By,
Head of Department
Dr Khawaja Rashid Hassan
Rawal college of Dentistry
Islamabad
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In cases where fitting surfaces of acrylic
dentures needs replacement to improve the
fit of the denture.
 Classified into 3 main groups
1. Hard reline materials.
2. Tissue conditioners.
3. Soft lining materials.

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Chair side relining technique is used.
Divided into 2 types.
Both types are categorized as auto
polymerizable resins.
 Both types polymerize easily at mouth
or room temperature.
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TYPE 1
POWDER
LIQUID
POLYMER BEADS
POLYMETHYLMETHACRYLATE
INITIATOR
BENZOYL PEROXIDE
PIGMENTS
INORGANIC SALTS
MONOMER
METHYLMETHACRYLATE
PLASTICIZER
Di-n-butylphthalate
CHEMICAL ACTIVATOR TERTIARY AMINE
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TYPE 2
POWDER
LIQUID
POLYMER BEADS
POLYETHYLMETHACRYLATE
INITIATOR
BENZOYL PEROXIDE
PIGMENTS
INORGANIC SALTS
MONOMER
BUTYLMETHACRYLATE
CHEMICAL ACTIVATOR
TERTIATY AMINE
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MANIPULATION:
 Grinding away some of the hard surface of
acrylic base.
 Powder and liquid are mixed.
 Applied over the fitting surface of the acrylic
base.
 Seated into the patient’s mouth.
 Closed mouth technique is used.
 Not allowed to remain in the patient ‘s mouth
throughout setting.
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1.
2.
3.
4.
5.
PROPERTIES:
Direct contact with the oral tissues is a
disadvantage.
Methyl methacrylate in the monomer may
cause allergic reaction.
Low values of glass transition temperature (Tg)
in both type 1 and type 2 materials.
May become porous due to air entrapment
during mixing.
Operator has little control over the thickness of
the material.
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
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Soft denture liners.
Applied to the fitting surface of the denture.
Provides cushion to the fitting surface.
Plastic flow continues for 24-36 hours after
mixing.
Several applications in denture works.
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Often applied to the dentures of the
patients undergone surgery.
 In case of immediate dentures,
 Addition of the tooth into the denture
base that needs to be extracted.
 Can be used as functional impression
material.

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COMPOSITION
POWDER
POLYMER
BEADS
POLYETHYMETHACRYLATE
LIQUID
SOLVENT
ETHYL ALCOHOL
PLASTICIZER
BUTYLPHTHALYL
BUTYLGLYCOLATE
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COMPOSITION
Amount of solvent and plasticizer is very
crucial.
 7.5% - 40% of liquid contains alcohol.
 Powder may be pigmented or
unpigmented.

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MANIPULATION
 On mixing powder and liquid, physical process
occurs.
 Smaller polymeric beads get dissolved and
larger beads swell up on absorbing solvent.
 Final set material is gel-like.
 High methacrylate, ethyl methacrylate,
plasticizer and solvent gives softness.
 Normally denture and patient’s soft tissues are
inspected after 2-3 days.
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
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PROPERTIES:
Initially very soft and Viscoelastic.
Undergo permanent deformation under even
small load.
Material do not remain permanently soft.
Time taken for the material to become hard and
loose the cushioning effect varies from days to a
couple of weeks.
Conditioner should be replaced after 2- 3 days
till the tissue has healed properly.
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
Can be sub divided into
a) Temporary soft lining
materials.
b) Permanent soft lining
materials.
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TEMPORARY SOFT LINING MATERIALS:
Almost similar to tissue conditioners.
Supplied as powder liquid formulation.
Composition and manipulation same as
tissue conditioners.
Retain their softness for longer duration.(
upto a month or two)
Selection of denture cleanser is very crucial
for temporary soft liners.
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
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PERMANENT SOFT LINING MATERIALS:
Commonly used in patients that cannot
tolerate a hard base.
In patients with thin mandibular mucosa.
These materials should remain permanently
soft for the life time of the denture.
Elasticity of these materials is very
important.
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 AVAILABLE
1. ACRYLIC:
 Heat cure.
 Cold cure.
2. SILICONE:
 Heat cure.
 Cold cure.
MATERIALS:
 Condensation.
 Addition.
3.
POLYPHOSPHAZINE:
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


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Heat cure acrylic is in powder liquid
formulation.
Powder consist of poly ethyl or poly butyl
methacrylate.
Liquid consists of butyl methacrylate and
plasticizer.
Dough is formed which is then heat treated.
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
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Heat cure silicone is used in the same way as
heat cue acrylic.
Presented in a single paste formulation.
Paste consist of poly di methylsiloxane
polymer.
The 2 cold cure silicone elastomers are similar
to the silicone elastomers used as impression
materials.
Cold curing silicones are cured at room
temperature.
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

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POLYPHOSPHAZINE:
Supplied in sheet form.
Polymerize by heat cure.
Curing cycle can be,
74°C for 8 hours.
OR
74 °C for 2½ hours followed by 100 °C for 30
minutes.
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PROPERTIES:
 All types are soft and give an adequate
cushioning effect.
 Cushioning effect depends upon the thickness of
material.
 2-3 mm is sufficient for adequate cushioning effect.


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Harden through loss of alcohol and leaching of
plasticizer.
Adequate bond with the denture base.
Denture cleansers effect the soft liners.
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THANKYOU
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