STRIP CROWN

1) L.A. 2) Isolation with cotton rolls and

saliva ejector or rubber dam.

3) Size selection

4) Caries removal Use a tapered diamond bur in

high speed headpiece the length of the crown is

reduced incisally. Mesial and distal slices are

made tapered to a knife edge at the gingival margin.

5) Shade selection 6) Trimming

The length and cervical length should be checked at this stage.

7) Vent holes 8) Base9) Calcium hydroxide paste or glass

ionomer cement. Composite resin is squeezed into

the crown form and hollowed out

in the center to reduce the amount of excess.

10) Acid etching : The teeth are etched for 20 seconds with etchant, washed and dried. The chalky appearance of enamel is evident.

11) Bond application 12) The crown forms , containing

composite resin are firmly seated on the prepared tooth

13) Excess composite resin is removed with a probe

14) Curing composite

15) Striping the crown

16) Finishing

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POLYCARBONATE CROWNINDICATION

It is used to be as a temporary esthetic restoration for permanent anterior teeth

CONTRAINDICATIONS:

Badly destroyed teeth. Deep overbite Patients with bruxism. TECHNIQUE:

1) Administer local anesthesia

2) Use a thin flame Polycarbonate crowns shaped diamond bur and prepare the mesial and distal portion 1 of the tooth, keep the long axis of the bur parallel to the long axis of the tooth2, Sweep the bur through to the embrasure 3 and be careful not to injure the neighboring tooth.

3) Reduction is done proximally to open the contact with neighboring tooth.

4) Approximately 1 to 1.5 mm. of tooth structure is removed at the INCISAL portion with slight less removal at the gingival area.

5) UNDERCUT can be added to the labial surface with inverted cone bur.

6) LABIAL AND LINGUAL surfaces are reduced 0.5 mm. to allow space to the crown form.

7) Carry the preparation 0.5-1.0 mm. under the gum margin

8) Crown adaptation. Finish line is preferred to be a chamfer.

9) Finally caries removal is done

CEMENTATION: Crown and bridge cement. Resin cement. Zinc oxide eugenol cement ??

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STAINLESS STEEL CROWNS COMPOSITION (Humphrey,

1950) TYPE 1 UNITEK TYPE 2 (3M

CROWN)Iron 67% Chromium 17% Nickel 12% Carbon Manganese 4% Silicon

Iron 10% Chromium 16% Nickel 72% Carbon Manganese 2% Silicon

TYPES OF STAINLESS STEEL CROWNS

A- Straight Side CrownsB- Pre-Trimmed Crowns (UNITEK)

Straight sides but are festooned to follow a line parallel to the gingival crest.

require contouring and some trimming.

C- Pre-Contoured Crowns(Ion Crowns 3M)

Festooned and are also precontoured.

They are available in 6 numbers for each primary tooth

ADVANTAGES AND DISADVANTAGES

ADVANTAGES DISADVANTAGES Very durable

Protect

Expensive preparation

remaining- Tooth structure

Not Aesthetic

INDICATIONS:

1- restoration of primary or young permanent teeth with caries involving > 2 surfaces. 2- restoration of hypoplastic teeth. 3- after pulpotomy or pulpectomy.

4- teeth with hereditary anomalies such as

dentinogenesis imperfect amelogenesis imperfecta.

5- as an abutment for space

maintainers . 6- restoration for disabled children or whom oral hygiene is extremely poor. 7- attachment for a habit breaking appliance, and space maintainers. 8. Trauma. 9. Bruxsim

INSTRUMENT

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CROWN SELECTION

Three main considerations in the selection of s.s. crowns:

1-Adequate mesio-distal diameter. 2-Light resistance to seating. 3-Proper occlusal seating.

Place the points of dividers on the mesial and distal surface of the tooth at the level of the lingual margin, select the crown with the same mesiodistal dimensions as that indicated by the dividers

PREPARATION OF STAINLESS STEEL CROWNS

1. Establish deep ANESTHESIA maxillary teeth by infiltration and lower teeth by inferior alveolar block. Before placing rubber dam CHECK THE CHILD'S OCCLUSION, observe for the following: A- The opposing tooth has extruded because of long standing carious lesion. B- Mesial drift has resulted because carious lesions have changed the occlusion of the adjacent tooth. -Tooth reduction is needed so that the restored tooth can be returned to normal function.

2. PLACE RUBBER DAM, use of rubber dam in preparing tooth for s.s.crowns specially if caries is deep and pulp exposure is possible: A-To protect the adjacent tooth structure. B-To improve visibility and efficiency. C-Manage behavior in a better way. D-To prevent ingestion of s.s. crowns during preparation.

3. REMOVE CARIES using excavators or large round burs at slow speed If caries is superficial shape of the

resulted cavity is not important as the cavity is later filled with the material used to cement the crown. (IRM)

Calcium hydroxide can be applied in deep cavities to protect the pulp.

TOOTH PREPARATION FOR SSCFathiahAzmi

Use a high-speed with water coolant: 1- OCCLUSAL REDUCTION: Penetrate the occlusal fissure with a

straight or pear shaped diamond to a depth of 1.0 to 1.5 mm.

Extend through the pits and fissures at this depth passing through any oblique ridges and extending to the buccal, lingual and proximal surface of the occlusal surface.

2- PROXIMAL REDUCTION: Place tapered diamond bur in contact

with tooth at buccal or lingual embrasures angled about 20 degree with its tip at the gingival margin, keep the instrument in their position while slicing through the tooth, this angling reduces the risk of injuring the adjacent tooth.

It is better to slice from buccal to lingual or vice versa rather than from occlusal to gingival (produces a shoulder which prevent the proper seating of the crown).

3- BUCCAL AND LINGUAL SURFACES:

No reduction, only roundation1 of the line angles and reverse bevel2 at the occlusal surface.

CROWN ADAPTATION

It may be necessary to remove rubber dam at this stage.

Try the selected crown on the tooth, place the crown on the lingual side and rotate it on the labial (buccally) surface

The crown should fit loosely with 2-3 mm. excess gingivally

The Crowns that is pre-festooned and contoured needs little or no trimming.

With a probe check that the edge of the crown is within the gingival

crevice.

If the length of the crown is too long scratch the gingival margin around the crown with a hand scaler, this scratch line indicates the portion of the crown to be removed.

Remove the crown from the prepared tooth exposing the scratch line with crown and bridge scissors cut the crown 1 mm. below the scratch

line.

Retry the crown on the tooth. If there is blanching of the gingiva it

may be necessary to retrim the crown Adapt and contour the crown

(crimping) with pliers, adaptation is very important to the gingival health of the supporting tissues

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A poorly adapted crown will serve as: 1) Collection point of bacteria. 2) Contribution to recurrent caries. 3) Increased periodontal disease. -If the crown has a loose fit on the tooth crimp the cervical margins.

A well fitted crown will make a POPPING OR SNAP NOISE when it removed from the tooth.

CROWN FINISHING

Use a large green stone to finish the cervical margin.

Smooth and polish the margins with a rubber wheel.

Polish the entire crown with polishing material to give the crown fine luster.

Try on the crown and check occlusion, evaluate the opposite side for proper cuspal and occlusal interdigitation.

CROWN CEMENTATION

Wash and dry the tooth and the crown. Isolate the tooth with cotton rolls and

saliva ejectors. The tooth and the crown must be clean

and dry for good adhesion of cement. Use an adhesive cement1,

polycarboxylate cement2 or glass ionomer cement3, mixed to creamy consistency.

Fill the crown with cement, seat the crown on the tooth from lingual to buccal and press it firmly into place first with finger pressure and then by

inserting band seater and ask the child to bite firmly on it

When the cement is set remove all excess particularly from the gingival contact and from interdentally areas using a probe and dental floss.

CAUSES OF STAINLESS STEEL CROWN FAILURE

1-Poor tooth preparation. 2-Poor crown adaptation. 3-Improper cementation technique. 4-Recurrent caries. 5-Crown perforation occlusally.

MODIFICATIONS OF STAINLESS STEEL CROWNS

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1- Over sized crown: a. Try the crown on the tooth. b. Use a pair of scissors to cut the

crown from the gingival to the occlusal surface either bucally or lingually as needed.

c. Pinch the crown together and again try the crown on the tooth.

d. Spot weld the overlapped edges together use solder and flux, polish and smooth. Check the crown for marginal adaptation, contour, crimp and cement the crown.

2- UNDERSIZED CROWN:

a. Check the crown on the tooth b. Cut a V shape in the crown on the

buccal or lingual side or both, as needed then try the crown on the tooth.

c. Use a strip of orthodontic band and spot welded over the V cut in the crown

d. Use #114 pliers to adapt the band material to the crown contour cut off the excess approximating the gingival contour of the crown.

RECENT ADVANCES

1- Stainless steel crowns may be esthetically improved by placement of composite resin in a buccal window cut into the labial face of The crown. 2- Crowns with prefabricated tooth colored buccal facings are available. Crown forms with bonded resin veneers for primary incisors were developed to serve as a convenient, durable, reliable and esthetic solution for restoring severely destructed primary incisors. 3-Pre-veneered stainless steel crowns resolve some of the problems associated with stainless steel crowns, open faced stainless steel crowns, and composite strip

crowns. 4-They were introduced in the mid 1990’s. They are aesthetic, placement and cementation are not significantly affected by hemorrhage and saliva and can be placed in a single appointment. The stainless steel crown is covered on its buccal or facial surface with a tooth colored coating of polyester/epoxy hybrid composite.

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