1. Dental Cements: Liners, Bases, and Temporary Restoration Materials
DHYG 113
Restorative Dentistry I

2. Objectives Describe the purpose and use of:
Calcium hydroxide
Zinc phosphate
Glass ionomer
ZOE
Temporary cement
Recall approximate setting times for each
Demonstrate proper mixing techniques (lab activity)

3. Terminology Dental cement Base Pulp protection Liner Cavity sealer
Dentin bonding agent
Varnish
Base
Liner
Luting agent
Obtundant
Exothermic

4. Use of Dental Cements Luting agent = cement
Pulp protection = liner or base
Temporary restoration
Caries control
Cavity sealer = varnish
Dentin bonding agent

5. Chemistry of Dental Cements
Dental cements are typically a powder/liquid system
The liquid is an acid
The powder is a base
Powder must be insoluble in oral fluids but reactive with acid

6. Composition of powder
Two materials used to make powders for dental cements:
Zinc oxide
Powdered glass

7. Zinc oxide
The only insoluble, nontoxic, reactive oxide or hydroxide to react w/an acid
Common additives are aluminum oxide and magnesium oxide
Has some antibacterial effects
Reactivity is controlled by manufacturing process

8. The chemical form- silicon oxide - is very un-reactive
Powdered Glass
The chemical form- silicon oxide - is very un-reactive
When oxides of sodium, calcium and potassium are added in sufficient quantities, the glass will react with strong acid.
Made of small translucent glass particles
Contains fluoride to reduce melting temp, improve flow of molten glass, and gives cement ability to release fluoride.
Reactivity is determined by composition of glass.

9. Dental cement liquids Eugenol Phosphoric acid Polyacrylic acid
Composition or strength of acid determines reactivity of the cement liquid.
Composition is controlled by the manufacturer
Liquids used in dental cements include:
Eugenol
Phosphoric acid
Polyacrylic acid

10. Eugenol Organic liquid- weak acid Major component of oil of cloves
Derived from phenol
Antibacterial
Obtundant -- reduces irritation to pulp
Inhibits free radical polymerization
Inhibits setting of composite restorative materials
Ethoxybenzoic acid (organic liquid) added to formulate cements.

11. Phosphoric acid Used as 2/3 acid and 1/3 water
Very acidic and irritating to tissue
Amount of water present affects reactivity of liquid by affecting ionization.
Different levels of humidity affect it

12. Polyacrylic acid Aqueous solutions 30-50% polyacrylic acid by weight
Very viscous liquid
Dispensing
Must be very accurate – independent drops important
Do not dispense liquid until ready to mix cement
Do not store in refrigerator
Carboxyl groups bond to calcium in tooth
Water hardening cements
Zinc oxide or glass powder mixed with anhydrous polyacrylic acid
Combined powder mixed with companion liquid (mostly water)
Polyacrylic acid dissolves in water then reacts with ZO or glass

13. Dental cements Combine one of the three cement liquids…
Eugenol
Phosphoric acid
Polyacrylic acid
With one of the two powders
Zinc oxide powder
Glass powder

14. Most commonly used Calcium hydroxide Zinc phosphate
Used as a base/liner under restorations in deep preps
Used as for pulp capping
Zinc phosphate
Used to lute restorations, ortho bands – also used as a base material under restorations
Zinc oxide-eugenol (ZOE)
Chalky and white, used when not concerned with aesthetics.
Obtundant – kind to pulp
Glass ionomer
Used for thermal insulation under restorations, luting agent

15. Zinc Phosphate Cement Use B. Related Information
1. Lute inlays, crowns, bridges, ortho brackets, etc.
2. Also used as a base material under restorations.
B. Related Information
When the powder and liquid are mixed, an exothermic (heat-releasing) reaction occurs.
To dissipate the heat of this reaction:
1. A large portion of the glass slab must be used during
mixing.
2. The powder must be added in small increments.
3. The mixing time must extend to 1.5 to 2 minutes.

16. Zinc phosphate cement/base material
Mixing
Set up time is 5-9 min.
Add powder to liquid in small increments

17. Mixing for luting consistency
Measure the powder
Measure the liquid
“fluff powder”
Fill scoop; do not pack
Divide powder into several small
increments
Hold bottle vertically
Dispense correct # of drops of liquid
Add powder in small increments
Should stretch ½ inch

18. Glass ionomer Use 1. Base, luting agent, restorative material
2. Thermal insulating material in deep preps
Characteristics
1. High strength, low solubility
2. Kind to pulp
3. Chemically bond to tooth structure; release fluoride
Dispensing systems
1. Powder/liquid systems
2. Disposable capsules – mixed in amalgamator
3. Paste/paste systems

19. Mixing for base or luting
Higher power/liquid ratio
Mix
Measured in same manner
Setting time is ~ 7 min.
Mixing time between seconds
Add about ½ the powder at first, then the rest
Mix is determined by ratio set by manufacturer, not “feel”
Clean up with soap and water before cement sets

20. Liners Used to protect pulp from chemical irritation
Stimulate dentin formation or release fluoride
Considerations:
Do not provide thermal insulation (too thin)
Too weak to support restorative materials or condensation forces (dental amalgam)
Once used under composites to prevent irritation-not much anymore

21. Calcium hydroxide liners and bases
Promote the formation of secondary dentin
Comes as paste/paste system
One is calcium hydroxide, one is salicylate.
Titanium oxide is an added filter
Setting reaction is accelerated by water
Sets very quickly on moist dentin

22. Dycal (Calcium Hydroxide)
A. Use
Calcium hydroxide may be used in pulp capping and as a base/liner under other dental restorative materials in deep preparations.
B. Protective Properties
Calcium hydroxide serves as a protective barrier between tooth tissues (dentin and pulp) and acid-containing cements and restorative materials.
C. Measuring
Dispense small, but equal, amounts on a paper mixing pad
D. Mixing
Mix thoroughly with the crook of a small, ball-pointed instrument until a uniform color is achieved
Mixing should be completed within 10 seconds.

23. Calcium Hydroxide, con’t
E. Application
Use the tip of the ball-pointed instrument to place the mixed material on the floor of the cavity preparation. Avoid placing the mixed material on walls and margins, and avoid placing it in large amounts.
F. Setting
The setting time of mixed calcium hydroxide is 2 to 3 minutes on the mixing pad at normal room temperature.
The setting time for a pulp capping or base/liner will be greatly decreased in the mouth because of the moisture of dentin.

24. Cavity Sealer Resins dissolved in a solvent
Varnishes
Copal Varnish
Resins dissolved in a solvent
Painted onto entire cavity preparation
Solvent evaporates, leaving thin resin layer
Used under amalgams
NOT used with composites (interferes with adhesion)

25. Cements as Pulp Protectors

26. Zinc-oxide eugenol (ZOE)
Use
Protective properties
One of the least irritating dental materials
1. Temporary cement
2. Insulating base under
permanent restorations
3. Provide obtundant
filling for sensitive
tooth
Thermal trauma
Sedative, soothing effect on dental pulp

27. Measuring ZOE Use scoop provided by manufacturer
Powder
Liquid
Use scoop provided by manufacturer
Place 1 scoop of powder onto glass slab or paper pad
Dispense 2 drops of eugenol by holding dropper perpendicular to slab/pad
Drops should not touch powder, but should be near to it

28. Mixing ZOE cement Hold spatula in “flat” position
Draw about half of powder into liquid
Use small area of mixing slab/pad
Push powder into liquid with quick motion
Continue incorporating small portions of powder
Mix should be complete in 1.5 minutes
Sticky consistency – use for cementing temporary crown
Thick, putty-like consistency – use for base or temporary filling

29. Intermediate Restorative Material
Reinforced ZOE
IRM
Stronger, less soluble than ZOE
Temp restorations
Intermediate bases
Additives include:
Alumina
Resins

30. Mixing IRM Measure 2 scoops of powder onto glass slab/paper pad
Place 1 drop of liquid onto slab/pad
Hold spatula in “flat” position
Draw about ½ of powder into the liquid
Use small mixing area; spatulate with quick motion
Continue incorporating powder into the mix by pressing powder into the mix
Mix must be thick, putty-like
Complete mix in about 1.5 minutes

31. Application Gather IRM into one mass on the mixing slab/pad
May be rolled with fingers to form a ball
Use flat-bladed instrument to carry portions of material to the cavity prep
May dip instrument into excess powder to prevent sticking
Sets up in about 3 – 3.5 minutes
Glass slab may be cleaned with alcohol wipe

32. Temporary Cement High flow to permit ease of seating restoration
Temp Bond
Properties
High flow to permit ease of seating restoration
Strong enough to withstand forces of chewing
Allow restoration to be easily removed

33. Temporary Cement Two tubes Catalyst Base
Measuring
Mixing
Two tubes
Catalyst
Base
Squeeze equal lengths of material onto pad
Mix together in 30 sec.
Homogenous color
Should form a string when stretched from mixing pad
Apply thin layer to restoration, sets in 2 min.

34. Temporary Crown Temporary crown
Crown prep leaves an exposed tooth which can be painful.
Temp crowns usually made of plastics and formed in mouth.
Also made of metal or plastic formed outside of mouth.
Temporary cement used to apply temp crown.
Placed at crown prep appointment, lasts few days or weeks.

35. How Temporary Restorations are used:
Remove all or part or decay from tooth, then allow pulp to heal before determining treatment.
Patients with many carious lesions (more than 10) to make the oral environment noncariogenic
A temporary filling on an “open” tooth in endodontic therapy.

36. Exposure controls/personal protection with Eugenol
Respiratory protection: In well ventilated areas respiratory protection is not normally required. In confined, poorly ventilated area respiratory protection may be necessary
Hand protection: Wear impervious gloves
Eye protection: Wear eye protection. e.g. Safety glasses/goggles

37. What you need to know to stay safe
As with most dental materials …read the label and look for hazardous or toxic products in the materials
Be aware of potential for allergic reactions
Follow OHSA exposure limits

38. Generic and brand names of base materials
Bases:
Shofu base cement (Shofu)
Ketac bond capsules (ESPC)
Zinc Phosphate (Mizzy)
ZOE B&T (Caulk)- Eugenol-containing material

39. Generic and brand name Liners
Liners:Heavy filled glass ionomers:
Fuji IX GP in capsule or powder/liquid form.
ESPE: provisional filler, larger non-stress-bearing build ups
SHOFU
Light cured resin modified glass ionomer
Vitre-bond (3M)
Fuji Lining Cement LC (G-C)

40. Group Activity Divide up into 5 groups – about 4 to a group
Discuss the case study your group is given, and answer these
questions:
What material will you select for your patient?
Why did you select that material?
How will you mix/apply the material?
How long would you expect the material to last?