Dr. lama khaled El Banna Faculty of Oral and Dental Medicine Al – Azhar University operative dentistry part two

2. College of DentistryCollege of Dentistry
Operative Dentistry IIOperative Dentistry II
Intermediary Liners & Bases -01-Intermediary Liners & Bases -01-
Dr. Hazem El AjramiDr. Hazem El Ajrami

3. Contents ofContents of Operative Dentistry IOperative Dentistry I
• Scope and Objectives of Operative Dentistry.Scope and Objectives of Operative Dentistry.
• Structures of the Teeth.Structures of the Teeth.
• Tooth Form & Occlusion.Tooth Form & Occlusion.
• Carious & Non Carious Lesions.Carious & Non Carious Lesions.
• Cavity Classifications & Nomenclatures.Cavity Classifications & Nomenclatures.
• General Principles of Cavity Preparation.General Principles of Cavity Preparation.
• Instruments and Instrumentation.Instruments and Instrumentation.

4. • Cement Bases and Liners.Cement Bases and Liners.
• Amalgam Restorations.Amalgam Restorations.
• Introduction to Adhesive Dentistry.Introduction to Adhesive Dentistry.
• Direct Esthetic Tooth-Colored Restoration.Direct Esthetic Tooth-Colored Restoration.
Contents ofContents of Operative Dentistry IIOperative Dentistry II

5. • The problem facing restorative dentistry is toThe problem facing restorative dentistry is to
substitute enamel and dentin that has been lost tosubstitute enamel and dentin that has been lost to
dental caries or removed during cavitydental caries or removed during cavity
preparation. As soon as enamel is involved therepreparation. As soon as enamel is involved there
is need for pulpal protection. Cavity liners andis need for pulpal protection. Cavity liners and
insulating bases are materials placed betweeninsulating bases are materials placed between
dentin (sometimes pulp) and restorative materialdentin (sometimes pulp) and restorative material
to provide pulpal protection or pulpal response.to provide pulpal protection or pulpal response.
These intermediate materials are adjuncts to theThese intermediate materials are adjuncts to the
restorative material and together they form therestorative material and together they form the
restorative system.restorative system.

6. • Prior to placement of the restoration, the pulpPrior to placement of the restoration, the pulp
might have been irritated by a variety of sources;might have been irritated by a variety of sources;
including caries and inevitable trauma from heatincluding caries and inevitable trauma from heat
and pressure during cavity preparation. Cuttingand pressure during cavity preparation. Cutting
with rotary instrumentation produces debris thatwith rotary instrumentation produces debris that
is compacted into a layer of the cut surface calledis compacted into a layer of the cut surface called
the smear layer. The dentinal smear layerthe smear layer. The dentinal smear layer
produces a degree to tubular sealing and is thusproduces a degree to tubular sealing and is thus
an effective barrier. However, it is 20-30%an effective barrier. However, it is 20-30%
porous and cannot therefore offer full sealing ofporous and cannot therefore offer full sealing of
tubules.tubules.

8. • Thus, cutting across dentinal tubules will lead toThus, cutting across dentinal tubules will lead to
opening of several direct pathways reaching toopening of several direct pathways reaching to
the pulp. Furthermore, the physical and chemicalthe pulp. Furthermore, the physical and chemical
properties of the permanent restorative materialproperties of the permanent restorative material
can, in itself, produce irritation or add to thatcan, in itself, produce irritation or add to that
which already exists. Thus, it is essential towhich already exists. Thus, it is essential to
prevent further irritation of tooth tissue as well asprevent further irritation of tooth tissue as well as
to improve the defensive and reparativeto improve the defensive and reparative
capabilities of the pulp-dentin organ.capabilities of the pulp-dentin organ.

9. • It is important to take into consideration that theIt is important to take into consideration that the
reaction of the pulp-dentin organ is not due to areaction of the pulp-dentin organ is not due to a
single factor, but it is multi-factorial and thesingle factor, but it is multi-factorial and the
resultant is cumulative. The fact that long termresultant is cumulative. The fact that long term
success of any restoration is dependent onsuccess of any restoration is dependent on
maintaining and preservation the pulp integritymaintaining and preservation the pulp integrity
requires the use of intervening materialrequires the use of intervening material
to encourage pulp recovery and prevent furtherto encourage pulp recovery and prevent further
irritation to the pulp-dentin organ.irritation to the pulp-dentin organ.

10. • There is no perfect replacement for lost enamel orThere is no perfect replacement for lost enamel or
dentin. In addition, sound dentin is the bestdentin. In addition, sound dentin is the best
barrier between the restorative material and thebarrier between the restorative material and the
pulp. The greater the thickness of the overlyingpulp. The greater the thickness of the overlying
dentin bridge, the lesser the irritation reaching thedentin bridge, the lesser the irritation reaching the
underlying pulp organ. Therefore, theunderlying pulp organ. Therefore, the
conservation of all possible sound dentin is againconservation of all possible sound dentin is again
emphasized.emphasized.

11. • Once the enamel has been lost and there is openOnce the enamel has been lost and there is open
dentinal tubules, fluid flow could occur throughdentinal tubules, fluid flow could occur through
the dentinal fluid. Thermal, chemical, mechanicalthe dentinal fluid. Thermal, chemical, mechanical
or osmotic stimuli at the exposed dentinal tubulesor osmotic stimuli at the exposed dentinal tubules
induce the movement of dentinal fluid whichinduce the movement of dentinal fluid which
stimulates pulpal nerve receptors and thereby,stimulates pulpal nerve receptors and thereby,
causes hypersensitivity. With the exception ofcauses hypersensitivity. With the exception of
properly bonded restorations, restorative materialsproperly bonded restorations, restorative materials
always suffer from a micro-gap at thealways suffer from a micro-gap at the
tooth/restoration interface which will allow fortooth/restoration interface which will allow for
varying degrees of micro-leakage.varying degrees of micro-leakage.

12. • This micro-leakage will cause hypersensitivityThis micro-leakage will cause hypersensitivity
through dentinal fluid flow as well as invitethrough dentinal fluid flow as well as invite
various types of irritants along the dentinalvarious types of irritants along the dentinal
tubules to the pulp. The need for sealingtubules to the pulp. The need for sealing
the dentinal tubules prior to restoration is thusthe dentinal tubules prior to restoration is thus
evident.evident.

14. • In addition, if further removal of diseasedIn addition, if further removal of diseased
dentin is required, this would increase thedentin is required, this would increase the
depth of the cavity and decrease the amount ofdepth of the cavity and decrease the amount of
remaining dentin thickness (also termed dentinremaining dentin thickness (also termed dentin
bridge) between the pulp and the restoration.bridge) between the pulp and the restoration.
In such case, there is a need for a dentinIn such case, there is a need for a dentin
substitute to provide pulpal protection.substitute to provide pulpal protection.

16.  Pulpal protection:Pulpal protection:
I.I. Chemical protection:Chemical protection: Sealing of dentinalSealing of dentinal
tubules is essential to provide chemicaltubules is essential to provide chemical
protection against the penetration of variousprotection against the penetration of various
types of irritants, such as metallic ions,types of irritants, such as metallic ions,
corrosion products, acids and chemicals fromcorrosion products, acids and chemicals from
the restorative material. Sealing also preventsthe restorative material. Sealing also prevents
the ingress of bacterial toxins, salivary ionsthe ingress of bacterial toxins, salivary ions
and various irritants through the micro-and various irritants through the micro-
leakage space at tooth/restoration interface.leakage space at tooth/restoration interface.
This sealing is best accomplished through theThis sealing is best accomplished through the
use of varnish, dentin sealer or dentin bondinguse of varnish, dentin sealer or dentin bonding
system.system.

18. II.II. Thermal protection,Thermal protection, from thermallyfrom thermally
conductive, metallic restorations such asconductive, metallic restorations such as
amalgam and cast gold.amalgam and cast gold.
III.III. Electrical protection;Electrical protection; against galvanismagainst galvanism
which could result from the use of dissimilarwhich could result from the use of dissimilar
metals e.g. amalgam and cast goldmetals e.g. amalgam and cast gold
restorations.restorations.
IV.IV. Mechanical protection;Mechanical protection; from condensationfrom condensation
of amalgam and cementation of inlays asof amalgam and cementation of inlays as
well as the stresses which occur duringwell as the stresses which occur during
masticatory function.masticatory function.

19. V.V. Biological protection (pulpal medication);Biological protection (pulpal medication);
this is accomplished through the use ofthis is accomplished through the use of
eugenol-containing formulations to reliefeugenol-containing formulations to relief
pulpal inflammation or calcium hydroxidepulpal inflammation or calcium hydroxide
that facilitates dentinal bridging throughthat facilitates dentinal bridging through
reparative dentin formation.reparative dentin formation.

21.  Ideal requirements for intermediaryIdeal requirements for intermediary
materials:materials:
No available material possesses all of theseNo available material possesses all of these
requirements; however, combining two or morerequirements; however, combining two or more
of these materials can accomplish all of the idealof these materials can accomplish all of the ideal
requirements:requirements:
1.1. The material should provide a sedative action toThe material should provide a sedative action to
the pulp, conductive to repair and healing. Itthe pulp, conductive to repair and healing. It
should provide no further irritation, beshould provide no further irritation, be
compatible with pulp-dentin organ and stimulatecompatible with pulp-dentin organ and stimulate
reparative dentin formation.reparative dentin formation.
2.2. It should improve the marginal sealing and theIt should improve the marginal sealing and the
adaptation to the cavity walls; preferably capableadaptation to the cavity walls; preferably capable
of bonding to tooth structure.of bonding to tooth structure.

22. 3.3. The material should possess thermal andThe material should possess thermal and
electrical insulating capacity at minimal filmelectrical insulating capacity at minimal film
thickness.thickness.
4.4. The material should have sufficient strength toThe material should have sufficient strength to
resist fracture or distortion under the forces ofresist fracture or distortion under the forces of
condensation of the permanent restoration ascondensation of the permanent restoration as
well as under masticatory forces transmitted towell as under masticatory forces transmitted to
it through the permanent restoration.it through the permanent restoration.

24. 5.5. It should have minimal effective film thicknessIt should have minimal effective film thickness
without compromising the bulk needed for thewithout compromising the bulk needed for the
future restoration.future restoration.
6.6. It should be compatible with overlyingIt should be compatible with overlying
restorative material and other intermediary baserestorative material and other intermediary base
materials; it should not interfere with setting ormaterials; it should not interfere with setting or
adaptation of the materials.adaptation of the materials.
7.7. The material should resist degradation in theThe material should resist degradation in the
oral fluids.oral fluids.
8.8. It should have adequate workability and be easyIt should have adequate workability and be easy
to apply.to apply.

25.  Types and classification of intermediaryTypes and classification of intermediary
materials:materials:
I.I. Liners:Liners:
A.A. Solution Liners:Solution Liners:
 Varnish.Varnish.
 Dentin sealer.Dentin sealer.
 Bonding systems.Bonding systems.
B.B. Suspension Liners.Suspension Liners.
C.C. Cement Liners.Cement Liners.
II.II. Cement Bases.Cement Bases.

27. I.I. Liners:Liners:
A.A. Solution Liners:Solution Liners:
These are thin film forming materials thatThese are thin film forming materials that
are used mainly for sealing of dentinalare used mainly for sealing of dentinal
tubules to provide chemical protection.tubules to provide chemical protection.
 Varnish:Varnish:
Form and Composition:Form and Composition:
It is supplied in the form of a liquidIt is supplied in the form of a liquid
composed of 10% natural gum (copal orcomposed of 10% natural gum (copal or
rosin) or synthetic resin dissolved in 90%rosin) or synthetic resin dissolved in 90%
organic solvent such as ether, acetoneorganic solvent such as ether, acetone
or chloroform.or chloroform.

29. Functions:Functions:
It forms a barrier against chemical irritation fromIt forms a barrier against chemical irritation from
the restorative material.the restorative material.
It seals dentinal tubules; thereby it reduces fluidIt seals dentinal tubules; thereby it reduces fluid
flow and decreases hypersensitivity.flow and decreases hypersensitivity.
It reduces the irregularities of the prepared surfaceIt reduces the irregularities of the prepared surface
thus improving the adaptation of the permanentthus improving the adaptation of the permanent
restoration and decrease micro-leakage space.restoration and decrease micro-leakage space.
It can provide electrical insulation. However, it isIt can provide electrical insulation. However, it is
too thin and cannot provide thermal or mechanicaltoo thin and cannot provide thermal or mechanical
insulation.insulation.
It is compatible with pulp-dentin organ, except ifIt is compatible with pulp-dentin organ, except if
remaining dentin thickness is less than l mm.remaining dentin thickness is less than l mm.

30. Indications:Indications:
Under amalgam restoration: It preventsUnder amalgam restoration: It prevents
penetration of metallic ions and corrosionpenetration of metallic ions and corrosion
products into dentinal tubules, thus preventingproducts into dentinal tubules, thus preventing
pulpal irritation and tooth discoloration (amalgampulpal irritation and tooth discoloration (amalgam
blues). It also decreases the initial micro-leakageblues). It also decreases the initial micro-leakage
space with amalgam.space with amalgam.
Under cast gold restoration: Used to seal tubulesUnder cast gold restoration: Used to seal tubules
but it should be compatible with the utilizedbut it should be compatible with the utilized
luting cement.luting cement.
Under acidic base material such as zinc phosphateUnder acidic base material such as zinc phosphate
cement.cement.

31. Contraindications:Contraindications:
 Under resin composite restorations: It is not logicalUnder resin composite restorations: It is not logical
to use varnish under resin composite as it willto use varnish under resin composite as it will
prevent the mechanical interlocking of the resinprevent the mechanical interlocking of the resin
with tooth structure. In addition, the residualwith tooth structure. In addition, the residual
organic solvent in the varnish may react with ororganic solvent in the varnish may react with or
soften the resin. Over more, the resin mightsoften the resin. Over more, the resin might
destroy the integrity of the copal varnish renderingdestroy the integrity of the copal varnish rendering
it void of value.it void of value.
 Under glass ionomer, resin modified glass ionomerUnder glass ionomer, resin modified glass ionomer
and polycarboxylate cement. The varnish wouldand polycarboxylate cement. The varnish would
eliminate adhesive potential and biocompatibilityeliminate adhesive potential and biocompatibility
of these cements, as well as hinder the fluorideof these cements, as well as hinder the fluoride
uptake from glass ionorner materials.uptake from glass ionorner materials.

32. Manipulation:Manipulation:
An example for a commercially availableAn example for a commercially available
product is Copalite Varnish. It is applied to allproduct is Copalite Varnish. It is applied to all
prepared enamel and dentinal surface in a thinprepared enamel and dentinal surface in a thin
film thickness of 2-5 µm. Usually 2-3 coats arefilm thickness of 2-5 µm. Usually 2-3 coats are
applied using a cotton pellet or a micro-brush. Asapplied using a cotton pellet or a micro-brush. As
each coat is dried, the solvent evaporates leavingeach coat is dried, the solvent evaporates leaving
a semi-permeable thin resinous film that sealsa semi-permeable thin resinous film that seals
and protects the underlying structure. A bottle ofand protects the underlying structure. A bottle of
solvent may be supplied in the varnish kit tosolvent may be supplied in the varnish kit to
remove excess varnish from external toothremove excess varnish from external tooth
surface and dilute the varnish bottle if it becomessurface and dilute the varnish bottle if it becomes
viscous due to solvent evaporation withviscous due to solvent evaporation with
continued use.continued use.

35. Dentin sealer:Dentin sealer:
An example for a commercially availableAn example for a commercially available
product is Gluma desensitizer. It comprises aproduct is Gluma desensitizer. It comprises a
resinous material that cures onto the smear layer,resinous material that cures onto the smear layer,
unlike the bonding or adhesive systems whichunlike the bonding or adhesive systems which
require smear layer removal or dissolving. It is justrequire smear layer removal or dissolving. It is just
used to seal dentinal tubules and desensitize dentin.used to seal dentinal tubules and desensitize dentin.
It possesses the same functions of the varnish and isIt possesses the same functions of the varnish and is
extremely efficient. It can be used under metallicextremely efficient. It can be used under metallic
restorations and have thus replaced or significantlyrestorations and have thus replaced or significantly
reduced the use of varnish.reduced the use of varnish.
It cannot, however, replace dentin bondingIt cannot, however, replace dentin bonding
agents as it does not produce micromechanicalagents as it does not produce micromechanical
bonding. Thus, it is not indicated with resinbonding. Thus, it is not indicated with resin
composite as well as with the chemically bondedcomposite as well as with the chemically bonded
glass ionomer cements.glass ionomer cements.

37. Bonding systems:Bonding systems:
These are resinous systems that dissolve orThese are resinous systems that dissolve or
penetrate the smear layer to bondpenetrate the smear layer to bond
micromechanically to tooth substrate. They aremicromechanically to tooth substrate. They are
usually polymerized by visible light curing andusually polymerized by visible light curing and
are used to bond resin composite to the toothare used to bond resin composite to the tooth
structure. They can also be used with bondedstructure. They can also be used with bonded
amalgam. They also seal the tubules andamalgam. They also seal the tubules and
eliminate micro-leakage if properly bonded.eliminate micro-leakage if properly bonded.

38. Thank YouThank You