Dental Cements Chapter 45 1 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 1

Chapter 45 Lesson 45.1 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6

Fig. 45-1 Casting ready to be cemented. What type of restoration is being cemented? What tooth is involved? (Supply the number.) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11

Chapter 45 Lesson 45.2 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12

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) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14

Types of Cements Glass ionomer Composite resin Zinc oxide–eugenol Polycarboxylate Zinc phosphate Zinc oxide-eugenol is often referred to as ZOE. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23

Fig. 45-4 Examples of composite resin cements supplied in variable systems. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 31

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 32

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 33

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 34

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 35

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 36

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 37

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. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 38

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? Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved. 39