Luting cements/prosthodontic courses

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

CONTENTS
 Introduction
 Ideal requirements of Luting agents:
 Cements used for Luting
 Zinc phosphate cement
 Zinc-oxide Eugenol and 3) Non- eugenol cements
 Zinc polycarboxylate cement (Zinc
polycarboxylate cement)

 Type I Glass Ionomer Cement / ASPA or
Aluminosilicate polycrylate / Alkeneate
 Resin Composite Cements
 Resin Modified Glass Ionomers / Hybrid
Ionomers
 Summary and Conclusion
 references

INTRODUCTION
 Numerous dental treatments necessitate
attachment of indirect restorations and
appliances to the teeth by means of a cement.
 These include metal, resin, metal-resin, metal-
ceramic, and ceramic restorations; provisional or
interim restorations; laminate veneers for
anterior teeth; orthodontic appliances; and pins
and posts used for retention of restorations

 The long-term clinical outcome of fixed
prosthodontic treatment depends, in part, on the
use of adhesives that can provide an impervious
seal between the restoration and the tooth
 . Schwartz et al in 1970 found that loss of crown
retention was the second leading cause of failure
of traditional crowns and fixed partial dentures.
 Therefore the clinical success of these luting
agents depends on the cementation procedure
and clinical handling of these materials.

 The word ‘luting’ is often used to describe the use
of a moldable substance to seal a space or to
cement two components together.
 There are several types of available luting
agents, each possessing unique properties and
handling characteristics

 No one product is ideal for every type of
restoration; some of them requiring multiple
technique sensitive steps.
 Although the establishment of optimal
resistance and retention forms are obtained from
proper tooth preparation, luting agents should
essentially serve the following purposes:

 Act as a barrier against microbial intrusion
 Seal the interface between the tooth and the
restoration.
 Hold the restoration and tooth together through
some form of surface attachment.
 This attachment may be mechanical, chemical or
a combination of both methods.

Ideal requirements of luting agents:
 Should provide a durable bond between
dissimilar materials.
 Should possess favourable compressive and
tensile strengths.
 Should have sufficient fracture toughness to
prevent dislodgement as a result of interfacial or
cohesive failures.

 Should be able to wet the tooth and the
restoration.
 Should exhibit adequate film thickness and
viscosity to ensure complete sealing.
 Should be resistant to disintegration in the oral
cavity.
 Should be tissue compatible.
 Should demonstrate adequate working and
setting times.

 Presently there are cements used for the
temporary or permanent cementation of fixed
prosthesis. They are:
Zinc phosphate.
Zinc oxide-eugenol.
Zinc oxide-non-eugenol.
Zinc polycarboxylate.
Glass ionomer Type I.
Resin composite cements or compomers.
Resin-modified glass ionomer or hybrid
ionomers.

ZINC PHOSPHATE CEMENT
Powder Weight (%)
Zinc oxide (ZnO) principal ingredient. 90.2
Magnesium oxide (MgO) reduces the temperature of
the calcination process.
8.2
Silicon dioxide (SiO2) inactive filler and aids in the
calcination process
1.4
Bismuth trioxide (Bi2O3) imparts a smoothness to the
freshly mixed cement in large amounts it may also
lengthen the setting time.
0.1
Barium oxide (BaO), Barium sulphate (Ba2SO4)
Calcium oxide (CaO)
0.1

 Tannin-fluoride may be added in some
commercial products.
 The ingredients of the powder are heated and
sintered at temperatures between 1000°C and
1400°C into a calcined mass, that is subsequently
pulverized to a fine powder which is sieved to
recover selected particle sizes.

Liquid Weight (%)
Phosphoric acid (H3PO4) (free acid) 38.2
Phosphoric acid combined with aluminium and zinc
Al and Zn partially neutralize the acid, temper its
reactivity and act as buffering agents which helps in
establishing a smooth, nongranular, workable cement
mass.
16.2
Aluminium (Al) 2.5
Zinc (Zn) 7.1
Water H2O 36.0

CONTROLING THE SETTING TIME
AND MECHANICAL PROPERTIES
 The water content controls the ionization of the
acid and influences the rate of setting reaction.
 This is important to the clinician because an
uncapped liquid bottle will permit loss of water
resulting in retarded set

 Setting reaction
• When powder particles are wet by the liquid,
phosphoric acid attacks the surface of the
particles and releases zinc ions into the liquid
• The resultant mass yields a hydrated, amorphous
network of zinc aluminophosphate gel on the
surface of the remaining portion of the particle.

 The set cement is a cored structure consisting
primarily of unreacted zinc oxide particles
embedded in a cohesive amorphous matrix of
zincaluminophosphate. In presence of excess
moisture formation of crystalline hopeite (Zn3
(PO4)2 4H2O) takes place.

 Manipulation
 No definite P/L ratio and maximum amount of
powder should be incorporated into the liquid.
 A cool mixing slab should be employed. The cool
slab prolongs the working and setting times.
 The liquid should not be dispensed until the
mixing is to be initiated to prevent loss of water.
 Mixing is initiated by incorporation of small
portions of powder into the liquid over a wide
area to minimize the heat and effectively
dissipate it.

 Spatulate each increment for 15 seconds before
adding another increment.
 Completion of the mix usually requires
approximately 1 minute 30 seconds.
 The casting must be seated immediately with a
vibratory action before matrix formation occurs.
 After the casting has been seated, it should be
held under pressure until the cement sets to
minimize air inclusion

 The procedure should be carried out in a dry,
clean environment.
 Excessive cement should be removed after it has
set and a layer of varnish should be applied to
the margin to decrease the initial dissolution.
 Frozen Glass slab Method

 In this method a glass slab cooled at 6°C or at –
10°C is used. Around 50% to 75% more amount of
powder can be incorporated into the liquid. The
working and setting times are prolonged with
little difference in physical and mechanical
properties.

PROPERTIES
 Working and setting times
 Working time is the time from the start of mixing
during which the viscosity of the mix is low
enough to flow readily under pressure to form a
thin film.

 Setting time mean that matrix formation has
reached a point where external physical
disturbance will not cause permanent
dimensional changes.
 Net setting time is 2.5 to 8.0 minutes at 37°C and
100% humidity it varies from 5-9 minutes.

FACTORS INFLUENCING THE
SETTING TIME:
 Those controlled by manufacturer:
 Powder composition.
 Degree of powder calcinations.
 Particle size.
 Buffering of liquid.
 Water content of liquid.

THOSE CONTROLLED BY THE
OPERATOR AND THEIR INFLUENCE ON
SELECTED PROPERTIES:
Manipulative
variables
Compressive
strength
Film thickness Solubility Initial acidity Setting time
Decreased P/L
ratio
Decrease Decrease Increase Increase Lengthen
Increased rate of
powder
incorporation
Decrease Increase Increase Increase Shorten
Increased
mixing
temperature
Water
contamination

PHYSICAL PROPERTIES
 When properly manipulated, the set cement
exhibits a compressive strength of 104MPa,
diametral tensile strength of 5.5MPa, modulus of
elasticity of 13GPa
 Thus it is quite stiff and resistant to elastic
deformation even when it is used for cementation
of restorations in high stress-bearing areas.
 The strength is influenced by P/L ratio,
composition, manner of mixing and handling of
the cement

SOLUBILITY AND
DISINTEGRATION
 The solubility in water in 24 hours is 0.2%.
Solubility depends on initial exposure to water of
the incompletely set cement resulting in
increased dissolution
 . Greater resistance to solubility can be obtained
by increasing the P/L ratio

CONSISTENCY AND FILM
THICKNESS
 Two consistencies are used i.e. luting and base.
The luting consistency is tenacious and provides
a mechanical interlocking between the surface
irregularities of the tooth and the restoration.#
 The maximum film thickness is 29µm. It depends
on the consistency and seating pressure.

VISCOSITY
 Viscosity increases with increased P/L ratio,
mixing time and higher temperature. Increased
viscosity can result in increased film thickness
and incomplete seating.

 Dimensional stability
 It exhibits shrinkage on hardening ranging from
0.04% to 0.06% in 7 days.
 Thermal and Electrical conductivity
 It is an effective thermal insulator and protects
against thermal trauma to the pulp

 Acidity
 The acidity of the cement is quite high at the
time of cementation of a prosthesis. Two minutes
after the start of mixing the pH is approximately
2. It increases rapidly but still is only about 5.5
at 24 hours.
 The pH remains relatively low for long durations.
 Microleakage, aggravated by dehydration in oral
fluids and an initial low setting pH may affect its
biocompatibility in clinical use.

 Applications
 Permanent luting of well-fitting, prefabricated
and cast posts, metal inlays, onlays, crowns,
FPDs, and aluminous all-ceramic crowns to tooth
structure, amalgam, composite, or glass ionomer
core build ups.

ZINC-OXIDE EUGENOL AND 3) NON-
EUGENOL CEMENTS
Powder Weight (%)
Zinc oxide 69.0
White resin (reduced brittleness of the set cement) 29.3
Zinc sterate (plasticizer) 1.0
Zinc acetate (improves strength) 0.7
Liquid
Eugenol 85.0
Olive oil 15.0

 To increase the strength of the cement for luting
purposes, two modifications have been made 
Type II luting agents:
 Methyl methacrylate polymer is added to powder
(20% by weight) (Kalzinol).
 Alumina (Al2O3) (30% by weight) is added to
powder and ethoxybenzoic acid (EBA) is added to
liquids (62.5% ortho EBA by weight).

 The non-eugenol cements contain an aromatic oil
and zinc oxide. Other ingredients may include
olive oil, petroleum jelly, oleic acid, and beeswax.

 Setting reaction
 The cement sets by chelation reaction to form
eugenolate and water. The presence of moisture is
essential for setting to occur.
 Manipulation
 A paper mixing pad is used. A P/L ratio of 4-6:1 is
employed. The bulk of the powder is incorporated in
the initial step, the mix is thoroughly spatulated, and
then a series of smaller amounts is added until the
mix is complete.
 Mixing time required is usually 90 seconds. The
reinforced cements are kneaded for 30 seconds and
then stopped for 60 seconds to develop a creamy
consistency.

 Properties
 Setting time ranges from 4 to 10 minutes. For
reinforced cements, since the P/L ratio increases,
the setting time decreases.
 Setting time depends on composition of powder,
particle size, P/L ratio, accelerator and
temperature

 Physical properties
 Type I luting cement has a compressive strength
of 2.0-14MPa,
non-eugenol cements have values of 2.7-4.8MPa,
polymer modified has a strength of 37MPa
with EBA-alumina having the highest strength
64MPa.
Elastic modulus ranges from  0.22 for Type I,
2.7 for Kalzinol
and 5.4 for EBA-alumina.

 Solubility and disintegration
 Due to the bleaching of eugenol, solubility is high
and ranges between 1.5 to 2.5%. addition of
additives decreases the solubility. The solubility
in water (%) in 24 hours for polymer modified
cements is 0.08 and EBA-alumina is 0.02-0.04.
 Film thickness
 Film thickness of polymer modified cement is
2.5µm and EBA alumina is 25-35µm.

 Shows a shrinkage of 0.9-2.5% on setting.
 Biologic properties
 It has a pH of 7-8.
 It does not cause any harm to the pulp but due to
leaching of eugenol, it is an irritant. Therefore
non-eugenol cements are used for some patients.

 Highly compatible with the pulp and has an
obtundant effect.
 It also has an antibacterial action.
 Its disadvantages such as decreased strength,
high solubility, irritant to soft tissues, poor
retention and difficulty in manipulation limit its
use for temporary cementation purposes.
 It should not be used for temporary luting
purposes when the permanent luting agent is
likely to be a resin cement as the eugenol inhibits
polymerization.

 Applications
 It is used primarily for temporary luting of
restorations.

ZINC POLYCARBOXYLATE
CEMENT
Powder Weight (%)
Zinc oxide 85
Magnesium oxide or stannic oxide 10
Stannous fluoride traces of silica dioxide, bismuth,
aluminium and colour pigments.
4-5

 Liquid
 Aqueous solution of polyacrylic acid or
copolymers of acrylic acid in the range of 30-40%.
 Molecular weight of 25,000 to 50,000.
 Tannic acid and malleic acid 10-45%.
 Tartaric acid prevents gelation on storage 5%.
 Water settable cements – Here the mixing liquid
is water – polyacrylic acid is frozen, dried,
powdered and mixed with the original P/L ratio
of these cements is very high.

 Setting reaction and adhesion to tooth
structure:
 When powder and liquid are mixed, a fast acid-base
reaction occurs as the powders are rapidly
incorporated into a viscous solution of high molecular
weight polyacrylic acid.
 The powder particles are attacked by the acid and
zinc, magnesium and tin ions are released. Zinc ions
react with the carboxyl group of polyacrylic acid of the
same chain and the adjacent chain to cause cross
linking.
 The calcium ions of the tooth structure react with the
free carboxyl groups of acid to form a metallic ionic
bond

 The bond between cement and dentin is 3.4 MPa.
Under ideal conditions the adhesion of
polycarboxylate cement to a clean, dry surface of
the tooth is greater than any other cement

 . The cement adheres better to a smooth surface
than to a rough one.
 It does not adhere well to gold and porcelain. The
failure is at the cement-metal interface.
 Cement cannot bond to the metal in chemically
dirty or pickled condition.
 Surfaces of the metal have to be sandblasted or
electrolytically etched to achieve optimum
bonding. Adhesion with stainless steel is
excellent.


 Manipulation
 P/L ration is 15:1.
 A glass slate is used for mixing to prevent absorption
of liquid. Firstly a meticulously clean surface is
essential to intimate contact and interaction between
the cement and the tooth. 10% polyacrylic acid
solution is used to clean the tooth surface for 10-15
seconds followed by rinsing with water for removal of
smear layer. After cleansing, isolate the tooth to
prevent further contamination by oral fluids. Blot the
surface before cementation.
 The powder is rapidly incorporated into the liquid in
large quantities for a period of 30 to 60 seconds.
Mixing on a cooled glass slab prolongs the working
time. The cement must be placed on the inner surface
of casting and on tooth surface before it loses its
glossy appearance. Loss of gloss indicates decreased
availability of carboxyl groups, poor bonding, poor
wettability due to stringiness and increased film
thickness causing incomplete seating of the cast

PRECAUTIONS
 Do not refrigerate the liquid dispense the liquid
just before mixing.
 Mixing should be rapid.
 Use only on cleaned surfaces.
 Use before glossiness disappears.
 Removal of excess cement
 During setting, the cement passes through a
rubbery stage. During this stage, excess cement
should not be pulled away from the margins as it
can leave voids at the interface. Remove excess
cement only after it becomes hard. Apply
petroleum jelly to the outer surfaces of the
prosthesis and soft tissues to prevent cement
from adhering to them.

 Properties
 Setting time is 6-9 minutes.
 Working time 2.5 – 3.5 minutes.
 Viscosity
 The set mix is pseudoplastic in nature. The
cement seems viscous, but during cementation
pressure, excess flows out from under the
margins of the restoration

 Physical and Mechanical properties
 The compressive strength of 24 hour set cement
is 57-99 MPa; tensile strength is 3.6-6.3MPa and
elastic modulus is 4.0-4.7GPa. Bond strength to
dentin is 2.1MPa, to enamel is 3.4-13MPa.
 Film thickness of polyacrylate cements is 25-48
µm.

 Solubility of cement in water is low (<0.05%) but
when it is exposed to organic acids with a pH of
4.5 or less, the solubility increases markedly.
Reduction of P/L ratio also increases solubility
and disintegration in the oral cavity.

 They show a linear contraction when setting at
37°C.
 Biologic properties
 The pH of the cement liquid is 1.7, but the liquid
is rapidly neutralized by the powder. PH
increases rapidly as the cement sets.
 Despite the initial acidic nature, these cements
produce minimal irritation to the pulp because of
quick neutralization and the lack of tubular
penetration of the sized polyacrylic acid
molecules.

 This excellent biocompatibility with the pulp is
one of the strongest clinical merits of this
cement.

 Advantages
 Low level of irritation and increased
biocompatibility with the pulp.
 Adhesion to tooth structure.
 Easy manipulation.
 Anticariogenic.
 Thermal insultor
 Hydrophilic and capable of wetting dentinal
surfaces.

 Disadvantages
 If acute proportioning is not done, properties are
affected i.e. solubility and disintegration
increases.
 Working time is short.
 Clean surface is required for adhesion.
 Absorbs water and softens into a gel.
 Increased solubility in acids.
 Difficult to remove flash.
 Failures occurs at cement-metal interface. After
hardening, polycarboxylate cements exhibit
significantly greater plastic deformation; thus
the cement is not well suited for use in regions of
high masticatory stress or in the cementation of
long-span prosthesis.

 Application
 Used for the cementation of single metal units in
low stress areas on sensitive teeth.

TYPE I GLASS IONOMER CEMENT /
ASPA OR ALUMINOSILICATE
POLYCRYLATE / ALKENEATE
 Akinmade and Nicholson in 1993 defined glass
ionomer cement as “a water based cement
wherein, following mixing, the glass powder and
the polyalkenoic acid undergo an acid base
setting reaction”.

 Mclean and Nicholson defined GIC as “a cement
that consists of a basic glass and an acidic
polymer which sets by an acid base reaction
between these components

 Composition
 Powder
 The basic component of a glass Ionomer cement
powder is a calcium fluoroalumino silicate glass
with a formula of:
 SiO2-Al2O3-CaF2-Na3 AlF6-AlPO4

Chemical Weight (%)
SiO2
Al2O3
CaF2
Na3AlF6
AlF3
AlPO4
29.0
16.6
34.3
5.0
5.3
9.8

 The raw materials are fused together to a
uniform flass by heating them to a temperature
of 1100°C.
 The glass is then ground to a powder having
particles in the range of 20 to 50µm. glasses high
in silica are transparent, whereas glasses high in
calcium fluoride or alumina are opaque.

 Fluoride is an essential constituent of GIC:
 It lowers the fusion temperature.
 Improves the working characteristics.
 Increases the strength of the set cement.
 Contributes to anticarcinogenic property perhaps the
rationale for using GIC as a luting agent is based on its
ability to release fluoride ions into the underlying dentin.
This helps prevent secondary caries which is the most cause
of failure.

 The powder is described as an ion-bleachable
glass that is susceptible to acid attack when the
Si/Al atomic ratio is less than 2:1.
 Cryolite is added to supplement the flexing
action of calcium fluoride and to increase the
translucency.
 Aluminium phosphate improves translucency
and adds body to the cement paste. Barium glass
may be added to provide radiopacity.

 Liquid
 The liquid typically is 4.75% solution of 2:1
polyacrylic acid / itaconic acid copolymer (average
molecular weight 10,000) in water.
 The itaconic acid reduces the viscosity of the
liquid and inhibits gelation caused by
intermolecular hydrogen bonding

 Intermolecular hydrogen bonding
 Tartaric acid is present in 5%, as an optically
active isomer and serves as an accelerator by
facilitating the extraction of ions from the glass
powder. Also tartaric acid prolongs the working
time, improves handling characteristics, enables
fluoride contact of glass to be reduced
 Water is the basic reaction medium and plays a
role in hydrating reaction products, that is metal
polyalkenoate salts and silica gel

 Water settable GIC
 To extend the working time, one GI formulation
consists of freeze dried acid powder and glass
powder in one bottle and liquid components in
another. The chemical reaction procedures in the
same way except that these cements have a
longer working time and a shorter setting time.

 Setting reaction and adhesion to tooth
structure
 The cement sets hydro acid base reaction and
consists of 2 stages. The first occurs during the
initial 5 minutes when the reaction between the
powder and the liquid forms a silaceous hydro
gel.
 The second stage requires about 24 hours and
occurs when a poly salt matrix completely
surrounds all of the initial reaction products.

 When the powder and liquid are mixed the following sequence of
events take place:
 Polyacid attacks the glass to release calcium, aluminium, sodium and
fluoride ions.
 These ions react with the polyanions to form a salt gel matrix.
 The polyacrylic acid chains are cross-linked by Ca++
in the first 3
hours.
 Subsequently aluminium ions react for atleast 48 hours.
 The fluorides and phosphates form insoluble salts and complexes.
 The sodium ions form a silica gel.
 Some of the sodium ions replace, the hydrogen ions of the carboxyl
groups and the rest combine with fluorine ions.
 The cross-linked phase is hydrated by water.
 The unreacted portion of glass particles are sheathed by silica gel.
 Thus, the set cement consists of an agglomeration of unreacted
powder particles surrounded a silica gel in an amorphous matrix of
hydrated calcium and aluminium polysalts.
 The glass ionomer chemically bonds to enamel and dentin. It seems
that bonding involves an ionic interaction with calcium and/or
phosphate ions from the surface of the tooth structure. This results in
chelation of carboxyl groups of the polyacids with the calcium in the
apatite of the enamel and dentin.

 Role of water in the setting process
 Water hydrates the cross-linked matrix, thereby
increasing the material strength. During the initial
reaction period, this water can be readily removed by
desiccation and is called loosely bound water.
 Also at this stage the GI readily absorbs moisture
into the glossy matrix resulting in a compromised
material.
 Therefore, any contact with saliva or oral fluids has to
be prevented for the first 24 hours to prevent early
disintegration and dissolution.
 As the setting continues the water becomes tightly
bound and cannot be removed. This hydration is
critical in yielding a stable gel structure and building
the strength of the cement

 Manipulation
 The prepared tooth structure and the inner
surface of the casting are cleaned. The tooth
surface is cleaned with a slurry of pumice, rinsed
and then dried but not dehydrated. Undue
desiccation opens up the dentinal tubules,
enhancing penetration of the acidic liquid.
 A glass slab or a paper pad is used for mixing. A
plastic spatula should be used. Use of a metal
spatula, causes abrasion by the glass particles of
the metal surfaces resulting in discoloration of
the set cement. P/L ratio for GIC Type I is 1.3 : 1.

 The powder is introduced into the liquid in large
increments and spatulated rapidly for 30 to 45
seconds. Encapsulated products typically are
mixed for 10 seconds in a mechanical mixer and
dispensed directly. Hand mixed cements often
contain bubbles of larger diameter, which may
contribute to a decrease in strength.
 The cement must be used before it loses its glossy
apperance. The field must be isolated completely.
Once the cement has achieved its initial set (7
minutes), the cement margins should be coated
with a varnish.

 Precautions:
Tooth should be conditioned.
Should be protected from moisture and drying
during setting.
Should be used before loss of glossy
appearance.
Flash should be removed only after cement
hardens.
 Properties :
 Setting time of GIC is within 6-8 minutes from
the start of mixing

 Physical and mechanical properties.
 The 24 hour compressive strength of GIC ranges
from 93-226MPa,
 tensile strength being 4.2-5.3MPa and elastic
modulus of 3.5-6.4 GPa.
 Strength increases between 24 hours and 1 year
and is significantly increased by initial protection
from moisture.
 Low values of elastic modulus make them
susceptible for elastic deformation increase of
high masticatory stress.

 The bond strength of GIC to dentin is 3-5MPa.
 The bond strength can be improved by treatment
of the dentin with an acidic leaching agent
followed by an application of a dilute aqueous
solution of FeCl3.
 The GIC bond well to enamel, stainless steel,
tin-oxide plated platinum and gold alloy.

 Solubility and disintegration
 A 24 hours solubility for GIC in H2O is 0.4-1.5%
solubility is less in acidic solutions and also
depends on initial exposure to water.
 Film thickness for GIC is 22-24µm.

 Biologic properties:
 Resistance to micro leakage
 The cement bonds to tooth structure and
prevents ingress of fluids at the interface. This is
probably because the coefficient of thermal
expansion of GIC is similar to that of the
adjacent tooth structure particularly the dentin.
 Anticariogenic due to the release of fluoride ions.

 Post cementation sensitivity
 This is related to the pH and the length of time
that this acidity persists. The pH of the mix at 2
minutes after mixing is 2.33 and it increases upto
5.67 in 24 hours but never reaches neutral pH.
 Also if the tooth is excessively dehydrated before
cementation, the tubules open up allowing acids
to seen through. If the crown is overfilled, the
excessive hydraulic pressure required to remove
excess cement caused sensitivity

 Advantages
 Chemical adhesion to tooth structure.
 Anticariogenic.
 Esthetic properties.
 Ease of manipulation.
 They possess low film thickness and maintain
relatively constant viscosity for a short time after
mixing. This results in improved seating of cast
restorations.

 Disadvantages
 Low film thickness can cause in-homogenous
distribution of curing stresses and micro cracks
resulting in cementation failure.
 Low elastic modulus
 Susceptibility to moisture attack and subsequent
solubility if exposed to water during the initial
setting period.
 Early exposure to moisture and saliva decreases
the ultimate strength.
 Susceptibility to dehydration and cohesive failure
due to micro cracks.
 Post cementation sensitivity

 Applications
 Used as permanent luting agent for cast posts,
metal inlays, onlays, crowns, FPDs and all-
ceramic crowns to tooth structure, amalgam,
composite core build ups

6) RESIN COMPOSITE CEMENTS
 Resin cements are variations of filled BIS-GMA
resin and other methacrylate.
 Composition
 The early resin cements were primarily
poly(methyl methacrylate) powder with inorganic
fillers and methyl methacrylate liquid.
 They include organophosphonates, hydroxyethyl
methacrylate (HEMA) and the 4-methacryl
oxyethyl tri mellitic anhydrite (4-META) system

 Manipulation
 The chemically activated systems are available in
powder-liquid system or as two paste systems.
The peroxide initiator is in one component and
the amine activator is contained in the other.
 The components are mixed on a paper pad for 20-
30 seconds.
 The restorations should be promptly seated and
excess cement should be removed immediately.

 Light activated systems are single component
systems.
 The time of exposure to light needed for
polymerization of the resin cement is dependent
on the light transmitted through the ceramic
restoration.
 It should never be less than 40 seconds

 Adhesion to tooth structure
 Application of an acid or dentin conditioner to
remove the smear layer
 The tubules are opened and widen with
demineralization of the top

 The acid dissolves and extracts the apatite mineral
phase that normally covers the collagen fibers of the
dentin matrix and opens 20 to 30nm channels around
the collagen fibers.
 These channels provide an opportunity to achieve
mechanical retention of subsequently placed
hydrophilic adhesive monomers.
 If application of the conditioner exceeds 15 seconds, a
deeper demineralized zone results which resists
subsequent resin infiltration.
 If complete infiltration of the collagen by the primer
does not occur, the collagen at the deeper
demineralized zone will be left unprotected and
subjected to future hydrolysis and final breakdown.
 After demineralization, the primer, a wetting agent
such as HEMA is applied.

 The agent is bi-functional, in that it is both
hydrophilic, which enables a bond to dentin, and
hydrophobic, which enables a bond to the
adhesive.
 The primer is applied in multiple coats to a moist
dental surface. Multiple coats are required to
replace the water in the damp dentin with the
resin monomers and to carry the adhesive
material into the tubules.

 The primer is gently dried so as not to disturb
the collagen network but to remove any
remaining organic solvents or water.
 Adhesive resin is then applied to the “primed”
surface to stabilize the primer infiltrated
demineralized dentin.

 Retention is achieved by the following means:
 Infiltration of resin into etched dentin, producing
a micromechanical interlocking with the open
tubules forming resin tags; which underlies the
hybrid layer of resin interdiffusion zone.
 Adhesion to enamel through the micromechanical
interlocking of resin to the hydroxyapatite
crystals and rods of etched enamel.

 Properties
 Their properties on dependent on compositional
differences, amounts of diluent monomers and
filler levels.
 Setting time  4-5 minutes at 37°C.
 Compressive strength  52-224MPa.
 Tensile strength  37-41 MPa.
 Elastic modulus  1.2-10.7 GPa.
 Bond strength to dentin  11-24 MPa with
bonding agent.
 Virtually insoluble in oral fluids
 Film thickness  13-20µm.

 Advantages
 Resin cements bond chemically to resin composite
restorative materials and to silanated porcelain.
 They increase the fracture resistance of ceramic
materials that can be etched and silanated.
 They demonstrate good bond strengths to
sandblasted base metal alloys, the 4-META resin
cements show strong adhesion as a result of
chemical interaction of the resin with an oxide
layer on the metal surface.
 Noble alloys may be electroplated with tin to
increase the surface area for bonding and enable a
chemical bond with tin oxide.

 Disadvantages
High filler content increases viscosity, which
reduces flow and increases film thickness and
chances of incomplete seating of the
restoration.
polymerization shrinkage.
Irritant to the pulp.

 Their ability to adhere to multiple substrates
high strength, insolubility and shade matching
potential have made them the adhesives of choice
for cementation of the following:
 Resin composite inlays and onlays.
 All-ceramic inlays and onlays.
 Veneers, crowns, FPDs.
 Fiber reinforced composite restorations.
 Luting base metal resin bonded bridges (“Maryland” type).


7) RESIN MODIFIED GLASS
IONOMERS / HYBRID IONOMERS
 To overcome inherent drawbacks of GIC such as
moisture sensitivity and low early strength,
polymerizable functional groups have been added
to the formulations to impart additional curing
processes and allow the bulk of the material to
mature through acid-base reaction.
 This group of materials are also known as light
cured GICs, dual cure GICs (light cure and acid
base reaction), tri-cure GICs (dual cure and
chemical cure), resin Ionomers, compomers and
hybrid Ionomers

 Composition and setting reactions
 The powder consists of ion-bleachable glass and
initiators for light or chemical curing or both. The
powder blends is formed of glass, tartaric acid and
polyacrylic acid.
 The liquid component may have only water or
polyacrylic acid modified with HEMA monomers and
methacrylate monomers. They contain hydroxyl
groups that make them water soluble. These are the
simplest form of resin Ionomers.
 They are mixed in the same way as conventional
GICs and remain workable for 10 or more minutes
provided they are not exposed to light. The reaction is
dual-setting once exposed to light.

 Acid base reaction : Calcium fluoroalumino
silicate glass (base) and polyacrylic acid =
calcium and aluminium polysalt hydro gel.
 Free radical or photochemical polymerization
HEMA and photochemical initiator / activator


 Poly HEMA Matrix
 Thus two matrices are formed; a metal
polyacrylate salt and a polymer. The initial set is
a result of polymerization of HEMA. The acid
base reaction serves only to harden and
strengthen the already formed polymer matrix

 Class I materials
 Composition
 Powder component: Calcium fluoroalumino
silicate glass, polyacrylic acid and tartaric acid.
 Liquid component (replaces water): Water
/HEMA, other difunctional hydroxy
dimethacrylates (such as ethylene glycol
dimethacrylate) and bis-GMA.
 Initiator / Activator.

 Chemically polymerized materials:
 Initiator  Hydrogen peroxide.
 Activator  Ascorbic acid.
 Co-activator  Cupric sulphate

 Light activated materials
 Visible light photochemical initiator 
Camphorquinone
 Activator  Sodium p-toluene sulphonate
 Photo accelerator  ethyl 4-N n-dimethyl
aminobenzoate.


 Properties
 Compomers have both advantages and
disadvantages compared to conventional GICs.
 They have improved setting characteristics.
There is a longer working time because HEMA
slows the acid-base reaction, and yet, they set
sharply once the polymerization reaction is
initiated by light

 They are also resistant to early contamination by
water because of the formation of an organic
matrix and so do not require protection by
varnish. This combination of properties is
clinically appealing.

24 hours in MPa
Class I Class II
Compressive strength 94 53-96
Flexural - 25.5
Tensile 21.9-33.9 11.2-12.4
Adhesion (dentine) 47 6.2-11.3

 Their adhesion to enamel and dentin, and their
fluoride release pattern is similar to GIC. They
also bond to resin composite. They have
cariostatic potential and show resistance to
marginal leakage.
 The biggest advantage is ease of mixing and use,
because multiple bonding steps are not required.
 They also have adequately low film thickness
(10-22µm). They have a bond strength to dentin
of about 10-12MPa without bonding agent and
14-20MPa with bonding agent.

 A significant disadvantage of the resin ionomers
is hydrophilic nature of poly HEMA which
results in increased water resorption and
subsequent plasticity and hygroscopic expansion.
 Although initial water sorption may compensate
for polymerization shrinkage stress, continual
water sorption has deleterious effects.
 Potential for substantial dimensional change
contraindicates their use with all-ceramic
feldspathic-type restorations.

 It is known that eugenol containing materials
inhibit the cross-linking of resin adhesives. They
should not be used for final cementation when
the luting agent for interim restoration has been
eugenol containing provisional materials

 Applications
 Luting metal or porcelain fused-to-metal crowns
and FPDs to tooth, amalgam, composite resin or
glass ionomer core build ups.

SUMMARY AND CONCLUSION
 Luting agents possess varied complex
chemistries that affect their physical properties,
longevity, and suitability in clinical situations. It
appears a single adhesive will not suffice in
modern day practice. To date, no adhesive can
completely compensate for the shortcomings of
preparation retention and resistance forms or ill-
fitting, low strength restorations. Practitioners
must be aware of the virtues and shortcomings of
each cement type and select them appropriately.

REVIEW OF LITRATURE
 Roland Frankenbergera etal done study on
Marginal quality of self-etch and etch-and-
rinse adhesives versus self-etch cements
 Objectives. To evaluate marginal integrity of IPS
Empress inlays luted with different adhesives
and cements before and after thermo-mechanical
loading (TML).
Results. All systems involving the etch-and-rinse
approach resulted in significantly higher
percentages of gap-free margins in enamel than
all other luting systems

 Claudia Mazzitellia Effect of simulated pulpal
pressure on self-adhesive
 cements bonding to dentin
 Objectives. To evaluate the bonding effectiveness of
self-adhesive luting cements to dentin
 in the presence of simulated hydrostatic intrapulpal
pressure
 Results. Bond strength of Calibra fell significantly
when PP was applied during bonding
 (p < 0.05). Rely X Unicem and Bis-Cem performed
better under PP. No significant differences
 for Multilink Sprint and G-Cem bonded specimens
were recorded with or without PP.

 Luiz Ricardo Menani etal done a study on Tensile
bond strength of cast commercially pure titanium and cast
gold-alloy posts and cores cemented with two luting agents
 Purpose. The purpose of this study was to compare
the tensile strength of commercially pure titanium
and type III cast gold-alloy posts and cores cemented with
zinc phosphate or resin cement
 Results. The 2-way ANOVA indicated that there were
no significant differences among the groups tested.
Retentive means for zinc phosphate and Panavia F
cements were statistically similar. The bond strength was
not influenced by the alloy, the luting material, or the
etching treatment. SEM analysis indicated that the etched
surfaces were smoother than those that did not receive
surface treatment, but this fact did not influence the
results.

REFERENCES
 1. Phillips science of dental materials – 11th edition –
Anusavice
 2. Restorative Dental Materials – 10th Edition –
Robert Craig
 3. Dental Materials – E. C. Coombe
 4. Applied Dental Materials – 8th Edition – McCabe
 Roland Frankenbergera, , Ulrich Lohbauera,∗
Rainer B. Schaiblea, Sergej A. Nikolaenkob,
Michael Naumannc Luting of ceramic inlays
in vitro: Marginal quality of self-etch and etch-
and-rinse adhesives versus self-etch cements
elsevier 2 4; ( 2 0 0 8 ); 185–191

 Claudia Mazzitellia, Francesca
Monticellia,b, Raquel Osoriob, Alessio
Casuccia, Manuel Toledanob, Marco Ferrari
Effect of simulated pulpal pressure on self-
adhesive cements bonding to dentin
elsevier ( 2 0 0 8)

 Luiz Ricardo Menani, DDS, MSci,a Ricardo
Faria Ribeiro, DDS, MSci, PhD,b and
Rossana Pereira de Almeida Antunes, DDS,
MSci, PhDc Tensile bond strength of cast
commercially pure titanium and cast gold-alloy
posts and cores cemented with two Luting agents
j prosthet dent;2008;99;141-147

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