BASES AND LINERS IN OPERATIVE DENTISTRY.ppt

2. Insulating and base materials
OR
Intermediary bases
( pulp protecting agents )

3. • No doubt that, dentino-pulpal
organ subject to a variety of
irritants with different degree
due to dental caries itself,
restorative procedures and from
restorative material being used
as fillings to restore carious
lesions.

4. • So, pulp tissues must be
protected from any further
irritating factor or insult
whether it is chemical ,
microbial or thermal or
electrical , or the pulp may
be not heal and recovery

6. • So dentist is responsible for
protection of pulp through insulating
base material which provide
protection against thermal shock ,
electrical and galvanic shock ,and
chemical ingredients which liberated
from restorations as well as ovoid
ingress and passage of the oral
fluids , bacteria and debris inter-
facially.

7. Insulating base
materials must fulfill
some important
requirements which
are:

8. • It must be act as impermeable
membrane .
• Biologically compatible with D-P
organ .
• Chemically compatible with
restorative filling materials and
dentino-pulpal organ .
Requirements of insulating base materials……..

9. •Material should withstand
forces of condensation of
filling without
deformation.

10. • Should be reduce or stabilize
dentin permeability to protect
the D-P organ against the
toxic ionic exchange after
application of filling material.
• It have capability to enhance
the formation of reparative
dentin

11. • It should be able to produce
and maintain a perfect cavity
seal to avoid ingress of fluids
,bacteria and debris .
• It should have thermal
insulating capacity .

12. • It should have chemical
insulating capacity .
• It should have electrical and
galvanic insulating capacity .

13. • Have a sedative and antiseptic
action
• From the esthetic view , did
not mask or change the color
or translucency of the tooth or
permanent restorations.

14. Classification of intermediary
bases ( pulp protecting agents)
Sub-bases
Film-Forming Resinous Materials:
Bases:

15. • Typical cavity varnish is a natural
gum or resins such as copal, rosin, or
synthetic resin dissolved in an
organic solvent such as acetone,
ether, chloroform, alcohol .
• applied in a thin film 5 - 10 micr.
• and in several applications to insure
minimal voids and porosities.
specifications
Write short notes about
varnishes…………………..

16. • It can be applied to both
the enamel and dentin walls
of the cavity preparation.
Specifications

17. Varnish
applications
Like nail
polish

18. • Varnish produce a positive
reduction of pulpal irritation
through reduce infiltration of
irritating fluids and ions through
marginal areas of the restoration
• Also, varnish can be prevent
penetration of corrosion products
of amalgam if it is resistant.

19. • Cavity varnish never be used
under resin composite and before
application of bonding system
because solvent present in varnish
may soften resin and discolored the
material and on, prevent proper
adhesion of bonding agent and the
composite resin material to cavity
walls and margins .

20. • A varnish never indicated
when glass ionomer filling is
used , the varnish coating
will prevent the chemical
adhesion between filling and
tooth structures enamel and
dentin.

21. Liners and sub-bases
• Much thicker than varnish.
• They are usually applied to
dentin only.

22. COH OR ZO EUGENOL
LINER (SUB-BASE)
PULP
CAVITY

24. • Are therapeutic materials
placed in deep portions OF
cavity preparation.
• has specific pharmacological
actions.

25. • sub-bases should
covered with a
supporting
base.

26. SUB-BASE

28. Bases:
• Are insulating materials that can
used directly on certain areas of
dentinal parts of the preparation.
• Also be used indirectly as
supporting, retaining modes for
sub-bases.

29. BASE

30. • Varnishes
• Zinc oxide and eugenol (ZOE)
• Calcium hydroxide (CAOH)
• Glass ionomer cement or
(ASPA)
• Zinc phosphate cement (ZPC)
• Polycarboxylate cement (PCC)
Materials Used for Intermediary Bases
Enumerate different types of insulating base
materials…………………………………………

31. • Calcium hydroxide : can be used as
powder condition
• in the form of pastes with distilled water
or sterile saline .
• used as a suspension in distilled water or
chloroform or methyl-cellulose .
Characters of CAOH as liner and sub-base
material……………………………………..

32. • Calcium hydroxide cement can be
supplied as two-paste system. One paste
is contain calcium hydroxide + monomer
of methyl-cellulose +chemical initiator and
other paste contain calcium hydroxide +
catalyst.
• calcium hydroxide here is not inter
in chemical reaction but carried by
polymeric meshwork which formed.

33. • This type can be activated
by laser or halogen light,
called light -cured one.

34. • There is calcium hydroxide
cement in which calcium
hydroxide itself inter a chemical
reaction with other ingredients
and called acid -base reaction
cement .

35. • Supplied in two separate paste, one
acidic paste, formed of a compound
salicylate + inert fillers ( titanium
oxide and/or barium sulfate)
for radiopacity, and the other paste is
basic paste formed of calcium
hydroxide .

36. • It is alkaline in nature.
• has anti-inflammatory, antiseptic
actions .
• Also have a bioactive power for
stimulation of odontoblasts and
undifferentiated reserve cells to
deposit reparative dentin.

37. • Calcium hydroxide cement
mass exclusively used for a
therapeutic action in the
form of a sub-base in deep
cavities (or as liner).

38. Zinc oxide eugenol cement
Characters of Zinc oxide eugenol cement……………….

39. • Supplied as powder and liquid
or a ready made paste or two
paste system . The principle
components of cement are zinc
oxide and eugenol oil (oil of clove
may replace eugenol oil)

40. Examples of modifiers used with ZOE:
1. Rosin
used to improve strength, homogeneity,
and smoothness of mix while decreasing
flow, brittleness and solubility.
2. Ethoxy Benzoic Acid
Increases strength of material, but also
increases solubility.

41. 3.Fillers
physically imbedded within the
mass, substantially improve
mechanical properties of
material. Multiple fillers can be
used. Examples of Polystyrene,
Silica, Alumina, Diatomaceous
earth, Cotton Fibers.

42. 4. Medicaments
Including coagulants, and
bactericidal and bacteriostatic
agents, may be incorporated .

43. • It is used in operative
dentistry
•as temporary luting agent,
•as temporary and inter-
mediate restorations,
•as a liner under certain filling
material except resin material
due to bad effect of eugenol.
specifications

44. • Also ,can be used as root
canal sealer
•and periodontal dressings.
•The reinforced cement may be
used as a cement base under
amalgam .
specifications

45. • The pH is approximately 7-8 at
the time they inserted in the
cavity and considered one of
the least irritating cement
material and provide an
excellent seal of the cavity
against micro-leakage of
bacteria , fluids and debris .
specifications

46. • It has anti-inflammatory,
antiseptic, sedative actions and a
palliative and obtundent response
• It has an effective thermal
insulating capacity.
specifications

47. • In case of deep carious lesions , it
is prefer to leave the last layer of
carious dentin and then sealed the
cavity by temporary ZOE cement
for a time ( REST TREATMENT).
•Why ?
specifications

48. We have four types according to
the formulations :
•Type I &II which are used as
temporary and inter-mediate luting
agents ,
•Type III which used as temporary
restoration
•and Type IV which used as cavity
liner .
specifications

49. this material take it's name from
the formulation of glass powder
and ionomeric acid (polyacrylic
acid) that contain a carboxyl
groups which essential for the
chemical union with tooth
structures enamel and dentin
specifications

50. • used as esthetic restorative
material
•as luting agents
• as a liner under composite
resin (sandwich technique ) .
specifications

51. • as pit and fissure sealant
material as preventive
agent to caries
• as root canal sealer
•and as core material
buildups .
specifications

52. So, according to the formulation of
the cement we have three types,
•Type I as a luting agent ,
•Type II as a filling material and
•Type III as a liner or base material
specifications

53. • It is composed of powder
and liquid
• or powder and water
(acid is freezing and added
to powder in one bottle) .
specifications

54. • The powder is acid-soluble calcium
alumino-fluoro-silicate glass . Barium ,
strontium or particles of zinc oxide is
added to provide radio-opacity
• liquid is composed of aqueous solution of
poly-acrylic acid with other acids of
maleic, itaconic and tartaric acids for
decrease viscosity and tendency for
gellation of poly-acrylic acid .
specifications

55. • When powder and liquid are mixed,
surface of powder particles attacked by
poly-acid Initiation the formation of silica
gel incorporated powder particles .
• Calcium , aluminum , sodium and
fluorine ions are leached into aqueous
medium (dispersed phase)
• calcium ions begin to cross linked chain
of poly-acrylic acid and form a solid mass
(gellation phase) .
Chemistry of setting :

56. • Within first 24 hours, aluminum ions
interfere within reaction with poly-acrylic
acid and bonded to cement matrix and lead
to more rigid and set cement .
• Sodium and fluoride ions not interfere
within reaction But present in form of free
ions or in form of sodium fluoride
dispersed within set cement .
Chemistry of setting :

57. • Some specifications of GI cement e.g.,
reasonably bio-compatible to pulp tissues,
but it is better to put a layer of calcium
hydroxide liner before in case of deep
cavities,
• chemically bond to the tooth structures
• have anti-cariogenic effect due to the
presence of fluoride salts
• and it has an insulating capacity.

58. Dental cement bases

59. Zinc phosphate cement
zinc poly-carboxylate cement
Glass ionomer cement

60. • ZPC is supplied in form of a powder
and a liquid. powder is almost 90% zinc
oxide, with magnesium oxide and traces
of tribismuth oxide and silicone dioxide.
• The reactivity of powder is controlled
by temperature, time, and by particle size
and shape.
ZPC (Zinc Phosphate cement):

61. • The liquid is a 33% aqueous
solution of orthophosphoric
acid.

62. • setting reaction, mainly
between zinc oxide and
phosphoric acid, is an ordinary
acid-base reaction. The mass
has very poor packing
characteristics and is extremely
porous. The material is used
only as a base or as a luting
agent.

63. • PCC is supplied in form of a powder
and a liquid. The powder is primarily
zinc oxide, with small amounts
(10%) of magnesium oxide and
traces of alumina.
• The liquid is an aqueous (40-50%)
solution of polyacrylic acid.
PCC (Polycarboxylate Cements):

64. • Sodium fluorides are
added to some cements.
They do not enter the setting
reaction, but they can be
released to surrounding
tooth structure.

65. •As we can predict, the matrix
structure is amorphous and
porous to some extent, but it
has better packing
characteristics than ZPC.
• The material is used only as a
base or as a luting agent.