The Denture Base Flashcards
What is the denture base of the removable partial denture?
Is the part of the denture , which rests on the foundation tissues and to which artificial teeth are attached.
Types of denture bases
1- bounded partial denture bases.
2- free-end partial denture bases. ( Distal extension base)
Functions of the denture base
1- carries the artificial teeth.
2- transfers occlusal stresses to the supporting oral structures and provides stimulation by massage of the underlying tissues.
3- provides support in distal extension dentures and long span bounded denture.
4- provides denture retention for distal extension dentures by physical means.
5- provides denture bracing against horizontal movement.
6- provides stabilization against tipping of the distal extension dentures.
7- the denture base and the artificial teeth serve to prevent migration and over eruption of the remaining teeth.
Requirements of an ideal denture base material.
1- accuracy of adaptation to the tissues.
2- sufficient strength in order to resist fracture and distortion.
3- low specific gravity.
4- biological acceptability.
5- allow thermal conductivity necessary for tissue stimulation.
6- can easily be kept clean
7- esthetic acceptability
8- potential for future relining
9- low initial cost.
The components of remaovebel partial denture
Denture bases
Artificial teeth
Supporting rests
Connectors major and minor
Retainers direct and indirect.
Support
The resistance of a denture to tissue ward movement
Retention
Resistance of a denture to vertical displacement force to move away from its tissue foundation.
Indirect retention
Resistance of denture rotation away from the tissues about an axis.
Bracing
Resistance of denture to lateral
Forces
Reciprocation
The Resistance of lateral forces on the abutment during insertion and removal of the denture
Stability
The resistance of a denture to tipping movement
Tipping movement
Vertical rotation causes twisting of the denture base
Denture base material
Metal
Acrylic resin
Combined
Advantages of metal bases as compared to resin bases
More rigid
Less bulky
Greater thermal conductivity
Fit more accurately
More hygienic
Indicated in short span bounded cases
Disadvantages of metal bases
Difficult to rebase, reline, and repair
Not esthetic
Combined bases used in the following conditions
Free end saddle cases as class I and II
Class 4 and 3 having long edentulous spans to facilitate future relining.
Patients are vulnerable to an increased rate of bone loss as diabetic patients or patients on steroid therapy.
Cases with extreme bone loss.
Methods of attaching denture bases
Acrylic resin bases are attached to metallic denture framework by means of minor connector designed so that a space exists
between it and the underlying tissues of the residual ridge.
Minor connectors are either made in the form of an open latticework (ladder-like pattern)
Or in a closed meshwork configuration (plastic mesh pattern)
Minor connectors include tissue stops
Tissue stops in the fitting surface of minor connectors.
Elevate the minor connectors, forming the denture base from the ridge by providing a space equal to the thickness of acrylic bases.
Tissue stops stabilizing the framework on the master cast during processing
Minor connectors include finishing line
Finishing lines are butt joints created at the junction of major connectors with the denture bases. In distal extension bases are made internal and external finishing lines while in short bounded metallic bases required only external finishing lines.
Properties of acrylic resin denture bases
Good esthetic
Acrylic bases are light in weight
Easy to reline ,rebase or repair.
Needs simple processing procedures.
Disadvantages of acrylic resin bases
Weak , brittle , and are liable to fracture.
Made bulky.
Low thermal conductivity.
Bad oral hygiene , bad odour and inflammation of the tissues.
Indications of acrylic removable partial dentures
Cases with extreme bone loss
When cost is a prime requisite.
During the healing process after extraction until the permanent restoration is made.
Denture base extension
a) anterior and posterior extension
B) buccally
C)lingually
Anterior and posterior extension of the denture
In bounded spaces it is determined by the abutment teeth.
In free-end spaces : the base extends from the abutment to cover the retromolar pad in the lower and the tuberosity in the upper.
Buccally extension
The flange should extend to the mucosal reflection.
Lingually extension
The flange of the lower denture base should extend to the full depth of the lingual sulcus .
The polished surface of partial denture
Concave form which is important for the retention and stability of the denture.
