Post on 13-Oct-2020
Assoc. prof. T. Uzunov, PhD
THE RESINS ARE
POLYMERS
The term "polymer" derives from the Greek word πολύς (polus,
meaning "many, much") and μέρος (meros, meaning "part"), and
refers to a molecule whose structure is composed of multiple
repeating units, from which originates a characteristic of high
relative molecular mass and attendant properties.
CHEMICAL REACTION
THE RESINS ARE
POLYMERS Synthesis of polymers
A classification of the polymerization reactions: Step-growth, Chain-growth and others.
THE RESINS ARE
POLYMERS Synthesis of polymers
STEP-GROWTH POLYMERIZATION
In step-growth (or step) polymerization, each step may
involve the combination of two polymer molecules of any
lengths to form a longer polymer molecule.
The average molar mass increases slowly and long chains
are formed only late in the reaction.
Step-growth polymers are formed by independent reaction
steps between functional groups of monomer units, usually
containing heteroatoms such as nitrogen or oxygen. Most
step-growth polymers are also classified as condensation
polymers , since a small molecule such as water is lost
when the polymer chain is lengthened.
THE RESINS ARE
POLYMERS Synthesis of polymers
CHAIN-GROWTH POLYMERIZATION
In chain-growth (or chain) polymerization, the only chain-extension
reaction step is the addition of a monomer to a growing chain with
an active center such as a free radical or ion.
Once the growth of a chain is initiated by formation of an active
center, chain propagation is usually rapid by addition of a sequence
of monomers. Long chains are formed from the beginning of the
reaction. Chain-growth polymerization (or addition
polymerization) involves the linking together of molecules
incorporating double or triple carbon-carbon bonds. These
unsaturated monomer have extra internal bonds that are able to
break and link up with other monomers to form a repeating chain,
whose backbone typically contains only carbon atoms.
THE RESINS ARE
POLYMERS Synthesis of polymers
Step-growth versus chain-growth
polymerization
1. CONDENSATION POLYMERIZATION
A condensation polymerization is a form of step-growth polymerization.
Small molecules react with each other to form larger structural units while
releasing smaller molecules as a byproduct, such as water or methanol.
THE RESINS ARE
POLYMERS Synthesis of polymers
CHEMICAL REACTION
large polymerization shrinkage
2. ADDITION POLYMERIZATION
An addition polymer is a polymer that forms by simple linking of monomers without the
co-generation of other products. Addition polymerization differs from condensation
polymerization, which does co-generate a product, usually water. Addition polymers
can be formed by chain polymerization, when the polymer is formed by the sequential
addition of monomer units to an active site in a chain reaction, or by polyaddition,
when the polymer is formed by addition reactions between species of all degrees of
polymerization.
THE RESINS ARE
POLYMERS Synthesis of polymers
CHEMICAL REACTION
less
polymerization
shrinkage
INITIATORS
HEAT IONIZING
RADIATION
ULTRAVIOLET RAYS
CHEMICAL REACTION
MONOMER POLYMER
INITIATED POLYMERIZATION
INITIATORS
Benzoyl peroxide
(С6Н5СОО)2 HEAT
ACTIVATOR
DMPT
BENZOILS AND
PHENYLS
FREE RADICALS
INITIATED POLYMERIZATION
CHEMICAL REACTION
1. Activation of monomer molecules by active
radicals
2. Growth of the polymer chain by
attachment of other activated monomer
molecules
3. Complete polymerization by saturating the
end of the polymer chain with another active
radical
INITIATED POLYMERIZATION
The degree of polymerization
The degree of polymerization, or DP, is the number of
monomeric units in a macromolecule or polymer or oligomer
molecule.
Increasing degree of polymerization correlates with
higher melting temperature, higher mechanical strength
and better biological properties.
DEGREE OF
POLYMERIZATION
MECHANICAL
PROPERTIES
BIOLOGICAL
PROPERTIES
The degree of polymerization
DEGREE OF
POLYMERIZATION MECHANICAL
PROPERTIES
Increasing degree of polymerization correlates with
higher melting temperature, higher mechanical strength
and better biological properties.
The degree of polymerization
Increasing degree of polymerization correlates with the
speed of polymerization.
DEGREE OF POLYMERIZATION
SPEED OF POLYMERIZATION
1. HARD (glassy) /ACRYLIC RESINS /
2. ELASTIC (rubbery) /ELASTOMERS/
TYPES OF POLYMERS
According to the degree
of cross-linking and their mechanical properties:
TYPES OF POLYMERS
According to the mode of activation of the
Benzoyl Peroxide (the initiator):
SELF-CURING RESINS
HEAT-CURING RESINS
LIGHT-CURING RESINS
SELF/LIGHT-CURING RESINS
Type Class (manufacturing) Group (presentation form)
Type 1 Thermopolymerizable resins
(>65°C)
Group 1: bicomponent powder and liquid
Group 2: monocomponent
Type 2 Autopolymerizable resins (<65°C) Group 1: bicomponent powder and liquid
Group 2: bicomponent powder and
casting liquid
Type 3 Thermoplastic resins Monocomponent system grains in
cartridges
Type 4 Light-cured resins Monocomponent system
Type 5
Microwave cured resins
Bicomponent system
The classification of resins according to DIN EN ISO 1567
Since the mid-1940s, the majority of denture bases has been fabricated using polymethyl methacrylate resins.
ACRYLIC RESIN
Pure polymethyl methacrylate is a colorless transparent solid. To facilitate its use in dental applications, the polymer can be tinted to provide almost any color, shade, and degree of
translucency.
ACRYLIC RESIN
Polymethyl methacrylate denture base material is commonly supplied as a powder-liquid system.
• The liquid contains mostly nonpolymerized methyl methacrylate
• The powder contains predominantly prepolymerized polymethyl methacrylate resin in the form of micro-sized beads (or spheres).
ACRYLIC RESIN
HEAT-ACTIVATED ACRYLIC RESIN
Съдържат:
LIQUID POWDER
MAIN COMPONENT
Methyl ester of methacrylic acid – methyl
methacrylate / ММА/
MAIN COMPONENT
Polymethyl ester of methacrylic acid –
polymethyl methacylate (PMMA)
CROSS-LINKING AGENT 5-15%
ethyleneglycol dimethacrylate /EGDMA/
triethyleneglycol dimethacrylate /TEGDMA/
INITIATOR – 0,2-0,5%
benzoyl peroxide
INHIBITOR – 0,005%
hydroquinone
Plasticizer – 5%
dibutyl phtalate /DBPh/ - limits the cross-linking
of the polymer
OPACIFIERS (OPAQUERS) – 0,5 - 1,5%
zinc oxide, titanium dioxide
Color agents
organic
non-organic
ACRYLIC RESIN
1.SANDY
When the
liquid and powder are
mixed in the proper
proportions (3:1 )
workable mass is
formed. Upon
standing, the resultant
mass passes through
five distinct stages.
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
Stages of polymerization:
Stages of polymerization:
2. STRINGY
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
3. DOUGH-LIKE
On a molecular level, an
increased number of polymer
chains enter the solution. Thus,
monomer and dissolved
polymer are formed.
Stages of polymerization:
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
It is important to note that a large quantity of swollen,
but undissolved polymer also remains. Clinically, the mass
behaves as a pliable dough. It is no longer tacky and does
not adhere to the surfaces of the mixing vessel or spatula.
Stages of polymerization:
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
3. DOUGH-LIKE
The physical and chemical characteristics exhibited
during the later phases of this stage are ideal for
compression molding. As a result, the material
should be introduced into the mold cavity during the
latter phases of the doughlike stage.
4. RUBBERY
(ELASTIC)
Stages of polymerization:
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
5. STIFFY
Stages of polymerization:
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
A cross-sectional
representation of the denture
flask and its contents.
As a rule, heat-
activated denture
base resins are
shaped via
compression
molding.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
At this stage, the master cast and
completed tooth arrangement are
removed from the dental articulator
The lower portion of a denture flask
is filled with freshly mixed dental
stone, and the master cast is placed
into this mixture. Upon reaching its
initial set, the stone is coated with
an appropriate separator.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The upper portion of the selected
denture flask is then positioned
atop the lower portion of the flask.
The dental stone is poured into
the denture flask. Care is taken to
ensure that the investing
stone achieves intimate contact with
all external surfaces of the
mounted teeth. The investing stone
is added until all surfaces
of the tooth arrangement and
denture base are completely
covered.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The lid of the flask is gently seated and the
stone is allowed to harden
After the stone has hardened, the record
base and wax must be removed from the
mold. To accomplish this task, the denture
flask is immersed in boiling water for 4
min.
The flask is then
removed from the water
and the appropriate
segments are
separated.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The record base and softened
wax remain in the lower portion
of the denture flask while the
prosthetic teeth remain firmly
embedded in the investing
stone of the remaining
segment.
The record base and softened wax are carefully removed
from the surface of the mold. Residual wax is removed from
the mold cavity using wax solvent. The mold cavity is
subsequently cleaned with a mild detergent solution and
rinsed with boiling water.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The placement and
adaptation of denture
base resin within
the mold cavity are
termed packing.
In a doughlike state, the resin is removed from its
mixing container and rolled into a ropelike form. Monomer
is painted over the necks of the denture teeth to promote
bonding to the denture base. Subsequently, the resin form is
bent into a horseshoe shape and placed into the portion of
the flask that houses the prosthetic teeth
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The flask assembly is placed
into a specially designed flask
press and pressure is applied
incrementally.
Slow application of pressure
permits the resin dough to flow
uniformly throughout the mold
space.
Excess material is displaced
eccentrically. The application of
pressure is continued until the
denture flask is fully closed.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The flask is transferred to a
flask carrier.
The flask carrier maintains
pressure on the flask assembly
during denture base
processing.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
The heating process used to control polymerization is termed
the polymerization cycle or curing cycle. This process
should be carefully regulated to avoid the effects of
uncontrolled temperature rise.
COMPRESSION MOLDING TECHNIQUE
HEAT-ACTIVATED ACRYLIC RESIN
ACRYLIC RESIN
PURPOSES OF HEAT POLYMERIZATION:
1. OPTIMAL ACTIVATION OF THE INITIATOR - 60 – 80 °C
2. THE EXOTHERMIC PROCESS SHOULD NOT CAUSE
BOILING OF THE MONOMER /ABOVE 100,3 °C /
3. ADDITIONAL HEAT POLYMERIZATION OF THE
REMAINING FREE MONOMER AFTER THE EXHAUSTION OF THE
BENZOYL PEROXIDE
Chemical activation is accomplished through the
addition of a tertiary amine, such as dimethyl-
para-toluidine, to the denture base liquid (i.e.,
monomer). Upon mixing of the powder and liquid
components, the tertiary amine causes
decomposition of benzoyl peroxide. As a result,
free radicals are produced and polymerization is
initiated.
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
Used for:
Denture Repairs
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
SELF-CURING ACRYLIC RESIN
Съдържат:
LIQUID POWDER
MAIN COMPONENT
Methyl ester of methacrylic acid – methyl
methacrylate / ММА/
MAIN COMPONENT
Polymethyl ester of methacrylic acid –
polymethyl methacylate (PMMA)
CROSS-LINKING AGENT 5-15%
ethyleneglycol dimethacrylate /EGDMA/
triethyleneglycol dimethacrylate /TEGDMA/
INITIATOR – 1,5%
benzoyl peroxide
INHIBITOR – 0,005%
hydroquinone
Plasticizer – 5%
dibutyl phtalate /DBPh/ - limits the cross-linking
of the polymer
ACTIVATOR – 0,75%
Dimethyl par toluidine /DMPT/
OPACIFIERS (OPAQUERS) – 0,5 - 1,5%
zinc oxide, titanium dioxide
Color agents
organic
non-organic
ACRYLIC RESIN
As might be expected, denture bases
fabricated using chemically activated
resins and heat-activated resins are quite
similar.
Five stages of changing consistency
They are not packed in gypsum molds
They polymerize without pressure
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
The fundamental difference between
heat-activated resins and
chemically activated resins is the
method by which benzoyl peroxide is
divided to yield free
radicals. All other factors in this
process (e.g., initiator and
reactants) remain the same.
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
The degree of polymerization achieved using
chemically activated resins is not as complete as
that achieved using heat-activated systems.
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
The degree of polymerization achieved using
chemically activated resins is not as complete as
that achieved using heat-activated systems.
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
The degree of polymerization achieved using
chemically activated resins is not as complete as
that achieved using heat-activated systems.
1. Initial hardening of the
resin generally will
occur within 30 min but
polymerization continues
for an extended period.
PROCESSING CONSIDERATIONS
Applied in limited areas –
denture repairs
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
Apparatus for hydro-pneumatic
polymerization
The polymerization is carried out in a
water bath at a pressure of 2-6 atm at
93-1150C for 10-15 minutes.
To ensure sufficient
polymerization, the
flask should be held
under pressure for a
minimum of 3 hours.
SELF-CURING ACRYLIC RESIN
ACRYLIC RESIN
MECHANICAL, PHYSICAL AND
BIOLOGICAL PROPERTIES OF ACRYLIC
RESINS
OPTIMAL when:
1. The monomer-to-polymer ratio is correct
2. Using the resin in the dough-like stage
3. Strictly following the recommended heat-curing cycle
4. Maintaining the pressure on the gypsum molds during the
polymerization process
MECHANICAL PROPERTIES
Comparative analysis
HEAT
ACTIVATED
CHEMICALLY
ACTIVATED
DEGREE OF POLYMERIZATION 2500 1800
HARDNESS - ВН N 20 16
ELASTIC MODULUS - МРА 3800 2600
WEAR RESISTANCE HIGHER LOWER
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
POROSITY
COLOR RESISTANCE
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
POROSITY
COLOR RESISTANCE
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
VOLUMETRIC CHANGES - SHRINKAGE
POSSIBLE INACCURACY OF THE PROSTHETIC CONSTRUCTIONS
MONOMER 0,945 g/cm2
POLYMER 1,16 – 1,18 g/cm2
relative density
MONOMER - POLYMER 21%
RESIN DOUGH - POLYMER 5%
If the resin is heat-activated or
hydropneumatically polymerized 0,5%
reduction up to
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
VOLUMETRIC CHANGES - SHRINKAGE
reduction up to
reduction up to
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
Water absorption is the property of materials to absorb liquids.
Imbibition is measured by the weight of the maximum amount
of water absorbed by a unit area of a given material and is
presented as WATER SORPTION in mg/cm2
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
The repeating change of
imbibition and drying causes
internal tension and fatigue of
the material.
Care should be taken for the
removable dentures.
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
Possibility for endogenic
discoloration
Compensates for the
shrinkage of resins.
Acrylic resins – expansion 0,04 %
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
DEFORMATIONS OF THE POLYMER STRUCTURE
Breaking of the covalent, hydrogen and
Van der Waals bonds
Fatigue /aging/of resins
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
REASONS
The difference in the thermal volumetric changes of the
resin and the volumetric changes of the metal and
porcelain elements of the prosthetic construction
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
Solubility is the reduction of materials’ volume when they are in contact
with liquids – solvents.
It causes the change in the shape, the dimensions and the properties of
dental materials in the mouth.
Solubility occurs during the materials’ contact with the oral fluids
(solvents) – saliva, gingival fluid, dentin fluid
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
In water and saliva
the free monomer
the plasticizers
in organic solvents
acrylic resins are soluble
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
POROSITY
Micropores exist even in the best processed and polished
acrylic resin:
1. They retain food particles and microorganisms
2. Cause exogenic discoloration
3. Increase with the aging of the resin
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
POROSITY
The pressure applied during
polymerization reduces the resins’
porosity.
PHYSICAL PROPERTIES
VOLUMETRIC CHANGES
WATER ABSORPTION (IMBIBITION)
INTERNAL STRESSES
SOLUBILITY
POROSITY
COLOR RESISTANCE
EXOGENIC DISCOLORATION - DUE TO POROSITY
ENDOGENIC DISCOLORATION - OXIDATION OF THE ACTIVATOR (chemically-
activated resins)
)
BIOLOGICAL PROPERTIES OF ACRYLIC RESINS
TOXICITY
ALLERGENIC POTENTIAL
TOXICITY OF ACRYLIC RESINS
RESIDUAL MONOMER
RESINS FOR HYDROPNEUMATIC
POLYMERIZATION - 0,3 %
HEAT-ACTIVATED RESINS - 0,5 %
CHEMICALLY- ACTIVATED RESINS - 5 %
QUALITATIVE REACTION FOR DETECTION OF RESIDUAL
MONOMER EXCEEDING 3%
TOXICITY OF ACRYLIC RESINS
TOXICITY OF ACRYLIC RESINS
TOXICITY OF ACRYLIC RESINS
QUALITATIVE REACTION FOR DETECTION OF RESIDUAL
MONOMER EXCEEDING 3%
TOXICITY OF ACRYLIC RESINS
QUALITATIVE REACTION FOR DETECTION OF RESIDUAL
MONOMER EXCEEDING 3%
REMOVAL OF THE RESIDUAL MONOMER 1. Under flowing water
TOXICITY OF ACRYLIC RESINS
REMOVAL OF THE RESIDUAL MONOMER 1. Under flowing water
2. By additional heat polymerization
TOXICITY OF ACRYLIC RESINS
ALLERGENIC POTENTIAL OF ACRYLIC
RESINS:
RESIDUAL MONOMER
COLOR AGENTS / Cd- salts /
OPAQUERS
INITIATOR
ACTIVATOR
INHIBITOR
BENZOYL PEROXIDE, HYDROQUINONE
RESIDUAL MONOMER
SOFT DENTURE LINERS
SOFT DENTURE LINERS
Denture Reline
is a restoration of the
fitting surface between
the denture and the
mouth tissue. It’s an
effective way to improve
the fit and extend the life
of dentures. They
improve stability and
seal off space between
the mouth and the
denture from food
particles.
• Stable bonding to the denture base
• Preservation of their elasticity,
color and volume over time
• Smooth surface
Requirements:
• ACRYLIC
• VINYL SILICONE
• POLYPHOSPHAZENE
According to the chemical composition of the polymer
I. 30 up to 60 % plasticizer -
dibutylphtalate
II. Hydroxyethyl methacylate
/НЕМА/
ACRYLIC
- Have a strong chemical bond with the PMMA prosthetic base.
- Their elastic properties are rapidly reduced due to the solubility and
loss of plasticizer
- The material hardens, becomes highly porous, the accumulation of
dyes and bacterial plaque increases.
Coe-Soft Denture
Reline Material
ACRYLIC
- The linear polymer chain of polydimethylsiloxane is extended and partially
crosslinked by polymerization - the material acquires an elastic consistency.
- The connection to the prosthetic base is weak, mechanical and requires pre-
bonding and application of special adhesives.
- The surface of the silicone materials is very smooth and the elasticity
remains long.
SILICONE
SILICONE
Creation of mechanical retentions
Application of adhesive
Application of lining material
Compression of the prosthesis with
the lining material Cutting off excess material
Application of sealing varnish
SILICONE
POLYPHOSPHAZENE
Based on polyphosphazene (PNF)
synthetic rubber, NOVUS is
radiopaque, permanently resilient, and
absorbs energy from chewing.
- It also has low water absorption
and resists fungal growth.
- NOVUS comes in individually
sealed “patties” with an
unlimited shelf life if refrigerated.
- During laboratory processing,
NOVUS chemically bonds to
fresh denture acrylics
THERMOPLASTIC RESINS
THERMOPLASTIC RESINS
Thermoplastic resins and co-polymers have many advantages
over conventional powder or liquid resin systems:
- Thermoplastic resins tend to have predictable long-term
performance
- They also exhibit high creep resistance and high fatigue
endurance as well as excellent wear characteristics and
solvent resistance.
- Thermoplastic resins typically have very little or almost no
free monomer in the material. A significant percentage of the
population is allergic to free monomer and these materials
offer a new safe treatment alternative for these individuals.
- Thermoplastic materials have almost no porosity, which
reduces biologic material build up, odors, and stains and
exhibit higher dimension and color stability.
INDICATIONS FOR THERMOPLASTIC RESINS At present, due to successive alterations in the chemical composition,
thermoplastic materials are suitable for manufacturing:
1. Metal-free removable partial
dentures
Dental Valplast Dentures
INDICATIONS FOR THERMOPLASTIC
RESINS
2. Partial denture frameworks
Zirlux Acetal is a semi-flexible, tooth colored material is ideal for partial denture
frameworks and other metal-free removable applications.
3. Complete dentures
4. Temporary or provisional
crowns and bridges
5. Orthodontic appliances,
flexible myofunctional therapy
devices
Zirlux Acetal - Temporary
provisional crowns and
bridges.
Flexite M.P.- complete dentures
INDICATIONS FOR THERMOPLASTIC
RESINS
6. Splints
7. Mouth guards
8. Anti-snoring
devices
INDICATIONS FOR THERMOPLASTIC
RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
1. THERMOPLASTIC ACRYLIC
2. POLYCARBONATE RESINS
3. POLYAMIDES (NYLON) RESINS
4. POLYOLEFINS RESINS
5. POLYOXY-METHYLENE (ACETAL) RESINS
6. POLYETHERETHERKETONE (PEEK) RESINS
7. ) )
• Thermoplastic acrylic has poor impact resistance,
but has adequate tensile and flexural strength for a
variety of applications.
• The material is easy to adjust, handle and polish. It
is relineable and repairable at the chair-side.
• Like most thermoplastic resins, acrylic resin is also
strong, resists fracturing, and is flexible.
1. THERMOPLASTIC ACRYLIC
CLASSIFICATION OF THERMOPLASTIC
RESINS
1. THERMOPLASTIC ACRYLIC
- However, acrylic does not wear as well as acetal
during occlusal forces and consequently will not
maintain vertical dimension over long periods of
time.
- Thermoplastic acrylic is
available in both tooth
and gingival colors, and
has both translucency
and vitality, providing
excellent esthetics.
CLASSIFICATION OF THERMOPLASTIC
RESINS
Flexite M.P. contains fully
polimerized acrylate, its
base component is methyl-
metacrylate. This material
was developed for making full
dentures, it doesn’t behave elastic,
but being a bit elastic, it is
practically unbreakable. It can be
polished easily.
Flexite M.P. has a surface
hardness of 55-65, making it
popular for bruxism appliances as
well as dentures.
1. THERMOPLASTIC ACRYLIC
CLASSIFICATION OF THERMOPLASTIC
RESINS
2. POLYCARBONATE RESINS
Polycarbonate is a polymer chain of bisphenol-A
carbonate. It is a popular material and has been used
in dentistry for a long time as preformed temporary
crown shells.
CLASSIFICATION OF THERMOPLASTIC
RESINS
- Polycarbonate resin is very strong, resists fracturing, and is quite flexible.
- However, polycarbonate does not wear as well as Acetal during occlusal
force and consequently will not maintain vertical dimension as long.
- The material has a natural translucency and finishes very well, yielding
excellent esthetics.
- Polycarbonate is ideally suited for provisional crowns and bridges but not
suitable for partial denture frameworks.
2. POLYCARBONATE RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
- Nylon is a resin derived from diamine and dibasic acid monomers.
- Because of its excellent balance of strength, ductility and heat
resistance, nylon is an outstanding candidate for metal replacement
applications. However, in dentistry, because of its inherent flexibility, it is
used primarily for flexible tissue born partial dentures.
- Nylon is specially indicated for patients allergic to methyl metacrylate,
being monomer-free.
- Thermoplastic nylon is injected at temperatures from 274 to 293
degrees Celsius.
3. POLYAMIDES (NYLON) RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
- Nylon exhibits high physical strength, heat resistance and chemical
resistance. It can be easily modified to increase stiffness and wear
resistance.
- Nylon is a little more difficult to adjust and polish.
- The resin can be semitranslucent and provides excellent esthetics for
flexible tissue born partial dentures.
- It does not have enough strength to use for occlusal rest seats, and
won’t maintain vertical dimension when used in direct occlusal forces.
Removable partial
denture of polyamide
combined with metal
3. POLYAMIDES (NYLON) RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
Vertex ™ ThermoSens is a
thermoplastic material to be used
for dental prothesis. The product
is based on a compounded
mixture of Polyamide and
pigments. Because Vertex™
ThermoSens is on a
polyamide basis and to be used
as a thermoplastic in the injection
technique, the product is suitable
for people allergic for residual
monomer, since the product
doesn’t contain residual
monomer.
3. POLYAMIDES (NYLON) RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
4. POLYOLEFINS RESINS
This group includes thermoplastic materials such as polybutene,
polyethylene, polypropylene. These are flavorless, inodorous, amorphous,
non-toxic polymers.
- Due to their good mechanical and aesthetic qualities they are
popularly utilized in dentistry.
- The most used member of this group is polypropylene - a semi-
crystalline transparent polymer with stable colour, that does not absorb
liquid.
- Polypropylene has a
molecular weight between
75,000 and 200,000 and
has high wear resistance.
It is indicated for partial
removable dentures,
temporary dentures and
implant supported dentures.
CLASSIFICATION OF THERMOPLASTIC
RESINS
Partial dentures made with
iFlexTM can be very thin and
flexible yet durable and are
designed to give long term
performance under normal
usage. iFlex™ is biocompatible,
and ideal for patients that are
allergic to monomers found in
acrylic dentures.
4. POLYOLEFINS RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
5. POLYOXY-METHYLENE (ACETAL) RESINS
Thermoplastic acetal is a poly(oxy-methylene)-based material,
which as a homopolymer has
good short-term mechanical properties but as a copolymer has
better long-term stability
Due to its resistance to wear and fracture,
combined with a certain amount of
flexibility, acetal resin is an ideal material
for:
- partial denture frameworks,
- preformed clasps for partial dentures,
- provisional bridges,
- occlusal splints ,
- implant abutments,
- artificial teeth for removable dentures
- orthodontic appliances
CLASSIFICATION OF THERMOPLASTIC
RESINS
6. POLYETHERETHERKETONE (PEEK) RESINS
Polyetheretherketone (PEEK) material is a polycyclic, aromatic,
thermoplastic polymer that is semi-crystalline and has a linear
structure.
- PEEK has good mechanical and
electrical properties such as
resistance to high temperature and
resistance to hydrolysis.
- When PEEK material and
components are examined, no
evidence has been shown of
cytotoxicity, mutagenicity,
carcinogenicity or immunogenicity in
the toxic form
- The most characteristic property
of PEEK material is that it has a
low elasticity modulus, close to
that of bone.
CLASSIFICATION OF THERMOPLASTIC
RESINS
- PEEK is used in dentistry as an
alternative to metal braces and
hooks in removable partial
prostheses.
- In comparison with chrome-
cobalt-based partial prostheses,
PEEK hooks have been shown to
have lower retentive strength.
6. POLYETHERETHERKETONE (PEEK) RESINS
Polyetheretherketone (PEEK) material is a polycyclic, aromatic,
thermoplastic polymer that is semi-crystalline and has a linear
structure.
CLASSIFICATION OF THERMOPLASTIC
RESINS
- They eliminate metallic taste and
allergic reactions, can be well
polished and have low plaque
retention.
- As PEEK is white in color and has
high resistance, it can be used in the
preparation of metal braces and
hooks.
Polyetheretherketone (PEEK) material is a polycyclic, aromatic,
thermoplastic polymer that is semi-crystalline and has a linear
structure.
6. POLYETHERETHERKETONE (PEEK) RESINS
CLASSIFICATION OF THERMOPLASTIC
RESINS
INJECTION TECHNIQUE IN MANUFACTURING
COMPLETE AND REMOVABLE PARTIAL DENTURES
The use of thermoplastic
resins in dental medicine is
continuously growing. The
material is thermally
plasticized and no chemical
reaction takes place.
The injection of
plasticized resins
into a mold represents a
new technology in
manufacturing complete
and removable partial
dentures.
INJECTION TECHNIQUE IN MANUFACTURING
COMPLETE AND REMOVABLE PARTIAL DENTURES
Injected under HEAT
No Shrinkage /
No Distortion
The SR Ivocap system is
based on a special injection
technique that is capable of
compensating for chemical
shrinkage. Controlled
heat/pressure
polymerization
compensates for acrylic
shrinkage by pressure
feeding additional material
into the mould.
INJECTION TECHNIQUE IN MANUFACTURING
COMPLETE AND REMOVABLE PARTIAL DENTURES