Transcript
Stages of framework construction from duplicated master cast, through wax pattern, and finally casting in cobalt, chrome alloy. Note lingual reciprocal arms on casting to relate the framework to PFM crown castings
Source: Jeff Shotwell, University of Michigan, 2008
•Removable dental prosthesis (appliance) replacing one or more natural teeth and associated oral structures
DefinitionThe Denture Base Is the Part of the Denture, Which Rests on the Foundation Tissues and to Which Artificial Teeth Are Attached
DefinitionIt is that part of the denture, which rests on the foundation tissues and to which artificial teeth are attached .It helps in transferring Occlusal stresses to the supporting oral structures
• The Resistance to Tissue Ward Movement
Support
• Distribute the Forces Over the Supporting Sttructure
• Transferring Occlusal Stresses to the Supporting Oral Structures
Types of Denture Bases
1-Bounded Partial Denture Bases
2- Free-end Partial Denture Bases (Distal-extension Base)
Functions of the Denture Base
3- Provides support
1- Carries the artificial teeth
2- Transfers Occlusal stresses to the supporting str. stimulation by massage of the tissues
4- Provides denture retention by physical means
5- Provides denture bracing
6- Provides stabilization against tipping of the distal-extension dentures
7- Prevent Migration and Over Eruption of the Remaining Teeth
Contribute to the functions ofContribute to the functions of bracing and stabilizationbracing and stabilization
Contribute to the functions ofContribute to the functions of bracing and bracing and stabilizationstabilization
1- Accuracy of adaptation to the tissues
4-Biological acceptability not irritant
Requirements of an Ideal Denture Base Material
8- Esthetically acceptability 9- Low initial cost ,easy manipulation
3-Should have low specific gravity,
2-Sufficient strength
5-Potential for future relining
6-Should allow thermal conductivity necessary for tissue stimulation
7-Can easily be kept clean
Denture Base Material• Non metal as acrylic resinA.R.bases attached to metallic denture framework
through metallic minor connectors
Metallic denture base
3- Greater Thermal Conductivity
1- More Rigid Than Resin Bases Even in Thinner Section
2- Less Bulky
4- Fit More Accurately to d Underlying Tissues
5- More Hygienic as the fitting surface is Polished and non-porous with less Tendency for Food Accumulation
Advantages
Disadvantages of Metal Bases
3- The Colour of Metal Bases Does Not Simulate the Natural Appearance of Oral Tissues
1-Difficult to Rebase or Reline When Ridge Resorption Occurs
2- Difficult to Repair
*chrome cobalt alloy Used in cast form
Rigid even in thin section
Has low specific gravity (1/2) that of gold
Provide high resistance to corrosion
Not easily abraded
Attain high polish surface
Dimensionally stable
Special machine for casting &polishing
Special investment& high casting temperature
Cast gold alloy
Less rigid than chrome cobalt alloy & more rigid than resin
More heavier than chrome cobalt alloy
Used in lower partial denture to aid in retention
Non-metallic, Acrylic Resin Denture Bases
3- Easy to Reline, Rebase or Repair
1- Eesthetically is Satisfactory due to Its Pink Colour
2- Light in Weight
4- Needs Simple Processing Procedures
Advantages
Disadvantages of Resin Base
1- Weak, Have Low Tensile Strength, Brittle And Are Liable To Fracture
2- To Attain Enough Strength, Resin Bases are Made Bulky
3- Have Low Thermal Conductivity
4- The fitting surface is porous and not polished bad oral hygiene, bad odour and inflammation of the tissues
INDICATIONS OF RESIN BASE
1- Free-end Saddle Cases
2- Increased Rate of Bone Loss As Diabetic Patients or Patients on Steroid Therapy
3- Cases With Extreme Bone Loss. The Presence of Acrylic Resin Is Necessary to Restore the Original Contour
Indications:
Extension base partial denture
Long span edentulous ridge
Future relining is anticipated in a short time
resin restore contour much more satisfactory than metal
*support is an important consideration in designing saddles
for extension base saddle
*support obtained from underlying structure as residual
ridge, buccal shelf, palate pear shaped pad
*maximum coverage without encroaching on movable tissue
To reduce stress on the abutment teeth
*need for future relining
*when denture cross gingival tissur it should be relieved to
avoid the impinge on gingival tissue which cause irritation
& periodontal damage.
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