
form). Harry L page 1938, Addison 1944.
 Dentures constructed by mucostatic
impression technique have shorter flanges.
 Short flanges are used to prevent the dentures
moving in lateral direction and NOT for border
seal.
 Metal bases which are dimensionally stable are
used.

58. Final impression (mucostatic).
 Dentures do not cover wide area.
 No border impression.
 Based on the adhesion, cohesion and surface
energy but not on the atmospheric pressure
(border seal).
 It works only when there is good ridge and
high alveolar bone.
 Denture mobility during function (mucous
depression is 4/10 – 10/10 mm)
(compressibility of periodontal tissue is 1/10
mm) .Bone compressibility is related to bone
quality ( cancellous or cortical ).

59. Final impression (selective
pressure).
 Boucher 1950.
 Principles of this technique is that
certain areas of the maxilla and the
mandible are by nature better adapted
to withstand extra loads from the forces
of mastication.
 Tissues adapted for withstanding extra
loads are recorded under slight
placement of pressure while other
tissues are recorded at rest (mucostatic)

60. Upper edentulous ridge

61. Lower edentulous ridge

62. Final impression (selective
pressure).
 In this way an equilibrium is created between
– the resilient and
- non resilient tissues.
Primary stress bearing areas are recorded under
pressure; crest of alveolar ridge, horizontal plate of
palatine bone in the maxillae and buccal shelf area
in the mandible.
Areas requiring minimum pressure; mid-palatine
suture, incisive papilla, crest of mandibular ridge,
mandibular tori, mental foramina, sharp painful
edge, flabby tissue, remaining roots in case of
over-denture and new extraction areas.

63. Final impression (selective
pressure).
 Posterior palatal seal has glandular and
soft tissues are readily to be displaced for
maintenance of peripheral seal.
 Sublingual area has similar tissue structure
and behaviour as the posterior palatal seal.
 Border impression includes all the borders
of the maxilla, but it includes just the buccal
shelf and the sublingual areas in the
mandible. (after a good prime impression).

64. Final impression (selective
pressure).
 Sublingual area is molded with the
tongue in repose.
 The tray is extended horizontally
backward over the sublingual glands
toward the tongue to affect border seal.
 Pts with old dentures should remove it
24 hours before the final impression.
( mucous tissues should be at rest and
normal situation).

65. Conclusion.
 In certain cases, even if all the steps
are well done mechanical qualities of the
dentures are spoiled so that patient will
not arrive to adapt on, these cases are
confronted in case of lack of saliva and
paralysis and low tonicity of the muscles
in relation with the dentures.
 Helping these Pts. Will be through the
use of denture adhesive to improve the
retention and the Pt. ability to adapt on.

66. Conclusion.
 Indication of denture adhesive;
 Xerostomia ( medication, systemic
diseases, irradiation and disease of
salivary glands)
 Neurological disorders;
 Oro-facial dyskinesia ( muscles of lips,
cheek, tongue and face )
 Medication side effects ( neuroleptic,
dopamine blocking drugs, pheothiazine
and GI medications ) .

67. Thanks for your
attention
E mail. ahbahjat@yahoo.fr