Applied Dental Material Second Year

1. Dental Cements

2. 
(n): 1. A powder of calcium oxide, silica,
and alumina used as an ingredient of
mortar and concrete.

2. A binding element. A substance which
makes objects adhere to each other or
something serving to unite firmly.

3. 



Dental cements are brittle materials.
They are supplied mainly as powder & liquid.
When mixed to a thin consistency , they are used to
retain - indirect restorations.
- orthodontic bands & brackets
When mixed to a thick consistency , they are used
as:- low strength bases [liner]
- high strength bases
- temporary filling
- root canal sealer

5. 
Dental cements can be classified according to the
basic constituent of the powder into:

Zinc oxide based cements

Ion leachable glass based cements

Resin based cements

Others

6. 



There are three types :
Zinc Oxide - Eugenol Cement
Zinc Phosphate Cement
Zinc Polycarboxylate Cement

7. Supplied Form: - Powder & Liquid
- Two pastes of contrast colors
- One ready made paste
 Composition :
 Powder:
- Zinc oxide [sintered to control
its reactivity ]
- Magnesium oxide
- Zinc acetate [accelerator]
 Liquid:
- Eugenol [component of oil of
cloves ; weak organic acid]
- Other oil *to mask taste
*to modify viscosity


8. 






Setting Reaction :
It is an acid base reaction [ chelation reaction ].
Base + Acid
Salt + H2O
It is a surface reaction
cored structure
P+L
Un-reacted ZnO
moisture +Free Eugenol
+Hydrated Zinc Eugenolate
[amorphous matrix ]
H20 changes ZnO into Zn(OH)2 to react with eugenol
Factors accelerating the setting reaction: * Heat
* Moisture
.·.It sets quickly in the patient`s mouth
The setting reaction is accompanied by slight expansion

9. 





Manipulation:
Proportioning according to use .
Optimum P/L should be obtained to achieve best
properties for the cement
or
Equal lengths of the two pastes
Mixing on oil resistant paper pad or glass slab with
stainless steel spatula .
Add all the powder into the liquid at once or
Mix the two pastes until uniform color is obtained
The mix is first putty , then by further mixing a
suitable consistency [thick & crumbly] is obtained
S.T.~10 min. M.T.~1-1.5 min W.T. long

10. 
Properties:
1.

Biological Properties:
Its pH is ~7 [neutral]
no chemical irritation
It is sedative in deep cavity [Eugenol]

N.B.

It is highly irritant to the exposed pulp


Anti-bactreial effect [ZnO +Eugenol]
Thermal insulation when used in thick layer
[>0.5mm]

11. Properties:
2. Consistency & Film Thickness:


They depend on
- Powder particle size
- Powder/Liquid [application]
- Viscosity of the mix

12. Properties :
2. Consistency & Film
Thickness :
 For luting application , thin
film thickness [free of
defects] is required
[less
than 25µm]
 A 2-3 cm string of the mix
occurs , when the flat
surface of the St. St.
spatula is pulled from the
mix


13. ZnO-E has a moderate film thickness 2535µm
 For other applications , a thick film
thickness is required
[not less than
40µm]
 The mix has the consistency of pie dough
; it can be rolled into a ball with fingers
[nonsticky]


14. 
Properties:
3.
Dimensional Changes During Setting :
There is slight expansion

Excellent initial sealing ability

15. 
Properties:
4.
Solubility :
It depends on

- Composition
- P/L [ high ratio is desirable]
- Handling of the mix

ZnO-E is the most soluble dental cement due to:
- Leaching of free Eugenol
- Hydrolysis of Zinc Eugenolate matrix

16. Properties :
5. Mechanical Properties :



They depend on - Composition
- P/L [high ratio is desirable]
- Handling of the mix
Poor mechanical properties .
- Compressive strength ~15 MPa
- Tensile strength
~ 5 MPa . ·.brittle
This makes the removal of excess after application &
complete setting
of the cement easier

17. 
Modulus of elasticity ~ 5×103 Mpa

Mismatch in the elastic moduli of the base &
restoration create tensile stresses at their
interface causing fracture of either material
.·.The conventional ZnO-E can not be used as a
base under amalgam restoration

19. 
Properties :
6.
Retention (Bonding) :
The bond strength of dental cement depends on :

- Strength of the cement
- Film thickness of the cement
- Surface texture of the tooth & restoration
- Design of the restoration

It bonds by mechanical interlocking

20. Properties :
7. Optical Properties :

The presence of un-reacted ZnO in the set mass

Opaque cement
.·.It is contraindicated to be used with translucent
restoration

21. 

1.

Modifications:
These are performed either for
powder
liquid
both
Zinc Oxide Noneugenol Cement :
The liquid is formulated with aromatic oils other
than eugenol for patients sensitive to it

22. Modifications :
2. Polymer Reinforced Zinc Oxide –Eugenol
Cement
 Powder : - ZnO
80%
- Resin
20 %
 Liquid : - Eugenol
- Polysterene
 This is for
Solubility
Strength

since the polymer is of low water solubility .

23. 
3.




Modifications:
EBA –Alumina Reinforced Cement :
Powder :
- ZnO
70%
- Alumina
30%
Liquid :
- Ethoxybenzoic acid 62%
pinkish in colour
- Eugenol
38%
Alumina in the powder is strong inert additive
The EBA in the liquid allows for the formation of stronger
crystalline matrix

24. Modifications
4.
Slow & Rapid Setting Cement :

The slow setting cement takes 24 hrs to set .

The fast setting cement takes only 5 min. to set .

This depends on * Nature of the powder
* Its particle size
* Concentration of accelerator

25. 









Applications :
Low strength base
[liner]
High strength base
[modified version]
Provisional restoration [ filling & cementation]
Final cementation
[ modified version]
Root canal sealer
[ slow setting version]
Periodontal dressing
Surgical dressing
N.B.
Never use ZnO-E with resin based restorations , because
eugenol inhibits their polymerization
strength & aesthetics of C.R.

26. 
Introduction :

It is the oldest & most popular cement ,
because of : * Its long history of clinical success
* Favorable handling properties
[i.e. well defined W.T. & rapid S.T.]
* Many applications

Supplied Form :
Powder & Liquid

27. 


Composition :
Powder : - Zinc oxide [sintered to control its
reactivity ]
- Magnesium oxide
- Other oxides
* Strength & Smoothness
- Fluorides [only when used for
cementation in orthodontic ]
Liquid : - Aqueous solution of phosphoric acid
Dilution is necessary for the ionization of the
acid to react with the powder
- Aluminum phosphate *Buffer
*Cement former

28. 




Setting Reaction :
It is an acid base reaction
Base + Acid
Salt + H2O
It is a surface reaction
cored structure
P + L Mg
Un-reacted ZnO
AL
+Hydrated Zinc-Alumino- Phosphate
[ porous amorphous matrix ]
The reaction is
* exothermic
* accompanied by slight shrinkage

29. 
Manipulation :

Proportioning according to use
Optimum P/L should be obtained to achieve best
properties for the cement

Mixing is done on glass slab with ST.ST. spatula

The setting reaction is exothermic causing the
ZnPH mix to set rapidly

S.T.~5-9 min. M.T.~1-1.5 min. W.T. well defined

30. 

1.
2.
3.
Manipulation :
For heat dissipation , the following should be
performed :
Use cool dry glass slab , not below the dew point
to avoid moisture condensation [ to keep H2O
content & reaction rate constant ]
Slow addition of small increments of powder to
the liquid
Mixing is done over large area of the glass slab
until the desired consistency is obtained

31. 




1.
2.
3.
Manipulation :
N.B.
Any delay after mixing, the viscosity increases rapidly
resulting in larger film thickness
This will impair the proper seating of the restoration during
cementation
Care of the liquid
To keep H2O content & reaction rate constant
Keep the liquid in stoppered bottles
Dispense the liquid just before mixing
Discard the last third [clear or cloudy ]

32. Properties :
1.
Biological Properties :

ZnPH is irritant to the pulp because of
- Its initial acidic pH reaching neutrality within 48 hrs
- No anti bacterial effect
- Slight setting shrinkage
.˙. ZnPH base should be preceded in deep cavity by
- Cavity varnish
- Subbase [cavity liner]
- Dentin bonding agent

Thermal insulation when used in thick layer [>0.5mm]

Fluoride release in certain formulations

33. 
1.


1.
2.
Properties :
Biological Properties :
N.B.
The patient may feel some pain during cementation
This can be the result of:
Acidic pH of the cement ; especially for too thin mix
Osmotic pressure developed by the movement of
fluid through the dentinal tubules
This pain is only transient & should subside within few
hrs

34. 



pH @ 3 minutes ~ 4
pH @ 1 hour ~ 6
pH @ 48 hours ~ 7
Low remaining dentin thickness (RDT)
requires pulp protection

35. 
Properties :
2.
Consistency & Film Thickness:
They depend on - Powder particle size
- Powder/Liquid [application]

- Viscosity of the mix

37. Properties :
2. Consistency & Film Thickness :
 For luting application , a thin film thickness [free of
defects] is required
[less than 25µm]
 A 2-3 cm string of the mix occurs , when the flat surface of
the St St spatula is pulled from the mix
 ZnPh is known as Crown & Bridge Cement , because
it has the thinnest film thickness
 For other applications , a thick film thickness is required
[not less than 40µm]
 The mix has the consistency of pie dough ; it can be rolled
into a ball with fingers [nonsticky]


39. 
Properties:
3.
Dimensional Changes During Setting :

There is slight shrinkage during setting

40. Properties :
4. Solubility :

It depends on




- Composition
- P/L [ high ratio is desirable]
- Handling of the mix
ZnPH is soluble in water for the first 24 hrs after
setting ~ 0.04 - 0.2%
Then the solubility is much reduced
The fluoride containing type shows some fluoride
release
decalcification around cemented
orthodontic bands

41. Properties :
Mechanical Properties :
They depend on - Composition
- P/L [high ratio is desirable]
- Handling of the mix
- Compressive strength ~100-150 MPa
- Tensile strength
~ 3-4 MPa . ·. Brittle
This makes the removal of excess after application &
complete setting of the cement easier
- Modulus of elasticity ~ 13×103 MPa [~to dentin]
Mismatch in elastic moduli of the base & restoration create
tensile stresses at their interface causing
fracture of either material
 .·.It can be used as a base under amalgam

5.


42.  Properties :
6. Retention (Bonding) :
 The bond strength of dental cement depends on :
- Strength of the cement
- Film thickness of the cement
- Surface texture of the tooth & restoration
- Design of the restoration
 It bonds by mechanical interlocking

43. Properties :
7. Optical Properties :

The presence of un-reacted ZnO in the set mass

Opaque cement
.·.It is contraindicated to be used with translucent
restoration

44. 
Applications :

High strength base

Provisional restoration [ filling]

Final cementation of - Metallic restorations
- Ceramometallic restorations
- Orthodontic bands

45. 



Supplied Form :
Powder & Liquid
Preproportioned capsule for mechanical mixing
Water settable cement
The liquid is freeze dried & added to the powder
This mixture will be only mixed with distilled H2O
This supplied form has been developed
- To achieve correct P/L , because the viscous
liquid does not make independent drops thus
giving inaccurate amount
- To avoid thickening of the liquid

46. 

Composition :
Powder :
-Zinc oxide [ sintered to control its
reactivity ]
- Magnesium oxide
- Other oxides * Strength
Smoothness
- Fluorides [ only when used for
cementation in
orthodontics ]

47. 
Composition :

Liquid :
-Aqueous solution of polycarboxylic acid
copolymer
Dilution is necessary for the ionization of
the acid to react with powder
Copolymerization is necessary to avoid
thickening of the liquid
- Sodium Hydroxide *Buffer
- Tartaric acid
*To control S.T. by
controlling the dissolution
of powder surface

48. 
Setting Reaction :

It is an acid base reaction
Base + Acid

Salt +H2O
It is a surface reaction
P+L
cored structure
- Un-reacted ZnO
+Hydrated Zinc Polycarboxylate
[amorphous matrix ]

Factors affecting setting reaction * Heat

49. 



Manipulation :
Proportioning according to use
Optimum P/L should be obtained to achieve
best properties for the cement
Mixing is done on glass slab with plastic
spatula , because ZnPolyc. adheres to the ST.
ST. spatula
S.T.~7-9 min. [long] M.T.~30-60 sec. W.T.
short

50. 

1.
2.

1.
2.
Manipulation :
Extend the W.T. by
Use of cool dry glass slab , not below the dew point to
avoid moisture condensation [to keep both H2O content
& reaction rate constant ]
The powder is added to the liquid in only two halves
N.B.
The correct consistency of the mix is viscous , but the mix
will flow under pressure
The mix should be only used as long as it has glossy
surface , otherwise there will be
* Initial setting of the cement
* No free COOH groups for adhesion

51. 
Manipulation :

Care of liquid :

To keep both H2O content & reaction rate
constant
1.
Keep the liquid in stoppered bottles
2.
Dispense the liquid just before mixing
3.
Discard the last third [ clear or cloudy ]

52. Properties :
1. Biological Properties :

Its pH is acidic
chemical irritation
It is less irritant than ZnPh , because the
following :
1. Polycarboxylic acid is weaker than
phosphoric acid
2. Rapid rise to neutrality within 24 hrs
3. Large molecular size of the acid
Difficult
penetration inside the dentinal tubules


53. 
Properties :
1.
Biological Properties :
Some antibacterial effect [ZnO]


Thermal insulation when used in thick layer
[>0.5mm]

Fluoride release in certain formulations

54. 
Properties :
2.
Consistency & Film Thickness:
They depend on - Powder particle size
- Powder/Liquid [application]

- Viscosity of the mix

55. 
2.





Properties :
Consistency & Film Thickness :
For luting application , thin film thickness [free of defects] is
required
[less than 25µm]
A 2-3 cm string of the mix occurs , when the flat surface of the
plastic spatula is pulled from the mix
ZnPolyc. has the highest film thickness 25-48µm
.·.It is difficult to completely seat a retentive well fitting
restoration
For other applications , a thick film thickness is required
[not
less than 40µm]
The mix has the consistency of pie dough ; it can be rolled into
a ball with fingers [nonsticky]

56. 
Properties :
3.
Dimensional Changes During Setting :
There is slight shrinkage during setting


57. Properties:
4. Solubility :
 It depends on



- Composition
- P/L [ high ratio is desirable]
- Handling of the mix
ZnPolyc. is ~as soluble as ZnPh
The fluoride containing type shows some fluoride
release decalcification around cemented
orthodontic bands

58. Properties :
5. Mechanical Properties :


They depend on - Composition
- P/L [high ratio is desirable]
- Handling of the mix
- Compressive strength ~55-95 MPa
- Tensile strength
~ 3-6 MPa
.·. Brittle This makes the removal of excess after application &
complete setting of the cement easier
- Modulus of elasticity ~ 4×103 MPa
Mismatch in elastic moduli of the base & restoration
create tensile stresses causing fracture of either material

59. 
6.


1.
2.
Properties :
Bonding :
The bond strength of dental cement depends on:
- Strength of the cement
- Film thickness of the cement
- Surface texture of the tooth & restoration
- Design of the restoration
It bonds by chemical bonding of COOH group to
Inorganic portion in enamel & dentin
Bond to enamel> Bond to dentin [ higher inorganic % in
enamel ]
Base metal alloys [ presence of surface oxide ]

60. Properties :
6. Bonding :

N.B.

Chemical bond of ZnPolyc>Chemical bond of
G.I. due to moisture sensitivity of G.I.

ZnPolyc. does not bond chemically to gold
alloy restorations
It bonds by mechanical interlocking


61. Properties :
7. Optical Properties :

The presence of un-reacted ZnO in the set mass

Opaque cement
.·.It is contraindicated to be used with translucent
restoration

62. 
Applications :

High strength bases

Provisional restorations [ filling]

Final cementation of - Metallic restorations
- Ceramometallic restorations
- Pediatric stainless steel crown
- Orthodontic bands

63. Non-resin Permanent luting cements
Liquid
Phosphoric acid
Powder
Zinc Phosphate
Polycarboxylate
(Zinc polyacrylate)
Zinc Silicophosphate
Polyacrylic acid
Zinc oxide
Glass Ionomer
Fluoroaluminosilicate
glass

64. Cement Base



Used to encourage recovery of the
injured pulp and to protect it against
further chemical or thermal insult
Serves as a substitute for dentin lost
due to decay or preparation
Primary difference between liners and
bases

THICKNESS (>0.75 mm)

65. 



Calcium hydroxide (Dycal)
ZOE (zinc oxide-eugenol)
Glass ionomer
Resin-modified glass ionomer
(Vitrebond)


Light-cured glass ionomer
Hybrid ionomer

66. 
Materials that have been used


Zinc phosphate cement
Reinforced zinc oxide-eugenol cement




IRM (Intermediate Restorative Material)
Zinc polycarboxylate
Glass ionomer cement
Resin-modified glass ionomer cement

68. 
Supplied Form : -Two pastes

Composition :

Base Paste :
- Calcium Hydroxide
- Filler
*Strength
*Radioopacity

Catalyst Paste : -Glycol Salicylate [weak
acid]

69. 



Setting Reaction :
It is an acid base reaction [chelation reaction]
Base + Acid
Salt + H2O
It is a surface reaction
cored structure
P+P
- Un-reacted Calcium Hydroxide
+ Calcium Disalicylate
[amorphous matrix]
Factors affecting setting reaction : *Moisture
.·.It sets quickly in the patient`s mouth

70. 
Manipulation :

Equal lengths of the two pastes are dispensed
on a paper pad

They are mixed with ST.ST. spatula to uniform
color

The mix is applied only to the cavity floor , as it
is highly soluble

S.T.~2-5min. M.T.~30 sec.

71. 
Properties :
1.
Biological Properties :

Its pH is alkaline
un-reacted Ca(OH) 2
.·. It stimulates secondary dentin precipitation ,
when placed in contact to minute traumatic pulp
exposure [direct pulp capping]

Antibacterial effect

Thermal insulation when used in thick layer

72. Properties :
2. Consistency & Film Thickness :
 Creamy consistency
Thin film thickness

3.

4.

Dimensional Changes on Setting :
Not mentioned
Solubility :
It is highly soluble
.·.It should not be left on cavity walls or margins

73. 
Properties :
5.
Mechanical Properties :

Low mechanical properties
Compressive strength ~20 MPa
Tensile strength
~1 MPa .·. Brittle
Modulus of elasticity
~0.5×103 MPa
6.
Bonding :
7.
Optical Properties :

74. 
Modification :

Light Cured Calcium Hydroxide :

It is supplied as one paste

It consists of - Ca (OH)2
- UDMA * Solubility
- Photoinitiator

75. 
Applications :

Cavity liner under C.R. , G.I. & ZnPh

Pulp capping material

Root canal sealer

76. 

Supplied Form :
- Liquid [clear ;yellowish]
Composition :
- Resin [natural or synthetic]
dissolved in organic solvent
[ alcohol ,acetone or ether ]

77. 





Manipulation :
It is applied by a disposable brush [to avoid
contamination] to all cavity walls
The solvent will evaporate leaving a thin coating
of resin
Use a gentle stream of air for drying
Repeat the application up to three times to
ensure a thin uniform coating of resin [more
protective than one thick application]
Tightly cap the cavity varnish bottle immediately
after use to avoid evaporation of solvent

78. 






Applications :
It decreases marginal leakage around restorations
It decreases the passage of chemicals from irritating
base, cement or restoration
It protects against the loss of constituents from the
surface of the filling
N.B.
It should not be used under C.R. because it interferes
with the action of the bonding agent which already seal
the dentinal tubules
It should not be used under G.I. because it interferes
with fluoride uptake & chemical bonding