Temporary crown and Impression for crown- power point

Temporary crown and Impression for crown
Temporary crown and Impression for crown

Dr
Dr, Ameer
, Ameer Hamdi
HamdiAL
AL-
-Ameedee
Ameedee

Ph.D
Ph.DEsthetic and Operative Dentistry
Esthetic and Operative Dentistry


Temporary Crown:
Temporary Crown:

A fixed prosthesis, designed to protect, enhance esthetics, stabilization and function
for a limited period of time, after which it is to be replaced by a definitive crown.


CLASSIFICATION:
CLASSIFICATION:

1-DEPENDING ON THE METHOD OF FABRICATION:

a-Custom made provisional restoration.

b-Prefabricated provisional restoration.

2-DEPENDING ON THE MATERIALS:

a-Polycarbonate.

b-Cellulose acetate.

c-Aluminiumand tin-silver.

d-Nickel-chromium.

3-DEPENDING ON THE TIME USED:

a-SHORT TERM ----for few days (upto2 weeks) ( e.g. ----Polycarbonate or aluminum
crowns ).

b-MEDIUM TERM ----for few weeks ( > 2 weeks) ( e.g. ----resin based provisionals).

c-LONG TERM ----for months ( e.g. ----mostly cast metal crowns).


TYPES:
TYPES:

1.Pre-formed crowns (made of plastic or metal):

a-Self cured resins.

b-Light cured resins.

c-Composites resins.

d-Heat cured acrylic resin.

e-Cast metal.

f-Fiber reinforced composite resins.

2
2.Pre
.Pre-
-formed crowns proprietary shells:
formed crowns proprietary shells:

a-Come in a series of sizes.

b-Usually need considerable adjustment marginally proximally and occlusally.

c-Plastic shells as polycarbonate or acrylic.

d-Metal shell as aluminum, stainless steel or nickel chromium.


4.Preformed metal crowns Aluminum shells:

a-Provide quick tooth adaptation due to the softness and ductility.

b-Rapid wear that results in perforation in function and/or extrusion of teeth.

c-An unpleasant taste Iso-Form Crowns (3M Dental Products).

d-Manufactured with high-purity tin-silver and tin-bismuth alloys.

e-Suitable ductility and can be contoured quickly.

f-Occlusal table is reinforced so they are more resistant to wear related failure

3
3.Polycarbonate resin crowns:
.Polycarbonate resin crowns:

a.Polymethylmethacrylate materials.

b.Crownscombine micro glass fibers with a polycarbonate plastic material.

c.Highimpact strength.

d.Highabrasion resistance.

e.Highhardness.

f.Agood bond with methyl-methacrylate resin.

.


REQUIREMENTS:
REQUIREMENTS:

1-Biological requirement:

a. Pulpal protection.

b. Periodontal health.

c. Occlusal compatibility and tooth position.

d. Prevention of enamel.

2-Mechanical requirement:

a. Resist functional loads.

b. Resist removal forces.

c. Maintain interabutmentalignment Restore.

3-Esthetic requirement:

a. Tooth contour.

b. Color.

c. translucency.

d. Texture.


FUNCTIONS:
FUNCTIONS:

1.Comfort/Tooth vitality: Essential to cover freshly cut dentine and prevent sensitivity,
plaque buildup, and subsequent caries and pulp pathology. It also sedate prepared
abutments.


2. Occlusion and Positional Stability: To prevent unwanted tooth movement.

3. Function.

4. Gingival Health and Contour: To facilitate oral hygiene and prevent gingival overgrowth.

5. Aesthetics.


To assess the effect of aesthetic and occlusal changes:

1) Calipers may be used to test the thickness of a provisional restoration to
ensure sufficient tooth preparation to accommodate the proposed restorative
material.

2) A provisional restoration may be used to provide a coronal build up for
isolation purposes during endodontic treatment.

3) Long-term provisional restoration may also be advisable to assess teeth of
dubious prognosis.

4) A provisional restoration may find a use as a matrix for core build ups in
grossly broken down teeth, by removing the coronal surface to allow
placement of restorative material.


5) Proposed changes to the shape of anterior teeth are best tried out with
provisional restorations to ensure patient acceptance, and, approval from friends
and family.

6) A patient’s tolerance to changes in anterior guidance or increased occlusal
vertical dimension is best tried out with provisional restorations.

7) Long-term wear of properly fitting and contoured provisional restorations
allows the health of the gingival margin to improve and its position to stabilize
before impressions are recorded for definitive restorations.

8) Altered function can be assessed (fine mouth movements and lip/tooth contact
required for speech production or sound generation in the case of a musical
instrument).

To assess the effect of aesthetic and occlusal changes:


IMPRESSION:

History:

.Philip P. 1756, First described taking impression with softened wax.
.Christopher F. 1820, Introduced the metal impression tray.
.Chapin H. 1853, First used Plaster of Paris for making impressions.
.Charles S. 1857, Introduced the first impression compound.
.Sears A. 1937, First used agar hydrocolloids for recording crown impressions.
.United States-1945, Introduced alginate during World War II.
.Pearson S. 1955, Developed synthetic rubber base impression materials
Polysulfide.
.Late 1950’S, First developed as an industrial sealant.
.Condensation Silicone-Early 1960’s.
.Addition Silicone-1970’s.
.Polyether-Late 1970’s.
.Polyether Urethane Dimethacrylate-Late 1980’s.



TERMINOLOGIES:

IMPRESSION:A negative likeliness or copy in reverse of the surface of an
object; an imprint of the teeth and adjacent structures for use in dentistry.

IMPRESSION TRAY :A receptacle into which suitable impression material is
placed to make a negative likeliness (or) a device that is used to carry, confine,
and control impression material while making impression.

IMPRESSION MATERIAL: Any substance or combination of substances used
for making an impression or negative reproduction.

IMPRESSION TECHNIQUE:A method and manner used in making a negative
likeness.


1) Complete plasticity before cure.

2) Sufficient fluidity to record fine detail.

3) The ability to wet the oral tissues.

4) Dimensional accuracy.

5) Dimensional stability.

6) Complete elasticity after cure.

7) Optimal stiffness.

8) Nontoxic.

Properties of an ideal impression:


Impression materials used in Fixed partial denture:

1)-Hydrocolloid impression material:

a) Reversible hydrocolloid.

b) Irreversible hydrocolloid.

2)-Elastomeric impression materials:

a) Polysulfide.

b) Addition silicone.

c) Condensation silicone.

d) Polyether Dimethacrylate.


Impression Techniques:

1. Stock tray technique:

a -Double mix.

b -Single mix.

2. Custom tray technique:

a -Single mix.

3. Closed bite double arch technique.

4. Copper band technique.

5. Reversible hydrocolloid technique:

a -Laminate Technique.

b -Wet Field Technique.

6. The matrix system.


Impression step techniques:

1. One step technique:

Impression material with one type of viscosity (mostly: medium viscosity
material) e.g. polyether.

2. Two steps technique:

Impression material with two viscosities (light and heavy consistency) we
mix separately the two types at the same time. The light body type is loaded in
the impression syringe; on the other hand the heavy body is loaded to the special
tray.

3. Putty wash technique:

Impression material with two viscosities (light and heavy consistency) we
mix the heavy body type, we remove the impression after it set inside the patient s
mouth after completion of the preparation we start to mix the light body.


EVALUATING FINAL IMPRESSION:

1-Elastomeric material should be present 0.5 mm beyond visible finish line.

2-Note presence of bur marks, the junction of smooth root surface, and
continuous finish line.

3-There should be no shiny smooth areas; if present, they suggest moisture
contamination.

4-There should be no tray shows though in any areas of the impression except
at tissue stops.

5-There must be no voids or no air bobbles present, they suggest mixing
problems or contamination.

6-There should be no thin areas leaving the finish line unsupported. These
areas distort under the weight of the stone.


Thank you