Stainless steel crowns

Stainless steel crowns

1. STAINLESS STEEL CROWNS

2. INDICATIONS
•Extensive caries
•Pulpotomy/pulpectomy
•Malformed/hypoplasticteeth
•Fractured teeth
•Severe bruxism
•Abutment for space maintainers
•are useful as an “emergency” measure in sensitive teeth
•Handicapped children
•Attachments for habit breaking and orthodontic
appliances.
•Correction of single tooth cross bite.

3. CONTRAINDICATIONS
•Esthetics
•Teeth that are nearing exfoliation
•Space loss

4. Classification of Crowns
Based on shape
•Pretrimmed eg. Ormco, Unitek
•Untrimmed eg. Rocky Mountain
•Precontoured eg.3M Crowns

5. •BASED ON COMPOSITION
stainless steel(18:8)
17-19% Cr
10-13% Ni
67% Fe
Ni-based crowns (Iconel 600)
72% Ni
14% Cr
6-10% Fe

7. Armamentarium
1.Burs & stones: Flame shaped or 330 TC
Green stone, Rubber wheel
Rouge or whiting polishing wheels
2.Pliers
•Johnson 114 pliers
•Gordon 137 pliers
•Abell112 Ball and socket pliers
•110 Straight Howe pliers
•800-417 Crimping pliers
3.Crown & bridge scissors
4.Sharp scaleror instrument
5.Luting cement, glass slab, spatula

8. Steps in Adaptation of SS crowns
1.Crown selection
2.Preoperative occlusalevaluation
3.LA administration
4.Rubber dam application
5.Placement of wedges
6.Tooth preparation
7.Trial fitting, trimming and contouring
8.Finishing the Crown
9.Cementation
10.Post cementation instruction

9. CLINICAL PROCEDURE
•Evaluation of pre-operative occlusion
•Selection of appropriate crown measuring
the mesio-distal width between the contact
points of the neighboring teeth with
calipers.

10. TOOTH PREPARATION
Occlusal reduction

12. TOOTH PREPARATION
Proximal reduction

13. No ledge should form just a
feather edge finish line
Rounding up of line angles

15. GINGIVAL CONTOURS OF CROWN

16. •Crimping: the gingival 1/3
rd
of the crown margin

17. •Seating of the crown: lingual to buccal
“click” sound for a snap fit

18. FINISHING & POLISHING

19. cementation

20. Modifications of SS Crowns
Adjacent stainless steel
In case of drifting and space loss
Modification of crown size –Over sized crown and
Under sized crown
Open contacts
Extension for deep proximal lesions
Bruxism
For anterior teeth
Adjacent class II restoration

21. Modifications –Adjacent crowns
1.Reduce one tooth at a time
2.Provide a 1.5 mm space between the teeth at the
gingival margin
3.Trim, contour both crowns for cementation.
4.Cement the distal tooth first
5.Check for proper contacts-HOWE no.110 plier is
suitable for this procedure

22. Modification –Drifting & space loss
•Use a larger crown and adjust the MD
width with a Howe plier
•Use the crown of diagonally opposite arch

23. Modifications –oversized crown
Cut the crown from the gingival to occlusal, either
buccally or lingually
Overlap the crown and try the crown on the tooth
Spot weld the overlapped edges
Contour, electropolish or solder

24. Modifications –Undersized crown
Mink & Hill 1971
Cut a V in the crown on the buccal or lingual side of
the crown
Use a strip of orthodontic band material to spot
weld over the ‘V’ cut
Contour using No.114 plier
Polish and solder

25. Modifications –Subgingivalcaries
1.Use unfestooned crown
2.Modify a festooned crown by spot welding an
additional band piece.

26. Modifications –Open contact (Except
the primate spaces)
1.Use a larger crown taking care not to disturb the path of
eruption of the adjacent permanent tooth
2.Contour with Abell 112 ball and socket plier if the gap
is little
3.Localized addition of solder

27. Modifications -Bruxism
Increase thickness of metal on the occlusal surface by
adding solder on the inner impression surface of the
crown –Croll’s technique

28. Modifications –Adjacent Class II
restoration
•Prepare Class II cavity, tooth for crown placement
•Adapt SS crown
•Place matrix band and wedges and fill Class II cavity
•Remove the SS crown with matrix band in place
•Finish amalgam restoration
•Finish and cement the SS Crown.

29. Modifications –Anterior teeth
1.Prepare a labial window and replace with composite
resin
2.Use preveneered crowns

30. Modifications –Single tooth cross bite
correction
A reversed SS crown is placed for 1 to 2 weeks

31. Methods for determining
adequate crown fit
Spedding (1984) observed that most stainless steel
crowns seemed acceptable when observed clinically.
Unfortunately, radiographs of the same crowns
revealed many to be over extended, with ragged
margins. To amend these discrepancies, he proposed to
principles, based on the morphology of the primary
teeth and gingival contour.

32. Principle 1 –Any point on the tooth occlusal to
the greatest diameter is on the visible clinical
crown, and any point on the tooth apical to the
greatest diameter is on an undercut surface of the
tooth and is not visible in the mouth.
Principle 2 –The contours of the buccal and
lingual marginal gingival should be carefully
observed and reproduced on the steel crown
margins so as to locate them at the correct
anatomic positions on the tooth.

33. Advantage of Stainless Steel Crowns
•Durable Inexpensive and cost-effectiveness Quick
placed
•Preventive aspect No potential for long-term folow-up
and parental compliance in home care

34. Disadvantages of Stainless Steel Crowns
•Appearance
•occlusal surface may wear
•Gingivitis is common around defective
margins

35. Complications of SS Crown
Formation of inter proximal ledge, leading to
inability to seat the crown
Over extension of the crown -Loss of
attachment and periodontal injury, discomfort to
the patient
Under extension –Vulnerable for debris and
plaque accumulation, caries formation
Crown tilt or Rotation –Malocclusion
Aspiration of crown

36. Restoration of primary incisors
•Indications:
1.Incisors with large interproximallesions.
2.Incisors that have received pulp therpay
3.Incisalfractures with loss of appreciable amount of tooth
structure
4.Incisors with multiple hyoplasticdefects
5.Discolored incisors that are esthetically unpleasing.
6.Incisors with small interproximallesions that also demonstrates
large areas of cervical decalcifications.

37. •Full coronal coverage of primary incisors
1.Adhesive resin based composite crowns (strip crowns/
celluloid crowns)
2.Anterior stainless steel crowns
3.Anterior open faced stainless steel crowns.
4.Prefabricated vaneeredstainless steel crowns.
5.Polycarbonate crowns

38. Anterior stainless steel crowns
•Nonvaneeredstainless steel crowns are not frequently used on
maxillary primary incisors because of poor esthetics.
•However, they are most often used on severely decayed canines and
mandibularincisors where esthetics are less noticeable.
•Steps
1.Tooth preparation
2.Crown selection
3.Trimming of cervical margins
4.Adjust mesiodistaldimension of crown using Howe no 110 plier
5.Crimping of the crown.
6.Trying of crown for marginal adaptation.
7.Polishing of margins and cementation.

39. Pre-veneered stainless steel crowns
Advantages
1.Esthetically pleasing
2.Relatively short operating time
3.Durable
4.Easy to place even when
moisture control is difficult
Limitations
1.Crimping is limited primarily to
lingual surfaces, not allowing as
close as adaptation
2.More costly
3.Part of vaneermay chip off

40. 3M ESPE Iso-Form Crowns
•The crowns are made from a high purity tin-silver alloy that is
soft and ductile.
•This not only gives 3M ESPE Iso-Form crowns their particular
degree of ductility, but also the advantage that a crown can be
stretched or burnished to alter the shape.
•The accurate anatomy of these crowns and their ability to
automatically stretch to fit the preparation margins make them
easy to place and time saving in use.