dental cements (3) dental material

dental cements (3) dental material

1. ACID-BASE REACTION CEMENTSACID-BASE REACTION CEMENTS
II. Cements based on phosphoric acidII. Cements based on phosphoric acid
A.A.Zinc phosphate cementZinc phosphate cement
B.B.Silicate cementSilicate cement
C.C.Silicophosphate cementSilicophosphate cement

2. II. Cements based on phosphoric acidII. Cements based on phosphoric acid
Zinc oxide
Fluro-alumino-
silicate glass
Phosphoric
acid
Silicate cementZinc-phosphate
cement
Silico-phosphate cement

3. A. ZINC-PHOSPHATE CEMENTA. ZINC-PHOSPHATE CEMENT
Powder :
Zinc oxide
Magnesium oxide
Other oxides and
Fluorides may be
present
Liquid :
Phosphoric acid
30-40% Water
ZnO or Al(OH)
3
as
buffering agents
COMPOSITION:

4. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION:MANIPULATION:

5. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION:MANIPULATION:
Zinc-phosphate material is mixed on Zinc-phosphate material is mixed on a a
thick,cooled glass slabthick,cooled glass slab using using stainless steel stainless steel
spatulaspatula (Freeze slab technique)(Freeze slab technique) to to ­­ W.T. and W.T. and
S.T.S.T.
Powder is added to liquid small increment by Powder is added to liquid small increment by
small increment to help in small increment to help in buffering the acidbuffering the acid
and to and to ­­ W.T. and S.T. W.T. and S.T.

6. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION: (Cont.d)MANIPULATION: (Cont.d)
Mixing should be done over a Mixing should be done over a wide areawide area
to help in heat dissipation to help in heat dissipation ­­ W.T. and W.T. and
S.T.S.T.
Thin mixThin mix (by (by­­L/P ration) L/P ration) is used for is used for
cementation purposescementation purposes
Thick mixThick mix (by (by ¯¯L/P ratio) L/P ratio) is used as is used as
cavity basecavity base or or temp. fillingtemp. filling

7. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION: (Cont.d)MANIPULATION: (Cont.d)
Precautions Precautions ………………….…………………. ;;
1.1.Liquid bottle should be Liquid bottle should be tightly closedtightly closed (Evaporation (Evaporation
of water will reduce the reactivity of the cementof water will reduce the reactivity of the cement))
2.2.Liquid with Liquid with Cloudy appearanceCloudy appearance discardeddiscarded
3.3.Shake the powder bottleShake the powder bottle before dispensing the before dispensing the
correct ratio and correct ratio and never usenever use powder of powder of other cements other cements
(e.g. ZOE…) (e.g. ZOE…) oror of other manufacturer of other manufacturer

8. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
SETTING REACTION:SETTING REACTION:
ExothermicExothermic chemical reactionchemical reaction of acid- of acid-
base type base type
ZnO + HZnO + H
3POPO
4 Zn Zn
3(Po(Po
4))
2 + H + H
2OO
Set materialSet material is composed of a is composed of a matrix of zinc matrix of zinc
phosphate saltphosphate salt infiltrated withinfiltrated with non-reacted zinc non-reacted zinc
oxide particlesoxide particles that are responsible for that are responsible for
material’s opacitymaterial’s opacity

9. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
SETTING REACTION: (Cont.d)SETTING REACTION: (Cont.d)
Control of setting timeControl of setting time
1.1.­­ L/P ratio L/P ratio ­­ S.T. S.T.
2.2.­­ Mixing Rate Mixing Rate ¯¯ S.T. S.T.
3.3.­­ Particle size Particle size ­­ S.T. S.T.
4.4.­­ Temperature Temperature ¯¯ S.T. S.T.
5.5.­­ Buffering of the liquid Buffering of the liquid ­­ S.T.S.T.
6.6.Presence of moisture Presence of moisture ¯¯ S.T. S.T.

10. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
CHARACTERS:CHARACTERS:
1.Biological properties:
Fresh mix of zinc phosphate cement is highly
acidic (pH 1.6-3.6) due to presence of strong
phosphoric acid causes pulp irritation
In deep cavity, cavity liner should be used
beneath
Thin mix is more irritant than thick mix
Set material becomes neutral within 48 hrs

11. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
CHARACTERS: (Cont.d)CHARACTERS: (Cont.d)
2. Interfacial properties:
Zinc phosphate cement shows no chemical
bonding either to tooth structure or
restoration surfaces (Mechanical retention
and physical adhesion)
3. Chemical properties:
Cement shows some degree of solubility , and
it is dependant on L/P ratio (thin mix ­
solubility)

12. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
CHARACTERS: (Cont.d)CHARACTERS: (Cont.d)
4. Mechanical properties:
Zinc phosphate cement is stronger than ZOE
(So it can be used for final cementation and as
cavity bases), but it is weaker than glass
ionomer and silico-phosphate cements
5. Esthetic properties:
Set cement is opaque (due to presence of non-
reacted ZnO particles), so it can not be used for
cementing ceramic restorations

13. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
CHARACTERS: (Cont.d)CHARACTERS: (Cont.d)
5. Thermal properties:
Has low thermal diffusivity used as cavity bases
under metallic restorations
6. Film thickness:
As low as 15 mm can be used for final cementation
7. Practicability:
Needs well-trend operator due to its short S.T.
Material is successfully used for a long time

14. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
APPLICATIONS:APPLICATIONS:
1.Final cementation of cast metal restoration
2.Cavity base
3.Temporary filling material
4.Cementation of orthodontic bands
5.Build the lost dentine up under amalgam
restorations.

15. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
RELATED MATERIALS:RELATED MATERIALS:
Either copper Either copper (Copper cement)(Copper cement) or silver salt or silver salt
(Silver cement)(Silver cement) is added to cement powder is added to cement powder
Resultant materials have Resultant materials have bactericidal effectbactericidal effect
They can be used for They can be used for filling 1ry teethfilling 1ry teeth and and
cementing orthodontic bandscementing orthodontic bands

16. B. SILICATE CEMENTB. SILICATE CEMENT
Results from theResults from the reaction of phosphoric acid reaction of phosphoric acid
with fluoro-alumino-silicate glass powderwith fluoro-alumino-silicate glass powder
 This type of cement was used asThis type of cement was used as esthetic esthetic
restorative restorative long time agolong time ago
Its Its drawbacksdrawbacks (Acidity, solubility, shrinkage, (Acidity, solubility, shrinkage,
discolorationdiscoloration,…) ,…) andand thethe development of new development of new
materialsmaterials ( (Composite resin, Glass ionomer,..Composite resin, Glass ionomer,..) )
limited its uselimited its use

17. C. SILICO-PHOSPHATE CEMENTC. SILICO-PHOSPHATE CEMENT
It is a It is a hybridhybrid of of silicatesilicate and and zinc phosphatezinc phosphate
cementscements
Powder :Powder : Mixture of zinc oxide and alumino- Mixture of zinc oxide and alumino-
silicate glasssilicate glass
Liquid:Liquid: Phosphoric acid Phosphoric acid
Applications:Applications:
1.1.Luting agentLuting agent
2.2.Filling of 1ry teethFilling of 1ry teeth
3.3.Die materialDie material

18. ACID-BASE REACTION CEMENTSACID-BASE REACTION CEMENTS
II. Cements based on polyacrylic acidII. Cements based on polyacrylic acid
(polyalkenoate cements)(polyalkenoate cements)
A.A.Zinc polycarboxylate cementZinc polycarboxylate cement
B.B.Glass-Ionomer cementGlass-Ionomer cement

19. Cements based on poly-acrylic acidCements based on poly-acrylic acid
(polyalkenoate cements)(polyalkenoate cements)
Zinc oxide
Fluro-alumino-
silicate glass
Poly-
acrylic
acid
Glass-Ionomer
cement
Zinc-
polycarboxylate
cement

20. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
CHARACTERS OF PAA:CHARACTERS OF PAA:
1.Viscous acid with higher molecular
weight than that of phosphoric acid
2.Has lower acidity (higher pH) than
phosphoric acid
3.Provide chemical adhesion with natural
tooth structure, base metal alloys, and tin
plated Noble metal alloys

21. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
ADHESION OF PAA-BASED CEMENTS ADHESION OF PAA-BASED CEMENTS
TO TOOTH STRUCTURE TO TOOTH STRUCTURE
Several postulations were drawn;Several postulations were drawn;
Smith DC (1968):Smith DC (1968): ((The inventor of polycarboxylates)The inventor of polycarboxylates)
ChelationChelation with Ca with Ca
++ ++
of hydroxyapatiteof hydroxyapatite
Beech DR (1973):Beech DR (1973):
Strong Strong ionic bondsionic bonds between polyacrylate and between polyacrylate and
surface Casurface Ca
++++
of apatite of apatite

22. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
ADHESION OF PAA-BASED CEMENTS ADHESION OF PAA-BASED CEMENTS
TO TOOTH STRUCTURE (Cont.d)TO TOOTH STRUCTURE (Cont.d)
Wilson AD (1974):Wilson AD (1974): ((The inventor of glass ionomerThe inventor of glass ionomer ) )
Initial adhesion is achieved by formation of Initial adhesion is achieved by formation of
strong hydrogen bondingstrong hydrogen bonding, then , then replaced with replaced with
ionic bondsionic bonds after a period of time after a period of time
Wilson et al. (1983):Wilson et al. (1983):
Polyacrylic ions enter the molecular structure of Polyacrylic ions enter the molecular structure of
hydroxyapatite, hydroxyapatite, displacing and replacing displacing and replacing
phosphate ionsphosphate ions

23. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
ADHESION OF PAA-BASED CEMENTS ADHESION OF PAA-BASED CEMENTS
TO TOOTH STRUCTURE (Cont.d)TO TOOTH STRUCTURE (Cont.d)
Wilson and McLean (1988): Wilson and McLean (1988):
Bonding of PAA to Bonding of PAA to collagencollagen !!! !!! (bond to enamel (bond to enamel
is better than bond to dentine)is better than bond to dentine)
Geiger et al. (1993):Geiger et al. (1993):
Formation of intermediate Formation of intermediate layer of Carbonato-layer of Carbonato-
apatiteapatite between cement and dentine between cement and dentine

24. A. ZINC-POLYCARBOXYLATE A. ZINC-POLYCARBOXYLATE
CEMENTCEMENT

25. A. ZINC-POLYCARBOXYLATE A. ZINC-POLYCARBOXYLATE
CEMENTCEMENT
Powder :Powder :
Zinc oxideZinc oxide
Magnesium oxideMagnesium oxide
Stannous fluoride Stannous fluoride in in
some productssome products
Liquid :Liquid :
Poly-acrylic acid Poly-acrylic acid (30-(30-
40%)40%)
waterwater
COMPOSITION AND
PRESENTATION:
1. Powder / liquid system

26. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
COMPOSITION: (Cont.d)
2. Single bottle system
Poly-acrylic acid is supplied as a dry powder blended
with cement powder
This mixture is mixed with regular water to get a
cement mix
3. Capsules
Recently available for automatic mixing

27. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
MANIPULATION:
Mixing of cement powder and liquid is carried
out on a glass slab using a stainless steel spatula
PAA is viscous and needs more effort during
mixing of material
Thin mix (P/L ratio= 1.5:1) used for cementing
purposes
Thick mix (P/L ratio = 2.5:1) used as cavity base

28. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
MANIPULATION: (Cont.d)
Polycarboxylate cement adhere to stainless
steel instrument, so any metallic instrument
should be cleaned while cement still unset
To achieve better bonding to tooth structure;
1.Tooth surface should be cleaned and dried from
saliva
2.Mixed cement should be applied to tooth
structure as fresh as possible

29. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
SETTING REACTION:
Chemical reaction of acid-base type
Zinc oxide + PAA ® Zinc-polycarboxylate
Set material: composed of zinc-polycarboxylate
matrix with un-reacted zinc oxide particles
dispersed in providing the cement its opacity
Speed of the reaction is affected by temperature,
P/L ratio, powder particle size, and mixing rate.

30. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
CHARACTERS:
1. Biological properties:
Very little irritating effect on the pulp because
1.Large molecular size of PAA acid, hinders its
passage through dentinal tubules
2.Lower acidity of the PAA
3.Chemical bonding of PAA to tooth enamel and
dentine

31. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
CHARACTERS: (Cont.d)
2. Interfacial properties:
PAA provides chemical adhesion to tooth
structure, base metal alloys, and tin-plated
noble alloys
3. Chemical properties:
Polycarboxylate cement is more soluble in water
than zinc-phosphate cement

32. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
CHARACTERS: (Cont.d)
4. Thermal properties:
Set cement has low thermal diffusivity (can be
used as cavity base)
5. Esthetic properties:
Set cement is opaque due to presence of un-
reacted zinc oxide particles ® not used to lute
ceramic restorations

33. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
CHARACTERS: (Cont.d)
6. Film thickness:
Similar to zinc-phosphate cement (15 mm ), so
can be used for final cementation of cast metal
restorations
7. Practicability:
Little more difficult to mix than other cement
with less viscous liquid

34. ZINC-POLYCARBOXYLATE ZINC-POLYCARBOXYLATE
CEMENTCEMENT
APPLICATIONS:
1.Final cementation of cast metal restorations
2.Cavity base
3.Temporary filling material
4.Cementation of orthodontic bands