Final materials in maxillo facial prosthetics/ orthodontics courses

GOOD MORNING
www.indiandentalacademy.com

MATERAIALS IN MAXILLO-
FACIAL PROSTHETICS
INDIAN DENTAL ACADEMY
Leader in continuing dental education

CONTENTS
 INTRODUCTION
 HISTORY
 REQUIRMENTS
 MATERIALS

BASE MATERIAL

PRIMERS

ADHESIVES

COLORS
 RECENT ADVANCES
 CONCLUSION

INTRODUCTION

HISTORY

 Pierre Fauchard (1678 – 1761) made a
monumental contribution to prosthetic
facial reconstruction; he made a silver
mask to replace the lost portion of the
mandilble for a french soldier named
Alphonse Louis

 William Norton (1819 – 1868)
 Kingsly – 1880
 Claude Martin – 1889
 Upharm - reported use of vulcanite
rubber
 Ottofy, Baird and Baker – 1905

 In 1913, gelatin – glycerin components
were introduced for use in facial
prosthesis
 Clarke (1945) - introduced Latex

 Acrylic resin introduced to dental
profession in 1937 replaced older
vulcanite rubber in both extra and intra
oral prostheses

 Mid part of twentieth century witnessed
the debut of elastomers
 Silicone elastomers gained popularity
because of its several desirable
features

 Gonzalez – polyurethane
 Lewis & Castleberry- siphenylenes
 Turner – isophorone

REQUIRMENTS
 The type of prosthesis that replaces facial
tissues, especially the overlying skin, must
meet stringent standards if it is to replicate
living movable tissues

 Many materials and manipulation techniques
are available, but none is ideal for simulating
and restoring replaced tissue

Some of the more desirable properties
 Ease of initial molding
 Both intrinsic and extrinsic colorability
 Flexibility simulating that of human skin
 Chemical and environmental stability
 Ease of adherence to human skin
 Resistance to tear and abrasion
 Ease of cleaning
 Non toxic, non irritating

Acc. to Lewis et al (1992)
1) Processing characteristics
2) Mechanical performance
3) Patient accommodation

Processing Characteristics
1. Low viscosity
2. Simple polymerization process
3. Use stone, acrylic or epoxy resin mold
4. Capable of adjustments, repair and
reline
5. Extended working time

7. Modifiable at margin areas
8. Low processing temperature
9. Can be bonded to other materials
10. Intrinsic and extrinsic coloring
11. Capable of layering in the mold for
depth and vitality in coloring
12. Translucence similar to skin

13. Surface texture and sheen consistent
with adjacent skin
14. Extrinsic coloring without modifying
surface characterization
15. Repeatable color matching

Mechanical Performance
1. High tensile strength
2. Dimensional stability
3. High percentage elongation
4. High edge strength
5. High modulus of elasticity
6. High tear strength
7. Sufficient hardness

7. Proper surface tension
8. Resistance to chemicals and UV light
9. Low coefficient of friction
10. Low specific gravity

Patient Accommodations
1. Compatible with human tissue
2. Non toxic, non allergic, odorless
3. Easy to clean
4. Non porous but permeable
5. Resistance to microbial contamination
6. Light weight
7. Compatible with adhesives

8. Resistance to environment
discoloration
9. Reasonable cost, readily available

M F Materials
VINYl POLYMERS
&
COPOLYMERS
ACRYLIC RESINS ELASTOMERS LATEXES
Polyvinyl chloride
Polyvinyl acetate
Methyl methacrylate
Polymethyl meth-
acrylate
Silicones- RTV, HTV
Polyurethane
sulphenylenes

Latexes
 Oldest material introduced by Clarke
 Advantages:
1. Inexpensive
2. Easy to manipulate
3. Life like to feel

 Disadvantages:
1. Change colour rapidly
2. Wear easily
3. Rapid degeneration
4. Poor edge strength

Synthetic latexes
 Butyl- acrylate (90%), methyl
methacrylate (.15%) & methacrylamide
(25%)
 Dimensionally stable
 Withstands outdoor weathering
 Difficult to color
 Lengthy and time consuming

Acrylic resins
 Derivatives of
ethylene and
contain a vinyl group
 Esters of polyacids-
methacrylic acid

 Liquid monomer, methyl methacrylate is
mixed with polymer powder to form
plastic dough which is polymerized by
different methods

Advantages
 Easy to work and to manipulate
 Durable
 Both intrinsic and extrinsic coloring possible
 Easy to reline
 Compatible with most adhesive systems
 Can be cleaned easily
 Readily available

Disadvantages
 Rigidity
 Relatively high thermal conductivity
 Poor margin esthetics
 Not life like
 Volume shrinkage during
polymerization
 Duplicate prosthesis not possible

Acrylic copolymers
 Eg. Palamed
 Acrylic combined with plasticizers
 Not rigid like original acrylic but soft
Advantages:
1. Superior flexibility
2. Better margin adaptation

Disadvantages :
1. Poor edge strength
2. Poor durability, stiffens with age
3. Degradation when exposed to sunlight
4. Difficult to color and process
5. Completed restoration become tacky,
predisposing to dust collection and
staining

 New generation of acrylic resins-
different polymerization methods,
incorporate high molecular weight
acrylic polymers with molecular blocks
of other type of polymers like
polyurethane, fluorocarbon, siloxane etc
 Overcome the shortcomings of
traditional acrylic resins

Polyvinyls and its copolymers
 Eg. Realistic, Mediplast, Prototype III
 Vinyls are derivatives of ethylene

 Polyvinyl chloride:
 Clear hard resin, tasteless, odorless
 Processed at reasonably low
temperature
 Darkens when exposed to light and
heat therefore needs light and heat
stabilization

 Polyvinyl acetate:
 Stable to light and heat
 Abnormally low softening point (35-45
degree)

 More flexible
 Adaptable to intrinsic and extrinsic
coloring
 Acceptable esthetics

 Deficiency arise because of
plasticizer migration and loss
resulting in:
 Discoloration
 Hardening of prostheses
 Poor edge strength, require reinforcement
with nylon fabric
 Easily stained and degrade in environmental
condition

 Lack life like translucency
 Tend to absorb sebaceous secretions etc.
 Require metal molds for curing
 Clinically useful for 1-6 months
 Improvement by limiting the amount of
plasticizers: 9-11 months

 Recently, a copolymer of 5% to 20%
vinyl acetate, with remaining
percentage being vinylchloride, has
been introduced. This copolymer is
more flexible but apparently less
chemically resistant than polyvinyl
chloride

Chlorinated polyethylenes
 Similar to PVC
 High heat curing of pigmented sheets of
thermoplastic polymer in metal molds
 Coloration, using oil soluble dyes and
repeated molding possible

 CPE 726/19-15
 Processing technique using steam
autoclave with gypsum molds was
developed and laminated technique of
coloring

Elastomers
Silicone Polyurethane
RTV HTV
Epithane - 3

Silicone elastomers
 Introduced in 1943
 First used in MF in 1960 by Barnhart
 Most widely used material

Silica elemental silicon + methyl
chloride
Dimethyl dichloro
siloxane
Polydimethyl
siloxane
water

 Add fillers for strength, colors and
antioxidants
 The long chained polymers are cross-
linked to create a network which is
difficult to separate

 Process of cross linking – vulcanization
 With or without heat
 Depends on catalyst or cross linking
agent used

 Acc. to application:
1. Implant grade
2. Medical grade
3. Clean grade
4. Industrial grade

HTV
 Require heat for vulcanization
Eg. Silastic 370, 372, 373, 4-4514, 4-4515
PDM siloxane etc
 White opaque material, putty like consistency,
1 or 2 component system
 Catalyst :
Dichlorobenzoyl peroxide (condensation)
Platinum salt (addition)

 Benzoic acid is by-
product
 Filler – varying
amounts, very pure
finely divided silica,
30 microns
 Requires
sophisticated
instrumentation and
high temperature

 Advantages:
1. Excellent thermal stability
2. Are color stable when exposed to UV
light
3. Biologically inert

 Disadvantages:
1. Not sufficiently elastic
2. Low edge strength
3. Opacity and lifeless appearance
4. Do not readily accept extrinsic colors
5. Metal molds necessary

 Q7-4635, 4650, 4735, SE-4524U
 New generation
 Better processing features – single
component system and unlimited shelf
life

RTV
 Vulcanize at room temperature
Eg. Silastic 382, 399
 Catalyst – stannous octate
 Cross linking agent – ortho alkyl silicate
 Condensation reaction-alcohol as byproduct
 Short chain silicone polymer
 Properties similar to HTV

 Available as clear
solution-translucent
prosthesis
 Dental stone molds
are required
 Poor edge strength
and are difficult to
color like HTV

Silicone prosthesis retained by implants

 MDX 4-4210
 Most popular, 41%
 Catalyst – chloroplatinic acid
 Crosslinking agent – hydro methyl
siloxane
 Addition reaction

 Improved qualities in relation to edge
strength and coloration
 More resistant to tear
 Increased elongation, adequate tensile
strength
 Surface texture and hardness close to
human skin

 Color stable
 Simple processing
 360 medical fluid can be used to modify
Controlled injection packing technique will
result in dense and porosity free
prosthesis

 Silastic 891
 Also known as silastic medical adhesive
silicone type A
 Translucent, non flowing paste
 Polymerizes at room temperature on
contact with moisture
 Use gypsum mold

 No catalyst required
 Acetic acid is released as by product
1987 – Udagama reported improving the
edge strength of prosthesis fabricated
by bonding medical adhesive type A to
prefabricated polyurethane film using
primer (S2260)

 Cosmesil
 Can be processed
to varying degrees
of hardness
 Higher tear strength
than MDX
Ray Winter demonstrating
cosmesil prosthesis

 A-2186
 Acc. To Sanchez and Moore et al
advantages of new material over MDX
4-4210:
1. Greater tensile strength
2. Greater tear strength
3. Larger percentage elongation
4. Better marginal integrity and esthetics

 Foaming silicone:
Eg. Silastic 386
 Additive releases gas forming bubbles
within the vulcanizing silicone resulting
in a spongy material
 Reduces weight of prosthesis

But …
 Reduced strength
 Susceptible to tearing
This can be partially overcome by coating
the foam with another silicone
But…
Increases stiffness

 Siphenylenes
 Siloxane copolymer containing both
methyl and phenyl groups
 Catalyst – stannous octate

 Advantages
 Biocompatibility
 Resistance to degradation on exposure
to light and heat
 Improved edge strength
 Low modulus of elasticity
 colorability

Polyurethane elastomer
Eg. Epithane-3
 Contains isocyanate and hydroxyl
groups
 Varying the amount of isocyanate
changes the physical properties of final
product

 Advantages:
 Elastic without compromising edge
strength
 Can be colored both intrinsically and
extrinsically
 Superior esthetics

 But….
 Difficult to process consistently
 Little margin of error when measuring
constituents
 Moisture sensitive- difficult to control
water contamination
 Not color stable

 Poor compatibility with existing
adhesive systems
 Difficult to clean
 Careful handling- Isocyanate is toxic

ADHESIVES

 To retain prostheses in place
 Pastes
 Liquids emulsions
 Spray- ons
 Double sided tapes
 Velcro

 Double sided tape
 most commonly used
 Ease of application and removal
 Easy to maintain
 Useful in materials with poor flexibility
and in patients with defects showing
little or no mobility

Velcro tape
Double Sided tape

 Single component RTV developed to
serve as adhesives for silicone
prostheses
 Type of adhesive and cleaning solution
should be chosen carefully as they can
have adverse effect on physical and
optical properties of MF material

 Daro adhesive
regular, extra
strength and
hydrobond
 adhesive in water
emulsion
 No solvents present
 Better patient
acceptance
Daro Adhesive

 Secure medical grade adhesive B-400,
B-401, BT-401
 Pressure sensitive
 Dispersed in ethyl acetate
 Unaffected by normal temperature
variation

Medical adhesive

 Secure Ex-strong Adhesive B-460, BT-
460, B-520
 Higher strength for when extra
adhesion is required
 Cosmesil adhesive C067, C106
 Pressure sensitive, water soluble
 Can be removed with soap and water

B - 520www.indiandentalacademy.com

 Additional research is needed to
determine:
 The compatibility of commercially
available medical adhesives with
different types of MF elastomers
 The compatibility of cleansing solvents
with MF elastomers

 An alternative to reduce the
dependency on medical adhesives for
retention is the use of osseointegrated
implants

Primers

 Promote bonding
between silicone
and other MF
prosthetic material
Eg. S-2260, A-4-4,
1205, 4040, Z-6032,
Z-6076

COLORS

 3 basic techniques:
 Extrinsic
 Intrinsic
 Combination of both
 Combination tech is
widely use
 Dry earth pigments
are most often used

 Largely depends on skill of clinician
 Also on color of individual and the light
source under which color is selected
 At present procedure is done
empirically by hit and trial method
 The base shade selected should be
slightly lighter than the lightest skin
tones of the patient

 Surface details and character can be
added by either intrinsic or extrinsic
coloration
 Intrinsic coloration is more long lasting
 Basic skin tones should be developed
into a shade guide for materials that are
used

 At present there is no definite and universal
scientific method developed for color
matching which involves quantitatively
describing the optical properties of colorants
and applying them to a mathematical model
which simulates the multilayered optical
characteristics of human skin

 Color stability:
 Discoloration may be due to color
change within base elastomer
 This is overcome by use of color
stabilizing agents

 Craig evaluated color stability of 6 MF
materials (PVC, polyurethane, silastic
382, 399, 4-4210 & 4-4515):
 PVC became lighter after 100 hours
 Polyurethane disintegrated after 600
hrs
 All silicone exhibited good color stability
especially Silastic 4-4210

RECENT ADVANCES

 Silicone block copolymers
 Incorporates PMMA into siloxane
blocks
 More tear resistant
 Polyphosphazenes
 Developed as resilient denture liners

CAD / CAM
3-D data collection3-D data collection
3-D computer model3-D computer model
Physical prototypePhysical prototype
CT Scanning
MRI
3-D optical scanning
CNC milling
Rapid prototyping

CONCLUSION

REFERENCES
 Maxillofacial prosthetics by Chalian
 Philip’s science Dental materials
 In vitro comparison of mdx and polymethyl
siloxane silicone material. JPD 1984 523-526
 Color stability of facial prostheses JPD dec
1995 613-618
 An assessment of recent advances in
external maxillofacial materials JPD 1980,
311-371
 Evaluation of improved maxillofacial
prosthetic materials JPD 1972, 297-305

 In vitro testing of bond between soft materials used
for maxillofacial prosthses JPD April 2001 401-408
 Evaluation of polymeric materials for maxillofacial
prosthetics JPD Sep 1977 319-326
 Comparison of physical properties of two types of
polydimethyl siloxane for fabrication of facial
prosthses JPD May 1992 679-682
 Effects of environmental factors on maxillofacial
elastomers: part I, II, III & IV JPD Aug-Dec 1992

Thank you
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Final materials in maxillo facial prosthetics/ orthodontics courses

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