DENTAL CEMENTS

:

2007/2008

Applications of Dental Cements:

Cementing agent for permanent restorations.Temporary restorations.Liners and bases.Cementing agents for orthodontic appliances.Periodontal dressing.Root canal fillers and sealers.Pulp capping agents.Anterior restorations.

2007/2008

Requirement of Dental Cements

Adequate mechanical properties.Non-irritating & non-toxic.Insoluble.Insulating the pulp from thermal, electrical and chemical irritants.Adhesive properties.Esthetic properties.Easy to manipulate.

2007/2008

Types of Dental Cements:1- Cements based on Zinc Oxide.2- Cements based on Alumino Silicate Glasses ( Ion leachable glasses ). 3- Other cements:

Resin cements.Calcium – Hydroxide cements.Cavity liners and Varnishes.

2007/2008

Zinc Oxide

1- Cements based on Zinc Oxide

Eugenol Phosphoric acid Polyacrylic acid

Zinc oxide eugenol cement

Zinc phosphate cement

Zinc polycarboxylatecement

2007/2008

2- Cements based on Alumino Silicate Glasses.

Phosphoric acid Polyacrylic acid

Alumino-Slicate Glass

Slicate cements Glass-ionomer cements

2007/2008

Zinc Oxide Eugenol Cement .

Composition

Powder Liquid

-Zinc Oxide 69.0% .-Magnesium Oxide 10% .-White Rosin 29.3%- Zinc Stearate 1.0%-zinc Acetate 0.7%.

-Eugenol 85.0%-Olive Oil 15.0%

2007/2008

Properties of ZOE:1- Working and Setting time.2- Film thickness.3- Solubility and disintegration.4- Strength.5- Biological properties.6- Bonding to enamel and dentin.

2007/2008

Modified Zinc Oxide EugenolCements.

1- Polymer reinforced cement (Resin bonded cement).

Powder :80% Zinc oxide .20%Polymethyl methacrylate.

Liquid :10% polystyrene dissolved ineugenol .

2007/2008

Modified Zinc Oxide Eugenol Cements

•2- E.B.A.cement.Powder :

70% Zinc oxide30% Alumina .

Liquid :37.5%Eugenol.62.5%Ethoxy benzoic acid .

2007/2008

Zinc Oxide Eugenol Cement .Uses :

1- Temporary filling.2- Temporary luting agent .3- Insulating base .4- Root canal sealer.5- Periodontal and surgical

dressing. 6- Permanent cementation.

7-Gingival tissue pack.

2007/2008

Zinc Phosphate Cement.Composition

Powder Liquid

-Zinc Oxide (ZnO) 90% .

-Magnesium Oxide (MgO) 10%.

-Silicon dioxide (SiO2) 1.4%.

-Bismuth trioxide (Bi2O3) 0.1%.

.

-Orthophosphoric acid (H3PO4) 40 %.

-Aluminum and Zinc oxide.

- Water (H2O) 33%.

2007/2008

Setting Reaction of Zinc Phosphate Cement.

ZnO+2H3PO4 Zn(H2PO4) +H2O

2007/2008

Manipulative variables:

The heat of reaction is most effectively dissipated when the cement is mixed over large area of cooled glass slab.

2007/2008

Manipulative variables:Initially mix small amounts of powder with the liquid, then larger amount is incorporated,and finally smaller amounts are incorporated…..desired consistency.The liquid is kept in a tightly closed bottle .

2007/2008

Properties of Zinc PhosphateCement:

1-Viscosity.2-Consistency and film thickness.3-Strength.4- Solubility.5-Bonding.6-Thermal and electrical conductivity .7-Biological properties.

2007/2008

Consistency and film thickness

Then consistency ( Inlay seating consistency)…….25µm.Particle size of the powder.Powder to liquid ratio.Pressure applied during seating.

Thick Consistency ( Cement base)

2007/2008

Zinc Phosphate Cement

Uses:1- Luting agent.2- Insulating base.3- Temporary filling material.

2007/2008

Zinc Phosphate Cement

Easy to mix.Sufficient mixing and working time.High compressive strength.

Irritant to the pulp.Brittle.No adhesive qualities (mechanical interlocking)Susceptibility to acid attack.

Advantages: Disadvantages:

2007/2008

Zinc Polycarboxylate Cement (Zinc Polyacrylate Cement)

Composition

Powder Liquid

-Zinc Oxide.

-Magnesium Oxide.

-Alumina, Silica, Fluoride &

Stainless steel fibers.

-Polyacrylic acid.

-Sodium hydroxide.

-Tartaric acid .

2007/2008

Setting Reaction of Zinc Polycarboxylate Cement

ZnO + Polyacrylic Acid Zinc polacrylate+ ZnO

2007/2008

Manipulation:

The proper powder /liquid ratio mixed on paper bad (1:1 or 2:1)Dispensing of the liquid should be done immediately before mixing.Cooled glass slap to extend working time. The consistency of the mix is creamy .

2007/2008

Manipulation:The Viscosity decreases as the shear rate increase,i.e.the flow increases as the spatulation increases

Should be used only as long as it still has a glossy surface.

2007/2008

Zinc Polycarboxylate Cement

Cementation of crowns and inlays.Base under restorations .

Uses :

2007/2008

Properties of Zinc Polyacrylate Cements:

1-Film thickness.2-Strength. 3-Solubility and disintegration.4- Bonding.5-Biological properties.

2007/2008

Glass Ionomer CementComposition

Powder Liquid

- Calcium fluoroalumino silicate glass .

- Barium glass or zinc oxide.

-Polyacrylic acid copolymer with itaconic, maleic, or tricarboxylic acid.

- Tartaric acid.

2007/2008

Setting Reaction of Glass Ionomer Cement:

Dissolution .

Gelation

Hydration

2007/2008

Unreacted glass particles.

Silica hydrogel sheath .

Amorphous matrix of cross- Linked polysalt hydrogel of Ca++&Al+++.

The structure of the set GIC

2007/2008

Types of GIC :

Type I :Luting cement for crowns and inlays.

Type II :Restorative material

Type III :Liner or base material.

2007/2008

Manipulation:The proper powder/liquid ratio is dispensed onto paper pad or glass slab,mixed for30-60 sec.Encapsulated products are mixed for 10 sec.in mechanical mixer.An extension of the working time to 9 minutes can be achieved by mixing on a cold slab.The cement should not be used once a “skin” forms on the surface or when the viscosity increases noticeably.

 

2007/2008

Manipulation: Once the cement has achieved its initial set (about 7 minutes), the cement should be coated with the coating agent supplied with the cement.

 

2007/2008

Properties of GIC:1- Working and setting time.2- Mechanical properties:3- film thickness.4- solubility and disintegration .5-Bonding.6-Fluoride release. 7- Biological properties.

2007/2008

Glass Ionomer Cement

Adhesion to tooth structure.

Biocompatibility. High compressive

strength. Low solubility.

Technique sensetive

Moisture sensitivity.

Short working time and long setting time.

Low abrasion resistance.

Brittlness.

Advantages Disadvantages

2007/2008

Modification of GIC :

A. Metal Reinforced GIC .1. Silver alloy admix.2. Cermet cement.

B. Hybrid Ionomer (Resin-Modified GIC)

Dual cure . Tricure .

C. Compomer (Polyacid modified resin composite materials ).

2007/2008

Properties of Resin-Modified GIC :

1. Superior mechanical properties.2. Better optical properties.3. Prolonged working time and rapid set.4. Adhesion to tooth structure.5. Less moisture sensitivity.6. Polymerization shrinkage. 7. Microleakage.

2007/2008

Applications of Resin-Modified GIC :

1) Restoration.2) Liners and bases.3) Fissure sealants.4) Core buld up.5) Cementation of orthodontic brackets.6) Retrograde root filling material.

2007/2008

Resin Cements

2007/2008

Types of resin-based cements

Self cure or auto-cure resin cements.

Light cure resin cements.

Dual-cure resin cements.

2007/2008

Properties:

1. Insoluble in oral fluids.2. Low viscosity.3. Then film thickness (<25µm).4. Easily manipulated.5. Early setting.6. Good bond strength to dentin.7. Radiopacity.8. High wear resistance.9. Low polymerization shrinkage.10. Biological compatibility.

2007/2008

Applications:Resin-bonded bridges.All-ceramic crowns.Ceramic inlays and onlays.Composite inlays and onlays.Orthodontic ceramic brackets.Porcelain laminate veneers.Porcelain repair. Metal base denture.Implants.Endodontic posts.

2007/2008

Presentation:Calcium Hydroxide Suspension.Two-paste system (chemically

cured).One-paste system (light cured).

Calcium Hydroxide Cements

2007/2008

Calcium Hydroxide Cements

Paste 1Calcium hydroxide.Zinc oxide .Zinc stearate..Ethyl toluene sulphonamide.

Paste 2Glycol salicylate.Titanium dioxide.Calcium sulphate.Calcium tungstate.

2007/2008

Properties of Calcium Hydroxide:

The freshly mixed cement is alkaline with a pH of 11-12 .Compressive strength, tensile strength and elastic modulus are low.Highly soluble.

2007/2008

Cavity Liners and Varnishes :

Cavity Liner :Suspension of calcium hydroxide and

some zinc oxide in a solution of natural or synthetic resin .

2007/2008

Cavity Varnishes and Liners:

Cavity Varnish:Solution of natural gum(copal) ,rosin,

or synthetic resin dissolved in an organic solvent such as acetone, chloroform or ether.

2007/2008

Applications :To seal the dentinal tubules and prevent penetration of chemicals into the pulp.To act as a temporary protection against the loss of constituents from the surface of a filling material.To seal the dentinal tubules under amalgam restorations and prevent penetration of metallic ions and corrosion products into enamel and dentin.

Effect on pulp - pH

Solubility Strength Film Thickness Adhesion to tooth

ZOE Not irritant- 7

Highly soluble 15 40 mµ mechanical

ZOE Not irritant- 7

soluble 38 40 mµ mechanical

ZOE Not irritant- 7

soluble 90 40 mµ mechanical

Zinc phosphate Irritant 1.5-.3.5

0.3 % Less soluble

100-135 5 MPa

25 mµ mechanical

Zinc polycarboxylate

Less irritant 1. 0.2 % 90 MPa15 MPa

25 – 40 mµ Chemical

Glass Ionomer Less irritant 0.3 % 100-135 5 MPa

25 mµ Chemical

Resin cements irritant insoluble 25 mµ bond

Calcium hydroxide

Not irritant- 12

weak Liner

Cavity varnishes liner