denture base resin

2. The Glossary of Prosthodontics Term
defines-
A Complete Denture as a removable dental
prosthesis that replaces the entire dentition
and associated structure of the maxilla and
mandible.
Such a prosthesis is composed of artificial
teeth attached to a denture base.
Denture Base Resin

3.  Ideal Requirement of DentureBase Resin-
Be dimensionally stable.
Be estheticallysatisfactory.
Have enough strength,resilience & abrasion resistance.
Be tasteless,odourless,nontoxic&non-irritantto the oral tissue.
Be easy to fabricate.
Usesof Denture Base Resin-
Fabrication of dentures.
Artificial teeth.
Orthodontics & pedodontics appliances.
Crown& FPDs facing.
Inlay& post core patterns.

4. Type1
• Heat Polymerizable
Polymer
Type 2
• Autopolymerisable
Polymer
Type3
• Thermoplatic
Blank
Type4
• Light Activated
Materials
Type5
• Microwave cured
Materials
Denture
Base Resin
CLASSIFICATION-

5. liquid-
Methyl Methacrylate
Dibutyl phthalate
Glycol dimethacrylate
hydroquinone
HEAT ACTIVATED DENTURE BASE RESIN
Composition-
Heat-activated materials are used in the
fabrication of nearly all denture bases.
Powder-
methyl methacrylate
ethyl methacrylate
Benzoyl peroxide
Dibutyl phthalate
Inorganic fillers
Compounds of mercuric sulfides

6. Technical Consideration-
COMPRESSION MOLDING TECHNIQUE-
 Preparation of wax pattern
Preparation of split mould
 Application of seprating media
 Mixing of powder & liqud
 Packing
 Curing
 Cooling
 Deflasking
 Finishing & polishing
Physical Stages Of Polymerization
Wet
sand
stage
Sticky
stage
Dough
stage
Rubbery
stage
Stiff
stage

7. POLYMERIZATION CYCLE
The heating process used to contol polymerization is termed as
polymerization or curing cycle.
The recommended curing cycles are-
 One technique involves processing the denture base resin in a
constant temperature water bath at 74°c for 8hrs or longer with no
terminal boiling temperature.
 A second technique consists of processing in a 74°c water bath
for 8hrs and then increasing the temperature to 100°c for 1 hr.
 A third technique involves processing the resin at 74°c for
2hrs and then increasing the temperature of water bath to 100°c
and processing for 1 hr.

8. CHEMICALLY ACTIVATED DENTURE BASE RESIN
Chemically activated acrylic resins polymerize at room temperature.
Also knowns as ‘self-curing’, ‘auto-polymerising’ resins.
Composition-
Powder-
methyl methacrylate
ethyl methacrylate
Benzoyl peroxide
Dibutyl phthalate
Inorganic fillers
Compounds of mercuric sulfides
liquid-
Methyl Methacrylate
dimethyl-P-toluidine
Dibutyl phthalate
Glycol dimethacrylate
hydroquinone

9. Technical Consideration-
COMPRESSION MOLDING TECHNIQUE
USES:
For making temporary crowns & FPDs.
 Construction of special tray.
 For denture repair,rebasing & relining.
 For making removable orthodontic appliances.

10. SELF CURED HEAT CURED
Heat is not necessary
for polymerisation.
 Porosity is greater.
 Material is not
strong.
 Shows greater
distortion.
 More initial
deformation
 Increased creep and
slow recovery.
 Easy to deflask
 Poor color stability.
Heat is necessary for
polymerisation.
 Porosity is less .
 Material is strong.
 Shows less
distortion.
 less initial
deformation
 Less creep and
greater recovery.
 Difficult to deflask
 Color stability is
good.
VS

11. PROPERTIES OF DENTURE BASE RESIN-
1.Taste and Odour:
Completely polymerized acrylic resin is tasteless and odourless.
2.Esthetics:
It is a clear transparent resin which can be pigmented easily to
duplicate oral tissue.
3.strength:
The strength of an individual denture base resin is dependent on
many factors such as –composition,processing technique etc.
Self cured resin generally have lower strength values.
4.Impact strength:
It is a measure of energy absorbed by a material when it is broken
by a sudden blow.
Heat-activated resin=0.98-1.27 joules
Chemically activated resin=0.78 joules
5.solubility:
Denture base resin are vitually insoluble in the oral fluids
6.colour-stability:
The color stability of self-cured acrylic resin is somewhat inferior
to heat-cured acrylic resin.
7.Biocompatibility:
Completely polymerized acrylic resin are biocompatible.

12. PROCESSING ERRORS-
Polymerization shrinkage-:
Processing shrinkage has been measured as 0.26% in chemically activated resin whereas it has
been measured 0.53% in heat-activated resin.
Porosity-:
INTERNAL-Results from the vaporization of unreacted monomer and low molecular weight
polymer,when the temp. of a resin surpasses the boiling point of the species
EXTERNAL-occurs due to-lack of homogeneity
lack of adequate pressure
Crazing-:
Formation of surface cracks on the denture base resin.
Cause-mechanical stresses
attack by solvent
incorporation of water.
Creep-:
When a denture base resin is subjected to a sustained load,the material exhibhit an initial
deflection,or deformation.if the load is not removed additional plastic deformation may occur
over time and this aditional deformation is termed as creep.
Chemically-activated resin have high creep value.