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1. INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

2. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
INTRODUCTION
 Flexible thermoplastics are resins which offer a
conservative and alternative approach to
conventional removable partial dentures, by virtue of
its flexibility, which utilizes undesired undercuts for
retention
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3. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
 Modern dentistry is showing inclination
towards flexible material for removable partial
dentures (RPDs) because it makes a better and
stronger appliance
Flexible material reduces the chair side time,
eliminates the invasive procedures and provides a
prosthesis which is comparatively less bulky,
more retentive, more esthetic and to a large
extent clinically unbreakable
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4. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
CONCEPT
The concept of flexible resins is based on their
inherent flexibility and ability to engage hard and
soft tissue undercuts for retention
Therefore, for clinical cases such as Kennedy's
Class I & II, which involve distal extension, the
flexible dentures by engaging the severe soft tissue
undercuts and clasping the adjacent teeth provides
excellent retention
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5. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Flexible Thermoplastic Resins were
discovered 50 years back and are presently
gaining popularity, due to improvement in
their physical and mechanical properties
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6. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Flexible resins have some outstanding properties which are
as ;
They are clinically unbreakable due to their property of shock
resistance as well to repeated stressing i.e., under fatigue conditions
availability in various tooth and tissue color
its lightness
flexibility
high heat resistance
lack of solubility in solvents
abrasion resistance
high melting point
monomer free www.indiandentalacademy.com

7. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Flexible denture based on Acetal resin, began to be used
in dentistry in 1971
The material in use nowadays is nylon based resin
(Lucitone FRS and valplast)
Nylon based resin were introduced by W.H Carothers
and associates of the Du Pont Chemical Co, during the
company’s search for a synthetic fiber forming material
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8. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Nylon is a generic name for a type of thermoplastic
polymers, belonging to the class known as
polyamides
Polyamide molecules contain the amide group ,
CONH2 spaced at intervals in a carbon atom
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9. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
There are many types of nylons commercially
available which include nylon 6, nylon 4/6,
nylon 6/6, nylon 6/10, nylon 6/12, nylon 11 and
nylon 12
 The ratio of carbon atoms is what gives each
nylon type its unique property characteristics
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10. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
The numerical nomenclature for nylon is
derived from the number of carbon atoms in the
diamine and dibasic acid monomers used to
manufacture it
e.g., nylon 6,6 in which repeated unit of the polymer
chain has two stretches of carbon atoms, each being six
carbon atoms long
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11. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Nylon is formed by two methods that are as follows:
 Condensation reaction between diamines and dibasic
acids produces a nylon salt. The first number of the
nylon type refers to the number of carbon atoms in the
diamine, the second number is the quantity in the acid
(e.g. nylon 6,12 or nylon 6,6)
The second process involves opening up a monomer
containing both amine and acid groups known as a
lactam ring. The nylon identity is based on the number
of atoms in the lactam monomer (e.g. nylon 6 or nylon
12 etc)
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12. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
PROPERTIES
Nylons are crystalline and are generally very tough
materials with good thermal and chemical
resistance
The different types of nylon have a wide range of
properties with specific gravity, melting point and
moisture content depending on nylon number
(type), tend to reduce as the nylon number increases
Nylon number Specific gravity
Melting point
Moisture content
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13. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Nylons tend to absorb moisture from their
surroundings and continue to do so until equilibrium
state is reached
In general, the impact resistance and flexibility of
nylon tends to increase with moisture content
Nylons tend to provide good resistance to most
chemicals, however their property can be effected by
strong acids, alcohols and alkalis
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14. COMMON FLEXIBLE THERMOPLASTICS IN USE
Materials Composition Manufacturers
VALPLAST Hybrid of four
nylon
Valplast International
Corp
FLEXITE Nylon based Talladium Uk - dental
THERMOFLEX Acetal based resin Austenal
LUCITONE FRS Nylon based Dentsply
FLEXIPLAST Nylon 12 Polyapress, GMBH,
Freiburg, FR Germany
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15. Materials
Flexural
modulus (MPa)
Flexural
strength (MPa)
Lucitone FRS 1714.4 55.3*
Properties of Lucitone FRS
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16. FLEXIPLAST VALUES UNIT
Impact
strength
1267 J X 10-4
Surface
Hardness
387 mm X 10-4
Glass
transition
Temperature
177.4 0
C
Water
absorption
1day 1wk 1month
0.71 1.36 1.37
%
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17. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
The material is available in
granular form as prepackaged
cartridge in various sizes
TECHNIQUE
Thermoplastic resins are
manipulated by injection molding
technique to construct flexible
dentures
Injection molding technique are
of two types; manual and the
hydraulic
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18. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Lucitone FRS
Resin in prepacked
cartridge is heated in
cartridge furnace, and then is
ready for precision injection
This material is used with
injection molded system
“success” by dentsply
Success Injection Unit
Heating Furnace
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19. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Processing time/temp 17 min @ 575o
F
Injection pressure 75 psi
Injection time 1 min
Cool time 5 min
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20. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
FINISHING AND POLISHING
Special finishing kits are available having cratex
wheels, green & pink stones & buff wheels
Polish with Tripoli and high shine
INSERTION
It can be adjusted chair side by immersing the
appliance in hot water (1000
C) for a minute and
allowed to cool to tolerable mouth temperature
prior to insertion www.indiandentalacademy.com

21. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
ADDITIONAL CLINICAL APPLICATIONS
Mouth guards
 Bite splints
 Gum veneers
 Space maintainer
Allergic to methacrylate denture base resin
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22. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
 Long term provisional prosthesis during implant
or complex restorative cases
 Obturators
 Patients with restricted mouth opening
 For patients prone to breaking dentures
It can be used in combination with metal
framework as combo dentures
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23. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
ADVANTAGES
Strength – fatigue and impact
Stiffness
Heat resistance
Chemical resistance to hydrocarbons
Wear resistance
Bicompatible – monomer free
Flexibility
Enhanced retention
Unbreakable in clinical conditions
Less time required for processing in comparison
to conventional
www.indiandentalacademy.com

24. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Offers the benefit of being strong, thin and
lightweight for superior patient comfort
Provides esthetics as color blends very
well with natural gums since available in
many shades
Resists stains and bacteria growth
Esthetic partial denture
Metal free
www.indiandentalacademy.com

25. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
DISADVANTAGES
Inability to bond to denture teeth, thus
sufficient interridge space is required for
bulk of tooth (mechanical retention)
Flexibility is not an advantage in complete
dentures, as the retentive peripheral seal
may break in function
 Difficult to repair, add teeth to, or reline
www.indiandentalacademy.com

26. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
Expensive equipment
Technique sensitive
Poor chemical resistance to strong acids
and bases
LIMITATIONS
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27. LIMITATIONS
Expensive equipment
Single cartridge of resin can be used in
one injection molding process, immaterial
of lesser or more requirement
Poor chemical resistance to strong acids
and bases
CASE REPORT
The patient presented with missing 31,
41, 36, 45, 46, 47
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28. www.indiandentalacademy.com