Stainless steel crowns in paediatric dentistry

1. STAINLESS STEEL CROWNS
IN PAEDIATRIC DENTISTRY

2. CONTENTS
• HISTORY
• COMPOSITION
• CLASSIFICATION
• INDICATIONS & CONRAINDICATIONS
• ARMAMENTARIUM USED FOR
PLACEMENT
• CLINICAL PROCEDURE
• MODIFICATIONS
• COMPLICATIONS

3. HISTORY
• 1947 -Chrome steel crowns were introduced
by the Rocky Mountain Company
• 1950- popularized by Humphrey and Engel.
• 1960- significantly improved crown (Unitek).

4. CLASSIFICATION

5. COMPOSITION
Stainless steel crowns
(18-8) austenitic type
(Rocky mountain)
• 17-19% chromium
•10-13% nickel
•67% iron
•4% minor elements
Nickel base crowns
(Inconell 600 alloy)
• 72% nickel
•14% chromium
•6-10% iron
•0.04% carbon
•0.35% manganese
•0.2% silicon

6. Chemical composition of two types
of crowns expressed as percentage
Manufacturer Iron Chromium Nickel Carbon,
Manganese,
Silicon
3M 10 16 72 2
Unitek 67 17 12 4
Brook & King. Dent Update 9:25, 1985

7. CLASSIFICATION BASED ON
MORPHOLOGY
Uncontoured/untrimmed
Pretrimmed crowns
Precontoured crowns

8. CLASSIFICATION
Untrimmed crowns (e.g.
Rocky Mountain)
•Neither trimmed nor
contoured
•Longer
•Lot of adaptation
•Time consuming
Pre trimmed crowns (e.g.
Unitek, 3M)
•Straight, nor-contoured sides
•Shorter
•Festooned
•Require contouring

9. Pre contoured crowns (Unitek
Stainless Steel Crowns, 3M)
Festooned, Pre contoured & pre
trimmed
Minimal amount of adjustment
necessary
More difficulty in adaptation since
trimming will result in removal of
manufacturers gingival crimp

10. AVAILABILITY
• Sizes 4& 5 are the most used
Crown shape Number of sizes
available
Width range
mm
Upper 1st primary molars 6 7.2-9.2
Upper 2nd primary molars 6 9.2-11.2
Lower 1st primary molars 6 7.3-9.3
Lower 2nd primary molars 6 9.4-11.4

12. INDICATIONS
• Restoration of carious primary molar
where more than two surfaces are
affected , or where one or two
surface carious lesions are extensive.
• If restoration is needed to last >2yrs.

13. • Child <6yrs SS crown preferrable to
restorations.
• Following pulpotomy or pulpectomy
procedures. (Kindelan 2008).

14. • Localizes or generalized developmental
problems e.g. Enamel hypoplasia,
• Restoration of fractured primary molars.

15. • Extensive tooth surface
loss due to : Attrition
Bruxism
• In patients with high
caries susceptibility.
• As an abutment for
certain appliances such
as space maintainers

16. CONTRAINDICATIONS
• If the primary molar is close to exfoliation
with more than half the root resorbed or
exfoliation with in 6-12 months.
• Clinical or radiographical evidence of
radicular pathology
• Tooth exhibits excessive mobility

17. • Partially erupted teeth
• In a patient with a known nickel allergy or
sensitivity.
• Sensitivity to nickel was observed in children
treated with old generation SSCs (72% nickel)
while on replacing them with new generation
SSC (9-12% nickel), no sensitivity was seen.
-Feasby et al; (1988)

18. ARMAMENTARIUM
• Burs and stones
• Bur no 169L or 69 L
• Tapered diamond bur
• Green stone or Heatless stone
• Burlew wheel

19. ARMAMENTARIUM
• Johnson’s contouring pliers (#114/ #134)
• Crown crimping pliers (#417)
• Howe plier (#110)
• Crown remover
• Crown scissors
• Stainless steel crown

20. #114 contouring plier #417 Crimping plier Round scissors

21. CLINICAL PROCEDURE
• Evaluate pre-operative occlusion
• Administer LA
• Place rubber dam
• Crown selection
• Tooth preparation
• Evaluation of tooth preparation
• Crown adaptation
• Crown finishing & polishing
• Crown cementation

22. TOOTH PREPARATION
• Aim of tooth preparation:
• To provide sufficient space for SSC
• To remove complete caries
• To have sufficient tooth for retention of
crown

23. OCCLUSAL REDUCTION
Humphery
1950
•All sides
reduced
•Retain crown
structure
Rapp 1966
• Occlusal
reduction to
keep atleast
4mm from
gingival
margin
Mink & Bennett
1968
• Uniform occlusal
reduction 1-1.5mm
•Troutman &
Kennedy support it

24. OCCLUSAL PREPARATION
• Evaluation of occlusal reduction:
• Forrester 1981- wax sheet
• Visual examination
• Mathewson: use of explorer

25. Create a “channel” 1.5 mm
deep between the cusps.
Reduce the cusps to the
depth of the channel.

27. OCCLUSAL PREPARATION

28. Proximal surfaces
a) 169L tapered fissure or thin tapered diamond
bur.
b) Break proximal contacts at appropriate depth in
single sweeping motion (or gradually).
c) Vertical proximal walls with slight convergence
in an occlusal and lingual/palatal direction.
d) Feather-edge finish line; common error: ledge
formation.

29. Meyers 1976 - proximal slices converge slightly towards the
occlusal & lingual

30. Proximal reduction: “open” the
proximal contacts, flat surfaces.

31. CONTROVERSIES
• Mathewson, Pinkham and Mink & Bennet:
First proximal reduction followed by
occlusal
• Stewart, Wellbury, Forrester & Brocre:
First occlusal reduction followed by
proximal

32. Buccal and lingual reduction.
• Prepare a slight bevel, at the occlusal 1/3
portion of the surface.
• Mathewson 1974, Andlow & Rock 1984, Mink
& Bennet 1964: large buccal bulge: buccal
reduction required

33. • Pinkham:
• Large mesiobuccal bulge: both buccal &
lingual
• Using preveneered crown: both buccal &
lingual

34. EVALUATION OF TOOTH
PREPARATION
• Occlusal clearance of 1-2mm
• Proximal slices converge towards occlusal &
lingual
• Explorer can be placed between the prepared
tooth & proximal tooth.
• Buccal & lingual surface if required reduced
0.5mm with feather edge margin

35. • Buccal & lingual surface converge slightly
towards the occlusal.
• All line & point angles rounded

36. CROWN ADAPTATION

38. CROWN ADAPTATION
• Try crown on tooth: lingual to buccal
• Mark scratch line
• Cut 1mm below it with scissors
• Place crown again:
• If blenching seen: retrim
• If doesn’t seat completely: reduce occlusal surface

39. CROWN CRIMPING

40. CROWN CONTOURING &
CRIMPING

41. CONTROVERSIES
• More and pink 1973- bitewing radiograph
• Johnson 1987- blanching

42. CROWN FINISHING & POLISHING
• If unpolished: accumulation of plaque &
gingivitis
• Large green stone: knife edge finish cervically
• Rubber wheel: to smoothen the margins
• Rouge: to give fine lusture

43. CROWN FIT
• Spedding 1984:
• Principal - The crown should be of a correct
length and its margins can be adapted closely
to the tooth.
• This can be achieved when the finished crown
is correctly seated on the prepared tooth with
its occlusal surface in the occlusal plane and
its margins placed just apical to the marginal
gingival crests.

44. • Spedding 1984:
• Principal 2
• Correct contours of
buccal & lingual gingival
margins of crown to
gingival tissues.
• Margins apical to the
greatest diameter : good
adaptation

45. CROWN CEMENTATION
• Crown and tooth has to be cleaned.
• Meyers 1983- cavity varnish should be
applied in case of vital tooth.
• Mathewson 1979- retention of SSC is due to
cementing medium rather than due to
mechanical adaptation.

46. Crown cementation
Place 2×2’’ gauze
posteriorly to
tooth
Tooth and
crown
cleaned
Isolation
mandatory
Apply vaseline
to contact areas
Mix luting
cement till 11/2
strings are formed

49. CLINICAL MOIFICATIONS
• Adjacent SSC
• Adjacent SSC with amalgam
restoration
• Adjacent SSC with arch length loss
• Undersized tooth/ oversized crown
• Oversized tooth / Undersized crown

50. Adjacent SSC (NASH, 1981)
Both placed at same time
Posterior prepared 1st
The crown adjusted over it and
fitted into occlusion
Crown reduction of adjacent
crown done
For broad contacts : # 110 how’s
plier used

52. ADJACENT SSC WITH, ARCH
LENGTH LOSS (Mc EVOY, 1977)
Crowns not
prepared at
same time
More reduction
in M-D
dimension
Flattering
Mesial &
Distal areas

53. UNDERSIZED TOOTH/ OVERSIZED
CROWN (MINK & HILL, 1971)

60. COMPLICATIONS
• Aspiration
Adewumi A. Kays DA. Stainless steel crown aspiration during sedation in pediatric
dentistry. Pediatr Dent.2008:30:59-62.

61. Protecting the airway

62. ALLERGY
• The nickel content in the
formulation of nickel
chromium crowns is around
70% greater than that of
contemporary stainless steel
crowns that contain 9-12%
nickel similar to that of many
orthodontic band and wires.

63. • Feasby WH et al; (1988) & Randall RC
(2002)
• Reported an increased nickel-positive patch
test result in children 8 to 12 years of age
who had received old formulation nickel-
chromium crowns.
• A second group of children with
conventional stainless steel crowns showed
no statistically significant difference in
patch test responses compared to a third
control group with no history of nickel-
containing dental appliance use.

64. • Sensitivity to nickel was observed in
children treated with old generation SSCs
(72% nickel) while on replacing them
with new generation SSC (9-12% nickel),
no sensitivity was seen.
• The nickel content in the discontinued
formulation nickelchromium crowns was
around 70%, significantly greater than
that of contemporary stainless steel
crowns, which contain 9%-12% nickel,
similar to that of many orthodontic bands
and wires.

65. References
• Stewart R. Pediatric dentistry. St. Louis:
Mosby; 1982.
• Babaji P. Crowns in pediatric dentistry.
• Adewumi A. Kays DA. Stainless steel crown
aspiration during sedation in pediatric
dentistry. Pediatr Dent.2006;30:59-62.

66. • Syed M, Chopra R, Sachdev V. Allergic
Reactions to Dental Materials-A Systematic
Review. J Clin Diagnostic Research.
2015;9(10):ZE04-ZE09
• Randall RC.Preformed metal crowns for
primary and permanent molar teeth: review of
the literature Pediatr Dent. 2002;24:489-500