1. Retentional factors

2. Retentional factors
1. Clinical anatomical features
2. Physical features
3. Retention aids

3. Functional stability= denture usage
Stability during
fonation:
The denture does not
move disturbingly from
the mucosal-bony base
during fonation ,mouth
opening and closing,
swallowing, articulation
in connection with
fonation
Stability during
mastication:
The denture does not
move disturbingly from
the mucosal-bony base
during mastication and
articulation in
connection with
mastication

4. 1. Clinical anatomy features
I. The size of the mucosal bony base that
is suitable for bearing mastication forces
II. The height of the edentulous alveolar
ridge
III. Retential areas
IV. Neuromuscular forces

5. The useable place which can bear the
masticatory pressure
Alveolar process is the edentulous alveolar
ridge after losing natural teeth.
In case of severe resorption the body of the
mandibule is covered by the base of the
denture.
The height of the alveolar process will inhibit
the horizontal displacement of the denture.

6. The useable place which can bear the
masticatory pressure
 Upper arch: 3937 mm2
 Lower arch: 1770 mm2
 It is approximately equal with the polished
surface of the baseplate
 This area play an important role in keeping
denture in place

7. The size of the mucosal bony base, that is suitable
for the retention of the denture, influence:
Effectiveness of the physical forces
Mastication force that loads the mucosal bony
base (24-25 N)

8. 1. Clinical anatomy features
III. Retentional areas
on the upper jaw:
Maxillary tuber
High and curved
quadrangular shaped
ridge
Undercut area between
the buccal frenules in
the vestibule

9. 1. Clinical anatomy features
III. Retentional
areas on the lower
jaw:
Lingual fossa

10. 1. Clinical anatomy features
III. Retentional
areas on the lower
jaw:
Edentulous ridge:
totally preserved high
ridge

11. 1. Clinical anatomy features
IV. Neuromuscular forces:
The surrounding muscles and active and
passive muscle functions have the most
important stabilizing effect
The oral mucosa (bucca, lips, tongue) and
the underlying musculature touch and
load the polished surface of the denture
with various forces during mastication (20-
30 N)

12. 2. Physical forces
1. Capillary pressure
2. Ventill effect (inner/outter)
3. Gravity
4. Masticatory pressure

13. I. Capillary pressure (upper/lower):
Surface tension of the saliva between the
denture baseplate and the mucosa
Adhesion: connecting force between unlike
molecules (mucosa-saliva)
Cohesion: connecting force between alike
molecules (saliva-saliva)
If the saliva film is thinner, the force of
retention will be better
Lack or overproduction of saliva affect
negatively for retention

14. II. Ventill effect (upper/lower):
Seal the border of the
denture
Vacuum is created under the
denture base
Inner ventill effect:
The border of the denture is
sinked into the mobile
mucosa
Outter ventill effect:
Connection between the
mucosal surface of the
denture and the

15. III. Gravity (lower)
Casted metal base
Casted metal arteficial teeth
Max.:32-35 g
The excessive loading cause atrophy
Masticatory pressure:
Natural dentition: 120-140 Kpa
Edentulous: 20-30 Kpa

16. IV. Masticatory pressure:
The denture stability by masticatory forces
depends on the occlusal pattern of the
arteficial posterior teeth:
 Anatomical arteficial posterior teeth:
Different OV width
Angle between the slope of the cusp and
horizontal plane is different (20-45 degree)
Material can be ceramic or acrilic
It has always shifter effect
It cause horizontal displacement of the
denture

17. 2. Physical forces
Non-anatomical arteficial posterior teeth:
It has stabilizing effect
Mechanical occlusal-surfaced molar:
the occlusal surface is non-anatomical
the vestibular, oral and approximal surfaces are
anatomical
Mechanical molar:
it is not compare of the natural teeth

18. French-type artifical posterior teeth
It was used on older
people in abrasive teeth

20. Myerson-type
Normal artificial teeth
has flat, shallow fissure
Transversal cutter
Marginal cutter

21. 2. Conclusion of physical forces
Prosthetic function is more important than
cosmetic ones in the posterior region:
Stabilization of the denture
Protection of the mucosal bony base
Better mastication

22. 3. Retention aid
Denture fixative:
Unfavourable situations
Nervus system disorders
Surgical or congenital defects
Shortening initial learning period

23. Retention aid
Microvalves, denture adhesives (Corega)
Suction disc (don’t use it)
Denture spring (don’t use it)
Grooves cut into the palate of the master cast