DH220 Dental Materials

Lecture #2

Prof. Lamanna RDH, MS

Restorative Dentistry

Intermediary Materials:

Dental Cements

Review

Chapters 44 & 45 Bird & Robinson

The tooth is prepared and an intermediary

material is placed.

What is the purpose of placing intermediary materials? Answer

Where are intermediary materials placed? Answer

Next

A. Which of Black’s

Classification is this

caries? B. Which of Black’s

Classification are

these preparations?

1 2

3

Answer

Answer

A. Class II - posterior interproximal surface(s)

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B. 1. Class II - posterior interproximal surface(s)

2. Class I - pits & fissures

3. Class I - pits & fissures This is a buccal pit – not Cl V at cervical third.

Return

Purpose:

- pulpal protection = insulating and/or sedative

- minimize the occurrence of secondary caries

- minimize post-operative sensitivity

Return

Intermediary materials are placed between the

tooth and restorative material.

Example 1- #30 base

Example 2 - #30 luting agent

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Varnish 1. Composition: resin = natural

or synthetic

2. Use: seal dentinal tubules, prevent

chemical irritation to the pulp, and

migration of metallic ions.

3. Application: 2 thin coats

4. Location: floor & walls in prep.

5. Special characteristics:

- Rapid evaporation due to solvent; during use

the cap must be replaced immediately.

- Easily abraded, negating functional purpose.

- Should not be used with composite or resin

restoration; inhibits proper curing.

Liner 1. Composition: Ca(OH)2*, ZOE, GI

2. Use: prevent bacterial invasion;

chemical irritation; pulp cap - *Ca(OH)2

only.

3. Application: thin layer

4. Floor of prep, dentin only

5. Special characteristics:

Ca(OH)2 – 1. bacteriostatic – inhibits bacterial spread

2. ↑ pH (11) – stimulus for 2° dentinal formation

3. ↑ solubility – used only in the deepest portion

of the cavity prep. – closest to the pulpal horn

4. compatible with ALL restorative materials

Glass Ionomer – 1. releases fluoride for therapeutic advantage

(anticariogenic effect)

2. direct (chemical) adhesion to enamel, dentin, and

cementum.

3. radiopaque

ZOE – 1. non-irritating to pulp – eugenol has a soothing (obtundent)

effect on the pulp.

2. not utilized as a direct pulp cap – eugenol in a high

concentration can be toxic to the pulp.

3. not used under composite restor. – interferes with polymerization.

Base 1. Composition: ZOE, GI,

ZOP, Zinc Polycarboxylate

2. Use: thermal/elect. insulator,

replacement for missing

dentin, mechanical support

for restoration

3. Application: Thick layer

4. Location: floor of prep,

dentin only.

base

5. Special characteristics:

ZOP - 1. Acidic cement – chemical irritant to the pulp – used in conjunction

with calcium hydroxide liner in deep cavities (< 1mm dentin remaining)

2. very specific mixing technique:

• mixed by increments (cut into several sections of powder)

• allows for exothermic reaction (release of heat)

Zinc Polycarboxylate –

1. direct (chemical) adhesion to enamel, dentin, and cementum.

2. polyacrylic acid – not as irritating to the pulp as phosphoric acid

3. not as strong as ZOP

Varnish, Liner, & Base Application

varnish

base

liner

*if pulpal

exposure –

Ca(OH)2 only

as pulp cap

*

Cement 1. Composition: ZOE, GI, ZOP,

Zinc Polycarboxylate, and

Resin cement

2. Use: luting agent

3. Application: runny, loose

4. Location: inside crown, bridge,etc.

5. Special Characteristics:

Resin cement:

1. material of choice for luting.

2. requires use of etching agent.

3. mechanical retention to enamel

by acid-etch technique

p. 94

Maryland Bridge

1. Facial view of bridge

2. Lingual view – luted

with resin cement

1

2

pontic

1

Weakest point of a crown is the margin.

Always carefully evaluate the margin for

washout when dental charting your

patients.

Marginal washout

Identify the following intermediary materials:

liner, base, or luting agent.

1

2

Answer

3

1. Base

2. Luting agent

3. Calcium hydroxide liner on deep dentinal areas.

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Composition: ZOE, ZOP, Zinc Polycarboxylate,

GI, and Resin Cement ** Use the bottom of page 8 or a separate piece of paper**

Differences between these

materials??????

1.

2.

3.

Temporary & Interim Restorations I. Temporary Restorations –

A. Use: - provisional for short term – days, weeks.

- pulpal healing for determination of treatment (ie: endo.)

- fabrication of lab work.

B. Material: - ZOE – obtundent effect ** not used if composite is placed!!!

- GI, ZOP, etc. WHY??

Answer

Answer:

Eugenol prohibits the polymerization (curing) of

composite restorative material.

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II. Interim Restorations –

A. Use: - provisional for long term – months, up to a year.

B. Material:

- preformed crowns

– stainless steel or aluminum

- crowns & bridges

– acrylic (polymer)

Periodontal dressing

1. Use: patient comfort from possible injury after

surgery, undisturbed healing, reduce possibility of

2º bleeding & infection, and acts as a splint.

2. Composition: zinc oxide & non-eugenol paste -

most commonly used material.

3. Handling: Lab

4. Placement: Lab

5. Ingredients: any item

listed cause concern??

(p. 7 in typed handout)

1. Before surgery

4. After surgery

2. 3.

Placement and removal

of dressing

Mixing Technique Reference Lab & separate handout

given in class.

ZOP

Glass ionomer -pull test for luting

consistency

ZOP – mixed for a base

consistency

Mixing & handling guidelines – see separate handout given in class.

Just a few -

** Go to the handout for special characteristics

of each material then…

It’s show time……mixing dental cements.

Mixing Glass Ionomer Mixing ZOP