Dental cement dental material

1. DENTAL
CEMENTS
2014

2. Cements
Substances used to glue 2 solid objects together
2014

3. 2014
In addition to the gluing function,
Dental Cements own many different applications

4. 2014
3 main Categories

5. 2014
Zinc Oxide
Alumino Silicate Glass
Phosphoric Acid Polyacrylic Acid
Eugenol
ZOE & Ca(OH)2
Zinc Polycarboxylate
Glass Ionomer
Silicate
Zinc Phosphate
Cements set via Acid-Base Rx

6. ZINC OXIDE EUGENOL (ZOE) CEMENT
2014

7. 2014
Presentation forms
Powder Liquid
• Zinc oxide
• Magnesium oxide
• Zinc Acetate- Accelerator
• Eugenol
• Olive oils
• Acetic acid- Accelerator
Two paste system
(Base & Catalyst)
Eugenol-Containing
Eugenol-Free
Single paste – sets in contact with water

8. 2014
How it sets? via acid-base Rx (Chelation)
• ZnO + H2O  Zn(OH)2 (1)
• Zn(OH)2 + E  Zinc Eugenolate (2)
Mixing
on either paper pad or glass slab using a stainless steel spatula at high P/L ratio (4 :1)
• Thin mix  for temp. cementation
• Thick mix  for temp. filling
Set material
Matrix of zinc eugenolate (chelate) + Dispersed non-reacted Zinc oxide particles
• Presence of water is essential – Saliva could help
• Zinc acetate dissolves faster in water  zinc hydroxide

9. 2014

10. 2014
1. Biological Characteristics
• Bacteriostatic -- kills bacteria of carious cavities
• Low thermal diffusivity -- insulate thermal and electrical irritations
• Obtundent effect -- reduces the pulpal pain
• High sealing ability -- minimize the leakage in temp. restored cavities
Material’s Characteristics (BMIECP)

11. 2014
2. Mechanical Characteristics
• Weak cement -- could not withstand either masticatory forces
-- could not withstand amalgam’s condensation forces
4. Esthetic Characteristics
• Opaque – not used to lute translucent ceramic restorations
3. Interfacial Characteristics
• Mechanically-retained -- to both tooth and restorations’ surfaces
-- adapt well to cavity walls
http://dentala2z.co.uk/Opt10057A2

12. 2014
5. Chemical Characteristics
• Water soluable -- dissolves in oral saliva
• Eluted Eugenol -- changes the color of overlying composite restoratives
-- retard the polymerization of overlying composite restoratives
-- swallowed E causes gastric troubles
6. Practicability
• Easily mixed – no special precautions but – it is better to mix it in thick consistency

13. 2014

14. 2014
Modified Materials

15. 2014
CALCIUM HYDROXIDE

16. 2014
Presentation forms
Ca(OH)2 powder
Single paste – methyl cellulose- sets in air
Light-cured Ca(OH)2 paste – resin matrix
Two paste -- the only sets via an acid-base Rx
Base Catalyst
• Calcium hydroxide
• Zinc oxide
• Zinc Acetate- Accelerator
• Liquid vehicle
• di-salicylate,
• Radio-opacifers,
• Fillers

17. 2014
1. Biological Characteristics --- related to material’s alkalinity (pH= 11-13)
• Bacteriostatic -- kills bacteria of carious cavities
• Neutralizes the acids produced by the cariogenic bacteria
• Help differentiate pulpal stem cells -- reparative dentin stimulator
Material’s Characteristics (BMIECP)
2. Mechanical Characteristics
• Weak cement -- could not withstand amalgam’s condensation forces
4. Esthetic Characteristics
• Opaque – not used to lute translucent ceramic restorations
3. Interfacial Characteristics
• Mechanically-retained -- does not adhere to the tooth structure
5. Chemical Characteristics
• Quite soluble -- dissolves in liquids even under leaked restorations

18. 2014

19. 2014
ZINC PHOSPHATE CEMENT

20. 2014
Powder Liquid
• Zinc oxide
• Magnesium oxide
• Other oxides &
fluorides
• Phosphoric acid (H3PO4)
• Water (30-40%)
• Buffering agents -- Zinc oxide, zinc
hydroxide
Presentation forms
Mixing
on thick, cool glass slab using stainless steel spatula
powder is added to the liquid in small increments
Mixing over a wide area
• Thin mix  for cementation
• Thick mix  for cavity base /temp. filling

21. 2014
How it sets?
Through a Fast , exothermic acid-base Rx (Crystallisation)
ZnO + H3PO4  Zn3(Po4)2 + H2O
Set material
matrix of zinc phosphate salt+ dispersed non-reacted zinc oxide particles
Controlling the Rx speed (setting time)
1. ↓ Powder particle size   reaction
2.  Temperature   reaction
3. ↓ Buffers   reaction
4.  P/L ratio   reaction
5.  Mixing rate (speed or time)   reaction
6.  Acid concentration   reaction

22. 2014
1. Biological Characteristics
• Pulp irritant -- fresh mix is highly acidic (pH 1.6-3.6)
-- Ca(OH)2 liner is needed in deep cavities
-- Thin mix is more irritant than the thick mix
-- Set material becomes neutral in 48 hrs
• Low thermal diffusivity -- insulate thermal and electrical irritations
Material’s Characteristics (BMIECP)
2. Mechanical Characteritics
• Stronger than ZOE and weaker than GI
-- withstand amalgam’s condensation forces (cavity bases)
-- could withstand masticatory forces ( permanent cementation /temp filling)
3. Interfacial Characteristics
• Mechanically-retained -- to both tooth and restorations’ surfaces
• Film thickness similar to that of zinc phosphate cement (15μm)

23. 4. Esthetic Characteristics
• Opaque – not used to lute translucent ceramic restorations
5. Chemical Characteristics
• Water soluble -- dissolves in oral saliva
-- thin mix dissolves more than the thick mix
2014
6. Practicability
• Material is successfully used for a long time
• Needs well-trained operator due to its short S.T.
• precautions –
1. Liquid bottle should be tightly closed all the time
2. Liquid with cloudy appearance should be discarded
3. Shake the powder bottle before dispensing the correct ratio
4. never use powder of other cements (e.g. ZOE…) or of other manufacturer

24. 2014

25. 2014
POLY-ACARYLIC ACID
in comparison to phosphoric acid
• Has lower acidity
• Has higher molecular weight --More viscous
• Bonds chemically to the inorganic part of tooth structure

26. 2014
ZINC POLYCARBOXYLATE CEMENT

27. 2014
1. Powder Liquid
• Zinc oxide
• Magnesium oxide
• Flourides
• Poly-acrylic acid (30-40%)
• Water
2. Powder in a
single bottle
water settable material
Freeze dried acid is blended with the powder
3. Capsules
Presentation forms

28. 2014
Mixing
On a glass slab using stainless steel spatula
PAA is viscous and needs more effort during material’s mixing
• Thin mix ( P/L ratio 1.5:1) for cementation
• Thick mix ( P/L ratio 2.5:1) for cavity base /temp. filling
How it sets?
Through a acid-base Rx
ZnO + PAA  Zn-polyacarylate + H2O
Set material
matrix of zinc polyacrylate salt+ dispersed non-reacted zinc oxide particles

29. 2014

30. 2014
1. Biological Characteristics
• Pulp irritant -- fresh mix is acidic But less than zinc phosphate cement is
-- Ca(OH)2 liner is needed in deep cavities
-- Thin mix is more irritant than the thick one
-- Set material becomes neutral in 48 hrs
• Low thermal diffusivity -- insulate thermal and electrical irritations
Material’s Characteristics (BMIECP)
2. Mechanical Characteristics
• Its strength is comparable to that of zinc phosphate cement
-- withstand amalgam’s condensation forces (cavity bases)
-- could withstand masticatory forces ( permanent cementation /temp filling)
3. Interfacial Characteristics
• Chemically adhere -- to the tooth and base metal restorations
• Film thickness similar to that of zinc phosphate cement (15μm)

31. 2014
4. Esthetic Characteristics
• Opaque – not used to lute translucent ceramic restorations
5. Chemical Characteristics
• More soluble in water than zinc phosphate cement
-- thin mix dissolves more than the thick mix
6. Practicability
• Viscous liquid make the mixing process a little pit difficult
• All metallic instruments should be cleaned up while the cement still unset
• To achieve better bonding
1. Tooth surface should be cleaned and dried from saliva
2. Mixed cement should be applied to tooth structure as fresh as possible

32. 2014

33. 2014