What is What is DentureDenture? ?

A substitute for the A substitute for the lost natural dentitionlost natural dentition

Substitutes the whole arch

Substitutes some teeth

Partial Denture

Parts of the dentureParts of the denture A. Denture baseA. Denture base Covers the residual ridge and Covers the residual ridge and

restore the lost gingival partsrestore the lost gingival parts Supports and holds the artificial Supports and holds the artificial

teethteeth Responsible for denture Responsible for denture

retentionretention

B. Artificial teethB. Artificial teeth A substitute for the lost natural A substitute for the lost natural

teeth doing their function teeth doing their function ((estheticesthetic, , chewing chewing and and phonationphonation))

Surfaces of the Surfaces of the denturedenture

Fitting surfaceFitting surface

Occlusal surfaceOcclusal surface

Polished surfacePolished surface

Requirements of denture Requirements of denture base materialsbase materials

1.1. Should be Should be biologically acceptablebiologically acceptable (non-toxic, (non-toxic, non-irritant, tasteless, and odorless).non-irritant, tasteless, and odorless).

2.2. Have Have adequate mechanical propertiesadequate mechanical properties such as such as impact, transverse and fatigue strengths.impact, transverse and fatigue strengths.

3.3. Have Have satisfactory thermal propertiessatisfactory thermal properties..

4.4. Light in weightLight in weight and have and have color matchescolor matches to to that that of gingival tissuesof gingival tissues

5.5. Have to be Have to be stable in different oral environmentstable in different oral environment (Resistant to degradation and the change in (Resistant to degradation and the change in temperature).temperature).

6.6. Should be Should be dimensionally stabledimensionally stable..

7.7. Should Should achieve chemical bond to the artificial achieve chemical bond to the artificial teeth.teeth.

8.8. Easily fabricated and repair .Easily fabricated and repair .

9.9. Should be of Should be of low costlow cost..

Requirements of denture Requirements of denture base materials base materials

Denture Base Denture Base AcrylicsAcrylics

1. Heat-cured Acrylic Resin 1. Heat-cured Acrylic Resin (PMMA) (PMMA) 2. Modified Acrylic Resin2. Modified Acrylic Resin

Heat-cured PMMAHeat-cured PMMA

Heat-cured PMMAHeat-cured PMMAA. Powder (polymer) CompositionA. Powder (polymer) Composition

Pre-polymerized PMMA…. Pre-polymerized PMMA…. (to reduce the (to reduce the polymerization shrinkage)polymerization shrinkage)

Benzoyl peroxide….Benzoyl peroxide….(Polymerization initiator)(Polymerization initiator) Co-polymer of PMMA-PEMACo-polymer of PMMA-PEMA Dibutyl phethalate….Dibutyl phethalate….(plasticizer)(plasticizer) Bromo-polymer additives.…Bromo-polymer additives.…(Radiopacifiers)(Radiopacifiers) Pigments….Pigments….(to give the gingival pink color)(to give the gingival pink color)

Heat-cured PMMAHeat-cured PMMAB. Liquid (monomer) CompositionB. Liquid (monomer) Composition

Monomer of MMA…. Monomer of MMA…. (The actual reactant)(The actual reactant) 0.0006% Hydroquinon….0.0006% Hydroquinon…. (polymerization inhibitor)(polymerization inhibitor) TEG-DMA…. TEG-DMA…. (Cross-linking agent)(Cross-linking agent) Dibytyl phethalate….Dibytyl phethalate…. (plasticizer)(plasticizer)

Setting of the Setting of the Heat-cured acrylic Heat-cured acrylic

resinresin

At FirstAt First

When the Powder and Liquid are mixed When the Powder and Liquid are mixed at the proper ratio at the proper ratio (3:1 Vol. or 2:1 Wt.) (3:1 Vol. or 2:1 Wt.) certain physical changes will happencertain physical changes will happen

1. Sandy stage1. Sandy stage- Due to wetting of polymer powder particles Due to wetting of polymer powder particles

with the liquid monomerwith the liquid monomer- The mix is The mix is FriableFriable and and looks like the wet sandlooks like the wet sand- Not adhere to glass wallNot adhere to glass wall

2. Stringy stage2. Stringy stage- Due to Due to dissolution of polymer particles in the dissolution of polymer particles in the

monomer (organic solvent)monomer (organic solvent)- Formation of stringsFormation of strings is a characterizing feature is a characterizing feature- The mix still The mix still Not coherent Not coherent and and Adhere to glass Adhere to glass

wallwall

3. Dough stage3. Dough stage- Due to Complete dissolution of polymer in the Due to Complete dissolution of polymer in the

monomermonomer- The mix looks The mix looks coherentcoherent and and putty like putty like mass mass - Not stick to and easily collected from glass Not stick to and easily collected from glass

wallwall- Few strings may be existFew strings may be exist- It is the proper stage for moldingIt is the proper stage for molding (shaping or (shaping or

packing) the acrylicpacking) the acrylic

5. Hard stage5. Hard stage- Due to evaporation of whole monomer as a Due to evaporation of whole monomer as a

result of prolonged waiting before activation. result of prolonged waiting before activation. - The mix looks as The mix looks as granulargranular (packed particles), (packed particles),

hard hard and and brittlebrittle mass mass

4. Rubber stage4. Rubber stage- Due to evaporation of some monomerDue to evaporation of some monomer- The mass becomeThe mass become rubbery, rubbery, - not easily moldednot easily molded (the workability is dramatically (the workability is dramatically

reduced)reduced)

Setting of the Setting of the Heat-cured acrylic Heat-cured acrylic

resinresin

ThenThen

The addition polymerization reaction The addition polymerization reaction starts starts onlyonly when the material is when the material is heated gradually above 65heated gradually above 65ooCC

1. Water bath curing1. Water bath curingA thermostatic-controlled water bath is usedA thermostatic-controlled water bath is used

A. Short curing cycleA. Short curing cycle

1- The flask is heated gradually to 741- The flask is heated gradually to 74ooC in 1.5 hrs. C in 1.5 hrs. (During this stage thick portions of the denture are (During this stage thick portions of the denture are cured)cured)

2- The temperature is then raised to 1002- The temperature is then raised to 100ooC in 30 C in 30 min and fixed for another 30 min. min and fixed for another 30 min.

(During this stage thin portions of the denture are (During this stage thin portions of the denture are cured)cured)

1. Water bath curing1. Water bath curingA thermostatic-controlled water bath is usedA thermostatic-controlled water bath is used

B. Long curing cycleB. Long curing cycle (over night curing)(over night curing)

The flask is heated gradually to 74The flask is heated gradually to 74ooC and C and maintained at this temperature for 8 or more maintained at this temperature for 8 or more hrs. hrs.

Using the short cycle results in acrylic with ;Using the short cycle results in acrylic with ;

1.1. Higher degree of polymerization, Higher degree of polymerization,

2.2. Higher mechanical properties and Higher mechanical properties and

3.3. Lower residual monomer contentLower residual monomer content

2. Microwave curing2. Microwave curing

Microwave oven is used Microwave oven is used as as an alternative heat sourcean alternative heat source to activate the to activate the polymerization of the heat-polymerization of the heat-cured PMMAcured PMMA

CharactersCharacters1.1. Utilizes only 4-5 min Utilizes only 4-5 min (Saves time )(Saves time )2.2. Requires Requires non-metallic flasknon-metallic flask (Polycarbonate flask).(Polycarbonate flask). 3.3. Requires a specially formulated acrylicRequires a specially formulated acrylic to reduce the to reduce the

expected porosityexpected porosity4.4. The resultant dentures show acceptable fitting and The resultant dentures show acceptable fitting and

physical propertiesphysical properties

Construction of Construction of Heat-cured acrylic Heat-cured acrylic

denture basesdenture bases

A. Using compression molding A. Using compression molding techniquetechnique

B. Using injection molding B. Using injection molding techniquetechnique

Compression molding Compression molding techniquetechnique

1. Denture Flask1. Denture Flask

Compression molding Compression molding techniquetechnique

2. Flasking procedure2. Flasking procedure

Compression molding Compression molding techniquetechnique

3. Cleaned mold 3. Cleaned mold

Compression molding Compression molding techniquetechnique

4. Packing of acrylic 4. Packing of acrylic dough dough

Compression molding Compression molding techniquetechnique

5. Finished dentures 5. Finished dentures

Injection molding Injection molding techniquetechnique

Making Dentures.flv