Ist Year - Dental Materials

1. ‫ا‬ ‫بسم‬

2. DENTAL CEMENTS

4. Dental cements are classified according to the type of matrix
present in the set material into;
1. Phenolate
2. Phosphate
3. Polyacrylate
4. Resin (i.e. polymeric)

5. Another classification according to uses;
Luting cements;
Applied as a thin (25 micron) layer to bond a restoration to the tooth or to
another restorative material.
Cavity base cements;
Placed under a permanent restoration to negate some undesirable properties
e.g.: high thermal diffusivity.
Cavity lining cements;
Applied in a thin layer to seal the surface of dentine.

6. Requirements of ideal dental cements
General properties
Non toxic , non irritant
Insoluble in fluids.
Antibacterial effect.
Obtunding effect (relief of pain).
Adhere chemically to tooth.

7. When used as base or liner:-
•thermal, electrical, and chemical insulation.
•high mechanical properties to allow condensation of
filling without fracture.
•high modulus of elasticity to resist fracture under
masticatory forces.

8. When used as filling material:
Neither dissolve nor absorb oral fluids.
High mechanical properties
match teeth structure in color, translucency, and refractive index
Their coefficient of thermal expansion should match that of tooth
structure.
Low thermal diffusivity.
dimensional stable on setting.
N.B.: No single material can fulfill all of these requirements.

9. Zinc oxide-eugenol (ZOE) cements
It is characterized by:
*Sedative effect on the pulp (due to the presence of
eugenol)
*Neutral PH.
Forms
Powder and liquid
Ready made paste

10. Types of Zinc oxide-eugenol cement
Unmodified ZOE
Resin-modified ZOE
EBA-ZOE

11. Unmodified ZOE
Composition
Powder
Zno; is the main reactant with eugenol.
Zinc acetate; acts as accelerator
Rosin; reduces brittleness, produces cohesive mass and
reduces solubility.
Liquid
Eugenol 85% the main reactant with ZnO
Olive oil 15% improves plasticity of the cement.

12. Setting reaction
It is called Chelation reaction
Zno + H2o Zn(OH)2
Zn(OH)2 + eugenol Zinc eugenolate + H2o
Factors affecting setting time
Moisture: increase moisture decrease setting time
Accelerator: increase accelerator decrease setting time
P/L ratio: increase p/L decrease setting time
Temperature: increase temperature decrease setting time

13. MANIPULATION
Equipments
Glass slab + Stainless spatula
Zinc oxide is slowly wetted by the eugenol, therefore, prolonged
and vigorous spatulation is required, especially for a thick mix.

14. PROPERTIES
1-Working and setting time
It has long working time because moisture is required for setting.
Setting time is controlled by;
Moisture availability
Accelerator
Powder/liquid ratio
2-Solubility
It is highly soluble in oral fluids.

15. 3-Strength
It has low tensile and compressive strength so it is not used as
a base or cavity liner.
4-Eugenol inhibit the set of resins
So eugenol containing cements can not be used in conjunction
with resin-based restorative materials.

16. 5-Biocompatibility
The set cement has a PH 6-8 and has little or no effect on the pulp when
placed in deep cavities.
The presence of eugenol has an obtundent effect on the pulp and
reduces pain.
It is irritant to the pulp when it is directly contact the pulp. So, it is not
recommended when there is pulp exposure.
6-Bonding
Zinc oxide eugenol do not adhere either to tooth structure or restoration
surface. It makes mechanical retention to surface irregularities.

17. Uses
Temporary filling material
Temporary cementation of cast restoration
Cavity linear in deep cavity
Root canal sealer
Gingival tissue pack to displace the gingival margins before taking the
impression for crown
Surgical dressing: in which a haemostatic agent such as tannic acid is added.

18. Advantages
ZOE has obtundent effect on the pulp
Good sealing ability.
Disadvantages
Low strength,
Low abrasion resistance,
High solubility.

19. Resin-modified zinc oxide eugenol
To overcome the disadvantages of unmodified ZOE, the
resin is added to its powder or to the liquid or both.
Forms
Powder and liquid and ready made paste
Composition
Powder
-Zinc oxide
-Polymethyl methacrylate
-Accelerator
Liquid
-Eugenol
-Dissolved resins
-Accelerator (acetic acid)
-Thymol (antimicrobial agent)

20. Properties
High compressive strength
Low solubility
Uses
Permanent cementation of cast restoration
Cavity liners and base materials
Temporary filling material

21. 4.3- Ortho-Ethoxybenzoic Acid-Alumina Modified Zinc Oxide
Eugenol (EBA-ZOE)
Powder
-Zinc oxide
-Al2o3
Polymethyl methacrylate
Liquid
EBA 66%
Eugenol 34%

22. Properties
Working time at room temperature is long. Setting time ranges between 7-
13 minute under oral conditions.
High compressive strength but low tensile strength
Low solubility
Uses
permanent cementation of inlays, crowns and bridges.
Base or lining material
Temporary filling

24. Forms
Suspension in water or organic solvent
Two-paste system (chemically cured)
One-paste system (light cured)

25. Composition of two paste system
Paste 1
-Ca(oH)2
-Zno
-Zinc stearate
-Ethyl toluene
-Sulphonamide
Paste 2
-Glycol salicylate
-Titanium oxide
-Calcium sulfate
-Calcium tungestate

26. Calcium hydroxide has been the standard material for maintaining pulp vitality.
Both clinically and histologically. It has been found to produce satisfactory
results in indirect and direct pulp capping,
because it is capable of stimulating the formation of tertiary dentin by the pulp.
In contact with vital pulp tissue it contributes to the Formation of reparative
dentin, a special variant of tertiary dentin, which seals exposures
by newly formed hard tissue.

27. Uses
Direct and indirect pulp capping
Protective liner
Properties
*Alkaline PH (11-12). This degree of alkalinity stimulates odontoblast cells
to produce secondary dentin
*They have antibacterial effect
*They can neutralize the free phosphoric acid of zinc phosphate cement
*Low mechanical properties
*High solubility
*Light cured type has high compressive strength

28. Indirect pulp capping