Dental Cements

Dental Cements

2. DENTAL CEMENTS

Dr. Nithin Mathew

3. CONTENTS

+ Glossary + Phenolate Based Cements
+ Introduction + Zinc oxide Eugenol cement
+ History

+ Reinforced Zinc oxide eugenol cement
+ EBA modified phosphate cement
+ Calcium Hydroxide Cement
+ Polycarboxylate Based Cements
+ Zinc Polycarboxylate
+ Glass lonomer cements

+ Classification

Ideal requirements of Dental Cements
» Phosphate Based Cements

+ Zinc Phosphate Cement

+ Modified Zinc Phosphate Cement

+ Silicophosphate Cement

Dental Cements - Dr. Nithin Mathew. 3

4. * Polymer Based Cements
+ Acrylic resin cement
Adhesive resin cement
+ Dimethacrylate cement

+ Agents for pulp protection
+ Cavity varnish
+ Cavity liner
+ Cavity base

+ Conclusion

+ References

Dental Cements - Dr. Nithin Mathew.

5. 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.

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6. LUTING AGENT

Aviscous 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.

Dental Cements - Dr. Nithin Mathew.

7. 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.

Dental Cements - Dr. Nithin Mathew.

8. + Definition:

+ Asubstance 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.

Dental Cements - Dr. Nithin Mathew.

9. 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 lonomers (Wilson & Kent)

Dental Cements - Dr. Nithin Mathew.

10. CLASSIFICATION

+ Based on the INGREDIENTS

Dental Cements - Dr. Nithin Mathew.

WATER BASED

Glass & Resin Modified Glass lonomer
Zinc Polycarboxylate
Zinc Phosphate

OIL BASED

Zinc oxide eugenol
Non-eugenol Zinc oxide

RESIN BASED

Composite and Adhesive Resins
Compomer

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11. + According to O’Brien (by Matrix type):

PHENOLATE

PHOSPHATE RESIN
Zinc Phosphate Polymethy Methacrylate
Zinc Silico phosphate Dimethyl Methacrylate
Adhesive

Zinc oxide eugenol
Calcium Hydroxide Salicylate

RESIN MODIFIED GLASS IONOMER

Hybrid lonomer

POLYCARBOXYLATE

Zinc Polycarboxylate
Glass Ionomer

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12. + According to Phillip’s:

Cement

Primary Use

Secondary Use

ZnPO,

Luting agent for restoration
and orthodontic bands

Intermediate restorations
Thermal insulating bases
Root canal restorations:

ZnPO, With Silver & Copper
Salts

Intermediate restorations

Copper Phosphate

Temporary and intermediate
restorations

ZOE

Temporary and intermediate
restorations

Luting agent

Thermal insulating bases
Pulp capping agents

Root canal restorations
Periodontic bandage

Poly Carboxylate

Luting agent
Thermal insulating bases

Luting agent for orthodontic
bands
Intermediate restorations

Dental Cements - Dr Nithin Mathew.

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13. Primary Use

Anterior fillings

Secondary Use

Luting agent for restoration

Intermediate restorations
Luting agent for orthodontic
appliances

Coating for eroded areas
Luting agent for restoration

Pit &fissure sealants
Anterior restorations
Thermal insulating bases

Luting agent

Temporary restorations

Cement
Silicate
Silicophosphates
GIC
Resin
Ca(OH),

Thermal insulating bases
Pulp capping agents

Dental Cements - Dr. Nithin Mathew.

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14. + According to Craig:

Functions

Final cementation of completed restorations

Cements

ZnPO, 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

ZnPO, Reinforced ZOE, Zinc poly
carboxylate, GIC

Temporary fillings

ZOE, Reinforced ZOE, Zinc poly carboxylate

Low strength bases ZOE, Ca(OH) ,
Liners Ca(OH) Jin a suspension
Varnishes Resin in a solvent

Dental Cements - Dr. Nithin Mathew.

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15. + According to Coombe:

+ Acid base reaction cements

+ Polymerising materials
Cyano acrylates
Dimethacrylate polymers
Polymer ceramic composites

+ According to ADA Specification:

Typel - Fine grain for cementation, luting

Typell - Medium grain for bases, orthodontic purpose

Dental Cements - Dr. Nithin Mathew.

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16. + According to Donovan:

Conventional Cements

Zinc Phosphate
Zinc oxide eugenol
Zinc polycarboxylate
Glass lonomers

Contemporary Cements

Resin Modified GIC
Resin Cements

Dental Cements - Dr. Nithin Mathew.

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17. USE MENT TYPE

Luting inlays, crown, posts, multiretainers, FPD GIC
Hybrid ionomers
Dual cure resins

Nonvital teeth with advanced pulpal recession and average ZnPO,
retention

Vital teeth with average retention, average pulpal recession, Zn poly carboxylate
thin dentin, especially for single unit and small span FPD

Multiretainer splints on vital teeth with above average Zinc oxide eugenol polymer based
retention, minimal dentin thickness, hypersensitive patients

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18. USE CEMENT TYPE

Provisional cementation Zinc oxide eugenol

Zinc poly carboxylate
Provisional cementation and stabilization of old loose Dimethyl resin composites
restorations, fixation of facings and acid etched cast
restorations
Base/liner
Cavity with remaining dentin thickness greater than0.5mm GIC,resin ionomer

Zinc poly carboxylate
Cavity with minimal dentin or exposure Zinc phosphate

Calcium hydroxide salicylate
Zinc oxide eugenol polymer

Dental Cements - Dr. Nithin Mathew. 18

19. 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

Dental Cements - Dr. Nithin Mathew.

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20. 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

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21. + Maximum allowable film thickness
+ For luting application : 20-25 um
+ For restorative application -temporary/final cementation : 40 um

+» 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

Dental Cements - Dr. Nithin Mathew.

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22. VISCOCITY

Resistance of a liquid to flow

+ Itisa measure of consistency

« Factors affecting viscosity
+ Increase in temperature and time - increase the viscosity of certain cements

Dental Cements - Dr. Nithin Mathew. 22

23. 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

Dental Cements - Dr. Nithin Mathew =

24. 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%

Dental Cements - Dr. Nithin Mathew. 2

25. 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)

RDT 2 2mm:

+ Cavity Liner only to be given on all internal
surfaces (for metallic restorations)

+ No liners or base for GIC or Composite

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26. + RDT<2mm: €
+ Base must be given on the pulpal and axial floor
(0.5 - 0.75mm)

RDT<2 mm

+ RDT<1mm:

+ Cavity Liner is given on all internal surfaces, over which
a Base is given.

r Nithin Mathew 25

Dental Cements -

27. 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

Dental Cements - Dr. Nithin Mathew.

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28. PHOSPHATE BASED
CEMENTS

29. 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

Dental Cements - Dr. Nithin Mathew.

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30. COMPOSITION

Dental Cements - Dr. Nithin Mathew.

POWDER % Function

ZnO 90.2% | Principle ingredient

MgO. 8.2% Reduce temperature of calcination process

SiO, 1.4% Improves the working characteristics

Bi,03 0.1% | Smoothness of mix &lengthen working time

Misc- BaO, Ba,SO, & CaO 0.1%

LIQUID

H, PO, 382% | Reacts with ZnO

Al 2.5% Essential for cement forming reaction

Zn 7.1% Moderator for reaction between powderé: liquid, allows
adequate working time

H,0 36% Controls the rate of reation

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31. TYPES

+ Type I - Fine Grained : (Film Thickness less than 251m)
+ Luting permanent metallic restorations
+ Cementation of orthodontic bands

+ Type II - Medium Grained : (Film Thickness of 40m)
+ High strength thermal insulating base

Dental Cements - Dr. Nithin Mathew.

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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.

+ 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 + 2H,PO, + H,0 == Zn,(PO,)).4H,0

Dental Cements - Dr. Nithin Mathew. 2

33. 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.

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34. + 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.
Dental Cements - Dr. Nithin Mathew

35. Mixing time

1.5 - 2mins (Phillips)

Working time

5mins (Phillips)

Setting time

5-9mins (Craig)
5-14mins (O’Brien)

Film thickness

20um

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%

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36. MECHANICAL PROPERTIES

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

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37. 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

+ Temperature of the mixing slab

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38. BIOLOGIC PROPERTIES

+» Freshly mixed ZnPO, - 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.

Dental Cements - Dr. Nithin Mathew.

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39. 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 ZnPO,

Less anticariogenic property

Silver cements : contain small percentage of salts of silver phosphate

Dental Cements - Dr. Nithin Mathew ES)

40. MODIFIED ZINC PHOSPHATE CEMENT
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

Dental Cements - Dr. Nithin Mathew. 40

41. MODIFIED ZINC PHOSPHATE CEMENT
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 Ill: Dual purpose material

Dental Cements - Dr. Nithin Mathew. a

42. COMPOSITION

POWDER

%

Function

ZnO

10-20

Principle ingredient

Silicate glass

Fluoride

12225

Mercury / Silver Compounds

Germicidal

LIQUID

Orthophosphoric acid

Reacts with ZnO

Al salts

Water

45

Dental Cements - Dr. Nithin Mathew.

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43. PROPERTIES

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

BIOLOGIC EFFECT
+ Prolonged low pH (4-5)
+ Pulpal protection necessary

+ Anticariogenic - fluoride release

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44. ADVANTAGES

DISADVANTAGES

Better strength, toughness, abrasion

Total acidity greater than zinc

resistance, fluoride release, phosphate
translucency
Better bonding than zinc phosphate High solubility

Dental Cements - Dr. Nithin Mathew.

45. PHENOLATE BASED
CEMENTS

46. 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 er
+ Longterm and short-term luting agents =
+ Temporary and intermediate restorations “i u

+» Root canal sealers AL tS

+ Surgical packs

Dental Cements - Dr. Nithin Mathew. 46

47. TYPES (ADA Specification No. 30)

+ Typel : Temporary restorations
+ Type II : Permanent cementation of restorations
+ Type III : Temporary restoration, thermal insulating bases

+ Type IV : Cavity Liner

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48. Dispensed As:
+ Two pastes
+ Powder and liquid

COMPOSITION
POWDER % Function
ZnO 69 Principal component
White rosin 293) Reduce brittleness of the cement
Zinc stearate al Accelerator, plasticizer
Zinc acetate 0.7 Improves strength of the cement
Silica Filler
LIQUID
Eugenol / oil of cloves 85
Olive oil 15 Plasticizer

Dental Cements - Dr. Nithin Mathew.

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49. SETTING REACTION

+ Hydrolysis of the ZnO
ZnO + H,0 == 7Zn(0H),
Zn(OH), + 2HE == ZnE, + 2H,0

+ 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

Dental Cements - Dr. Nithin Mathew.

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50. 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.

Dental Cements - Dr. Nithin Mathew.

51. PROPERTIES

Base / Temporary Permanent Cavity liner
mater ial cement cement

Film Thickness (um)

Setting Time (mins) 2-10 4-10 4-10 4-10
Solubility (wt%) 25 15
Compressive strength (Mpa) 25) 35) 35 35
Tensile strength (Mpa) 1-2 1-2 1-2 1-2
Thermal diffusivity 0.38 mm2/s

Linear COTE Bx MGC

Dental Cements - Dr. Nithin Mathew. 51

52. 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

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53. ADVANTAGES

DISADVANTAGES

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

Dental Cements - Dr. Nithin Mathew.

PROS

CONS

53

54. REINFORCED ZINC OXIDE EUGENOL CEMENT

To overcome the shortcomings of the zinc oxide cements

APPLICATION
+ Cementing crowns and FPD

+ Cavity liner

REINFORCED
ZOE,

+ Base materials | AF 1

+ Provisional restoration

Dental Cements - Dr. Nithin Mathew =

55. COMPOSITION

POWDER

%

ZnO

Finely divided natural / synthetic resin

10-40

Accelerators

LIQUID

Eugenol

Dissolved resins

Accelerators : Acetic Acid

Antimicrobial agents : thymol / 8-hydroxyquinolone

Dental Cements - Dr. Nithin Mathew.

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56. 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

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57. PROPERTIES

Setting time 7-9 mins
Film Thickness 35-75 um
Compressive Strength 35-55 Mpa
Tensile Strength 5-8Mpa
Modulus of elasticity 2-3Gpa
Solubility 1wt%

+ 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

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58. ADVANTAGES DISADVANTAGES
Minimal biologic effects Low strength
Good initial sealing ability Higher disintegration

Adequate strength for final
cementation of restoration

Softening and discoloration

Dental Cements - Dr. Nithin Mathew.

59. EBA MODIFIED ZINC OXIDE EUGENOL CEMENT

APPLICATION
+ Cementation of inlays, crowns, FPD’s and for provisional restoration
+ Base / lining material

COMPOSITION

POWDER %

ZnO 60-75
Aluminium oxide 20-35
PMMA 6

LIQUID

Eugenol 87

EBA 63 —

Dental Cements - Dr. Nithin Mathew.

60. 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
« 5-6g/ml : liners and bases

+ Vigorous spatulation is required for about 2 mins to incorporate all of the powder

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61. PROPERTIES

Setting time 7-13 mins
Film Thickness 40 - 60 um
Compressive Strength 55 - 70 Mpa
Tensile Strength 3 - 6 Mpa
Modulus of elasticity 5 Gpa
Solubility 1wt%

Plastic deformation

0.1mm/min at 37°C

BIOLOGIC EFFECTS

+ Similar to ZnO eugenol cement

Dental Cements - Dr. Nithin Mathew.

62. 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

Dental Cements - Dr. Nithin Mathew. 62

63. APPLICATION

+ Liners in deep cavity preparations
+ Intracanal medicaments

+ Direct and indirect pulp capping

+ Apexification procedures

COMPOSITION
+ 2 Pastes - Base and Catalyst

BASE

Calcium tungstate / Barium sulphate

Radio-opacifier

Tribasic calcium phosphate

Zinc oxide

Glycol salicylate

Dental Cements - Dr. Nithin Mathew.

© DHARMA

CALCIUM
HYDRO:

63

64. CATALYST
Calcium hydroxide
ZnO

Zn Stearate

Ethylene Toluene

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.

Dental Cements - Dr. Nithin Mathew.

65. MANIPULATION

+ Equal lengths of the 2 pastes are mixed to a uniform color

PROPERTIES

Working time

3 - 5 mins (depends on availability of moisture
1-2 mins (rapid)

Compressive Strength

At7 mins : 6MPa
Atihr : 10MPa
At 24hrs : 14-20MPa

Tensile Strength

At7 mins: 1.5MPa
Atihr :1.5MPa
At24hrs : 1.7-2MPa

Dental Cements - Dr. Nithin Mathew.

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66. + Solubility in 50% phosphoric acid during etching procedures is significant.

+ Subject to Hydrolytic Breakdown : marginal leakage and finally complete dissolution of the
lining occurs

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67. BIOLOGIC EFFECTS

* Strong Antibacterial Action

+ Tonic dissociation of calcium hydroxide into calcium ions and hydroxy] 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.

Dental Cements - Dr. Nithin Mathew Ed

68. + 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

Dental Cements - Dr. Nithin Mathew. 68

69. ADVANTAGES DISADVANTAGES

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

Dental Cements - Dr. Nithin Mathew E

70. LIGHT ACTIVATED CALCIUM HYDROXIDE

+ Recently introduced cement

COMPOSITION

Calcium Hydroxide

Barium sulphate

Radio-opacifier

Urethane dimethacrylate

HEMA

Activators - camphorquinone

+ They have longer working time

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71. ADVANTAGES

Less brittle than conventional 2 paste
system

Improved strength

No solubility in acids

Minimal solubility in water

Longer working time

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72. DYCAL

+ Introduced in 1979
+ Asaliner/pulp capping agent in deep cavities

+ Radio-opaque calcium hydroxide which is self setting

Dycal toy

ADVANTAGES
High early strength

DISADVANTAGES

Lower water solubility

Excellent handling characteristics

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73. CALYXL

+ Calcium hydroxide containing sodium and potassium salts

+ Allows maintenance of normal dentinogenesis by protecting the pulp against irritation from
operative procedures

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74. POLYCARBOXYIATE
BASED CEMENTS

75. SILICATE CEMENTS (ADA SP. NO. 96)

+ Fletcher in 1871

+ Oldest direct tooth colored materials

+ Steenbock later introduced an improved version of the cement

CA POWDER LIQUID
Silicon Dioxide 35 - 50% Phosphoric acid
Sodium fluoride Sodium & Aluminium phosphate

Calcium fluoride

Aluminium fluoride

Aluminium trioxide

Sodium fluoride
Dental Cements - Dr. Nithin Mathew 75

76. 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.

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76

77. 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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77

78. ADVANTAGES DISADVANTAGES
Translucency High pulpal irritant
Anticariogenic Highly soluble

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78

79. 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

+ Thermal insulating bases

+ Cementing orthodontic bands

+ Cementing SS crown in pediatric dentistry

Dental Cements - Dr. Nithin Mathew Ea)

80. COMPOSITION

POWDER %
ZnO

SnO / MgO 1-5
Aluminium oxide 10-40

Stannous Fluoride : Modified setting time

LIQUID

40% Aqueous solution of Polyacrylic Acid

Dental Cements - Dr. Nithin Mathew.

80

81. 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.

Dental Cements - Dr. Nithin Mathew.

81

82. 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)

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82

83. 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.

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83

84. PROPERTIES

Film Thickness 25 um
Compressive Strength 55 - 85 Mpa
Tensile Strength 8-12 Mpa
Modulus of elasticity 6 Gpa

Bond strength to enamel 3.4 - 4.7 Mpa
Bond strength to dentin 2.1 Mpa

Thermal diffusivity

0.223mm?/sec

+ Solubility in water is low

+ In organic acid with pH < 4.5 : increased solubility

+ Reduced P:L ratio : increases solubility in oral cavity

Dental Cements - Dr. Nithin Mathew.

85. BIOLOGIC EFFECTS

+ Good biocompatibility
+ Low intrinsic toxicity

+ Rapid rise in pH towards neutrality

+ Fluoride release

Dental Cements - Dr. Nithin Mathew. 85

86. ADVANTAGES

DISADVANTAGES

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

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86

88. ACRYLIC RESIN CEMENT

APPLICATION

+ Cementation of restorations, facings and crowns

COMPOSITION

POWDER
MMA polymer or Copolymer

Benzyl Peroxide

Mineral Filler

Pigments
LIQUID
MMA monomer

Dental Cements - Dr. Nithin Mathew: Amine Accelerators

88

89. 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.

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89

90. 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

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90

91. ADVANTAGES

DISADVANTAGES

High strength

Marked pulpal irritation

High toughness

Short working time

Low solubility

Difficulty in removal of the excess cement

Dental Cements - Dr. Nithin Mathew.

PROS

CONS

91

92. 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

Dental Cements - Dr. Nithin Mathew. 92

93. 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

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94. 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.

Dental Cements - Dr. Nithin Mathew.

95. COMPOSITION

Dental Cements - Dr. Nithin Mathew.

POWDER

Borosilicate / silica glass

Polymer powder

Peroxide initiator

LIQUID

Bis-GMA / dimethacrylate monomer

Amine Accelerators

95

96. 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

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96

97. PROPERTIES

Film Thickness 20 - 60 um

Setting Time 3 - 7 mins

Compressive Strength 70 - 200 Mpa

Tensile Strength 25 - 40 Mpa

Modulus of elasticity 4-6 Gpa

Solubility 0.05 wt%
BIOLOGIC EFFECTS

+ Polymerization shrinkage

+ Microleakage

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98. ADVANTAGES DISADVANTAGES
High strength Higher film thickness
Low solubility Microleakage
High micromechanical bonding Pulpal sensitivity

Difficulty in removing excess cement

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C4

98

99. IAGENITS'FORIPUND)

BROTECTION) © Les |

100. 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.

+ Provide barrier for protection of pulp from residual reactants f
diffusing out of a restoration. EX

+ Prevent oral fluids that may penetrate leaky restorations from
reaching the pulp through the dentin

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100

101. 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 lonomer Cement or Resin composites
Dental Cements - Dr. Nithin Mathew 101

102. COMPOSITION

Solid

Copal Resin, Rosin Or Synthetic Resin

Solvent

90% Ether, Acetone Or Alcohol

Medicinal Agent

Chlorbutanol, Thymol, Eugenol

MANIPULATION

+ Applied by means of small cotton pellets / brush / applicator

+ 2-3 layers - sufficient protection

+ Volatile solvents evaporate quickly after application, leaving a thin resin film

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102

103. PROPERTIES

Film thickness 1-4um
Tensile strength <1 Mpa
Low solubility in water

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103

104. 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.

Dental Cements - Dr. Nithin Mathew. 104

105. PROPERTIES

Film thickness 1-4 pm
Tensile strength <1Mpa

+ No significant thermal insulation
+ Soluble : should not be applied to margins of restorations

+ Fluoride compounds are added to newer compounds to prevent secondary caries

Dental Cements - Dr. Nithin Mathew.

106. MANIPULATION

+ (Similar to varnishes)

+ Applied by means of small cotton pellets / brush / applicator
+ 2-3 layers - sufficient protection

+ Volatile solvents evaporate quickly after application, leaving a thin resin film

Other Liners

+ Type III Glass lonomer Cement

+ Type IV Zinc Oxide Eugenol

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106

107. BASES

+ Material that is used to protect the pulp in a prepared cavity by providing thermal
insulation

+ le 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 lonomer

Dental Cements - Dr. Nithin Mathew. 107

108. 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)

+ 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)

Dental Cements - Dr. Nithin Mathew.

A

108

109. 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)

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109

110. 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

Dental Cements - Dr. Nithin Mathew. 110

111. Compre | Tensil Setting | Solubility Pulp
i response

ANSI 70 N/A N/A 25 5 0.20

/ADA 8

ZnPO, 104 55 13.5 20 55 0.06 0 Moderate 3.11X10* 35X 10-6/0C
Znpoly 55 62 44 21 6 1.25 Ail Mild

carboxyla

te

ZOE 25) 1-2 0.22 25 4-10 0.04 0 Mild 3.98X 10

Silico 140 - 7 - 25) 3.5-4 a Moderate 4.38 X 10

Phosphat 170
e

GIC 93-226 42-53 35.64 25 2.5-8 04-15 3-5 Mild -
moderate

composit 25-70 no - <25 2-4 0-0.1 0 Mild
ev

| Cements - Dr. Nithin Mathew

112. 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.

Dental Cements - Dr. Nithin Mathew. a2

113. REFERENCES

» Phillip's Science of Dental Materials : Anusavice ( 12' Edition )

» Phillip's Science of Dental Materials : Anusavice ( 10' Edition )

» Craig’s Restorative Dental Materials ( 13' Edition )

+ Craig’s Restorative Dental Materials ( 12* Edition )

+ Dental Materials and their Selection : William J O’Brien ( 4' Edition )

+ Materials Used in Dentistry : S.Mahalexmi ( 1* Edition )

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