1. Dental Cements Chapter 45 1
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2. Chapter 45 Lesson 45.1
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3. Learning Objectives Pronounce, define, and spell the Key Terms.
Describe luting cements and differentiate between permanent and temporary cements.
Discuss the factors that influence luting cements.
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4. Introduction
Dental cements are a classification of dental materials that are routinely used in the placement of indirect restorations.
What are some examples of indirect restorations?
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5. Classification of Cements
Type I
Luting agents, which include permanent and temporary cements
Type II
Restorative materials, such as glass ionomers
Type III
Liners or bases placed with the cavity preparation
What is a luting agent?
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6. Luting Agent
Type I dental cements act as adhesives to hold together the casting and the tooth structure.
Luting agents are designed to be either permanent or temporary.
What type of restorations can be cemented permanently?
Why would a dentist cement a restoration temporarily?
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7. Fig. 45-1 Casting ready to be cemented.
What type of restoration is being cemented?
What tooth is involved? (Supply the number.)
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8. Permanent Cement
Permanent cement is used in the long‑term cementation of gold and ceramic restorations such as inlays/onlays, crowns, bridges, veneers, and orthodontic fixed appliances.
Most restorations are cemented permanently once they have been fabricated in the laboratory.
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9. Temporary Cement
Temporary cements are used if a restoration would have to be removed as a result of sensitivity or other symptoms, as well as for the temporary cementation of provisional coverage.
What is provisional coverage?
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10. Variables Affecting Cements
Mixing time
Before mixing, follow the manufacturer's directions.
Measure the powder and liquid according to the intended use.
Separate the powder and liquid to make space for mixing.
Divide the powder into increments.
When increment sizes vary, smaller increments are incorporated first.
Incorporate each powder increment into the liquid and then mix thoroughly. (Cont’d)
Each type of cement has its own mixing time.
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11. Variables Affecting Cements
(Cont’d)
Humidity
Premature exposure to warm temperatures or humidity can result in a loss of water from the liquid or addition of moisture to the powder.
Powder-to-Liquid Ratio
Incorporating too much or too little powder will alter the consistency.
Temperature
Some cements undergo an exothermic reaction.
Always dispense the powder first, then the liquid, to minimize the loss of water resulting from evaporation.
Always wait to dispense powder and liquid until you are ready to mix them.
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12. Chapter 45 Lesson 45.2
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13. Learning Objectives
List the five cements discussed in this chapter and identify their similarities and differences.
Mix and prepare glass ionomer for cementation.
Mix and prepare composite resin for cementation.
Mix and prepare zinc oxide-eugenol for cementation.
Mix and prepare two-paste zinc oxide–eugenol (Tempbond) for temporary cementation.
(Cont’d)
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14. Learning Objectives Mix and prepare polycarboxylate for cementation.
(Cont’d)
Mix and prepare polycarboxylate for cementation.
Mix and prepare zinc phosphate for cementation.
Remove cement from permanent and temporary cementations.
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15. Types of Cements Glass ionomer Composite resin Zinc oxide–eugenol
Polycarboxylate
Zinc phosphate
Zinc oxide-eugenol is often referred to as ZOE.
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16. Glass Ionomer Chemical makeup
Liquid: itaconic acid, tartaric acid, maleic acid, and water
Powder: zinc oxide, aluminum oxide, and calcium
Adheres to enamel, dentin, and metallic materials.
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17. Types of Glass Ionomer Type I Type II Type III
For the cementation of metal restorations and direct‑bonded orthodontic brackets
Type II
Designed for restoring areas of erosion near the gingiva
Type III
Used as liners and dentin-bonding agents
Available in self-curing and light-curing formulas.
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18. Benefits of Glass Ionomer
Powder is an acid‑soluble calcium. The slow release of fluoride from this powder helps inhibit recurrent decay.
Glass ionomer causes less trauma or shock to the pulp than do many other types of cements.
Glass ionomer has a low solubility in the mouth.
It adheres to a slightly moist tooth surface.
It has a very thin film thickness, which is excellent for seating ease.
If glass ionomer is light-cured, what additional equipment will need to be used?
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19. Supply of Glass Ionomer
Type I (powder/liquid)
Mixed manually on a paper pad or a cool, dry glass slab (slab increases the working time of the cement)
Type I (premeasured capsules)
Triturated and expressed through a dispenser.
Will a cool glass slab decrease or increase the working time?
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20. Fig. 45-3 Premeasured capsules of glass ionomer permanent cement.
Advantages of capsules:
Convenience
Decreased mixing time
Consistent mixes because of controlled ratios
What additional equipment will need to be used for capsules?
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21. Composite Resin Chemical makeup
Physical properties comparable to those of composite resins
Low film thickness (thinner in consistency than composite resins)
Insoluble in the mouth
What does insoluble mean?
The tooth must be free of plaque and debris before being etched.
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22. Uses of Composite Resin
Cementation of ceramic or resin inlays and onlays.
Cementation of ceramic veneers.
Cementation of orthodontic bands.
Direct bonding of orthodontic brackets.
Cementation of all metal castings.
Is etching necessary?
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23. Supply of Composite Resin
Powder and liquid mix
Syringe-type applicator
Base and catalyst
Light-cure/dual-cure system
Recommended portions of either application are dispensed onto a paper pad and mixed rapidly with the use of a spatula.
Composite resin is used for veneers.
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24. Fig. 45-4 Examples of composite resin cements supplied in variable systems.
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25. ZOE
Chemical makeup
Liquid: eugenol, H2O, acetic acid, zinc acetate, and calcium chloride
Powder: zinc oxide, magnesium oxide, and silica
What effect does eugenol have on the pulp?
ZOE has a pH close to 7.0, making it less acidic than other cements.
Smells like cloves.
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26. Types of ZOE Type I Type II
Lacks strength and long‑term durability and is used for temporary cementation of provisional coverage
Type II
Has reinforcing agents added for the permanent cementation of cast restorations or appliances
What is provisional coverage?
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27. Fig. 45-5 ZOE type I cement for temporary cementation.
This photo is an example of two-paste system.
Dispense equal amounts from each tube but leave room on the paper pad to mix them together.
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28. Fig. 45-6 ZOE type II cement for permanent cementation.
This is an example of a powder/liquid system.
Dispense powder on one side and liquid on the other side of the paper pad or glass slab.
Be sure to follow the manufacturer’s instructions for measurement and mixing.
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29. Supply of ZOE Type I (paste) Type II (liquid/powder)
Supplied as a two‑paste system as temporary cement
Pastes dispensed in equal lengths on a paper pad and mixed
Type II (liquid/powder)
Mixed on an oil‑resistant paper pad
Mixing time of 30 to 60 seconds
Setting time in the mouth of 3 to 5 minutes
Both systems are mixed on an oil-resistant paper pad; the pad will not absorb the liquid.
When a slower set is required, a glass slab is used.
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30. Polycarboxylate Cements
Chemical makeup
Liquid: polyacrylic acid, itaconic acid, maleic acid, tartaric acid, and water
Powder: zinc oxide
Polycarboxylate cement is also known as polyacrylic cement.
Can be used as a nonirritating base under composite and resin restorations.
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31. Use of Polycarboxylate
Permanent cement for cast restorations, stainless-steel crowns, and orthodontic bands
As a nonirritating base under both composite and amalgam restorations
As an intermediate restoration
Polycarboxylate is less irritating to tooth pulp than zinc phosphate cement.
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32. Supply of Polycarboxylate
Powder/liquid
Liquid may be measured with the use of either a plastic squeeze bottle or a calibrated syringe‑type liquid dispenser.
The liquid has a limited shelf life because it thickens as its water evaporates.
Mixing is carried out on a nonabsorbent paper pad.
What would be used if a longer working time was needed?
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33. Fig. 45-7 Powder and calibrated syringe of polycarboxylate cement.
This product is usually mixed on a paper pad.
The liquid part of the product comes in a syringe.
Do not dispense liquid until you are ready to mix the cement.
Could you mix the cement on a glass slab? Why would you do this?
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34. Zinc Phosphate Chemical makeup
Liquid: phosphoric acid, aluminum phosphate, and water
Powder: zinc oxide, magnesium oxide, and silica
Zinc phosphate is the oldest cement used in dentistry.
Is zinc phosphate a permanent or temporary cement?
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35. Types of Zinc Phosphate
Type I (fine grain)
This type is used for the permanent cementation of cast restorations such as crowns, inlays, onlays, and bridges. It provides the very thin film layer necessary for accurate seating of castings.
Type II (medium grain)
This type is recommended for use as an insulating base for deep cavity preparations.
Phosphoric acid can be irritating to the tooth pulp.
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36. Supply of Zinc Phosphate
Type I (powder/liquid)
Powder is divided into increments of varying sizes.
It is critical that the powder be added to the liquid in very small increments.
The cement must be spatulated slowly over a wide area of a cool, dry, thick glass slab to dissipate the heat.
What does dissipate mean?
Powder and liquid should be dispensed just before being mixed.
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37. Fig. 45-8 Zinc phosphate type I cement for permanent cementation.
Dispense the powder at one end of the slab and liquid on the other; mix them in the middle.
Is the mixing process (1) add powder to liquid or (2) add liquid to powder?
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38. Cement Removal Operator preparedness and knowledge
The procedure requires certain instruments:
Explorer, mouth mirror, excavator
Use a fulcrum.
Use dental floss in and around the embrasure areas.
If excess cement is not removed, what could happen to the gum tissue?
The floss is usually knotted.
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39. Fig. 45-9 Excess cement must be removed after the setting process.
Wait to remove cement until the initial setting is complete.
Who can remove cement from a permanent restoration?
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