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:
5. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION:MANIPULATION:
Zinc-phosphate material is mixed onZinc-phosphate material is mixed on aa
thick,cooled glass slabthick,cooled glass slab usingusing stainless steelstainless steel
spatulaspatula (Freeze slab technique)(Freeze slab technique) toto ↑↑ W.T. andW.T. and
S.T.S.T.
Powder is added to liquid small increment byPowder is added to liquid small increment by
small increment to help insmall increment to help in buffering the acidbuffering the acid
and toand 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 aMixing should be done over a wide areawide area
to help in heat dissipationto help in heat dissipation ↑↑ W.T. andW.T. and
S.T.S.T.
Thin mixThin mix (by(by↑↑L/P ration)L/P ration) is used foris used for
cementation purposescementation purposes
Thick mixThick mix (by(by ↓↓L/P ratio)L/P ratio) is used asis used as
cavity basecavity base oror temp. fillingtemp. filling
7. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
MANIPULATION: (Cont.d)MANIPULATION: (Cont.d)
PrecautionsPrecautions ………………….………………….;;
1.1. Liquid bottle should beLiquid 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 withLiquid with Cloudy appearanceCloudy appearance discardeddiscarded
3.3. Shake the powder bottleShake the powder bottle before dispensing thebefore dispensing the
correct ratio andcorrect ratio and never usenever use powder ofpowder of other cementsother cements
(e.g. ZOE…)(e.g. ZOE…) oror of other manufacturerof other manufacturer
8. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
SETTING REACTION:SETTING REACTION:
ExothermicExothermic chemical reactionchemical reaction of acid-of acid-
base typebase type
ZnO + HZnO + H3POPO4 ZnZn3(Po(Po4))2 + H+ H2OO
Set materialSet material is composed of ais composed of a matrix of zincmatrix of zinc
phosphate saltphosphate salt infiltrated withinfiltrated with non-reacted zincnon-reacted zinc
oxide particlesoxide particles that are responsible forthat 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 ratioL/P ratio ↑↑ S.T.S.T.
2.2. ↑↑ Mixing RateMixing Rate ↓↓ S.T.S.T.
3.3. ↑↑ Particle sizeParticle size ↑↑ S.T.S.T.
4.4. ↑↑ TemperatureTemperature ↓↓ S.T.S.T.
5.5. ↑↑ Buffering of the liquidBuffering of the liquid ↑↑ S.T.S.T.
6.6. Presence of moisturePresence 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 µm 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
15. ZINC-PHOSPHATE CEMENTZINC-PHOSPHATE CEMENT
RELATED MATERIALS:RELATED MATERIALS:
Either copperEither copper (Copper cement)(Copper cement) or silver saltor silver salt
(Silver cement)(Silver cement) is added to cement powderis added to cement powder
Resultant materials haveResultant materials have bactericidal effectbactericidal effect
They can be used forThey can be used for filling 1ry teethfilling 1ry teeth andand
cementing orthodontic bandscementing orthodontic bands
16. B. SILICATE CEMENTB. SILICATE CEMENT
Results from theResults from the reaction of phosphoric acidreaction 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 estheticesthetic
restorativerestorative long time agolong time ago
ItsIts drawbacksdrawbacks (Acidity, solubility, shrinkage,(Acidity, solubility, shrinkage,
discolorationdiscoloration,…),…) andand thethe development of newdevelopment 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 aIt is a hybridhybrid ofof silicatesilicate andand zinc phosphatezinc phosphate
cementscements
Powder :Powder : Mixture of zinc oxide and alumino-Mixture of zinc oxide and alumino-
silicate glasssilicate glass
Liquid:Liquid: Phosphoric acidPhosphoric 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 CEMENTSADHESION OF PAA-BASED CEMENTS
TO TOOTH STRUCTURETO 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 Cawith Ca++++
of hydroxyapatiteof hydroxyapatite
Beech DR (1973):Beech DR (1973):
StrongStrong ionic bondsionic bonds between polyacrylate andbetween polyacrylate and
surface Casurface Ca++++
of apatiteof apatite
22. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
ADHESION OF PAA-BASED CEMENTSADHESION 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 ofInitial adhesion is achieved by formation of
strong hydrogen bondingstrong hydrogen bonding, then, then replaced withreplaced with
ionic bondsionic bonds after a period of timeafter a period of time
Wilson et al. (1983):Wilson et al. (1983):
Polyacrylic ions enter the molecular structure ofPolyacrylic ions enter the molecular structure of
hydroxyapatite,hydroxyapatite, displacing and replacingdisplacing and replacing
phosphate ionsphosphate ions
23. CEMENTS BASED ON POLY-CEMENTS BASED ON POLY-
ACRYLIC ACIDACRYLIC ACID
ADHESION OF PAA-BASED CEMENTSADHESION 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 toBonding 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 intermediateFormation of intermediate layer of Carbonato-layer of Carbonato-
apatiteapatite between cement and dentinebetween cement and dentine
28. ZINC-POLYCARBOXYLATEZINC-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-POLYCARBOXYLATEZINC-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.
