1. Principles of complete denture
Lecturer
Hatem Dousouky Ahmad

2. Lecture out line Steps of complete denture construction.
Indications and contra indications of complete dentures.
Difference between natural and denture teeth.
Retention in complete dentures.
Support in complete dentures.
Stability in complete dentures.

3. 1-Steps of complete denture construction.
Clinical steps
Laboratory steps
Step 1
Examination and diagnosis.
primary impression.
Pouring the 1ry impression to obtain primary cast.
Construction of special tray.
Step 2
Final impression
Pouring final impression to obtain master cast.
Construction of occlusion blocks.
Step 3
Jaw relation record.
Selection of artificial teeth.
Mounting the occlusion blocks.
Setting up of teeth.
Step 4
Try in stage
Waxing up.
Flasking, wax elimination, packing of acrylic resin, curing, remount and finishing. 5
Clinical remount (if needed). 6
Delivery of complete dentures

4. 2- indications and contraindication of complete dentures
Contra indications:
All edentulous arches are indicated for complete dentures unless there is a temporary or a permanent reason preventing the treatment
Temporary factors:
Remaining roots or teeth.
Local pathos's as cysts.
Overwhelming disease.
Permanent contraindications:
Epileptic patients and other psychological disorders preventing the neuromuscular control over the denture to avoid suffocation.

5. 3- difference between natural and artificial teeth.
Natural teeth
Denture teeth

6. Quality of complete denture
Physical requirements of a successful denture
Retention
Support
Bracing
Stability
A denture is said to be successful when it is:
Stable in place at function and rest.
Performs it’s masticatory and esthetic functions.
Preserves the foundation tissues.

7. At least four possible movements of the dentures exist
I- Tissue-ward movements
II- Tissue-away movements
III- Horizontal movements:
A) Lateral movements
B) Antero-posterior movements.
IV- Rotational movements

8. General movements of the denture
Direction of movement
Cause of movement
Resisted by
Tissue away movement
Sticky food
Gravity in upper denture
Retention
Tissue ward movement
Mastication.
support
Rotational movement
Chewing on one side
stability
Horizontal movement:
A- antro-posterior.
B-medio-lateral.
Chewing, clenching,side to side movement, muscleeffect
bracing

9. I- Tissue-ward movements
Mastication, Swallowing And Aimless Tooth Contact. Biting Forces
C.D. should be designed to resist this movement by providing adequate supporting from the foundation tissues
This function of the complete denture is called “Support”

10. 1-Support
The quality of the denture to transfer Occlusal Stresses to the Supporting Oral Structures and decrease forces / unit area
It is the Resistance to Tissue Ward Movement
Obtained by adequate Distribution of Forces Over the Supporting Sttructures.

11. The Resistance to Tissue Ward Movement
Decrease forces/unit area
Adequate Distribution of Forces Over the Supporting Sttructure

12. Tissue-away forces occur due to
The action of muscles acting along the periphery of the denture
Gravity acting on upper dentures or by sticky food adhering to the artificial teeth or to the denture base.
This function of the complete denture is called “Retention”

13. 2-Retention 1-Adhesion 2-Cohesion 4-Interfacial s.t.
Physiological
Mechanical
Physical
Physical condition
The physiologic molding of the tissues around the polished surfaces
neuromuscular control
Degree of tissue tone
Quality and quantity of saliva
Condition of mucosa and submucosa
Ridge characteristics
Ridge relationship
Parts of the denture engaging tissue undercuts.
Occlusion
Leverage
Contour of denture bases
1-Adhesion
2-Cohesion
4-Interfacial s.t.
*Viscosity (interfacial viscous tension)
4-At. pressure
5-Gravity

14. 3- Bracing Horizontal movements
Horizontal forces developed when the mandible moves from side to side during function while the teeth are in contact
Lateral movements have a destructive effect

15. Adequate extension of the flanges
This Function Is Mainly Provided By:
Adequate extension of the flanges

16. 4-Stabilization
Is the Resistance of the Denture to rotational forces (Tipping - Rocking)

17. 2-Retention 1-Adhesion 2-Cohesion 4-Interfacial s.t.
Physiological
Mechanical
Physical
Physical condition
The physiologic molding of the tissues around the polished surfaces
neuromuscular control
Degree of tissue tone
Quality and quantity of saliva
Condition of mucosa and submucosa
Ridge characteristics
Ridge relationship
Parts of the denture engaging tissue undercuts.
Occlusion
Leverage
Contour of denture bases
1-Adhesion
2-Cohesion
4-Interfacial s.t.
*Viscosity (interfacial viscous tension)
4-At. pressure
5-Gravity

18. 1-Physiologic factors

19. Physiological
Physical condition of the tissues and the patient(the better the physical condition the better is the retention.
Degree of tissue tone
Quality and quantity of saliva
Condition of mucosa and submucosa
Neuromuscular control
Ridge characteristics
Ridge relationship

20. Oral And Facial Musculature
Muscular control is an important aspect of successful complete denture therapy. providing that:
The Polished Surfaces Are Properly Shaped,
The Teeth Are Positioned In The Neutral Zone And
The Denture Bases Are Properly Extended To Cover The Maximum Area Possible,

21. The Polished Surface Contour

22. 2-Physical factors

23. 2-Retention 1-Adhesion 2-Cohesion 4-Interfacial s.t.
Physiological
Mechanical
Physical
Physical condition
The physiologic molding of the tissues around the polished surfaces
neuromuscular control
Degree of tissue tone
Quality and quantity of saliva
Condition of mucosa and submucosa
Ridge characteristics
Ridge relationship
Parts of the denture engaging tissue undercuts.
Occlusion
Leverage
Contour of denture bases
1-Adhesion
2-Cohesion
4-Interfacial s.t.
*Viscosity (interfacial viscous tension)
4-At. pressure
5-Gravity

24. Adhesion and Cohesion
Adhesive failure refers to the interface between two bodies; cohesive failure to within a material itself.
Note: the cohesive strength of saliva is much greater than the adhesion of mucosa to PMMA

25. Adhesion
Adhesion of saliva to the mucous membrane and the denture base is achieved through ionic forces between charged salivary glycoprotein and surface epithelium

26. Cohesion
Physical attraction of like molecules for each other creates retentive force and usually occurs with saliva that is present between the denture base and the mucosa.
Normal saliva is not very cohesive, and unless the interposed saliva is modified with the use of denture adhesive, retentive force cannot be achieved.

27. Retention supplied by Adhesion depend on :
The area covered by the denture
the close adaptation of the denture to the supporting tissues
The fluidity of saliva

28. Atmospheric pressure
If The Dentures Have An Effective Seal Around Their Borders. This Is Called ‘Suction’ Because It Is The Resistance To Removal In A Direction Opposite To That Of Insertion. But There Is No Suction Or Negative Pressure, Except When Another Force Is Applied

29. Atmospheric pressure
Displacement of a sealed bellows-like device results in a vacuum in the emergent space, the displacing force being balanced by that from atmospheric pressure. There is no static retaining force otherwise. Comparable conditions are unlikely to occur in the mouth

30. vacuum
All valve and suction retention systems are similar: a spring of some description attempts to maintain a region of lowered pressure.
These all fail to be effective in the long run for physiological reasons

31. For atmospheric pressure to be effective, the denture must have
a perfect seal around its entire border

32. Interfacial Surface Tension
It is attributed to the attractive forces or cohesion of the surface molecules of the liquid.

33. Interfacial Surface Tension
Is A Resistance To Separation By The Film Of Liquid Between The Denture Base And Supporting Tissues.
It Combines The Actions Of Adhesion And Cohesion And Is Similar To Capillary Attraction.

34. Surface tension
Bulging liquid surfaces imply a higher pressure within the liquid; incurving surfaces imply a lowered pressure

35. When is interfacial surface tension most effective?
When the salivary film is very thin, there is a perfect adaptation of the denture base and the soft tissues are firmly attached to underlying bone and not distorted.

36. What effect does distance between the denture base and the mucous membrane have on retention and what is it called?
"Capillary attraction"

37. Simplified cross-section to illustrate the seal arising from compliant tissue, flow restriction in narrow spaces, and the effect of surface tension in a well-fitting denture

38. Viscosity
It is the resistance by one part of A liquid in moving over another part.
The rate of separation of two surfaces under an applied force,
Very thin watery saliva does not seal the denture well and the seal can be easily broken.
The need for a good base adaptation to the tissues
Full surface area covered by the denture. This may be relevant to the maxillary denture.
The mandibular denture are bathed in saliva, surface tension, viscosity and film thickness may not play a role in lower denture retention

39. Gravity
The weight of a lower prosthesis constitutes a negligible gravitational force and is insignificant in comparison with the other forces acting on a denture.
this may be beneficial in cases where other retentive forces and factors are marginal.

40. Base Adaptation
the narrowness of the gap contributes a retentive force through the effects of surface tension, via the curvature that results in the liquid surface

41. Border seal
Attention was drawn under 'Surface Tension' to the fact that along most of the border of a denture there is double contact of acrylic and soft tissue such that displacing the denture in the separation sense does not open a gap along that border

42. Soft tissue
Denture retention is therefore a dynamic issue as it mostly depends on factors controlling the flow of the interposed fluid.
The better the fit to the tissue, and the better the linear extent of the seal at the border, the better the denture will resist short term displacing forces.

43. Ultimately, the central factors for the success of a denture depend primarily on the quality of the fit of the denture to soft tissue. This in turn hinges on the impression technique and subsequent denture base design and fabrication

44. 3. Strong movements of the tongue
The effect of physical forces is less applicable to lower dentures than upper because:
Have less surface area.
Are bathed in saliva.
3. Strong movements of the tongue

45. This Function Is Mainly Provided By:
1-Mechanical -- Undercuts
2- physiologic forces on polished surfaces of denture bases
3- physical forces on fitting surfaces of denture bases

46. Thank you