SUBMITTED BY-JITENDRA VISHWAKARMAJYOTI PATAWARIKAILASH KALDHARI

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

Ideal Requirement of Denture Base Resin-Be dimensionally stable.Be esthetically satisfactory.Have enough strength,resilience & abrasion resistance.Be tasteless,odourless,nontoxic &non-irritant to the oral tissue.Be easy to fabricate.Uses of Denture Base Resin-Fabrication of dentures.Artificial teeth.Orthodontics & pedodontics appliances.Crown & FPDs facing.Inlay & post core patterns.

Type1• Heat

Polymerizable Polymer

Type 2• Autopoly

merisable Polymer

Type3• Thermopl

atic Blank

Type4 •Light Activated Materials

Type5 •Microwave cured Materials

Denture Base Resin

CLASSIFICATION-

Liquid-Methyl MethacrylateDibutyl phthalateGlycol dimethacrylateHydroquinone

HEAT ACTIVATED DENTURE BASE RESIN

Composition-

Heat-activated materials are used in the fabrication of nearly all denture bases.

Powder-Methyl methacrylateEthyl methacrylateBenzoyl peroxideDibutyl phthalateInorganic fillersCompounds of mercuric sulfides

ADVANTAGES- They are rigid and accurate. They are stable,not subject to distortion.

DISADVANTAGES- Require considerable time. More expensie.

USES- For fabrication of complete denture.

The heating process used to control 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.

POLYMERIZATION CYCLE

Physical Stages Of PolymerizationWet

Sand

Stage

Sticky

stage

Dough

Stage

Rubbery

Stage

Stiff Stag

e

CHEMICALLY ACTIVATED DENTURE BASE RESINChemically activated acrylic resins polymerize at room

temperature.Also knowns as ‘self-curing’, ‘auto-polymerising’ resins.Composition-

Powder-Methyl methacrylateEthyl methacrylateBenzoyl peroxideDibutyl phthalateInorganic fillersCompounds of mercuric sulfides

Liquid-Methyl MethacrylateDimethyl-P-toluidineDibutyl phthalateGlycol dimethacrylateHydroquinone

USES:For making temporary crowns & FPDs. Construction of special tray. For denture repair,rebasing & relining. For making removable orthodontic appliances.

ADVANTAGES- Good strength no need for reinforcement. Good dimensional stability. Does not wrap during manipulation. Closely fit to master cast.

DISADVANTAGES- Require more time in fabrication. Difficult to control the thickness. Residual monomer can cause irritation to oral tissue

SELF CURED HEAT CUREDHeat 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

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 joulesChemically activated resin=0.78 joules5.solubility:Denture base resin are vitually insoluble in the oral fluids6.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.

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 speciesEXTERNAL-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.