Materials used for maxillo facial construction/ dental crown & bridge courses

MATERIALS USED FOR
MAXILLO-FACIAL
RECONSTRUCTION.
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

CONTENTS
 INTRODUCTION
 OBJECTIVES OF MAXILLO-FACIAL
PROSTHESES.
 IDEAL REQUISITIES OF MAXILLO-FACIAL
MATERIALS.
 CRITERIA FOR MAXILLO-FACIAL
MATERIALS
 TYPES OF MATERIALS
 A)IMPRESSION PHASE
 B)MODELLING PHASE
 C)FABRICATION PHASE

COLORATION
CAD-CAM MAXILLO-FACIAL
PROSTHESIS
REVIEW OF LITERATURE
SUMMARY
CONCLUSION
REFERENCES

INTRODUCTION
“It is the God-given right of every human
being to appear human.”

OBJECTIVES OF MAXILLO-
FACIAL PROSTHESES
 Restoration of esthetics or cosmetic
appearance of the patient.
 Restoration of function.
 Psychologic therapy.
 Therapeutic or healing effect.
 Protection of tissues.

IDEAL REQUISITES OF
MAXILLO-FACIAL
MATERIALS
 Biocompatibility
 Flexibility
 Color and translucency
 Chemical and environmental stability
 Thermal conductivity

 Ease of Processing
 Strength
 Ease of duplication
 Dimensional stability
 Weight

CRITERIA FOR MAXILLO-
FACIAL MATERIALS
A) Processing Characteristics –
1. Visosity at ambient temperature - <75000 cps
2. Color - colorless
3. Solubility parameter (required - 9-11 cal 1/2
range for conventional colorants)
4. Pot life (working time) - 15-60 mins.
5. Curing temperature - <100 deg C
6. Curing time - 1-2 hrs.

B) Performance Characteristics - (mechanical and physical
properties)
1. Tear strength - 30-100 ppi
2. Tensile strength - 1000-2000 psi
3. Modulus at 100% elongation - 50-200 psi
4. Elongation at break - 400% - 800%
5. Glass transition temperature - < 0 deg C
6. Heat distortion temperature - > 120
deg C
7. Critical surface tension - 30-45 dynes/cm
8. Coefficient of friction - 0.4 - 0.6
9. Hardness - 25-35 Shore A
10.Water absorption - none

Materials used for maxillo-facial
reconstruction
 Surgical reconstruction
 (Alloplastic implantable
material)
 Dimethylsiloxane
 Polytetrafluoroethylene
 Polyethylene
 Polyesters-
 Polyethylene terphthalate
 Resorbable polymers
 Polyamide
 Acrylic
 Metals-stainless steel, viatalliun,
titanium.
 Cyanoacrylate
 Prosthetic reconstruction
 Impression phase
 Modeling phase
 Fabrication phase

Types of materials
IMPRESSION
PHASE
MODELING
PHASE
FABRICATION
PHASE

PROSTHESES MATERIALS
 Acrylic Resins.
Methyl Methacrylate.
Poly Methyl Methacrylate.
 Latex.
 Vinyl Polymers and Copolymers.
 Polyurethane.
 Silicone.
Room Temperature Vulcanizing.
Heat vulcanizing
 Ventured Structural Polymers.
Silphenylene elastomer.

ACRYLIC RESINS
 Methyl Methacrylate
 Plasticized methyl methacrylate
PALAMED
 Polymethylmethacrylate

Methyl Methacrylate
Material of choice in the past….
Limited use…..
 It is a clear, transparent liquid at room
temperature.
 Melting point - 48 deg C &
 Boiling point - 100.8 deg C,
 Density - 0.945gms/cubic cm
 Heat of polymerization - 12 Kcal/molecule.

 High vapour pressure & excellent organic
solvent.
 Polymerization can be initiated by UV light,
heat or chemicals
Disadvantages:
 Rigid nature of the material  tendency to
dislodge the prosthesis  irritation of
underlying tissues.
 Rigidity  difficulty in duplicating prosthesis

Advantages:
 Can be satisfactorily colored….
 Internally/externally coloring.
 Preferred for restoring defects….
 Useful in cases of rapidly changing defects …
 Easily available, economical & familiar.

Plasticized methyl methacrylate:
PALAMED
 formulated with a foaming agent…..
 foaming agent releases gas…..
 resulting product is spongy…..
 size of the pores varies directly with cross-
sectional thickness of the mold…..
 Palamed should be carefully
proportioned…..

 the molds are under filled by 10 % …..
 to compute the correct amount of
palamed…..
 tackiness of the surface…..
esthetically satisfactory material with a life
of six to seven months…..

Polymethylmethacrylate
transparent resin of remarkable clarity.
 extremely stable.
 does not discolor in UV light, and
exhibits remarkable aging properties.
takes up water ……

Properties:
 Tensile strength 8000 psi
 Elongation (%) 2-10
 Specific gravity 1.18
 Modulus of elasticity 4.5 psi x 106
 Thermal conductivity 4-6 x 10-4
cal/sec

LATEX
 Natural latex
 Synthetic latex
 Silicone foam rubber

VINYL POLYMERS AND
COPLOYMERS
 Vinyl chloride and vinyl acetate…..

Introduced in 1940…..
Susceptible to degradation …..
In the pure state…..
quality of the cured vinyl plastisol is time
dependant…..

 Method:

Property Polyvinyl
chloride
Polyvinyl
acetate
Specific gravity 1.16-1.53 1.35-1.45
Water absorption, 0.15-0.75 0.07-0.40
Tensile strength (psi) 1500-3000 5000-9000
Modulus of elasticity (MPa ) 4.32 3.5-6
Compressive strength(psi) 900-1700 8000-13000

POLYURETHANE
Polyurethane, urethane or “isocyanate”
polymers
Three component system…..
Formulation is very technique sensitive…..

The formation of polyurethane …..
Diisocyanate + polyol
initiator
Polyurethane

Advantages:
life-like feel.
flexibility compatible with flesh.
excellent strength and elastic properties.
Can be easily stretched several times in
length without deformation.
Can be intrinsically and extrinsically
colored

Disadvantage:
Quite susceptible to ULTRAVIOLET
LIGHT.
Limited duration of use.
Technique sensitive.
Product- Epithane-3

Procedure

SILICONE ELASTOMERS
 synthetic materials
 constitute a special class of chemical polymers,
polydimethylsiloxane
 composed of an alternating chain of silicone and
oxygen atoms.
 by adjusting the length of this silicon-oxygen
chain…..

 can only be produces synthetically.
 two-step process: creating a carbon-silicon bond,
then making the silicon-oxygen bond that forms
the chain.
 In the first step, an organic chloride vapor +hot
silicone powder in the presence of a copper
catalyst series of molecules (carbon, silicon,
and chlorine atoms.)
 In the second step, the chlorine is replaced with
oxygen through a process of hydrolysis and
distillation to produce the silicone product .

 the silicon oxygen bond is much stronger than the
carbon-carbon bond of organic polymers, silicones
make better electric insulators and are more resistant
to oxidation.
 In addition, the silicon-oxygen chain is easily
twisted, and the organic side groups can rotate
freely around the bonds. As a result, silicones have
weak forces of attraction, low surface tension, and
low freezing points.

 Silicone elastomers retain their elasticity, strength
and flexibility in temperatures ranging from
-108ºF (-78ºC) to higher than 570ºF (300ºC).
 silicone polymer is vulcanized; this changes it
from a liquid or putty like paste to a solid rubber.

RTV Silicone Elastomer
 composed of comparatively short chain
silicone polymers…. partially end-blocked
with hydroxyl groups.
cross-linking agent such as
tetraethyoxysilane (ethyl orthosilicate).
addition of a catalyst such as stannous
octoate condensation takes place.

Advantages:
Simple fabrication technique.
Faster fabrication technique, compared to
other materials.

 Disadvantages:
 Air entrapment, while mixing with the catalyst.
 Inadequate tear resistance.
 Incorporation of silica to improve tensile strength,
compromises translucency of the material, making
intrinsic coloring difficult.
 “ZIPPER EFFECT ”
 Silicones are stiffer than flesh.

HTV Silicon Elastomer
Mechanism for formation
Polydimethyl siloxane (diorganopolysiloxane)
Benzoyl peroxide
Cross-linking of methyl groups
+
Benzoic acid
+
heated

 superior strength
 more translucent than RTV silicones.
 Cut & rolled in the milling machine before
packing into molds. Colors & fibers incorporated
during rolling.
 Dow corning products- MDX 4-4514, MDX 4-
4515 & MDX 4-4516
 Factor II- MDX 4-4210

VENTURED STRUCTURAL
POLYMERS
 Silphenelyenes: are combinations of carbon and
silicone polymers and therefore they have many
advantages of both the polymers.
 Consists of 3 unit kit – base resin,
tetrapropoxy silane (cross linking agent) & an
organotin catalyst.
 Formulated as viscous, pour able, RTV liquid.
Advantages:
 High tensile strength & low modulus of elasticity.
 Feels like skin
 Incorporation of fillers  ↑tear strength

COLORATION
 Intrinsic coloring:
 According to Chalian et al (1972, 1974), intrinsic
coloring in HTV silicones is accomplished with a
milling machine.
Metallic oxides/pigmented silicone concentrates are
generally used & red fibers may be incorporated to
simulate blood vessels.
Coloring in RTV silicones (MDX 4-4210) is
accomplished by adding various dry earth
pigments.
 According to Chalian et al (1972) & Beder (1974),
the intrinsic colouring is more effective than
extrinsic techniques due to longer service life.

 Extrinsic coloring
 J.E.Ouellete (1969) described spray coloring of
silicone elastomer maxillofacial prosthesis.
Pigments selected to match the patients’ skin are
mixed in proper proportions with clear elastomers &
solvents & the mixture is sprayed on to the prosthesis
until the desired color is obtained.
 According to Schahf (1970), the colour easily peals
off or rubs off during manipulation of the prosthesis
or during daily cleansing.
He introduced tattooing for surface characterization
using standard artist’s oil paints which were applied
on to the prosthesis surface using tattooing machine.

CAD-CAM MAXILLO-FACIAL
PROSTHESES
 Acquisition of the “Facial Impression”- A laser
data of the patients facial defect.
The unit consists of two laser beams and two
change coupled device camera. Then the image
from the camera is transferred into an image
processor to generate three dimensional image.
 Production of wax model- Two alternative
CAD-CAM three dimensional modeling
techniques i.e. Laser litrographaic model and
numerically controlled milling model are
connected to fabricate the prototype wax model.

 Completing the final silicone facial prostheses-
The prototype wax model is tried on the patients
face to check for the fit and proper adaptation of
the margins as well as the shape. The wax model
is then flasked and fabricated in the conventional
way.

REVIEW OF LITERATURE
 Dorsey J. Moore et al (1977) in their study
evaluated a polymeric material MDX-4-4210
Elastomer (which was not in use at that time) for
its modulus of elasticity, resistance to tear
propagation and hardness. They compared this
material to Silastic 382 (commonly used for
maxillo-facial prostheses).They concluded that
– MDX 4-4210 had a modulus of elasticity approximately
one-fourth that of Silastic 382.
– MDX 4-4210 had better resistance to tear propagation
than Silastic 382.
– MDX-4-4210 was softer than silastic 382.

 Juan B.Gonzalez (1978) in his study evaluated
polyurethane elastomer with polyvinyl resins
and polysiloxanes. The criteria used for
comparison were the properties an ideal
material should have. He concluded that
polyurethane was relatively better material
compared to polyvinyl resins and polysiloxanes.

 Juan B.Gonzalez (1978) in his study evaluated the effect
of altering the component ratio of polyurethane on its
physical and mechanical properties, such as, surface
hardness, tensile strength, initial modulus and percentage
of elongation. He concluded that-
– with every increase of 0.1 gms of Part B or the
addition of the catalyst there was an increase in
surface hardness, tensile strength, initial modulus of
elasticity.
– Whereas there was decrease in percentage elongation
with the same alterations in formulations.

 E.R.Doootz, A.Koran, R.G.Craig (1994)
evaluated the effect of accelerated aging on the
physical properties of three maxillo-facial materials
i.e. MDX 4-4210, A-2186, Cosmesil. The samples
were processed according to manufactures
instructions and then stored in humidor for 24 hrs
followed by placement in an accelerated-aging
chamber. Each material was evaluated for tensile
strength, tear resistance, shore A hardness,
percentage of elongation before and after
accelerated aging.www.indiandentalacademy.com

 They concluded that cosmesil substance showed
maximum effect, and MDX 4-4210 the least
change in their properties, of aging.
 -Cosmesil showed a decrease in tensile strength,
decrease in elongation, increased hardness and
 -an increase in tear rersistance.

 Mark A. Pigno, Millicent C. Goldschmidt and James
C. Lemon (1994) evaluated the efficacy of antifungal
agents incorporated into facial prosthetic silicone
elastomer. The purpose of the study was -
1. to determine whether fungal growth is associated
with the black discoloration of the prostheses.
2. to determine the inhibitory effect of antifungal agents
nystatin and clotrimazole incorporated into the silicone .
3. to determine the longevity of the antifungal action.

 They concluded that-
– The SEM studies of the sample revealed the
black discoloration to be associated with fungi
of genus penicillium.
– Clotrimazole inhibited fungal growth even after
repeated testing over several months.
– Nystatin exhibited no inhibitory action.

 J.H.Lai, J.S.Hodges(1999) conducted a study to
evaluate the effect of processing parameters on
physical propeties of the silicone maxillofacial
prosthetic materials.They compared the physical
properties i.e. hardness,tensile srength, ultimate
elongation and tear strength of A-2186 cured in
stainless steel molds and stone molds.
 They concluded that hardness, tensile strength and
ultimate elongation of A-2186 cured in stainless
steel mold is higher than those cured in stone
mold.

 M.G.J.Waters, R.G.Jagger, G.L.Polyzois (1999)
conducted a study to evaluate the wettability and
surface energy of commercialy available silicone
material and acrylic material. Contact angle and
surface energies were measured by using a
dynamic contact angle measuring technique.
 They concluded that the surface energy and
wettability of silicone materials was less compared
to that of acrylic resin.

SUMMARY
Acrylic Resins.
Methyl Methacrylate.
Poly Methyl Methacrylate.
Latex.
Vinyl Polymers and Copolymers.
Polyurethane.
Silicone.
Room Temperature Vulcanizing.
Heat vulcanizing
Ventured Structural Polymers.
Silphenylene elastomer.

CONCLUSION
 Because no material presently available for
external maxillo-facial prostheses is
completely durable, periodic replacement is
a major problem.

REFERENCES
 J.E.Ouellete, Spray coloring of silicone elastomer
maxillofacial prostheses. J.Prosthet.Dent.
1969;22:271-275.
 V.A.Chalian, A.A.Majid, W.R.Leckrone, Milling
machine for coloring heat-vulcanizing silicone
materials in maxillofacial prostheses.
J.Prosthet.Dent. 1974;31:78-82.
 Council on Dental Materials and Devices,
Maxillofacial prosthetic materials. JADA.
1975;90:844-848.
 Dorsey J .Moore et al : Evaluation of polymeric
materials for maxillofacial prosthetics,
J.Prosthet.Dent. 1977;38:319-326.

 Jaun B.Gonzalez :Polyurethane elastomer for facial
prostheses, J.Prosthet.Dent. 1978;39:179187.
 Jaun B.Gonzalez: Physical and mechanical behaviour
of polyurethane elastomer formulations used for
facial prostheses, J.Prosthet.Dent. 1978;39:307-318.
 D.H.Lewis, D.J.Castleberry, An assessment of recent
advances in external maxillofacial materials.
J.Prosthet.Dent.1980;43:426-432.
 Mark A. Pigno, Millicent C. Goldschmidt and James
C. Lemon, The efficacy of antifungal agents
incorporated into facial prosthetic silicone elastomer.
J.Prosthet.Dent. 1994;71:295-300.

 E.R.Doootz, A.Koran, R.G.Craig: Phsical
properties of three maxillofacial materials as a
function of accelerated aging, J.Prosthet.Dent.
1994;71:379-383.
 J.H.Lai, J.S.Hodges, Effect of processing
parameters on the physical properties of the silicone
maxillofacial prosthetic materials.
Dent.Materials.1999;15:450-455.
 M.G.J.Waters, R.G.Jagger, G.L.Polyzois,
Wettability of silicone rubber maxillofacial
prosthetic materials. J.Prosthet.Dent.1999;81:439-
443

 Gupta A., Jain D. Materials used for
maxillofacial prosthesis reconstruction: A
literature review.J.I.P.S;2003:3(1): 11-15.
 Rahn A.O., Boucher L.J. Maxillofacial
prosthetics: Principles and Concepts.W.B
Saunders Company 1970,pgs 113-69.
 Lontz J.F. State-of-the-art materials used for
maxillofacial prosthetic reconstruction. DCNA
1990; 34: 307-25.

 Chalian V.A., Drane J.B., Standish S.M.
Maxillofacial prosthetics. W&W
Company 1972, pgs 284-304.
 Laney W.R., Chalian V.R. : Maxillofacial
Prosthetics ;Post graduate dental handbook, PSG
company 1979. Pgs-257.

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