dh220 dental materials
TRANSCRIPT
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.
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Purpose:
- pulpal protection = insulating and/or sedative
- minimize the occurrence of secondary caries
- minimize post-operative sensitivity
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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