3. 1st in a relatively small deciduous teeth
neglected carious can destroy tooth’s
integrity faster than in large teeth in
permanent dentition.
2nd the deciduous teeth pulp is larger
than permanent pulp whereas the
enamel and dentin is less in thickness,
thus it is difficult to make dentinal stump
for a gold casting or to use a pin system
of retention for more extensive amalgam
restoration.
4. 1.
2.
3.
It has respect to life span, replacement,
retention and resistance.
They are acceptable by both patient
&dentist.
They are also more cost effective
because of comparatively simple
procedures in restoring.
5. To achieve biological compatible
,competent for mastication .
To maintain the form and function and
when possible the vitality of the teeth to
be maintained .
6. Untrimmed crowns: e.g. Rocky mountain
2. Pretrimmed crown: straight, non contoured
sides but are festooned to follow a line
parallel to the gingival crest, e.g. (Unitek
stainless steel crowns, 3M Co., and Denvo
crowns, Denvo Co. Arcadia, CA).
3. Precontoured crown : festooned and
precontoured, (e.g. Ni-Chro Ion crowns
and Unitek stainless steel crowns and 3M
Co.).
1.
8. Stainless Steel Crowns
17-19% chromium
10-13% nickel
67% iron
4% minor element
• These crowns are available in various sizes.
• Mostly these crowns are used in posterior teeth
which undergone pulp therapy.
9.
Nickel – base Crowns
72% nickel
14%chromium
6-10% Iron
0.04% carbon
0.35% manganese
0.2% silicon
• The alloys have good formability and ductility
necessary for clinical adaptation of crowns and
wear resistance to resist opposing occlusal forces.
10. Extensive decay in primary & young permanent teeth.
2. For teeth deformed by developmental defects or
anomalies.
3. For teeth with hypoplastic defects.
4. Following pulp therapy.
5. As preventive restoration.
6. As an abutment.
7. Temporary restoration of a fractured tooth.
8. In sever cases of bruxism.
9. Single tooth crossbite.
10. For replacing prematurely lost anterior teeth.
1.
11. Dental age of the patient.
2. Cooperation of the patient.
3. Motivation of the parents.
4. Medically compromised/disabled child.
1.
12.
•
•
•
Evaluate the preoperative occlusion
Take the alginate impression of U/L jaws.
Pour the cast with dental stone
Note the dental midline and the cusp fossa relationship
bilaterally
Selection of crown
•
The correct size crown is selected by the M-D
dimensions of the tooth to be restored using Boley
gauge.
To produce steel crown margins of similar shape
examine the contour of gingiva of the buccal &
lingual marginal gingiva.
•
14.
Occlusal reduction
A 69L or 169L bur is used to reduce the occlusal
surface by 1.5-2.0mm .
Proximal slices
place the wooden wedges in the interproximal
embrasures, the 69L bur is moved B-L acrossthe
proximal surface.
Buccolingual reduction
Round off all the line angles
It is done by using side of bur.
16.
Two principles related to SSC length and margin
shape that are based on an understanding of the
tooth morphology and gingival tissue contours were
presented by Spedding 1984
The crown should be of a correct length and its
margins should be adapted closely to the tooth.
For shaping the crown margins mark 3 light points on
the metal at the (mesiolingual, lingual and
distolingual)and at (mesiobuccal, buccal,
distobuccal) surfaces at the crest of respective
marginal gingiva without compressing the marginal
gingiva.
Final finished margins are placed approximately 1mm
below these marks.
17. Now the crown is tried on the preparation
by seating the lingual first and applying
pressure in a buccal direction so that the
crown slides over the buccal surface into
the gingival sulcus.
Resistance should be felt as the crown slips
over the buccal bulge.
18.
Initial crown contouring is performed with a 114
plier in the middle 1/3rd of the crown to produce a
belling effect.
This will give the crown a more even curvature.
Crown crimping
The tight marginal fit aids in:
1. Mechanical retention of the crown.
2. Maintenance of gingival health.
3. Protect of cement from exposure to oral fluids.
20. The crown should be replaced on the
preparation after the contouring
procedure to see that it snaps securely into
place.
The occlusion should be checked at this
stage to make sure that the crown is not
opening the bite or causing a shifting of
mandible into an undesirable relationship
with opposing teeth.
21. Accumulation of plaque and inflammation
of gingiva is commonly seen in practice of
restorative dentistry due to rough and
unpolished restoration.
To avoid these complications crown should
be polished prior t o cementation with
rubber wheel to remove all scratches.
23. SSC should be cemented
only on clean dry mouth, isolation of
teeth with cotton roll is recommended.
Rinse and dry the crown inside & out side
and prepare to cement it.
A zinc phosphate, polycarboxylate or
GIC is preferred.
24. Before the cements set ask the patient to close
into centric occlusion by applying pressure
through a cotton roll and confirm that the
occlusion has not been altered.
Remove the excess cement by an explorer or
scaler & for interproximal area can be cleaned
by passing dental floss through them.
26.
Quadrant dentistry ( Nash, 1981)
-Prepare the occlusal reduction of one tooth completely
before beginning the other as there is tendency to under
reduce both when reduction on them is done at the same
time.
-Reduce the adjacent proximal surface of the teeth being
restored more than when only one tooth is restored.
-Both crown should be trimmed, contoured and prepared
before cementation simultaneously to allow for
adjustment in inter proximal space and establish proper
contact area.
Crown in area of space loss(Mc - Evoy 1977)
Preparing a SSC adjacent to a class II amalgam (Mc - Evoy 1985)
27.
1.
2.
3.
4.
5.
In 1971, Mink & Hill report several way of
modifying the SSC when they are either too
large or too small
Undersize tooth or the oversize crown.
Oversize tooth or undersize crown.
Deep subgingival caries.
Open contact.
Open-faced stainless steel crown.