Dental acrylic resins/ dental implant courses

Dental acrylic resinsDental acrylic resins
www.indiandentalacademy.comwww.indiandentalacademy.com

IntroductionIntroduction
 Early fabrication of orthodontic appliances usedEarly fabrication of orthodontic appliances used
vulcanized rubber, which was introduced byvulcanized rubber, which was introduced by
Charles Goodyear in 1839Charles Goodyear in 1839
 It was the material used by C. A. Hawley in hisIt was the material used by C. A. Hawley in his
original removable retainer design. .original removable retainer design. .
 Acrylic resins were introduced in 1936 in theAcrylic resins were introduced in 1936 in the
monomer/polymer form.monomer/polymer form.
 The autopolymerized or "cold-cured" resins,The autopolymerized or "cold-cured" resins,
perfected in Germany during the 1940sperfected in Germany during the 1940s

HistoryHistory
 Before 1936, the materials used were vulcanite,Before 1936, the materials used were vulcanite,
nitrocellulose, phenol formaldehyde, vinyl plastics &nitrocellulose, phenol formaldehyde, vinyl plastics &
porcelain.porcelain.
VULCANITE – contains rubber with 32% sulfur &VULCANITE – contains rubber with 32% sulfur &
metallic oxides for color pigment.metallic oxides for color pigment.
Advantages-Advantages-
 non toxicnon toxic
 non irritantnon irritant
 excellent mechanical propertiesexcellent mechanical properties
 material is sufficiently hard to polish.material is sufficiently hard to polish.

Limitations-Limitations-
 absorbs saliva & becomes unhygienic due to bacterialabsorbs saliva & becomes unhygienic due to bacterial
proliferation,proliferation,
 unpleasant odorunpleasant odor
 poor esthetics due to opacity of the rubberpoor esthetics due to opacity of the rubber
 Dimensional changes occur due to: thermal expansionDimensional changes occur due to: thermal expansion
during heating in the vulcanizer & contraction of 2-4%during heating in the vulcanizer & contraction of 2-4%
during addition of sulfur to rubberduring addition of sulfur to rubber
NITROCELLULOSENITROCELLULOSE
 Dimensionally stableDimensionally stable
 Excessive warpageExcessive warpage
 High water absorption poor color stabilityHigh water absorption poor color stability
 Contains unpleasant tasting plasticizersContains unpleasant tasting plasticizers

PHENOL FORMALDEHYDEPHENOL FORMALDEHYDE
 Becomes discolored and unestheticBecomes discolored and unesthetic
 Difficult to repairDifficult to repair
PORCELAINPORCELAIN
 Difficult to fabricateDifficult to fabricate
 brittlebrittle

ClassificationClassification
 Based on thermal behaviourBased on thermal behaviour
1.1. ThermoplasticThermoplastic – eg. Polymethyl
methacrylate, polyvinyl acrylics,
polystyrene
2.2. Thermosetting – eg. Crosslinked polyThermosetting – eg. Crosslinked poly
(methyl methacrylate), silicones(methyl methacrylate), silicones

Ideal requirementsIdeal requirements
1.1. Biologic compatibilityBiologic compatibility - tasteless, Odorless,- tasteless, Odorless,
Nontoxic, nonirritatingNontoxic, nonirritating
 Completely insoluble in saliva or in any other fluidsCompletely insoluble in saliva or in any other fluids
and should be impermeable to oral fluidsand should be impermeable to oral fluids
 If used as a filling or cementing material, it shouldIf used as a filling or cementing material, it should
set fairly rapidly and bond to tooth structure toset fairly rapidly and bond to tooth structure to
prevent microbial ingrowth.prevent microbial ingrowth.
2.2. Physical PropertiesPhysical Properties -It should possess adequate-It should possess adequate
strength and resiliencestrength and resilience
 It should be resistant to biting or chewing forces,It should be resistant to biting or chewing forces,
impact forces, and excessive wearimpact forces, and excessive wear
 It should be dimensionally stable under all conditionsIt should be dimensionally stable under all conditions
of service, including thermal changes and variationsof service, including thermal changes and variations
in loading.in loading.
 It should have a low specific gravity.It should have a low specific gravity.

3. Manipulation3. Manipulation-It should not produce toxic fumes or-It should not produce toxic fumes or
dust during handling and manipulation.dust during handling and manipulation.
 It should be easy to mix, insert, shape, and cure, andIt should be easy to mix, insert, shape, and cure, and
it must have a relatively short setting time and beit must have a relatively short setting time and be
insensitive to variations in these handlinginsensitive to variations in these handling
procedurestheproceduresthe
 The final product should be easy to polish, and inThe final product should be easy to polish, and in
case of unavoidable breakage, it should be possiblecase of unavoidable breakage, it should be possible
to repair the resin easily and efficientlyto repair the resin easily and efficiently
4.4. Aesthetic Properties-Aesthetic Properties- it should exhibit sufficientit should exhibit sufficient
translucencytranslucency
 It should be capable of being tinted or pigmentedIt should be capable of being tinted or pigmented
5.5. Economic ConsiderationsEconomic Considerations
6.6. Chemical StabilityChemical Stabilitywww.indiandentalacademy.comwww.indiandentalacademy.com

UsesUses
 Dentures (bases, liners, andDentures (bases, liners, and
 Artificial teethArtificial teeth
 Cavity-filling materials ("composites")Cavity-filling materials ("composites")
 Equipment (mixing bowls)Equipment (mixing bowls)
 Cements (resin-based)Cements (resin-based)
 Orthodontic & pedodontic appliancesOrthodontic & pedodontic appliances
 SealantsSealants
 Impression materialsImpression materials
 Crown & bridge facingsCrown & bridge facings
 Maxillofacial prosthesis (obturators for cleft palate)Maxillofacial prosthesis (obturators for cleft palate)
 Inlay & post core patternsInlay & post core patterns
 DiesDies
 Temporary crowns & bridgesTemporary crowns & bridges
 Athletic mouth protectorsAthletic mouth protectors
 Impression traysImpression trays
 Splints & stentsSplints & stents
 ModelsModels

FUNDAMENTAL NATURE OFFUNDAMENTAL NATURE OF
POLYMERSPOLYMERS
 Polymer- Chemical compound consisting of largePolymer- Chemical compound consisting of large
organic molecules formed by the union of manyorganic molecules formed by the union of many
repeating smaller monomer units.repeating smaller monomer units.
 Polymerization-Chemical reaction in which monomersPolymerization-Chemical reaction in which monomers
of a low molecular weight are converted into chains ofof a low molecular weight are converted into chains of
polymers with a high molecular weight:polymers with a high molecular weight:
PolymerizationPolymerization
 Monomer + Monomer + MonomerMonomer + Monomer + Monomer
Mer - Mer - Mer - Mer –Mer - Mer - Mer - Mer –www.indiandentalacademy.comwww.indiandentalacademy.com

Chain length & molecular weightChain length & molecular weight
 The longer the chain length,The longer the chain length,
the more difficult it is tothe more difficult it is to
distort the polymericdistort the polymeric
material, and thus suchmaterial, and thus such
properties as rigidity,properties as rigidity,
strength and the meltingstrength and the melting
temperature increase withtemperature increase with
the chain lengththe chain length
 Consider the analogyConsider the analogy
between the behavior of abetween the behavior of a
polymer molecular chainspolymer molecular chains
and a plate of spaghetti.and a plate of spaghetti.

Branching and Cross-Branching and Cross-
LinkingLinking

Copolymer StructuresCopolymer Structures
 Random copolymerRandom copolymer
-ABBABABAAABAAAABABBBBABAAAABABAB-ABBABABAAABAAAABABBBBABAAAABABAB
B ...B ...
 Block copolymer -...Block copolymer -...
AAAAABBBBBBBAAAABBBBBBBAAABBBAAAAAAAABBBBBBBAAAABBBBBBBAAABBBAAA
A …A …
 Graft or branched copolymer...Graft or branched copolymer...
….AAAAAAAAAAAAAA ….….AAAAAAAAAAAAAA ….
B BB B
B BB B
B BB B

Molecular OrganizationMolecular Organization

PHYSICAL PROPERTIES OFPHYSICAL PROPERTIES OF
POLYMERSPOLYMERS
Deformation and recoveryDeformation and recovery
 PlasticPlastic deformation is irreversible and results indeformation is irreversible and results in
a new permanent shapea new permanent shape
 ElasticElastic deformation is reversible and will bedeformation is reversible and will be
completely recovered when the stress iscompletely recovered when the stress is
eliminated.eliminated.
 ViscoelasticViscoelastic deformation results in a combinationdeformation results in a combination
of elastic and plastic strain but recovery of onlyof elastic and plastic strain but recovery of only
elastic strain occurs as the stress is decreased.elastic strain occurs as the stress is decreased.

Rheometric PropertiesRheometric Properties
 Rheometry, orRheometry, or flowflow
behaviorbehavior
 Plastic flowPlastic flow
 Elastic recoveryElastic recovery

 The following characteristics describe the generalThe following characteristics describe the general
nature of polymers:nature of polymers:
 The longer the chains (the higher the molecularThe longer the chains (the higher the molecular
weight), the more slowly a polymer dissolves.weight), the more slowly a polymer dissolves.
 Polymers tend toPolymers tend to absorbabsorb a solvent, swell, and soften,a solvent, swell, and soften,
rather than dissolverather than dissolve
 Cross-linking prevents complete chain separation andCross-linking prevents complete chain separation and
retards dissolutionretards dissolution
 Highly cross-linked polymers cannot be dissolved.Highly cross-linked polymers cannot be dissolved.
 Elastomers swell more than plastics.Elastomers swell more than plastics.
 A small amount of swelling of dental polymeric devicesA small amount of swelling of dental polymeric devices
can have undesirable results on the fit of prostheses.can have undesirable results on the fit of prostheses.
 Absorbed molecules (e.g., water) spread polymerAbsorbed molecules (e.g., water) spread polymer
chains apart and facilitate slip between chains. Thischains apart and facilitate slip between chains. This
lubricating effect is calledlubricating effect is called plasticization.plasticization.

 Cross-linkage provides a sufficient number ofCross-linkage provides a sufficient number of
bridges between linear macromolecules to form abridges between linear macromolecules to form a
three-dimensional network that decreases waterthree-dimensional network that decreases water
sorption, decreases solubility, and increases thesorption, decreases solubility, and increases the
strength and rigidity of the resin.strength and rigidity of the resin.
 Plasticizers are often added to resins to reducePlasticizers are often added to resins to reduce
their softening or fusion temperatures.their softening or fusion temperatures.
 A plasticizer acts to partially neutralize secondaryA plasticizer acts to partially neutralize secondary
bonds or intermolecular forces that normallybonds or intermolecular forces that normally
prevent the resin molecules from slipping past oneprevent the resin molecules from slipping past one
another when the material is stressed.another when the material is stressed.
 External plasticizerExternal plasticizer
 Internal plasticiserInternal plasticiserwww.indiandentalacademy.comwww.indiandentalacademy.com

CHEMISTRY OFCHEMISTRY OF
POLYMERIZATIONPOLYMERIZATION
Monomers may be joined via one of twoMonomers may be joined via one of two
types of reaction:types of reaction:
additionaddition polymerizationpolymerization
 step-growthstep-growth or condensationor condensation
polymerizationpolymerization

Addition polymerizationAddition polymerization
 Four distinct stages in the addition polymerization chainFour distinct stages in the addition polymerization chain
reaction process: induction, propagation, chain transfer,reaction process: induction, propagation, chain transfer,
and termination.and termination.
 Induction. Two processes control the induction stage:Induction. Two processes control the induction stage:
activation and initiationactivation and initiation
 ActivationActivation
R-R + external energy 2 R·R-R + external energy 2 R·
 RequisitesRequisites
 presence of an unsaturated group, that is, apresence of an unsaturated group, that is, a
double bond,double bond, as well as a source of freeas well as a source of free
radicals.radicals. www.indiandentalacademy.comwww.indiandentalacademy.com

InitiationInitiation

PropagationPropagation
RH2
C-CH2
• + H2
C=CH2
RH2
C-CH2
-H2
C-CH2
•
RH2
C-CH2
-H2
C-CH2
• + H2
C=CH2
RH2
C- (CH2
- H 2 Ch -CH2
•.. etc.www.indiandentalacademy.comwww.indiandentalacademy.com

Chain TransferChain Transfer

TerminationTermination

Inhibition of AdditionInhibition of Addition
PolymerizationPolymerization

Step growth PolymerizationStep growth Polymerization
 In step-growth polymerization, a linear chain ofIn step-growth polymerization, a linear chain of
repeating mer units is obtained by the stepwiserepeating mer units is obtained by the stepwise
intermolecular condensation or addition of theintermolecular condensation or addition of the
reactive groups in whichreactive groups in which bifunctionalbifunctional or trifunctionalor trifunctional
monomers are all simultaneously activatedmonomers are all simultaneously activated
 For example:For example:
HO-(Silicone)-OH + n HO-(Silicone)-OHHO-(Silicone)-OH + n HO-(Silicone)-OH
HO-(Silicone)-(O-Silicone) n-OH+ n H20HO-(Silicone)-(O-Silicone) n-OH+ n H20

COPOLYMERIZATIONCOPOLYMERIZATION

Multifunctional MethacrylateMultifunctional Methacrylate
and Acrylate Resinsand Acrylate Resins
 To quantify the efficiency of polymerization and cross-To quantify the efficiency of polymerization and cross-
linking,the ratio, R, of unreacted methacrylate grouplinking,the ratio, R, of unreacted methacrylate group
before & after polymerization.before & after polymerization.
 TheThe degree of conversion,degree of conversion, expressed in percentage ofexpressed in percentage of
consumed methyl methacrylate groups, can be deterconsumed methyl methacrylate groups, can be deter
mined from the formulamined from the formula
 (1 - R) x 100 = degree of conversion(1 - R) x 100 = degree of conversion

Acrylic ResinsAcrylic Resins
 The acrylic resins are derivatives of ethylene andThe acrylic resins are derivatives of ethylene and
contain a vinyl (-C=C-) in their structural formula:contain a vinyl (-C=C-) in their structural formula:
 There are two acrylic resin series that are of dentalThere are two acrylic resin series that are of dental
interest.interest.
 Acrylic acid CH2=CHCOOHAcrylic acid CH2=CHCOOH
 methacrylic acid CH2=C(CH3)COOHmethacrylic acid CH2=C(CH3)COOH
CH2=C (CH3) -CH2-C (CH3)-CH2-C (CH3)-CH2=C (CH3) -CH2-C (CH3)-CH2-C (CH3)-
COORCOOR COORCOOR COORCOORwww.indiandentalacademy.comwww.indiandentalacademy.com

HEAT-ACTIVATED DENTUREHEAT-ACTIVATED DENTURE
BASE RESINSBASE RESINS
powder & liquidpowder & liquid
Gels - sheets & cakesGels - sheets & cakes
Commercial names- stellon (DPI), LucitoneCommercial names- stellon (DPI), Lucitone
(Bayer), Travelon (Dentsply)(Bayer), Travelon (Dentsply)

CompositionComposition
liquidliquid
 Methyl methacrylateMethyl methacrylate
 Dibutyl phthalateDibutyl phthalate
 GlycoldimethacrylateGlycoldimethacrylate
 HydroquinoneHydroquinone
PowderPowder
 Poly(methyl methacrylate)Poly(methyl methacrylate)
 Benzoyl peroxideBenzoyl peroxide
 Compounds of mercuric oxide, cadmium sulfideCompounds of mercuric oxide, cadmium sulfide
 Zinc or titanium oxideZinc or titanium oxide
 Dibytyl phthalateDibytyl phthalate
 Glass fibers or beadsGlass fibers or beads

Methyl methacrylateMethyl methacrylate
 Methyl methacrylate is aMethyl methacrylate is a
transparent liquid at roomtransparent liquid at room
temperature with the followingtemperature with the following
physical properties:physical properties:
 Molecular weight = 100Molecular weight = 100
 Melting point = -48° CMelting point = -48° C
 Boiling point = 100.8° C (noteBoiling point = 100.8° C (note
how close this is to the boilinghow close this is to the boiling
point of water)point of water)
 Density = 0.945 g/mL at 20° CDensity = 0.945 g/mL at 20° C
 Heat of polymerization = 12.9Heat of polymerization = 12.9
kcal/molkcal/mol
CH3CH3
//
H2C=CH2C=C

C=OC=O
//
OO

CH3CH3

Poly (Methyl Methacrylate)Poly (Methyl Methacrylate)
 Poly (methyl methacrylate) is a transparent resin ofPoly (methyl methacrylate) is a transparent resin of
remarkable clarityremarkable clarity
 It is a hard resin with a Knoop hardness number of 18It is a hard resin with a Knoop hardness number of 18
to 20.to 20.
 Tensile strength approximately 60 MPaTensile strength approximately 60 MPa
 Density of 1.19 g/cm3Density of 1.19 g/cm3
 Modulus of elasticity approximately 2.4 GPa (2400Modulus of elasticity approximately 2.4 GPa (2400
MPa).MPa).
 Extremely stableExtremely stable
 It is chemically stable to heat and 1250 CIt is chemically stable to heat and 1250 C
 Above 1250 depolymerization takes place.Above 1250 depolymerization takes place.
 At approximately 4500 C, 90% of the polymerAt approximately 4500 C, 90% of the polymer
depolymerizes to form the monomerdepolymerizes to form the monomer

Polymerization reactionPolymerization reaction
 Powder + liquidPowder + liquid
(polymer + initiator) (monomer+ inhibitor)(polymer + initiator) (monomer+ inhibitor)
+ heat+ heat
Polymer + heatPolymer + heat
 Techiques – compression moulding technique &Techiques – compression moulding technique &
injection moulding techniqueinjection moulding technique

Seperating mediaSeperating media
TypesTypes
o TinfoilTinfoil
o Cellulose lacquersCellulose lacquers
o Solution of alginated compoundSolution of alginated compound
o Calcium oleateCalcium oleate
o Soft soapsSoft soaps
o Sodium silicateSodium silicate
o starchesstarches

Sodium alginate solutionSodium alginate solution
Most commonly usedMost commonly used
Water solubleWater soluble
Rects with calcium of plaster or stone toRects with calcium of plaster or stone to
form a film of insoluble calcium alginateform a film of insoluble calcium alginate
Composition- 2% sodium alginate inComposition- 2% sodium alginate in
water, glycerin, alcohol, sodium phosphatewater, glycerin, alcohol, sodium phosphate
& preservatives& preservatives

Mixing of powder & liquidMixing of powder & liquid
 Polymer monomer proportion = 3:1 by volume orPolymer monomer proportion = 3:1 by volume or
2:1 by weight2:1 by weight
 If too much monomer- greater polymerizationIf too much monomer- greater polymerization
shrinkage, more time before packing, porosityshrinkage, more time before packing, porosity
may occur.may occur.
 If too little monomer- granular cured acrylic,If too little monomer- granular cured acrylic,
inhomogeneous mix may not fuse into ainhomogeneous mix may not fuse into a
continuous unit.continuous unit.

Physical stages after mixingPhysical stages after mixing
Stage I- Wet Sand Stage:Stage I- Wet Sand Stage: The polymer gradually settlesThe polymer gradually settles
into the monomer forming a fluid, incoherent mass.into the monomer forming a fluid, incoherent mass.
Stage II- Sticky Stage:Stage II- Sticky Stage: The monomer attacks theThe monomer attacks the
polymer by penetrating into the polymer by penetratingpolymer by penetrating into the polymer by penetrating
into the polymer. The mass is sticky and stringyinto the polymer. The mass is sticky and stringy
(cobweb like) when touched or pulled apart.(cobweb like) when touched or pulled apart.
Stage III- Dough or Gel Stage:Stage III- Dough or Gel Stage: As the monomer diffusesAs the monomer diffuses
into the polymer, it becomes smooth & dough like. Itinto the polymer, it becomes smooth & dough like. It
does not adhere to the walls of the jar. It consists ofdoes not adhere to the walls of the jar. It consists of
undissolved polymer particles suspended in a plasticundissolved polymer particles suspended in a plastic
matrix of monomer & dissolved polymer.matrix of monomer & dissolved polymer.

Stage IV- Rubbery Stage:Stage IV- Rubbery Stage: The monomer disappears byThe monomer disappears by
further penetration into the polymer &/or evaporation.further penetration into the polymer &/or evaporation.
The mass is rubberlike, non plastic & cannot beThe mass is rubberlike, non plastic & cannot be
moulded.moulded.
Stage V- Stiff Stage:Stage V- Stiff Stage:
Final stage in which the mass is stiff and hard.Final stage in which the mass is stiff and hard.
 Working time - Time elapsing between stage II &Working time - Time elapsing between stage II &
beginning of stage IVbeginning of stage IV
 5 min5 min

CHEMICALLY ACTIVATED DENTURECHEMICALLY ACTIVATED DENTURE
BASE RESINSBASE RESINS
CompositionComposition
 liquidliquid
 Methyl methacrylateMethyl methacrylate
 Dimethyl-p-toluidineDimethyl-p-toluidine
 Dibutyl phthalateDibutyl phthalate
 Glycoldimethacrylate 1-2%Glycoldimethacrylate 1-2%
 Hydroquinone 0.006%Hydroquinone 0.006%
PowderPowder
 Poly(methyl methacrylate)Poly(methyl methacrylate)
 Benzoyl peroxideBenzoyl peroxide
 Compounds of mercuric oxide, cadmium sulfideCompounds of mercuric oxide, cadmium sulfide
 Zinc or titanium oxideZinc or titanium oxide
 Dibytyl phthalateDibytyl phthalate
 Glass fibers or beadsGlass fibers or beads www.indiandentalacademy.comwww.indiandentalacademy.com

Advantages & disadvantagesAdvantages & disadvantages
 Better initial fit because of less thermalBetter initial fit because of less thermal
contractioncontraction
 Inferior color stability because of oxidation ofInferior color stability because of oxidation of
tertiary aminetertiary amine
 Inferior properties because of less degree ofInferior properties because of less degree of
polymerizationpolymerization
 Preferable for denture repairPreferable for denture repair
 Greater chances of porosityGreater chances of porosity
 Lower average molecular weightLower average molecular weight
 Less strongLess strong

ManipulationManipulation
Sprinkle on techniqueSprinkle on technique
Adapting techniqueAdapting technique
Fluid resin techniqueFluid resin technique
Compression moulding techniqueCompression moulding technique
Injection moulding techniqueInjection moulding technique

Light activated denture base resinsLight activated denture base resins
 It consists of a urethane dimethacrylate matrix withIt consists of a urethane dimethacrylate matrix with
an acrylic copolymer, microfine silica fillers, and aan acrylic copolymer, microfine silica fillers, and a
camphoroquinone amine photo initiator systemcamphoroquinone amine photo initiator system
 Supplied as premixed sheetsSupplied as premixed sheets
 Cured in a curing unit with blur light of 400- 500 nmCured in a curing unit with blur light of 400- 500 nm
from high intensity quartz halogen bulbsfrom high intensity quartz halogen bulbs

 To examine the applicability of visible light-To examine the applicability of visible light-
cured resins to orthodontics. In all physicalcured resins to orthodontics. In all physical
property testing, it was found that VLC resinsproperty testing, it was found that VLC resins
met or exceeded required values as establishedmet or exceeded required values as established
by ADA Specification No. 12 for denture baseby ADA Specification No. 12 for denture base
polymers.polymers.
 In vitro bacterial adherence studies showed thatIn vitro bacterial adherence studies showed that
more organisms adhered to heat-curedmore organisms adhered to heat-cured
specimens than to the other specimens. In vivospecimens than to the other specimens. In vivo
studies using split-palate Hawley retainersstudies using split-palate Hawley retainers
demonstrated slightly less bacterial adherencedemonstrated slightly less bacterial adherence
to BC than to the other resinsto BC than to the other resins

Properties of denture resinsProperties of denture resins

 Biocryl ICE is an ultra-clear, non-yellowing acrylic resin shown by CIE colorBiocryl ICE is an ultra-clear, non-yellowing acrylic resin shown by CIE color
measurements to be the clearest acrylic available. Period. Biocryl ICE is ameasurements to be the clearest acrylic available. Period. Biocryl ICE is a
fast setting, extremely workable material ideal for splints and a variety offast setting, extremely workable material ideal for splints and a variety of
other appliances. The exceptional clarity of Biocryl ICE makes it the perfectother appliances. The exceptional clarity of Biocryl ICE makes it the perfect
choice for esthetic-conscious patientschoice for esthetic-conscious patients

Dental acrylic resins/ dental implant courses

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