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Denture base
Dr. Shaima’a Ahmed Radwan
Partial denture component
Artificial teeth
Denture base
(saddle) Clasps
(retainer)
Major connectors
Minor
connector
Supporting
rest
The part of a denture that rests on the foundation tissues and to which teeth are attached
Types of denture base
Bounded partial denture base Free end partial denture bases (distal-extension base)
Functions 1.Carries the artificial teeth. 2.Transfers occlusal stress to the supporting oral structures
Vertical forces acting in gingival direction tending to move the denture towards the tissues
3.(support)Tissue-ward movements
3.(support)Tissue-ward movements
Vertical forces acting in gingival direction tending to move the denture towards the tissues
4.Retention
5.Bracing
Resistance to Lateral Movement of the Partial Denture
6.Stability • It is the resistance to tipping forces
7.Prevent migration and over eruption of remaining teeth
• Accuracy of Adaptation To Tissues With Low Volume Change
• Sufficient strength Resistance to fracture/distortion
Low specific gravity – Lightness in mouth Biologically Compatible with tissues
• Good Thermal conductivity. • Esthetics .
Materials
Metallic Bases
• Small edentulous spaces (no room for grid work)
Beaded Metal Base
Prosthetic teeth are attached to the metal base with a plastic base (acrylic resin) or by
retentive posts on the metal surface.
Retentive Posts
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.
2. When a facing, metal pontic, or metal
reinforced denture tooth is to be used.
Contraindications:
1- Tooth-tissue supported edentulous space.
2- 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).
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.
5. Less porous than resin and therefore easier to clean (more hygienic). 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.
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. Difficult to make adjustment and corrections or teeth addition
3. Difficult to Reline or repair
Non-metallic denture base
2. 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.
Indications:
1. Tooth-tissue supported edentulous spaces.
2. Tooth supported edentulous spaces where bone
resorption will necessitate a reline/rebase.
3. Where considerable missing alveolar tissue
must be replaced.
4. Where esthetics is a primary concern.
Advantages:
1. Can be easily relined.
2. Esthetically superior to metal bases
3. Easy to fabricate, adjust, finish and polish, and
repair.
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.
3. More porous than metal and therefore more
difficult to clean.
4. Low thermal conductivity.
III. Combined
Free end saddle cases I,II
Long class III,IV
• Diabetic patients , steroid therapy
• Extreme bone loss
Methods of Attaching denture base
Closed meshwork
Open lattice ladder
Tissue stops
They are formed by making holes in the relief wax during preparation of the master cast
before duplication. They are essential part in the fitting surface of minor connectors. They
are 2 or 3 in number that contact the cast.
1- Stabilize the framework on the master cast during processing as the acrylic resin is
packed in the retention spaces.
2- Elevate the minor connectors forming the base from the ridge by providing space equal
to the thickness of the acrylic bases.
Tissue stops
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.
Finish Lines
- Finish lines are : Internal and External finish
lines.
-The Internal finish line formed by carving the
relief wax on the master cast before duplication to
create space for packing acrylic resin under mesh
minor connector.
-The external finish line formed during formation of wax pattern by carving a sharp definite angle at the junction between the major connector and the minor connectors forming the denture base (the angle should be less than 90 degree).
It should be located approximately
2 mm lingual to the lingual surface of the
replacement denture teeth.
During designing denture base important
notes should be take into consideration:
- Support is an important consideration in designing saddles
for extension base saddle.
- Maximum coverage to the residual ridge, buccal shelf, palate, and pear shaped pad.
- Maximum coverage without encroaching on movable tissue
to reduce stress on the abutment teeth.
- When denture cross gingival tissue it should be relieved to
avoid the impinge on gingival tissue which cause irritation
& periodontal damage.
-Wide distribution of the load on the teeth and the
mucosa.
- Need for future relining.
Acrylic Resin Finish Lines
a
major connectoredentulous ridge
slight undercut
staggered finish lines
gridwork
Acrylic denturebase
• Internal & external finish lines should not coincide