1. Components of Removable Partial
Dentures
Denture Bases and Artificial Teeth
Mohammad Zakaria Nassani DDS, PhD
Al-Farabi College for Dentistry and Nursing
Prosthetic Dental Sciences Department

2. What is a denture base?
 A denture base is that part of a denture which
rests on the foundation areas and to which teeth
are attached (The glossary of prosthetic terms. 6th
ed. St. Louis, C V Mosby, 1994)

3. Functions of denture bases
1. Attach the prosthetic teeth to the RPD.

4. Functions of denture bases
2. Stress distribution: Transfer occlusal forces to
the abutment teeth and, in tooth-tissue supported
RPDs, to the denture foundation area.

5. Functions of denture bases
3. Improve esthetics: Replace the missing alveolar
tissue in bulk and appearance

6. Functions of denture bases
4. Contribution to bracing, retention and indirect
retention of the RPD

7. Functions of denture bases
4. Contribution to bracing, retention and indirect
retention of the RPD

8. Requirements for an ideal denture base material
1. Accuracy of adaptation to the tissues, with minimal
volume change (Dimensional stability).
2. Dense, nonirritating surface capable of receiving and
maintaining a good finish
3. Thermal conductivity

9. Requirements for an ideal denture base material
4. Lightweight in the mouth
5. Sufficient strength; resistance to fracture or
distortion
6. Easily kept clean

10. Requirements for an ideal denture base material
7. Esthetic acceptability
8. Potential for future relining
9. Low initial cost

11. Requirements for an ideal denture base material
 Such an ideal denture base material does not exist,
nor is it likely to be developed in the near future.
 However, any denture base should come as close
to this ideal as possible.

12. Types of denture bases
1. Acrylic Resin Bases
There are two types of
RPD denture bases:
2. Metal Bases

13. Acrylic Resin Bases
 Acrylic resin bases are the most common types used in
removable partial dentures.
 The acrylic resin denture bases have the plastic material in
contact with the edentulous ridge.
 They should be routinely used in distal extension cases to
allow for relining of the base to maintain mucosal support.

14. Acrylic Resin Bases
 Indications
1. Tooth-tissue supported edentulous spaces.
2. Tooth supported edentulous spaces where bone resorption
will necessitate a reline/rebase.

15. Acrylic Resin Bases
 Indications
3. Where considerable missing alveolar tissue must be
replaced.
4. Where esthetics is a primary concern.

16. Acrylic Resin Bases
 Note:
 Where protrusive or lateral occlusal guidance will be on
the prosthetic teeth, the use of acrylic resin bases can be
considered a risk factor for artificial teeth detachment in
the corresponding area

17. Acrylic Resin Bases
 Advantages
1. Can be easily relined.
2. Esthetically superior to metal bases
3. Easy to fabricate, adjust, finish and polish, and repair.

18. Acrylic Resin Bases
 Disadvantages
1. Dimensional stability less than metal bases – risk of
warpage
2. Lower strength than metal
 Requires more bulk for rigidity than metal
 Easily abraded.
 Easily fractured.

19. Acrylic Resin Bases
 Disadvantages
3. More porous than metal and therefore more difficult to
clean.
4. Low thermal conductivity

21. Metal Bases
 The metal denture base has metal in contact with the
edentulous ridge.
 Prosthetic teeth are attached to the metal base with a
plastic base (acrylic resin) or by retentive posts on the
metal surface.

22. Metal Bases
Retentive posts can be particularly useful
in anterior regions

23. Metal Bases
 Indications
 Metal bases can be used wherever acrylic resin bases are
used.
1. A tooth supported edentulous space where further bone
resorption is not anticipated.

24. Metal Bases
 Indications
2. When a facing, tube tooth, metal pontic, or metal
reinforced denture tooth is to be used.

26. Metal Bases
 Contraindications
 Tooth-tissue supported edentulous space.
 Tooth supported edentulous space where bone resorption
is expected (in areas where teeth have been removed
within 12 months, resorption will still be occurring at an
increased rate and relining will be usually be required).

27. Metal Bases
 Advantages
1. Very rigid
2. Very stable form – Maintain their accuracy
3. High abrasion resistance
4. High thermal conductivity - improved thermal perception
may lessen the feeling of the denture as a foreign object.

28. Metal Bases
 Advantages
5. Less porous than resin and therefore easier to clean. Also
this character lessens food, plaque and calculus
accumulation, thereby maintaining healthy tissues.
6. Minimal weight and bulk - The metal bases can be cast
thinner than resin bases while maintaining adequate
strength.

29. Metal Bases
 Diasadvantages
1. Metal not esthetic - the esthetic result can be
compromised unless the metal can be veneered with
sufficient thickness of acrylic. If an insufficient veneer is
used, a greyish hue of the underlying metal becomes
visible.
2. Metal bases cannot be relined.

31. Denture Base and flange extension
1. Denture bases for tooth-tissue supported partial dentures
(Class I and II) should be extended to provide the greatest
available surface area for support and retention, without
overextension or impingement on movable border tissues.

32. Denture Base and flange extension
2. Tooth supported partial dentures (Class III and IV) need
not necessarily be extended maximally, since most of the
support for these dentures comes from the teeth.

33. Denture Base and flange extension
2. Tooth supported partial dentures (Class III and IV)
 The level of extension may be dictated by esthetic
considerations

34. Denture Base and flange extension
3. Maxillary distal extension denture bases should terminate
in the hamular notches.

35. Denture Base and flange extension
4. Mandibular distal extension denture bases should
terminate on the pear-shaped retromolar pads.

36. Denture Base and flange extension
 Occasionally, the path of insertion can cause the denture
flanges to impinge on the mucosa above undercut portions
of the residual ridge, when the partial denture is being
seated.
 In these instances, it is usually preferable to shorten the
flange, rather than relieving the internal surface.
 If the internal surface is relieved significantly, a space will
exist between the denture base and the tissues when the
denture is fully seated.
 Food may become trapped in the space and work its way
under the partial denture.

37. Deep lingual undercut Do not relieve internally Shorten flange
(difficulty seating, pain) (food trap) (maintain usable undercut)
(for retention)

38. Acrylic resin finish lines
 Denture bases should have internal and external finish
lines which do not coincide.
 Internal finish lines should be placed furthest from the
abutment teeth
 Offsetting improves the strength at the metal/denture base
junction.

39. Acrylic resin finish lines
 The purpose of finish lines is to create a distinct resin-metal
interface and to prevent the acrylic resin from becoming too
thin
 Because acrylic resin gains its strength with increasing bulk, it
should not be finished to a thin edge.
 If this is attempted, the material may chip or fracture.
 This can create unhygienic and potentially irritating conditions.

42. Acrylic resin finish lines
 Finish lines should be slightly undercut to provide a
margin with maximum bulk of resin strength and
maximum retention of the resin.

43. Acrylic resin finish lines
 The external metal finish line should be located
approximately 2 mm lingual to the lingual surface of the
replacement denture teeth.

44. Acrylic resin finish lines
 Finish line on right is too far toward midline of palate.
 The location of the finishing line at the junction of the
major and minor connector should be based on restoring
the natural palatal shape, taking into consideration the
location of the replacement teeth.
location of finishing lines minimizes bulk of
resin attaching the artificial teeth.
Palatal contours are restored, enhancing
speech and contributing to a natural feeling
for the patient

45. Acrylic resin finish lines
 If the finishing line is located too far medially, the natural
contour of the palate will be altered by the thickness of the
junction and the acrylic resin supporting the artificial teeth
 If, on the other hand, the finishing line is located too far
buccally, it will be most difficult to create a natural contour of
the acrylic resin on the lingual surface of the artificial teeth.

47. Partial Denture Replacement Teeth
 Prosthetic teeth:
 Artificial teeth used on a denture to substitute for natural
teeth.

48. Partial Denture Replacement Teeth
By substituting for the missing
natural teeth, prosthetic teeth
provide esthetics
Function of
Prosthetic teeth Prosthetic teeth aid the function
of mastication
The prosthetic teeth transfer
occlusal forces to the denture
base and subsequently to the
supporting structure (natural
teeth and/or edentulous ridges)
and thus provide the function
of support
Prosthetic teeth preserve the
stability of the natural dentition

49. Partial Denture Replacement Teeth
Acrylic teeth
Material
Porcelain teeth

50. Partial Denture Replacement Teeth
 Acrylic denture teeth should be used in most
instances since they will not wear the opposing
dentition to the same degree as porcelain teeth.

51. Partial Denture Replacement Teeth
 Porcelain denture teeth cause accelerated wear of
the natural dentition, particularly once the surface glaze
has been broken.
 Acrylic teeth are easier to arrange, modify and adjust.

52. Partial Denture Replacement Teeth
 Tooth Form
 The selected tooth form should be selected to harmonize
with the opposing teeth.

53. Partial Denture Replacement Teeth
 Tooth Form
 Where the replacement teeth oppose natural dentition with
minimal wear, a 30 or 33 tooth form may be indicated.

54. Partial Denture Replacement Teeth
 Tooth Form
 Where the opposing dentition exhibits advanced occlusal
wear, a form with more shallow or no cuspal inclinations
might be indicated.

55. Partial Denture Replacement Teeth
 Tooth Form
 In almost all instances where the teeth will oppose a
natural dentition, adjustment of the occlusal surfaces will
be necessary to provide acceptable occlusal contacts.

56. Partial Denture Replacement Teeth
 Denture teeth should be selected to harmonize with the
shade, shape, length and width of the remaining dentition.

57. Partial Denture Replacement Teeth
 Appearance will be most compromised if there is a vast
difference in tooth length between the replacement tooth
and adjacent natural teeth.

58. Partial Denture Replacement Teeth
 In order to improve esthetics, teeth adjacent to the abutment teeth may
have to be modified to ensure the proximal plates and other
framework components do not interfere with proper positioning of the
denture teeth.
 Replacement teeth may be modified so they can veneer over proximal
plates and other framework elements to provide the best possible
appearance.
Note on the facial surface that the denture tooth slightly overlaps
the proximal plate to hide this portion of the framework.

59. Final anterior denture teeth and waxed
Anterior denture teeth ground and denture base conceal metal bar.
fitted to metal bar

60. Thank You For Your Attention