This document discusses dental base and liners. It describes their classifications, properties, and considerations for use. The main classifications discussed are varnishes, liners, sub bases, and high strength bases. Key properties addressed include thermal properties, protection against chemical insults, physical properties, and pulp reaction. Different materials are compared, including zinc oxide-eugenol, calcium hydroxide, glass ionomers, resin-modified glass ionomers, zinc phosphate, and zinc polycarboxylate. Requirements, manipulation, and indications for use are also outlined.

1. Dental Base and
Liners
Dr Rasha Alsheikh
B.D.S., M.S.D
KFU

2. Irritants
Decay.
Cavity preparation
procedure.
Restorative materials used.
Leakage and Secondary caries
lesions.
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3. Pulp Reaction to
Irritation
Healthy Reparative Reaction.
Unhealthy Reparative
Reaction.
Destructive reaction.
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4. Objective
To prevent further irritation of the
dento-pulpal tissues as well as to
improve the defensive capability of the
dento-pulpal tissues.
Serve as a barrier against thermal
changes, chemicals (irritants within
the material), leakage (bacterial
byproducts).

5. Condition of the tooth to be restored.
configuration of cavity preparation, amount
of the remaining dentin thickness (RDT).
type of restoration to be used.
Considerations

6. Classification
Varnishes
Liners
Sub bases
High strength bases
Resin in a solvent
Calcium hydroxide
Calcium hydroxide, Zinc
oxide-eugenol, Glass
Ionomers.
Glass ionomers, Resin-
modified glass ionomers,
Re-inforsed zinc oxide-
eugenol, Zinc phosphate,
Zinc polycarboxilate

7. Requirement:
1.should be capable an impervious layer on
cut vital dentin, with thickness not
compromising the bulk of the overlying
restoration or its mechanical properties.
2.biologically compatible dento/pulpal
tissues.
3.chemically compatible with both the dento/
pulpal tissues and the restoration.

8. 4.the material should not discolor
neither the restoration nor the
tooth.
5.should harden quick enough to allow
subsequent insertion of the
restoration.
6.should withstand (without change in
shape or location) the condensation
forces involve with the placement of
the over laying restoration.

9. 7. stabilize or further diminish dentin
permeability.
8.easily manipulated during
preparation or insertion.

10. Thermal Properties
ZOE , GI, Calcium Hydroxide, Z
Polycarboxilate falls within the range of
recognized insulators.
minimal thickness 0.75mm

11. Protection against
chemical insults
Calcium hydroxide and ZOE provide an
effective barriers against the penetration
of irritants.
GIC and Z-polycarboxilate can also be used
as chemical insulators.
Z-phosphate acidity is a concern.

12. The ability to with stand the occlusal
stresses and to support the restoration is
affected by the modulus of elasticity.
Strength must be developed quickly.
Low solubility.
Physical properties

14. Fluid and water absorption: the more
porous the material the greater will be
the chance for fluid uptake.
Calcium hydroxide is the most soluble
followed by ZOE then ZPC. GIC least
soluble.
Coefficient of thermal expansion, ZOE
is the closest to the tooth structure.
viscosity: calcium hydroxide followed
by ZOE had the highest flow. ZPC the
highest viscosity.

16. Pulp Reaction
Zinc Oxide-Eugenol:
• the least irritant to the pulp
• when placed within an effective depth +
healthy pulp = reparative reaction.
• when in direct contact with the pulp:
- healthy and sound pulp slight inflammation
will take place that might remain confined
or may progress to involve all the pulp or
may exacerbate to acute inflammation.

17. - if placed in direct contact with acute
inflamed pulp the acute inflammation
will subside then chronic
inflammation takes place, further
prognosis is similar to the healthy
pulp exposure.

18. Calcium hydroxide:
• it can be irritant
• if placed at 100 micron or more
healthy reparative reaction will
occur.
• if placed at less than 100 micron an
unhealthy reparative reaction occur.

19. • if placed in contact with the pulp
tissue:
- if healthy pulp, pulp will deposit
organic matrix which will mineralize
within 4-6 weeks.
- if degenerative pulp, the degeneration
will convert to calcific degeneration,
RCT is indicated before complete
obliteration of the pulp space.

20. Zinc phosphate:
• the most irritant base used:
- acidity during setting (PH 3-4 at first)
can be reduced by increasing the P/L
ratio.
- Microleakage as its soluble.
- exothermic reaction.

21. • at 2.5 mm depth ZP can induce healthy
reparative reaction.
• at 1.5-2 mm depth an unhealthy
reparative reaction will occur.
• at depth < 1.5 mm there will be
distraction in the pulp tissue.

22. Zinc polycarboxilate:
• minimally irritating:
- exothermic reaction
- porosity
- acidity (less than Zp)

23. • at 1 mm depth healthy reparative
reaction occur.
• at depth < 1 mm unhealthy reparative
reaction or further distruction can
take place.
• when come in contact with the pulp
distractive reaction occurs.

24. LINERS: relatively thin layers of material
used primarily to provide a barrier to
protect the dentin from residual reactants
diffusing out of the restoration or from
the oral fluids that may penetrate the
tooth/restoration interface.
They provide electrical insulation, some
thermal protection.
Terminology

25. some materials can provide pulpal
treatment.
indicated in with the pulpally extended
metallic restorations that are not well
bonded to tooth structure and not
insulating ( amalgam, cast gold and other
indirect restorations).

26. BASE: applied in thicker layers to
provide thermal protection for the
pulp and to supplement mechanical
support for the restoration by
distributing local stresses from the
restoration to the underlying dentin.
provide support during condensation
of amalgam in case of thin dentin
layer remaining.

27. Varnishes:
A natural gum (copal), rosin, or
synthetic resin dissolved in organic
solvent.
thin film
Reduce leakage around the margins and
walls of the cavity, prevent penetration
of corrosive products of amalgam into
dentin.
Not to be used under composite
restorations(interfere with the setting
reaction) or glass ionomer restorations
(prevent fluoride release).

28. Varnish is applied using a small
cotton pledget.
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30. Liners:
Dispersed calcium hydroxide in aqueous or
resin carrier solution.
Calcium hydroxide formation of
reparative dentin
PH = 11
only on dentin.
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32. Glass-Ionomer Liners
Faster setting
Flow
Contain hydroxidyl
methacrylate
no conditioning
required
Powder/Liquid Light cured GIC
serve as an intermediate bonding
material between dentin/composite
restoration

33. Bases
Thicker protective layers of cement that
are placed under restorations, encouraging
the recovery of the pulp
and to protect the pulp
from further insults.

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Zinc Oxide- Eugenol
Contain eugenol oil sedative
effect.
Powder/liquid or two pastes.
Setting reaction mainly wetting of the
ZO particles by the oil, chelating
reaction follow.
Retard penetration of acids and
reduce any possible discomfort.
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35. Thin layer little thermal insolation.
Strength and modulus of elasticity are low.
Used in less stress bearing area, but can
withstand the application of restorations.
High strength base is often placed over.
contra indicated under composite
restorations( interfere with the setting
reaction)

36. MANIPULATION
MIX ON TREATED PAPER PAD
START WITH A LARGE AMOUNT FIRST
CONTINUE ADDING SMALL AMOUNTS
UNTIL DESIRED CONSTITUENCY
WATER WILL ACCELERATE SETTING TIME.

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38. Calcium Hydroxide
Cement
Used for direct & indirect pulp caping
beneath composite restorations.
Two pasts, the reaction result in the
formation of amorphous calcium
disalicylate.
Contain radiopaque fillers.
Light cured product Urethane
dimethacrylate & calcium hydroxide + low-
viscosity monomer.

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LOW COMPRESSIVE STRENGTH
GREAT SOLUBILITY
Thin layer little thermal insolation.
Stimulate the formation of reparative
dentin.
Setting time 2 to 7 min

40. Zinc Phosphate
Water based cement.
Powder/Liquid: powder oxide mixed (ZO &
MO) & sol. of phosphoric acid.
Exothermic reaction hydrated
amorphous network of z-phosphate
surrounds incompletely dissolved
particles.
Setting time 5-9 min.

41. Fast setting
High mechanical properties.
Low acidity of the set cement.
low solubility.
Mixing over a large area in a cold
slab.
high acidity (pulp irritation)

42. Zinc Polycarboxilate
Water based cement
Powder/liquid: ZO/ viscous sol. of
polyacrylic acis
forms amorphous network of Z-
polyacrylate surrounding the
unreacted ZO particles.
Not as strong as the Z-phosphate but
less irritating to the pulp.

43. Moderate viscosity, moderate
strength.
Bond to enamel, mildly acidic.
Histologic reaction similar to ZO-
euginol.
Short working time 3 min.
Mix over a small area with a stiff
spatula.

44. Glass Ionomer Cements
Water based cement.
Powder/Liquid or pre-packed capsules:
powder (flouroaluminosilicate)
liquid(aquas solution of polycarboxilate
acid)
slow acid base reaction result in the
formation of amorphous silicate network
surrounding the unreacted particles.
chelating effect on tooth surface
resulting in bonding to enamel and dentin.

45. SLOW RELEASE OF FLUORIDE AIDS IN
INHIBITING RECURRENT CARIES.
LESS TRAUMATIC TO THE PULP.
HAS VERY LOW SOLUBILITY.
ADHERES TO A SLIGHtly MOIST
TOOTH SURFACE.
HAS A THIN FILM THICKNESS.
Very sensitive to water exposure.

46. Type I: Cementation of indirect
restoration and orthodontic brackets.
Type II: Restoring areas near the
gingival tissue ( class V)
Type III: used as liner and dental
bonding agent.

47. Resin Modified GIC
Were introduced to over come the
problim of water sensitivity of GIC.
and to improve the mechanical
properties of GIC.
powder/liquid: powder
(flouroaluminosilicate), liquid (aquas
solution of polycarboxilate acid
modified with pendant methacrylate
group, HEMA)

49. liner base cement advantage Limitation
varnish X low cost
long history of use
washes out at
the margin
Calcium
hydroxide x
x
tepm.
low cost
long history of use most effective
zinc oxide
eugenol x x x
antibacterial
long history of use
sealing ability
unable to
withstand
condensation
forces
zinc
polycarbixilate
x x long history of use
thickness may
inhibit the
seating of cast
glass ionomer x x fluoride release moisture
sensitive
resin x x strength sensetive

50. Temporary Filling:
Maintain the position of the prepared
tooth.
Seal, insulate the preparation and protect
the margins.
Establish proper vertical dimension.
Aid in diagnosis and treatment planning.
Aid to evaluate candidate for esthetic
replacement.

51. Function:
Protection of the dentin-pulp organ.
Sedation of the irritated pulp.
Restoration & protection of normal
occlusion by preventing over eruption and
tilting of teeth.
Protection of periodontium.
Restoration of tooth

52. Have enough strength and retention
to withstand forces to which it will
be subjected.
Easily handled, contoured, polished
and removed.
Dimensionally stable.
Short setting time.
Doesn’t interfere chemically with

53. Types of Temporary
Direct PR
Intra coronal
Prefabricated
Indirect PR
Extra coronal

54. Temporary Fillings:
GI
RMGI
Z Ph
ZOE
Reinforced ZOE
Non E-ZO
Z-polycarboxilate
Resin
Acrylic
Polycarbonate
Cellulose acetate
Aluminum

55. ANY QUESTION?