Dental Cements

DENTAL CEMENTS
Dr. Nithin Mathew

CONTENTS
• Glossary
• Introduction
• History
• Classification
• Ideal requirements of Dental Cements
• Phosphate Based Cements
• Zinc Phosphate Cement
• Modified Zinc Phosphate Cement
• Silicophosphate Cement
3
• Phenolate Based Cements
• Zinc oxide Eugenol cement
• Reinforced Zinc oxide eugenol cement
• EBA modified phosphate cement
• Calcium Hydroxide Cement
• Polycarboxylate Based Cements
• Zinc Polycarboxylate
• Glass Ionomer cements
Dental Cements - Dr. Nithin Mathew

• Polymer Based Cements
• Acrylic resin cement
• Adhesive resin cement
• Dimethacrylate cement
• Agents for pulp protection
• Cavity varnish
• Cavity liner
• Cavity base
• Conclusion
• References
4Dental Cements - Dr. Nithin Mathew

GLOSSARY
ACID – BASE REACTION
Chemical reaction between a compound with replaceable hydrogen ions (acid) and a
substance with replaceable hydroxide ions (base) that yields salt and water.
BASE
A material that is used to protect the pulp in a prepared cavity by providing thermal
insulation.
FILM THICKNESS
According to ADA/ANSI Sp. No. 96, it is the thickness in micrometers of set cement
10minutes after a load of 150N has applied by a flat plate against another flat surface.

LUTING AGENT
A viscous cement-like material that fills the gap between bonded materials
SETTING TIME
The time elapsed from the start of mixing to the time at which the setting reaction
essentially stops as measured by reaching a desired hardness or consistency.
WORKING TIME
The elapsed time from the start of mixing to the time at which the consistency of a
material is no longer suitable for its intended use or a rapid rise in viscosity occurs.

INTRODUCTION
• Dental cements have been in use in dentistry for a very long time.
• They serve several purposes such as retaining restorations and prosthesis in the mouth.
• Also restorative, endodontic, orthodontic, periodontic as well as surgical procedures.
• Last 2 decades have seen a variety of changes in the dental cement composition and also
introduction of newer advanced biocompatible materials.

• Definition:
• A substance that hardens from a viscous state to a solid state to join 2 surfaces.
• In dentistry, A cement acts as a base, liner, filling material or adhesive to bind
devices and prosthesis to tooth surfaces or to each other.

HISTORY
• First used dental cement- silicate cement
• 1871- Silicate cements (Fletcher)
• 1879- Zinc phosphate cements (Otto Hoffman)
• 1920- Calcium hydroxide (Hermann)
• 1942- Zinc oxide eugenol (Chrisholm)
• 1947- Methyl methacrylate resins
• 1960- Composites
• 1972- Glass Ionomers (Wilson & Kent)

CLASSIFICATION
• Based on the INGREDIENTS
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WATER BASED
Glass & Resin Modified Glass Ionomer
Zinc Polycarboxylate
Zinc Phosphate
OIL BASED
Zinc oxide eugenol
Non-eugenol Zinc oxide
RESIN BASED
Composite and Adhesive Resins
Compomer

• According to O’Brien (by Matrix type):
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PHOSPHATE
Zinc Phosphate
Zinc Silico phosphate
PHENOLATE
Zinc oxide eugenol
Calcium Hydroxide Salicylate
POLYCARBOXYLATE
Zinc Polycarboxylate
Glass Ionomer
RESIN
Polymethy Methacrylate
Dimethyl Methacrylate
Adhesive
RESIN MODIFIED GLASS IONOMER
Hybrid Ionomer

• According to Phillip’s:
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Cement Primary Use Secondary Use
ZnPO4 • Luting agent for restoration
and orthodontic bands
• Intermediate restorations
• Thermal insulating bases
• Root canal restorations
ZnPO4 With Silver & Copper
Salts
Copper Phosphate • Temporary and intermediate
restorations
ZOE • Temporary and intermediate
restorations
• Luting agent
• Pulp capping agents
• Root canal restorations
• Periodontic bandage
Poly Carboxylate • Luting agent
• Luting agent for orthodontic
bands

13
Cement Primary Use Secondary Use
Silicate • Anterior fillings
Silicophosphates • Luting agent for restoration • Intermediate restorations
• Luting agent for orthodontic
appliances
GIC • Coating for eroded areas
• Luting agent for restoration
• Pit &fissure sealants
• Anterior restorations
Resin • Luting agent • Temporary restorations
Ca(OH) 2 • Thermal insulating bases
• Pulp capping agents

• According to Craig:
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Functions Cements
Final cementation of completed restorations ZnPO4, zinc silicophosphates
Reinforced ZOE,Zinc poly carboxylate ,GIC
Temporary cementation of completed
restorations/cementation of temporary restorations
ZOE,Non eugenol zinc oxide
High strength bases ZnPO4, Reinforced ZOE, Zinc poly
carboxylate, GIC
Temporary fillings ZOE, Reinforced ZOE, Zinc poly carboxylate
Low strength bases ZOE, Ca(OH)2
Liners Ca(OH)2 in a suspension
Varnishes Resin in a solvent

• According to Coombe:
• According to ADA Specification:
15
• Acid base reaction cements
• Polymerising materials
Cyano acrylates
Dimethacrylate polymers
Polymer ceramic composites
Type I - Fine grain for cementation, luting
Type II - Medium grain for bases, orthodontic purpose

• According to Donovan:
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Conventional Cements
Zinc Phosphate
Zinc oxide eugenol
Zinc polycarboxylate
Glass Ionomers
Contemporary Cements
Resin Modified GIC
Resin Cements

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USE CEMENT TYPE
Luting inlays, crown, posts, multiretainers, FPD GIC
Hybrid ionomers
Dual cure resins
Nonvital teeth with advanced pulpal recession and average
retention
ZnPO4
Vital teeth with average retention, average pulpal recession,
thin dentin, especially for single unit and small span FPD
Zn poly carboxylate
Multiretainer splints on vital teeth with above average
retention, minimal dentin thickness, hypersensitive patients
Zinc oxide eugenol polymer based

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USE CEMENT TYPE
Provisional cementation Zinc oxide eugenol
Zinc poly carboxylate
Provisional cementation and stabilization of old ,loose
restorations, fixation of facings and acid etched cast
restorations
Dimethyl resin composites
Base/liner
Cavity with remaining dentin thickness greater than 0.5mm
Cavity with minimal dentin or exposure
GIC,resin ionomer
Zinc poly carboxylate
Zinc phosphate
Calcium hydroxide salicylate
Zinc oxide eugenol polymer

IDEAL REQUIREMENTS
• Non-toxic, Non-irritant to pulp and tissues
• Insoluble
• Mechanical properties
• Adhesion to enamel and dentin
• Bacteriostatic
• Obtundant effect on pulp
• Thermal, chemical and electrical insulation
• Optical properties

CHARACTERISTIC PROPERTIES OF DENTAL CEMENTS
FILM THICKNESS & CONSISTENCY
Height of space between two surfaces separated by cement
Eg:distance between tooth surface and cemented crown
• Determines the adaptability and retention of restoration
• Consistency of the cement should be thick and plastic enough for ease of handling and
placement into the cavity
• Heavier the consistency
 Greater the film thickness
 Less complete seating of restoration

• Maximum allowable film thickness
• For luting application : 20-25 µm
• For restorative application -temporary/final cementation : 40 µm
• Ultimate film thickness depends up on the
• Particle size of the powder
• Concentration of the powder in liquid
• Viscosity of liquid
• Consistency of cement
• Amount of force

VISCOCITY
Resistance of a liquid to flow
• It is a measure of consistency
• Factors affecting viscosity
• Increase in temperature and time - increase the viscosity of certain cements

SETTING TIME
The elapsed time from the start of mixing to the point at which the mixture reaches a
desired hardness or consistency
Net setting time:
Time elapsed between the end of the mixing and the time of setting
Working time:
Elapsed time from the start of mixing to the point at which the consistency of the
material is no longer suitable for its intended use

STRENGTH
• ANSI /ADA specification recomends that the standard luting consistency of dental cement
must exhibit a minimum 24 hr compressive strength of 70 Mpa
SOLUBILITY
• Solubility in oral fluids & water
• Water based cements are more soluble than resin or oil-based cements
• Decrease in P:L ratio : higher solubility and disintegration rate
• ADA - 0.2Wt%
• Maximum permissible rates of dissolution
• GIC : 0.1 wt%
• Zinc Phosphate : 0.2 wt%
• Zinc Polycarboxylate : 0.3 wt%

REMAINING DENTIN THICKNESS
• Type of material to be used depends upon the minimum thickness
of the dentin left between the pulp floor and the dental pulp –
Remaining Dentin Thickness (RDT)
25
• RDT ≥ 2mm :
• Cavity Liner only to be given on all internal
surfaces (for metallic restorations)
• No liners or base for GIC or Composite

• RDT < 2mm :
• Base must be given on the pulpal and axial floor
(0.5 – 0.75mm)
• RDT < 1mm :
• Cavity Liner is given on all internal surfaces, over which
a Base is given.

LUTING MECHANISM
• By Schillinburg
• Non-Adhesive:
• Cement fills the restoration-tooth gap and holds by engaging in small surface
irregularities
• Micromechanical Bonding:
• Surface irregularities are enhanced by air abrasion or acid etching
• Improves the frictional retention
• Molecular Bonding:
• Chemical bond formation between cement and the tooth structure

ZINC PHOSPHATE CEMENT
• Introduced by Dr. Otto Hoffman during the 1800s
• One of the oldest cement
• Acts as the gold standard by which newer materials are compared.
APPLICATION
• Luting of restorations
• Luting of orthodontic bands
• High strength bases

COMPOSITION
30
POWDER % Function
ZnO 90.2% Principle ingredient
MgO 8.2% Reduce temperature of calcination process
SiO2 1.4% Improves the working characteristics
Bi2O3 0.1% Smoothness of mix &lengthen working time
Misc- BaO, Ba2SO4 & CaO 0.1%
LIQUID
H3 PO4 38.2% Reacts with ZnO
Al 2.5% Essential for cement forming reaction
Zn 7.1% Moderator for reaction between powder& liquid, allows
adequate working time
H20 36% Controls the rate of reation

TYPES
• Type I – Fine Grained : (Film Thickness less than 25µm)
• Luting permanent metallic restorations
• Cementation of orthodontic bands
• Type II – Medium Grained : (Film Thickness of 40µm)
• High strength thermal insulating base

• Exothermic reaction.
• The final set cement is a cored structure consisting primarily of unreacted zinc oxide
particles embedded in a cohesive amorphous matrix of zinc aluminophosphate.
3ZnO + 2H3PO4 + H2O Zn3(PO4)2.4H20
32
SETTING REACTION
• Phosphoric acid attacks the surface of the particles
• Releases zinc ions into the liquid
• Aluminium forms complexes with phosphoric acid, reacts
with zinc forming zinc aluminophosphate gel.

MANIPULATION
• P:L ratio of 1.4g : 0.5ml
• Amount of powder that can be incorporated into a given quantity of the liquid greatly
determines the properties of the mixed mass of the cement.
• This is because increase in P:L ratio generally provides more desirable properties.
• Powder is dispensed onto the glass slab
• Divided into 4 – 6 increments.

• Powder is incrementally incorporated into the liquid
• Spatulated over a large area to dissipate heat produced during the
reaction.
• Powder quantity being minimal, heat generated is less
• Helps to achieve slow neutralization of the liquid and better
control of setting reaction
• During middle of mixing, larger portions are added to further
saturate the liquid.
• Finally,smaller increments are added to get the desired consistency.
• Each increment is spatulated for 15-20secs.
• Total mixing time is 60 – 90 secs.

Frozen Glass slab Technique:
• To prolong working time and shorten setting time.
• Glass slab cooled at 6°C or – 10°C.
• 50 – 75% more powder incorporation.
• Working time is increased by 4 – 11 mins
• Setting time shortened by 20 – 40%
35
Mixing time 1.5 – 2mins (Phillips)
Working time 5mins (Phillips)
Setting time 5-9mins (Craig)
5-14mins (O’Brien)
Film thickness 20µm

MECHANICAL PROPERTIES
36
Compressive Strength 104 Mpa
Tensile Strength 5.5 Mpa
Elastic Modulus 13.5 Gpa
Solubility in water 0.06 wt%
Thermal conductivity 0.0028°C/cm

FACTORS AFFECTING SETTING TIME
• P:L ratio
• Reducing the P:L ratio increases the working time and setting time
• Low initial pH which will impair the mechanical properties
• Smaller increments mixed for first few increments
• Prolonging the spatulation time
• Temperatureof the mixing slab

BIOLOGIC PROPERTIES
• Freshly mixed ZnPO4 - highly acidic pH - pulpal irritation
• Very thin mixes must be avoided as it can be highly acidic.
• Pulp protection : High P:L ration must be used, Calcium hydroxide or cavity varnish.
• ADHESION : By mechanical interlocking of the set cement with cavity surface roughness
• Acts as a good thermal insulator.

MODIFIED ZINC PHOSPHATE CEMENT
COPPER & SILVER CEMENTS
• Black copper cements : Cupric oxide
• Red copper cements : Cuprous oxide
• Depending on the type of copper cement, concentration of the copper varies between 2%
and 97%.
• Lower P:L ratio – for satisfactory manipulation characteristics
• Highly acidic
• Higher solubility
• Lower strength than ZnPO4
• Less anticariogenic property
• Silver cements : contain small percentage of salts of silver phosphate

FLUORIDE CEMENTS
• Stannous fluoride (1-3%)
• Higher solubility and lower strength – due to dissolution of Fluoride
• Fluoride uptake by enamel : Reduced enamel solubility and Anticariogenic

SILICOPHOSPHATE CEMENTS (ADA Sp. No. 96)
• Presence of silicate glass: translucency, improved strength, fluoride release.
APPLICATIONS
• Type I : Cementation of fixed restorations
• Type II : Provisional restorative material
• Type III : Dual purpose material

COMPOSITION
42
POWDER % Function
ZnO 10 -20 Principle ingredient
Silicate glass
Fluoride 12 – 25
Mercury / Silver Compounds Germicidal
LIQUID
Orthophosphoric acid Reacts with ZnO
Al salts 2 – 5
Water 45

PROPERTIES
BIOLOGIC EFFECT
• Prolonged low pH (4-5)
• Pulpal protection necessary
• Anticariogenic – fluoride release
43
Working time 4 mins
Setting time 5 – 7 mins
Compressive Strength 140 - 170 Mpa
Tensile Strength 7 Mpa
Solubility 1 wt%
Toughness/Abrasion resistane Higher than phosphate cements

44
ADVANTAGES DISADVANTAGES
Better strength, toughness, abrasion
resistance, fluoride release,
translucency
Total acidity greater than zinc
phosphate
Better bonding than zinc phosphate High solubility

ZINC OXIDE EUGENOL (ADA SP. NO. 30)
• Introduced by Chrisholm in 1873
• Commonly used for luting and intermediate restorations
• Obtundant property on exposed dentin
APPLICATION
• Longterm and short-term luting agents
• Temporaryand intermediate restorations
• Root canal sealers
• Surgical packs

TYPES (ADA Specification No. 30)
• Type I : Temporary restorations
• Type II : Permanent cementation of restorations
• Type III : Temporary restoration, thermal insulating bases
• Type IV : Cavity Liner

Dispensed As:
• Two pastes
• Powder and liquid
COMPOSITION
48
POWDER % Function
ZnO 69 Principal component
White rosin 29.3 Reduce brittleness of the cement
Zinc stearate 1 Accelerator, plasticizer
Zinc acetate 0.7 Improves strength of the cement
Silica Filler
LIQUID
Eugenol / oil of cloves 85
Olive oil 15 Plasticizer

SETTING REACTION
• Hydrolysis of the ZnO
• Zinc hydroxide reacts with acid eugenol forming zinc eugenolate which crystalizes and
strengthens the cement
• Set cement also contains free zinc oxide embedded in a matrix of zinc eugenolate
• Reaction is reversible, zinc eugenolate can easily be hydrolysed by moisture in the oral
cavity to eugenol and zinc hydroxide
49
ZnO + H2O Zn(OH)2
Zn(OH)2 + 2HE ZnE2 + 2H20

MANIPULATION
• P:L = 3:1 / 4:1 (maximum strength)
• Powder and liquid are dispensed onto the glass slab.
• Zinc oxide is incorporated into the liquid
• Prolonged vigorous spatulation in circular motion is
required with a stiff bladed stainless steel spatula.
• Larger increments are incorporated first and then smaller
increments until desired consistency is obtained.
• More powder is added to the mix, more stronger is the
cement and more viscous the mixed cement.

PROPERTIES
51
Base / Filling
material
Temporary
cement
Permanent
cement
Cavity liner
Film Thickness (µm) 40 25
Setting Time (mins) 2 – 10 4 – 10 4 – 10 4 – 10
Solubility (wt%) 2.5 1.5
Compressive strength (Mpa) 25 35 35 5.5
Tensile strength (Mpa) 1 – 2 1 – 2 1 – 2 1 – 2
Thermal diffusivity 0.38 mm2/s
Linear COTE 35 x 10-6/°C

BIOLOGIC EFFECTS
• Bacteriostatic
• Obtundant property
• pH (6.6 – 8) : mild pulpal response
• Volumetric shrinkage : 0.9%
• When in direct contact with connective tissues, it is an irritant
• Reparative dentin formation in exposed pulp is variable

53
Obtundant effect on pulpal tissues Low strength and low abrasion
resistance
Good sealing ability Microleakage
Resistance to marginal penetration Disintegration in oral fluids
Good thermal insulation Less anticariogenic
Solubility is highest among all cements

REINFORCED ZINC OXIDE EUGENOL CEMENT
To overcome the shortcomings of the zinc oxide cements
APPLICATION
• Cementing crowns and FPD
• Cavity liner
• Base materials
• Provisional restoration

COMPOSITION
55
POWDER %
ZnO
Finely divided natural / synthetic resin 10 – 40
Accelerators
LIQUID
Eugenol
Dissolved resins
Accelerators : Acetic Acid
Antimicrobial agents : thymol / 8-hydroxyquinolone

SETTING REACTION
• Similar to ZnO eugenol
• Acidic resin such as colophony may react with zinc oxide, strengthening the matrix
MANIPULATION
• (Method similar to ZnO eugenol)
• More powder is required for cementing mix
• Proper P:L ratio must be followed for adequate strength properties
• Mixing pad/slab should be completely dry

PROPERTIES
• Solubility is lower than ZnO eugenol cement due to the presence of resin
BIOLOGIC EFFECTS
• Inflammatory reaction in the connective tissue is present
• Softening and discoloration of the resin material
57
Setting time 7 - 9 mins
Film Thickness 35 – 75 µm
Tensile Strength 5 - 8 Mpa
Modulus of elasticity 2 – 3 Gpa
Solubility 1 wt%

58
Minimal biologic effects Low strength
Good initial sealing ability Higher disintegration
Adequate strength for final
cementation of restoration
Softening and discoloration

EBA MODIFIED ZINC OXIDE EUGENOL CEMENT
APPLICATION
• Cementation of inlays, crowns, FPD’s and for provisional restoration
• Base / lining material
COMPOSITION
59
POWDER %
ZnO 60 – 75
Aluminium oxide 20 – 35
PMMA 6
LIQUID
Eugenol 37
EBA 63

SETTING REACTION
• Not fully known
• Appears to form chelate salt between EBA, eugenol and zinc oxide.
MANIPULATION
• Similar to ZnO eugenol
• Cement mixes readily to very fluid consistency even at a high P:L ratio
• For optimal properties : use high P:L ratio as possible
• 3.5 g/ml : cementation
• 5 – 6 g/ml : liners and bases
• Vigorous spatulation is required for about 2 mins to incorporate all of the powder

PROPERTIES
BIOLOGIC EFFECTS
• Similar to ZnO eugenol cement
61
Setting time 7 - 13 mins
Film Thickness 40 - 60 µm
Modulus of elasticity 5 Gpa
Solubility 1 wt%
Plastic deformation 0.1mm/min at 37°C

CALCIUM HYDROXIDE
• Hermann – 1920
• Useful water setting cement which has osteoconductive and osteoinductive property
• As a pulp capping agent facilitates formation of reparative dentin – alkaline pH ,
antibacterial and protein lyzing property.
TYPES:
• Non setting (pH : 11 – 13) – intracanal medicament
• Setting (pH : 9 – 10) – cavity liner

APPLICATION
• Liners in deep cavity preparations
• Intracanal medicaments
• Direct and indirect pulp capping
• Apexification procedures
COMPOSITION
• 2 Pastes – Base and Catalyst
63
BASE
Calcium tungstate / Barium sulphate Radio-opacifier
Tribasic calcium phosphate
Zinc oxide
Glycol salicylate

SETTING REACTION
• Calcium hydroxide reacts with the salicylate forming a chelate, amorphous calcium
disalicylate.
• Hydroxyl ions from the cement neutralize the acids produced from the clast cells and create
an optimum pH for pyrophosphatase activity necessary for mineralization.
64
CATALYST
Calcium hydroxide
ZnO
Zn Stearate
Ethylene Toluene

MANIPULATION
• Equal lengths of the 2 pastes are mixed to a uniform color
PROPERTIES
65
Working time 3 – 5 mins (depends on availability of moisture
1 – 2 mins (rapid)
Compressive Strength At 7 mins : 6MPa
At 1 hr : 10MPa
At 24hrs : 14-20MPa
Tensile Strength At 7 mins : 1.5MPa
At 1 hr : 1.5MPa
At 24hrs : 1.7-2MPa

• Solubility in 50% phosphoric acid during etching procedures is significant.
• Subject to Hydrolytic Breakdown : marginal leakage and finally complete dissolution of the
lining occurs

BIOLOGIC EFFECTS
• Strong Antibacterial Action
• Ionic dissociation of calcium hydroxide into calcium ions and hydroxyl ions.
(54.11% and 45.89% respectively)
• Hydroxyl ions induces chemical injury on the organic components of the
cytoplasmic membrane of the bacteria, causing destruction of phospholipids or
unsaturated fatty acids.

• Dentin Bridge Formation (Pulp Capping)
• Activates enzymes such as alkaline phoshphatase which is responsible for
mineralization
• Free calcium hydroxide helps in remineralization of carious dentin

69
Easy manipulation Low strength even when fully set
Rapidly harden in thin layers Exhibit plastic deformation
Good sealing ability Dissolve under acidic conditions
Beneficial effects on carious dentin and
exposed pulp

LIGHT ACTIVATED CALCIUM HYDROXIDE
• Recently introduced cement
COMPOSITION
• They have longer working time
70
Calcium Hydroxide
Barium sulphate Radio-opacifier
Urethane dimethacrylate
HEMA
Activators – camphorquinone

71
ADVANTAGES
Less brittle than conventional 2 paste
system
Improved strength
No solubility in acids
Minimal solubility in water
Longer working time

DYCAL
• Introduced in 1979
• As a liner/pulp capping agent in deep cavities
• Radio-opaque calcium hydroxide which is self setting
72
High early strength
Lower water solubility
Excellent handling characteristics

CALYXL
• Calcium hydroxide containing sodium and potassium salts
• Allows maintenance of normal dentinogenesis by protecting the pulp against irritation from
operative procedures

SILICATE CEMENTS (ADA SP. NO. 96)
• Fletcher in 1871
• Oldest direct tooth colored materials
• Steenbock later introduced an improved version of the cement
COMPOSITION
75
POWDER LIQUID
Silicon Dioxide 35 – 50% Phosphoric acid
Sodium fluoride Sodium & Aluminium phosphate
Calcium fluoride
Aluminium fluoride
Aluminium trioxide
Sodium fluoride

SETTING REACTION
• Acid – Base Reaction
• Powder particles are attacked by acid releasing Calcium, aluminium and fluoride ions.
• These ions precipitate as phosphates which form continuous cement matrix along with and
forms a silica gel.
• Fluoride ions donot take part in this reaction. Present as free ions.
• Most of the powder particles are not dissolved, only the surfaces are dissolved.
• Finally the set cement contains a phosphate matrix containing unreacted powder particles
surrounded by acid gel and fluoride ions.

PROPERTIES
• Anticariogenic : large amounts of fluoride
• Soluble in saliva. High in acidic conditions
• Coefficient of thermal expansion: close to tooth structure : Microleakage is minimal
• Good optical properties
• pH remains low as 3 for few days : pulpal irritation
• pH remains below 7 even after a month: severe pulpal irritant
• Adhesion : mechanical bonding to tooth structure

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Translucency High pulpal irritant
Anticariogenic Highly soluble

POLYCARBOXYLATE CEMENT (ADA SP. NO. 96)
• Dennis Smith : 1968
• First cement system with adhesive bond to tooth structure
• Also known as polyacrylate cement
APPLICATION
• Luting alloy restorations
• Cementing orthodontic bands
• Cementing SS crown in pediatric dentistry

COMPOSITION
80
POWDER %
ZnO
SnO / MgO 1 – 5
Aluminium oxide 10 – 40
Stannous Fluoride : Modified setting time
LIQUID
40% Aqueous solution of Polyacrylic Acid

SETTING REACTION
• Powder particles are attacked by the acid releasing Zn, Mg, Sn ions.
• Ions bind to the polymer chain via the carboxyl groups.
• Ions also react with carboxyl group of adjacent polyacid chains to form cross linked salts.
Bonding to tooth
• Polyacrylic acid reacts with Calcium ions via the carboxyl groups on the surface of enamel
and dentin.

MANIPULATION
• P:L = 1.5g : 1ml
• Mixing should be done on a surface that do not absorb liquid.
• Most of the powder should be incorporated into the liquid in one large increment.
• Mixed over a small area with a stiff spatula
• More powder is then added to obtain the required consistency
• Mix should be used while it is still in the glossy state.
• Mixed rapidly in 30 – 40 secs
• Working time : 2.5 – 3.5 mins
• Setting time : 6-9mins (at 37°C)

Methods to Increase the working time
• Cooling glass slab :
• Thickening of the liquid
• Difficulty in mixing
• Powder refridgerated before mixing
• Reaction occurs on cool surface, cool temperature retards the reaction without
thickening of the liquid.

PROPERTIES
• Solubility in water is low
• In organic acid with pH < 4.5 : increased solubility
• Reduced P:L ratio : increases solubility in oral cavity
84
Film Thickness 25 µm
Modulus of elasticity 6 Gpa
Bond strength to enamel 3.4 – 4.7 Mpa
Bond strength to dentin 2.1 Mpa
Thermal diffusivity 0.223mm2/sec

BIOLOGIC EFFECTS
• Good biocompatibility
• Low intrinsic toxicity
• Rapid rise in pH towards neutrality
• Fluoride release

86
Low irritation Lower compressive strength
Chemical bond to tooth structure and
alloys
Greater viscoelasticity
Easy manipulation Need for clean surfaces for adhesion
Adequate strength Short working time
Low solubility
Adequate film thickness
Anticariogenic

ACRYLIC RESIN CEMENT
APPLICATION
• Cementation of restorations, facings and crowns
COMPOSITION
88
POWDER
MMA polymer or Copolymer
Benzyl Peroxide
Mineral Filler
Pigments
LIQUID
MMA monomer
Amine AcceleratorsDental Cements - Dr. Nithin Mathew

MANIPULATION
• Liquid is added to powder with minimal spatulation to avoid incorporation of air.
• Short working time – mix must be used immediately
• Excess material is removed only after final set.
• When cement is hard, and not when rubbery since it creates marginal deficiencies.

PROPERTIES
• Stronger and less soluble
• Low rigidity and visco-elastic properties
• No effective bond to the tooth structure in the presence of moisture
BIOLOGIC EFFECTS
• Marked pulpal response

91
High strength Marked pulpal irritation
High toughness Short working time
Low solubility Difficulty in removal of the excess cement

ADHESIVE RESIN CEMENT
• Formulated by adding the following to MMA monomer:
• 4 methacryloxy ethyl trimellitate anhydride (4-META)
• Tributyl boron initiator (helps in adhesion)
APPLICATION
• Luting FPD and base metal
• Bonding amalgam to dentin and composite

PROPERTIES
• (similar to acrylic resin)
• Stronger and less soluble
• Low rigidity and visco-elastic properties
• No effective bond to the tooth structure in the presence of moisture
• Moderate strength and high deformation under a load.
PROPERTIES
• Marked pulpal response

DIMETHACRYLATE CEMENTS
• Composition is similar to resin composites.
• Combinations of an aromatic dimethacrylate with other monomers containing various
amounts of ceramic filler.
APPLICATION
• Bonding crowns, FPD, inlays and veneers.

COMPOSITION
95
POWDER
Borosilicate / silica glass
Polymer powder
Peroxide initiator
LIQUID
Bis-GMA / dimethacrylate monomer
Amine Accelerators

MANIPULATION
• Paste materials are mixed in the ratio 1:1 (equal lengths)
• P:L , thorough mixing to minimize air inclusion until uniform mix is obtained.
• On mixing, polymerization of monomers occurs leading to a highly cross-linked resin
composite structure
TYPES based on the method of curing
• Chemically cured : for cementing ceramic, metal and opaque metal ceramic restorations
• Dual cured : for cementing translucent restorations
• Light cured / dual cured : used for both light cure and dual cure applications

PROPERTIES
BIOLOGIC EFFECTS
• Polymerization shrinkage
• Microleakage
97
Film Thickness 20 - 60 µm
Setting Time 3 – 7 mins
Tensile Strength 25 – 40 Mpa
Modulus of elasticity 4 – 6 Gpa
Solubility 0.05 wt%

98
High strength Higher film thickness
Low solubility Microleakage
High micromechanical bonding Pulpal sensitivity
Difficulty in removing excess cement

PURPOSE OF A CAVITY LINER / VARNISH
• Serve as a physical barrier to ingress of bacteria/ bacterial byproducts.
• To provide therapeutic effect such as antibacterial, anticariogenic or pulpal anodyne effect.
100
• Provide barrier for protection of pulp from residual reactants
diffusing out of a restoration.
• Prevent oral fluids that may penetrate leaky restorations from
reaching the pulp through the dentin

CAVITY VARNISH
• A solution of one or more resins which when applied to the cavity walls, evaporates,
leaving a thin resin film that serves as a barrier between the restoration and the dentinal
tubules.
APPLICATION
• Prevents post-op sensitivity from galvanic shock
• Minimize penetration of acid from zinc phosphate cements
• Prevent diffusion of corrosion products from dental amalgam into dentin
CONTRAINDICATION
• Not to be used with Glass Ionomer Cement or Resin composites

COMPOSITION
MANIPULATION
• Applied by means of small cotton pellets / brush / applicator
• 2 – 3 layers – sufficient protection
• Volatilesolvents evaporate quickly after application, leaving a thin resin film
102
Solid Copal Resin, Rosin Or Synthetic Resin
Solvent 90% Ether, Acetone Or Alcohol
Medicinal Agent Chlorbutanol, Thymol, Eugenol

PROPERTIES
103
Film thickness 1 – 4 µm
Tensile strength < 1 Mpa
Low solubility in water

CAVITY LINER
• Suspensions of calcium hydroxide in a volatile solvent.
• Used like a cavity varnish to provide barrier against the passage of irritants
from the cements and other restorative materials.
COMPOSITION
• Suspension of calcium hydroxide in an organic liquid such as methyl ethyl
ketone or ethyl alcohol.

PROPERTIES
• No significant thermal insulation
• Soluble : should not be applied to margins of restorations
• Fluoride compounds are added to newer compounds to prevent secondary caries
105
Film thickness 1 – 4 µm
Tensile strength < 1 Mpa

MANIPULATION
• (Similar to varnishes)
• Applied by means of small cotton pellets / brush / applicator
• 2 – 3 layers – sufficient protection
• Volatilesolvents evaporate quickly after application, leaving a thin resin film
Other Liners
• Type III Glass Ionomer Cement
• Type IV Zinc Oxide Eugenol

BASES
• Material that is used to protect the pulp in a prepared cavity by providing thermal
insulation
• Ie these are those cements commonly used in thicker dimensions beneath permanent
restorations to provide for mechanical, chemical and thermal protection to the pulp.
• Eg:
• Zinc Phosphate
• Zinc Oxide Eugenol
• Calcium Hydroxide
• Zinc Polycarboxylate
• Glass Ionomer

INDICATIONS OF A CAVITY BASE
• To protect the pulp against thermal injury, galvanic shock and chemical irritation. (Zinc
phosphate under amalgam restoration)
• To withstand the forces of condensation of the restorative material and act as shock
absorbers. (Zinc phosphate under amalgam restoration)
108
• To substitute dentin in deep cavities. (all high strength bases)
• To serve as intermediate bonding material between the tooth
and composite restoration. (GIC in sandwich technique)

CLASSIFICATION
• Low strength bases
• Zinc oxide Eugenol, calcium hydroxides
• Calcium hydroxide as a sub-base
• High strength bases
• GIC, reinforced ZOE, Zinc phosphate, Zinc polycarboxylate
• Used under direct and indirect metallic restorations
• Only some bases are indicated under composite resins (GIC)

CLINICAL CONSIDERATIONS
Clinician must observe certain general guidelines for placement of bases:
• Base should be 0.5 – 0.75mm thick.
• Very thick bases compromise the bulk of the restoration
• Increase the potential for fracture of the restoration
• It is not recommended to remove sound tooth structure inorder to provide space
for a base
• Bases are applied only on internal walls of the cavity preparation to prevent
dissolution by saliva

111
Compre
ssive
strengt
h
(MPa )
Tensil
e
streng
th
(MPa )
elastic
modulu
s
(GPa)
Film
thickn
ess
(mm)
Setting
time
(min)
Solubility
(Wt%)
Bond
strength
to
dentin
Pulp
response
C TC
(0C/cm)-1
CTE
ANSI
/ADA 8
70 N/A N/A 25 5 0.20
ZnPO4 104 5.5 13.5 20 5.5 0.06 0 Moderate 3.11 X 10-4 35X 10-6/0C
Zn poly
carboxyla
te
55 6.2 4.4 21 6 1.25 2.1 Mild
ZOE 25 1-2 0.22 25 4-10 0.04 0 Mild 3.98X 10-4
Silico
Phosphat
e
140 -
170
7 - 25 3.5-4 1 Moderate 4.38 X 10-4
GIC 93-226 4.2-5.3 3.5-6.4 25 2.5-8 0.4-1.5 3-5 Mild -
moderate
composit
e
25-70 - - <25 2-4 0-0.1 0 Mild

CONCLUSION
• No single type of cement satisfies all of the ideal requirements or is best suited for
all indications in dentistry
• Each situation must be evaluated based on the environmental, mechanical and
biological factors and finally decide on which material to be used in each case.

REFERENCES
• Phillip’s Science of Dental Materials : Anusavice ( 12th Edition )
• Phillip’s Science of Dental Materials : Anusavice ( 10th Edition )
• Craig’s Restorative Dental Materials ( 13th Edition )
• Craig’s Restorative Dental Materials ( 12th Edition )
• Dental Materials and their Selection : William J O’Brien ( 4th Edition )
• Materials Used in Dentistry : S.Mahalexmi ( 1st Edition )

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