Maxillofacial Prosthesis materials

Contents • Introduction • History • Classifications• Ideal properties • Individual material & their advantages &

disadvantages• Comparison of physical properties• Technique of fabrication• Limitations & degradation of the material• Conclusion • References

Introduction

History• Before 1600 AD- ancient Chinese culture• Tycho Brahe (1546-1601)- nose from gold.

• Ambroise Pare (1510-1601)- nose from gold, silver, paper.

• Pierre Fauchard (1678-1761)- silver mask.

• William Morton (1819-1868)- enameled porcelain.

• Claude Martin (1889)- ceramic

History• 1900-1940

• Upham – vulcanite rubber.

• 1905 Ottofy, Baird & Baker- vulcanite rubber.

• 1913 –Gelatin- glycerin compounds.

• Bulbulian & Clarke - Latex Vulcanite prosthesis given to Sigmond

Freud (Austrian psychiatrist) in 1923.

History• 1937- Acrylic resin.• Tylman – resilient Vinyl copolymer• 1960 to 1970-

Barnhart – Silicone & acrylic resin polymer stains.• 1970 to 1990-

Lontz - modified Polysiloxane elastomers.

Lewis & Castleberry – Siphenylenes.

Udagama & Drane- Silastic medical adhesive type A.• 1990 to present-

Antonocci & Stansberry – new generation acrylic resin

Gettleman - Polyphosphazenes

ClassificationClassification of materials used in Maxillofacial Prosthodontics

Impression materials

Materials for fabrication

Pigmentation materials

Auxiliary materials

Materials for Retention

Composition

Macro-cellular foam

Plaster of Paris

Plaster bandage

Alginate

Mould making

Pattern materials

Prosthetic materials

Flasks

Separating medium

Comfeel

Stellon crown

Silastic foam

Aerosil 130

Extrinsic sealant

Others

Implants

Magnets

Adhesives

Primers

Silicone putty

Extrinsic

Intrinsic

Classification of Maxillofacial Prosthesis

materials• According to Beumer:1. Acrylic resins.2. Acrylic copolymers.3. Polyvinyl chloride & copolymers.4. Chlorinated polyethylene.5. Polyurethane elastomers.6. Silicone elastomers – HTV, RTV, Foaming

silicones.7. New materials- Silicone block copolymers,

Polyphosphazenes.

Classification of Maxillofacial Prosthesis

materials• According to ANUSAVICE:

1. Latex- a tripolymer of Butyl acrylate, Methyl methacrylate & Methyl methacrylamide.

2. Vinyl Plastisols.

3. Silicone Rubbers.

4. Polyurethane Polymers.

Ideal properties 1. Ideal Physical & Mechanical properties:a. Dynamic properties comparable to tissues.b. High edge strength, high elongation, high resistance

to abrasion, high tear strength & high tensile strength.

c. Low coefficient of friction, low glass transition temperature, low specific gravity, low surface tension & low thermal conductivity.

d. Odorless, Non-inflammable, No water sorption.e. Translucent.f. Softness compatible to tissue & variable flexibility

without addition of leachable plasticizer.

Ideal properties 2. Ideal Processing characteristics:a. Adjustability.b. Chemically inert after processing.c. Dimensionally stable during & after processing.d. Ease of intrinsic & extrinsic coloring.e. Ease of mold fabrication & processing.f. Ease of repair & refabrication if needed.g. Fidelity of detail reproduction.h. High viscosity for maintaining even dispersion of

colorants. i. Long shelf life & working time.

Ideal properties

2. Ideal Processing characteristics: (contd)

j. Low viscosity for ease of processing.

k. Low processing temperature.

l. Low sensitivity to contamination during processing.

m. Non-inflammable, non-toxic & non-porous.

n. No polymerization by-products.

o. Reusable molds.

p. Retain intrinsic & extrinsic coloration during use.

q. Short processing time.

Ideal properties 3. Ideal Biological properties:a. Compatible with supporting tissues.b. Non allergic & non toxic.c. Cleansable with disinfectants without losing details

at surface or margins.d. Color stability & dimensional stability.e. Flexibility comparable to tissue & stable at high

temperatures.f. Inert to solvents & skin adhesives.g. Resistance to environmental discoloration & growth

of microorganisms.h. Inexpensive.

Individual material1. ACRYLIC RESINS:

- used in areas with little movement. (Orbital or Ocular etc)Advantages: readily available, easy in

coloring, good strength, compatible with adhesives, long service, color stability, easily repaired or relined.

Disadvantages: rigidity, discomfort, high thermal conductivity, no duplication possible.

Individual material2. ACRYLIC COPOLYMERS:

Advantages: soft & elastic.

Disadvantages: poor edge strength, degrade in sunlight, processing & coloration is difficult, gets stained easily .

- Antonucci & Stansbury reported new generation development in this.

Individual material3. POLYVINYL CHLORIDE (PLASTISOLS) &

COPOLYMERS: ( Realistic, Mediplast, Prototype III)

- a rigid , clear, tasteless & odorless - glass transition temperature higher - plasticizers are added - cross linking agentsRecently a copolymer – 5%to 20% Vinyl acetate in it.It is more stable, more flexible but less chemically

resistant.

Individual material3. POLYVINYL CHLORIDE (PLASTISOLS) &

COPOLYMERS: ( contd)

Advantages: flexible, adaptable to coloration to yield good appearance.

Disadvantages: leaching of plasticizers, tear easily, easily stained, degrade easily, soil easily, metal molds required, short service life, poor dimensional stability.

Individual material4. CHLORINATED POLYETHYLENE:

- Lewis & Castleberry

- similar to Polyvinylchloride in both chemical composition & physical properties.

- Gettleman also reported (CPE 726/19-15)

- clinical trials just initiated

Individual material5. POLYURETHANE ELASTOMERS:

- Diisocyanate + Polyol

- processing (1000C)

Advantages: elastic (without compromising edge strength), flexible, easy coloration, superior cosmetic results.

Disadvantages: difficult to process, moisture sensitive, no color stability, service life less, poor compatibility with adhesives, toxic.

initiator

Individual material6. SILICONES:

- Production

- dimethyl dichlorosiloxane + water

Classified into four groups:

i) Implant grade

ii) Medical grade

iii) Clean grade

iv) Industrial grade

Individual materiala. HEAT VULCANIZED SILICONES (HTV) :

- Polydimethyl vinyl siloxane copolymer with approx. 0.5% vinyl side chains, 2,4-dichlorobenzoyl peroxide as an initiator & a silica filler obtained from burning methyl silanes.

- processing temperature ( 2200C).

- difficult to pigment.

Individual materiali. SILASTIC 370, 372, 373, 4-4514, 4-4515:

- white opaque material, highly viscous.

- dichlorobenzoyl peroxide or platinum salt as catalyst

- fillers added to harden (silica)

-Advantages: excellent thermal stability, color stability, biologically inert.

-Disadvantages: less elastic, low edge strength, opaque & lifeless, difficult to color extrinsically, require metal molds.

Individual materialii. PDM SILICONES:

- Lontz and Schweiger& Lontz

- Abdelnnabi evaluated properties

Individual materialiii. Q7-4635, Q7-4650, Q7-4735, SE-4524U:

- a new generation evaluated by Bell

- single component system

- unlimited shelf life

Individual materialb. ROOM TEMPERATURE VULCANIZED

SILICONES (RTV) :

- used more often then any other

- good physical & mechanical properties

- vinyl & hydride containing siloxanes

- chloroplatinic acid as ctalyst

- tetraethoxysilane as cross-linking agent

Individual materiali. SILASTIC 382, 399 :

- stannous octoate catalyst & orthoalkyl silicate as cross linking agent

- Advantages: color stable, clear solutions, easy to process, require stone molds

- Disadvantages: poor strength, difficult to color, cosmetic results inferior

Individual materialii. MDX4-4210 :

- chloroplatinic acid catalyst & hydro-methyl siloxane as cross-linking agent. (800C for 1 hour)

-Moore reported improved properties

Advantages: no reaction by-product,

increased elongation,

surface texture & shore hardness,

non-toxic, color stable,

simple processing,

compatible with adhesives

Individual materialiii. SILASTIC 891 (Silastic Medical Adhesive

Silicone Type A) :

- Udagama & Drane

- translucent, non flowing, polymerizes in air

- Advantages: no need of molds, no catalyst,

compatible with wide range of colorants.

- in 1987 Udagama used it along with polyurethane film to improve its edge strength.

- Farah suggested a combination of:

40% MDX4-4210 + 60% MED.A 891

Individual materialiv. COSMESIL / SILSKIN 2 SYSTEMS :

- Woofaardt described it

- two curing system:

a) Platinum cure:

- utilizes vinyl terminated Silicone & a platinum catalyst

- addition reaction so no by-products. Hence no shrinkage

- poisoned by latex

- working time 1 hr & curing at 1000C for 1 hr

Individual materialiv. COSMESIL / SILSKIN 2 SYSTEMS (contd) :

(b) Tin cure:

- utilizes hydroxy terminated silicone fluids & a Tin catalyst

- condensation reaction so by-product is formed

- is very robust & cures against most substrates/ conditions

- working time 1hr & cures in 24 hr at room temperature.

Individual materialv. A-2186 (FACTOR II) :

- a recently developed material initially showed improved properties.

- but Haug reported that it doesn't retain them when subjected to environmental variables.

- two types of curing system similar to Cosmesil

Individual material7. NEW MATERIALS:

(i) Silicone block copolymers:

- incorporates Polymethyl methacrylate into Siloxane blocks.

- more tear resistant

(ii) Polyphosphazenes:

- developed as a resilient denture liner

Physical properties

• Tensile strength

• Maximum Elongation

• Pants Tear energy

• Dynamic Modulus

Physical properties (CRAIG)Material Tensile

strength (psi)

Max. % elongation

Pants tear test

(dynes/cm×106

Dynamic modulus (MPa)

Plasticized polyvinylchloride

3.99 215 4.3 4.32

Polyurethane 0.83 422 6.7 3.46

HTV 5.87 441 Doesn't tear but stretches as

in tensile

4.66

RTV 4.20 445 Elongation. 2.12

Physical properties (BEUMER)

Elastomer A-2186 Silastic 382 MDX4-4210 MDX4-4515 MDX4-4516

Manufacturer Factor II Dow corning

Dow corning

Dow corning

Dow corning

Color Translu-cent

Gray Translucent Translucent Translucent

Shore hardness 25 43 >25 52 72

Tensile strength (psi)

900 350 >550 1350 1175

%Elongation 650 160 >350 450 370

Tear strength (psi)

90 NA 50 NA NA

Specific gravity 1.12 1.13 1.12 1.15 1.21

Physical properties (CHALIAN)

Silastic S-6508

Silastic 382 Silastic 399

Durometer 26 45 50

Tensile (psi) 785 300 525

%Elongation 490 100 230

Tear (psi) 65 20 29

Mold making materialsSilicones.Surgical plaster of Paris- for investing of all

prosthesis & blanking out undesired areas of impression models.

Kaffir “D” dental stone- for all impression models.Beta Dur 700 hard stone- vacuum mixed & used as a

topping investment as it is hard & protects fine recorded details. Its color allows easy placement of localized color.

Plaster / pumice- 30/70 ratio used for blanking areas that need to be free of silicone in the mold

(Keith Thomas)

Flasks

Two part rectangular Aluminium alloy flasks, self clamping.

Available in sizes :

Small 6” × 4 ¼” × 3 ¼ ”

Medium 6 ¾ ” × 6 3/8 ” × 6 1/12 ”

Large 9” × 6” × 7 ½ ”

Shallow 8” × 5” × 2 ¾ ”

(Keith Thomas)

Separating media

Soap- useful for two part plaster moulds, also if used in a 5% solution may be used as a releasing agent for silicone prosthesis.

Cold mould seal- all plaster moulds, also as a

releasing agent for silicone.

Medi-Mould wax mould sealant & releasing agent- sealing porous mould surfaces. Release agent for silicone.

Pattern materials

Waxes: hard, soft , skin colored etc.

- Baseplate wax , Korecta wax ,

Utility Wax

Clay

Materials for retention

Double sided adhesive tape

Primers & Adhesives

Materials for retention

Implants

Materials for retention

Adhesive magnet plate

Neo- mini magnets

Materials for retention

SpectaclesSprung steel head band

Other materials

Materials for Pigmentation

Extrinsic & intrinsic pigments.Basic shades are mainly metal oxides like:

Nickel oxide - Brown

Manganese oxide - Lavender

Titanium oxide - Yellowish brown

Iron oxide - Brown

Copper oxide - Green

Auxiliary materialsExtrinsic sealantAerosil 130- to reduce shine & alter viscositySilastic foam dressingMacrocellular foamStellon crown & bridge- to facilitate construction of

custom made finger nails.

Adhesive removers or solvents

Auxiliary materialsComfeel ( skin conditioner)

- it is Ethoxyethyl acid copolymer ethyl acetate

- creates an elastic protective barrier

- applied to clean skin & after 1-2 min it forms a film.

Fabrication of the Prosthesis

Master cast

Color matching/ intrinsic pigmentation

Wax / clay pattern

Impression

Try-in

Processing Compression molding

Two part or three or four part mould Investment

Surface / extrinsic pigmentation

Finishing

Limitations & DegradationDiscoloration due to –

- external environmental factors.

- due to loss of external coloration.

Degradation of properties –

- tear at margins

- change in surface texture

- elongation at margins

- deterioration of static & mechanical properties

Conclusion Ultimate challenge to a material is its clinical

performance.Laboratory testing should be correlated to

clinical performance.Sweeney in 1972 & Lewis & Castleberry in

1980 gave specifications for maxillofacial elastomer.

Future research:

- improving the properties to service life.

- color stable & better color matching.

References

• Prosthetic Rehabilitation - Keith Thomas

• Maxillofacial Rehabilitation - Beumer & Curtis

• Maxillofacial Prosthetics - Chalian

• Restorative dental material - Craig

• Philips’ science of dental materials - Anusavice

• Oral cancer - Silverman

• Cosmesil & Factor II catalogue