RESIN AKRILIK 2012

Polymer

Heat Activated Resin Chemically activated

Resin Light Activated Resin Microwave Activated

Resin Nylon base Resin

POLYMER

Polymer : chemical compound consisting of large organic molecules formed by the union of many repeating smaller monomers unit

Polymerization : chemical reaction in which monomer of low molecular weight are converted into chain of polymers with a high MW

Classification of Resin

Thermoplastic - refers to resin that can be

repeatedly softened and moulded under heat and

pressure

Thermoset - refers to resin that can be

moulded only once, they set when heated and

cannot softened by reheating

Application of resin in Dentistry

To restore Replace tooth structure & missing

Dentures (base, liner, artifial teeth) Cavity-filling material (composites)

Sealant Impression material

Cement resin carboxylate

Requirement of dental resin Be tasteless, odorless, non toxic, non irritant

Be esthetic, the color should be permanent Be dimensionally stable Have enough strength, resilience, abrasion

resistance Be insoluble and impermeable to oral fluid Have a low specific gravity (light in weight) Tolerate temp. well above without undue

softening or distorsion Be easy fabricated and repair Have good thermal conductivity Be radio-opaque

Uses of Dental Resin

1. Denture base

2. Artificial teeth

3. Filling materials

4. Bone substitute

5. Mouth protector

6. etc

Application in Medicine

Ortopedic Soft tissue - cardiovascular - benang bedah

Dental Polymer Polymer chemical compound consisting of large

organic molecules formed by the union of many repeating smaller monomer units (mers)

Is capable of limitless configuration & conformations

Most polymer molecules can be described as macromolecules ( > 5000 molecular weight)

The traditional polymer can consist of inorganic polymer

- silicon dioxide : ceramic resin composite

Structure of polymers

Linear

Branched

Cross-linked

+

Cross-linked

Copolymer : structure that have only 2 or more type repeating unit

- random copolymer AABBBBABBAAAAAA… etc - Block copolymer AAABBBBBAAABBBBB … etc -graft / branched AAAAAAA B B B

Molecular Organization

Amorphous structure - disordered pattern

Crystalline structure - highly ordered

Factors that prevent crystallinity:

Copolymerization …… decrease the ability Long branched polymer … inhibit chain Random arrangement of substituent.. Large

side groups that polymer chain separated Plasticizer ….. Tend to separate the chains

Physical properties of polymer:

Plastic deformation - is irreversible, new permanent shape Elastic deformation - is reversible, completely recovere Viscoelastic deformation - combination of elastic & plastic strain, but

recovery of only elastic stran Plastic flow -irreversible strain with slide & permanent

deformation Elastic recovery - reversible strain, return to their original location

Characteristic of polymer:

The longer chain, the more slowly polymer dissolves

Polymer tend to absorb a solvent: swell, soften Cross-linked prevent complete chain separation

and retard dissolution Highly cross-linked polymer can not dissolved Elastomers swell more than plastics A small amount of swelling can have undesirable

on fit of prostheses Absorbed molecules (water) spread polymer

chains apart and facilitate slip between chains

Properties of denture base resin

Resin Hardness

KHN, MPa

Transferse

Strength (MPa)

Elastic modul

us (GPa)

Impact strengt

h (J/m2)

ConcentionalSelf cureRapid cureHigh impactLight cure

170 160

150-170140175

80-9584

79-8678-95

80-110

3.81.6

1.3-1.62.4-2.52.1-3.1

15-1715

12-1524-31

13

Chemistry of Polymerization

Step-growth polymerization (Condensation

polymerization) Addition polymerization - induction - propagation - chain transfer - termination

STEP-GROWTH POLYMERIZATION (CONDENSATON POLYMERIZION)

Is preferred /called as step-Growth polymeriza- tion than condenzation polymerization (because has broadened meaning)

A linear chain of repeating mer units is obtained by stepwise intermolecular condensastion or addition of the reactive groups which bifunctional or trifuncfinal monomer are all simultaneously activated

The primary compounds react, often with the formation of by product (water, alcohol, halogen acid, ammonia) or without side product

Addition Polymerization Induction

- Activation …. generates a free radicals

- Initiation ….. Electron attack to double bond

to form an electron pair

and a covalent bond ( free-radical monomer complex as new radical)

Propagation - dimers new

radical with monomer to form polymer and continued

Chain transfer

Termination - direct coupling if

two free radical chain end or

exchange of H+ from one growing chain another

ACRYLIC RESIN (POLYMETHYL METHACRYLATE)

The majority of denture base have been fabricated using poly methyl methacrylate resins

Is a colorless and transparent solid Its color and optical properties stable under

normal intraoral condition Its physical properties have proven adequate for

dental application Is supplied as powder and liquid system The powder contains prepolymerized resin in the

form of small bead The liquid contain nonpolymerized resin

Type of Denture base Resin

Heat activated denture base resin - Heat-cured - Microwave-cured Chemically activated denture base

resin (cold-cured, self-cured) Light activated denture base resin

HEAT ACTIVATED DENTURE BASE ACRYLIC RESIN

Available as :

Powder & liquid Gels- sheet Cakes

Commercial names: Stellon, Lucitone, Trevelon

Composition:

Liquid - Methyl methacrylate : plasticizes the

polymer - Dibutyl phthalate : plasticizer - Glycol dimethacrylate : cross-link agent - hydroquinone : inhibitor setting Powder - Polymethyl methacrylate & copolymer - benzoyl peroxide : initiator - Zinc oxide / titanium oxide : opacifier - dibuthyl phthalate : plasticizer - dye

Polymerization reaction :

Powder + liquid (monomer)

Polymer + heat (exothermal)

Heat external

Properties of Denture Resins

Is clear, transparent, volatile, sweetish odor Physical : - melting point - 48oC - Boiling point 100oC - Density 0.945 g/ml - Heat of polymerization 12.9 Kcal/mol Volume shrinkage 21%

Methyl Methacrylate Monomer

Polymethyl methacrylate

Completely polymerized resin is tasteless & odorless

A high amount of porosity resulting an unpleasant taste and odor

Esthetics, clear transparent, can be pigmented easily, compatible with dyed synthetic fillers

Density : 1.19 g/cm3 Compressive strength : 75 MPa Tensile strength : 52 MPa Hardness : 18-20 KHN (HC), 16-18 KHN (SC) (easily scratched and abraded)

Self cured resin have lower

Modulus elasticity : sufficient stiffness (2400 MPa) Dimensional stability is good, the processing

shrinkage is balanced by the expansion due to water sorption (reversible)

Water sorption : 0.6 mg/cm3 and expand Is virtually insoluble in water and oral fluids

(soluble in: ketone, ester, aromatic & chlorinates hydrocarbon; alcohol causes crazing)

Thermal properties Thermal conductivity : poor Coefficient of thermal expansion is high Color stability : good Residual monomer: 26.2% (before start curing),

6,6% ( 1 hour), 0.29% (at 100oC) Self life : the best (P/L), lower (gel)

Processing Errors

Porosity (internal & external) - internal porosity is in the form voids or

bubles cause is due to the vaporization of monomer - external porosity ; causes by lack of homogenity and lack of adequate pressure Crazing - is formation of surface crack (microscopic

/macroscopic) …… hazy or foggy - cause fractire - causes by mechanical stress, attack by

solvent, incorporation of water

Strength of Polymers depend on :

1.Molecular weight

2.Degree of polymerization

3.Chain structural

4.Thermal properties

- thermoplastic

- thermo setting

5. Plasticizer

Monomer-Polymer Interaction

Stage 1 : The polymer gradually settles into the monomer to form a incoherent mass, mixture may be coarse or grainy (sandy phase)

Stage 2 : The monomer attack the polymer, the layer polymer penetrated sloughs off and is dispersed in the monomer. Its characterized by stringiness and adhesive (stringy phase, sticky phase)

Stage 3 : the mass becomes more saturated with polymer in solution, it becomes smooth and dough like, it does not adhere to the wall of the mixing jar (dough phase/gel phase), it is packed into the mold

Stage 4 : the mass becomes more cohesive and rubberlike, it can not be molded (rubbery phase)

Stage 5: stiff phase, very dry & resistant to mechanical deformation

HEAT ACTIVATED RESIN

Heat activated denture base resin are shape

By compression molding technique

Compression molding technique

Articulator mounting Tooth arrangement & wax contouring

Flasking & deflasking Selection & application separating

medium Packing Pressure Curing

Flasking

Wax elimination

Placement of alginate-base separatingmedium

of alginate-base separatingmedium of alginate-base separatingmedium of alginate-base separatingmedium Involves the application of an approproate

separating medium onto the wall of mold cavity

Failure to place may be lead to - water permitted to diffuse into the

denture base resin and affect the polymerization rate, optical aand physical

- dissolved polymer (free monomer ) produce compromises inthe physical and esthetic properties

Currently, the popular agent is CMS (cold mold seal) a water-soluble alginate solution (formed a calcium alginate)

Selection & application separating medium

Packing of Dentures Base The placement and adaptation of

denture base within mold cavity The processes the most critical steps in

denture base fabrication The mold cavity be properly filled at the

times of polymerization Overpacking (excessive thickness)

causes malposition of prosthodontic teeth, too underpacking (little material) causes porosity

The resin removed from its mixing container and

rolled into a ropelike form and

bent into a horseshoe shape and

place into the portion that house the prosthetic teeth

Placed over the resin a polyethylene sheet

Flask is reassembled and pressure

Transferred to a flask carrier

a horseshoe shape

Proof pressure

Excess material is removed

Polymerimarization Cycle

At slight above 70oC, the benzoyl perixide becomes free radical increased rate of polyme- rization and exothermis heat

The first technique constant waterbath 74oC - 8 hours / longer The second technique constant waterbath 74oC - 8 hours, 100oC- 1

hour The third technique constant waterbath 74oC - 2 hours, 100oC- 1

hour

After processing (polymerized)

Removed from waterbath and bench cooled for 30 minutes

Immersed in cooled tap water (15 minutes)

Deflasking

Finishing & Polishing

Finishing & Polishing Denture Base Resin

C ontour with tungten carbide burs and sand paper

Use a rubber point to remove the scratches

Apply pumice with rag wheel, felt wheel,nbristle brush or propy cup

Apply tripoli or mixture of chalk and alcohol with rag wheel

CHEMICALLY ACTIVATED RESIN

The application of thermal energy leads to decomposition of benzoyl peroxide and produce free radical

Chemical activator (in liquid) : tertier amine (dimethyl para toluidine)

Degree of polymerization is not as complete Unreacted monomer created major difficulties: - acts as plasticizer - serves potential irritant Slightly less shrinkage, color stability is inferior

Initial hardening will occur within 30 minute of final flask closured

To ensure sufficient polymerization should be held under for minimum of 3 hour

Exhibits 3 -5% of residual monomer Failure to achieve a high degree of

polymerization will predispose - dimensional instability - lead soft tissue irritation

Comparison of heat and self cure resins

Less creep and quicker recovery

Greater creep and quicker recovery

Color stability is good Color stability is poor

Difficult to deflask Easy to deflask

Increased rate monomer diffusion at higher temperature

-

Heat Cure Resin Self Cure Resin

Heat is necessary Heat is not necessary

Porosity of material is less Porosity of material is greater

Higher MW Lower MW

Lower residual monomer content

Higher residual monomer content

Material is strong Material is not strong

Shows less distortion Shows greater distortion

Less initial deformation More initial deformation

LIGHT – ACTIVATED RESIN

Material as composite having a matrix of urethane dimethacrylate, microfine silica, acrylic resin monomer high MW (beads as filler organic)

Visible light is the activator and camphorquinone serves initiator

Opaque investing media prevent the passage of light

Instead, teeth are arranged and denture base is molded on an accurate cast

is exposed to a high intensity visible light source for appropraite period

Following polymerization is removed from cast, finished and polished

Microwave Activated Resin

Composition - Powder (similar with heat cured) - Liquid : triethylene glycol dimethacrylate or tetraethylene glycol dimethacrylate Used non metallic flask (high impact composite

plastic) Heat from magnetron, at 2450MHz wave length Residual monomer is lower than conventional Processing time is greatly speeded up & less

porosity Fit the denture is comparable or superior

Kuvet untuk plimerisasi gel.mikro

55

NYLON – BASED THERMOPLASTIC

“VALPLAST”

Properties of Nylon –based thermoplastic

Retention – flexes into a retentive position below the undercut

Comfort – thin, lightweight, and flexible Aesthetics – pink shades that allow your

patient's natural tissue tone to appear through the material

Strength – clinically unbreakable, more durable than acrylic, and won't absorb stains or odors

Ease – no tooth or tissue preparation is required, so you can offer patients a conservative and less painful solution

Biocompatibility Patient with resin acrylic allergic Used to partial and full denture Untuk pasien yang tidak

menghendaki fixed denture atau implan

Trauma karena GT sering patah

Characteristic Nylon Base Resin

1. Mechanical strength2. Abrasion resistance3. Toughness

cukup

4. Low coefficient of friction

5. Absorbs water6. Absorbs some liquid

Flexite Plus (Polyamide Nylon) Comparable with Valplast, more flexible

and color stable Unbreakable Biocompatibility Can added and repaired in non flexible

areas with rapid set and adhesive Can be relined and added mayor areas by

reinjecting and using repair liquid adhesive Design are mostly tissue supported Requires less precision in the design and

blockout of undercut US Dental Depot

Mould preparation for Valplast:(Ali, Rahdaa, 2011)

The same as in heat cured mould preparation With wax sprue were prepared (6-8 mm) Wax elimination was performed using boiling water Injecting the polymer - preheated inside an oven set at 65oC - started with heating cylinder inserted into the slot

at present inside the electrical furnace - furnace was allowed heating was 287oC –removed -valplast cartridge, metal disc, solid metal cylinder inserted into the heating cylinder cylinder and left inside the furnace for to allow the granules inside the cartridge to melt - give pressure according the leaflet

Critical of Denture Base Resin

Polymerization shrinkage Porosity Water absorpsion Solubility Crazing Creep Growth of microorganism

Polymerization shrinkage :

The density of the mass changes volumetric shrinkage of resin acrylic 21%, but by the polymerization mass approximately 7%

The high vol shrinkage can be used to produce clinically satisfactory denture base

Must consider the effect of linear shrinkage, causes upon denture base adaptation and cuspal interdigitation

Porosity :

To develop in thicker portion of denture base, result from vaporation of unreacted monomer and low MW

Result from: - low MW vaporation - rapid tempearture elevation - inadequate pressure or insufficient in

mold - associated with fluid resin appear to be

caused by air inclusion incorporated

High water absorption Decrease strength Decrease esthetica (discoloration) Poor hygyene halitosis Growth of microorganism : biofilm,

candidiasis

Light micrographs of yeast cells attached to bacteria adherent on PMMA

(Busscher & Evans. Oral Biofilm and Plaque Control. 1998. pg.182)

SEM images of biofilm formation on PMMA

( Ramage et al. Biofilm formation.J Clin Micro, 2001: 39 (9): 3234-40 )

Candidiasis

Water Absorption :

Is facilitate by the polarity and mechanism by diffusion

Water penetrate the PMMA and occupy position between polymer chain causes:

- a slight expansionof the polymer mass - interfere with the entanglement of

polymer chain and act as plasticizer Affect the physically, mechanically and

dimensional properties

Crazing :

Is incidenced by small linear cracking that appear hazy or foggy

Is predispose a denture resin to fracture Solvent-induced crazing from prolonged

contact with ethyl alcohol Tensile stress most responsible for

crazing and is producedby mechanical separation of individual polymer chains

Rebasing Denture Base

Rebasing involves replacement of the entire denture base

The cast and denture are mounted in a device designed to maintain the correct vertical and horizontal relationship

The teeth are repositioned in their respective indices

The denture base is waxed to desired form Following elimination of the wax and resin

introduced into the mold cavity The prothesis consist of new denture base in

conjuction with teeth from previous denture

Relining denture base

Relining involves replacement of the tissue surface of an exciting denture

The tissue surface is cleaned to enhance bonding the excisting resin and the reline material

An appropriate resin is introduced and shaped using a compression molding technique

A low polymerization temp is desirable to minimize distorsion of the remaining denture

Chemically activated resin is chosen

Rebasing / Relining

Reparation of Denture Base

The fracture prosthesis must realign and lute component together using an adherent wax or modeling plastic

The fracture surface are trimmed to provide sufficient space for repair material

Are preffered chemically activated resin (polymerized at room temp)

A small amount of monomer is painted onto prepared surface of the denture to facilitate bonding of the repair material

Repairs