2. • Denture base is “ that part of a denture which
rests on the oral mucosa and to which teeth
are attached”
• “that part of a complete or removable partial
denture which rests upon the basal seat and
to which teeth are attached”
3. Ideal requirements
The requirements of an ideal denture base are:
• Accurate tissue adaptation with minimal change in
volume
• Thermal conductivity
• Sufficient strength to resist fracture or distortion under
function
• Cleans ability
• Ability to be relined if necessary
• Cost affectivity
• Low specific gravity, weight less ness with in oral cavity
• Ability to achieve a good finish
4. Types of denture bases
The most commonly used types of denture
bases include:
• Acrylic
• Metal
• combination
5. Acrylic resin denture bases
• are used along with acrylic tooth
replacements .
• Its mainly used for distal extension partial
dentures
• The resin should be at least 1.5mm thick to
have adequate strength.
6. Ad vantage
• Anterior teeth can be replaced at their original
position(esthetic level ) even in cases with
residual ridge resorption
• Restores the contour of the edentulous ridge
• Brings out the normal contours of the lips and
cheeks
• Can be relined
7. Disadvantages
• They should rest on a large area for adequate
stress distribution
• Since ADB should be thick to withstand the
occlusal forces, the amount of space available for
the placement of artificial teeth is reduced. This
becomes more problematic in cases with
reduced inter-arch distance.
• May break on usage
• Tend to distort by the release of internal strains
• Tend to accumulate mucus deposits. This leads
to calculus formation and soft tissue irritation.
8. Metal denture bases
• Metal denture bases are mainly used for tooth
supported partial dentures.
Advantages:
• Accurate soft tissue adaptation leads to better
retention and restoration of facial contours
• Permanent maintenance of from within the oral
cavity without any distortion
• Easy to clean and mucous deposits do not
accumulate under metal bases
9.
10. • Stronger then acrylic even in thin sections
• Thinner metal bases can be given for cases with
severe ridge resorption
• They produce less interference with the tongue
• They transfer the thermal changes in the oral cavity
to the underlying soft tissues producing a
physiologic stimulation. This eliminates the feeling
of a foreign object(denture) within the mouth.
• Better soft tissue respond. This because these
materials have high density and they are also
bacteriostatic
11. Disadvantage
• Difficult to trim and adjust
• over- extension can injure the soft tissues
• Under-extension can lead to ridge resorption,
as the stresses are concentrated within a
smaller area
• Poor aesthitics
• Difficult to reline or rebase.
12. 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.
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.
13. 3. Maxillary distal extension denture bases
should terminate in the hamular notches.
4. Mandibular distal extension denture bases
should terminate on the pear-shaped
retromolarpad.
5. 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.
14. • In these instances, it is usually preferable to
shorten the flange, rather than relieving the
internal surface.
Deep lingual undercut Do not relieve internally Shorten flange
(difficulty seating, pain) (food trap) (maintain usable undercut)
(for retention)
16. • The term tooth replacement refers to the
artificial teeth placed in a denture.
• These artificial teeth are attached to the denture
base in the following methods:
a) Acrylic teeth fused with the denture base acrylic
resin
b) Porcelain or acrylic tube teeth are usually
cemented to the metal base
c) Resin teeth processed directly over the metal
base. The strength of the metal teeth junction is
determined by the microscopic interlocking.
17. d)Metal teeth are cast along with the frame work
e)Chemical bonding of acrylic with the metal base
19. Acrylic teeth
• They are the most commonly used types of
artificial tooth replacements.
• They easily crosslink with the denture base
resin , have superior aesthetics and good
retention.
• These teeth cannot be rebased and they have
poor wear resistance
20. Porcelain teeth
• Porcelain teeth have better hardness and
abrasion resistance than plastic teeth.
• They are mechanically retained .
• They have very high wear resistance and they can
maintain the vertical dimension of the patient for
a longer period.
• They have the best aesthetic appeal
• When opposed by natural teeth , porcelain
produces extensive wear of enamel, but they
have poor fracture resistance.
21. Plastic teeth
• They have to be trimmed to conform to the
edentulous space and the metal framework
underneath.
• this weakens the porcelain tooth.
• They are used only when the partial denture has
an opposing complete denture and when there is
sufficient inter-occlusal clearance.
• The porcelain tooth is mechanically retained to
the acrylic denture base with the help of its
retentive pins.
22. • They have high impact strength but poor wear
resistance compared to porcelain.
• They have adequate strength even in smaller
dimensions.
Advantage:
• Most esthetic
• Wider stress distribution
• Easy to reline
• Can restore the lost ridge contour
24. Metal teeth with facing
• They have higher strength , hence , they are used
in patients with reduced occlusal clearence.
• The facing must be well adapted to the ridge to
achieve a natural look.
• Broad well –healed ridges are essential for
fabricating these teeth
• They are aesthetically inferior because the metal
backings to show through the acrylic or porcelian
facings.
25. • In cases with deep bite, the natural teeth
occlude with the metal backing leading to
rapid tooth wear.
• Relined is not possible when these teeth are
used.
27. Plastic teeth
• They have reduced wear resistance and tend
to flatten under mastication.
• This leads to loss of vertical dimension and
inefficient mastication.
• Hence , the patients must be frequently
reviewed to detect occlusal wear.
28. Porcelain teeth
• They are used only when the opposing tooth
is also a tooth replacement like acrylic or
porcelain.
• These teeth are retained by acrylic resin by
their diatoric holes
29. Metal pontics
• It may be a full-metal crown with a tooth-
coloured veneer.
• They are given in cases where acrylic or
porcelain teeth can not be given
example: when there is reduced occlusal
clearance or when there is limited inter-dental
space.
• Its is made up if gold or chrome alloy.chrome
alloy abrades the natural teeth very quickly.
30. • Hence, the occlusal surface should be covered
with tooth colured resin.
• Gold is preferred as it has adequate strength
and restores occlusion to the maximum limit.
31. Bonding between the teeth and the
denture base
• The mechanism of bonding varies according to
the type denture base and tooth replacement
used.
• Denture base-teeth bonding can be broadly
grouped in to:
a) Mechanical
b) Chemical
c) Acid etching(microretention)
