A crown is a tooth shaped covering which is cemented to the tooth structure & its main function is to protect the tooth structure & retain the function
3. CONTENTS
Introduction
History
Composition
Classification
Indications
Contraindications
Armamentarium used for placement
Clinical procedure
Modifications
Common errors
Esthetic crowns
Relevant articles
Conclusion
References 3
4. STAINLESS STEEL CROWNS (SSCS)
A crown is a tooth shaped covering which is
cemented to the tooth structure & its main function is
to protect the tooth structure & retain the function
4
5. HISTORY
1950- Humphrey and Engel recommended stainless
steel crowns
1968-Mink and Bennett encouraged familiar
treatment modality
1960s - significantly improved crown (Unitek)
5
6. CLASSIFICATION: BASED ON COMPOSITION
1. Stainless Steel crown ( Unitek and Rocky Mountain
crowns)
2. Nickel-Base crowns (Ion Ni-chro from 3M)
3. Tin –base crowns
4. Aluminum -base crowns
7. 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
7
8. Chemical Composition of Two types of Crowns Expressed
Manufactur
er
as Percentages
Iron Chromium Nickel Carbon,
Manganes
e, Silicon
Unitek 67 17 12 4
3M 10 16 72 2
Brook & King. Dent Update 9:25, 1985. 8
9. CLASSIFICATION: BASED ON MORPHOLOGY
1. Uncontoured/ untrimmed crowns (Unitek)
2. Pretrimmed crowns (Unitek stainless steel
crowns,3M,De novo crowns)
3. Precontoured crowns( Ni-chro ion crowns and
Unitek)
10. Classification
10
Untrimmed crowns (e.g.
Rocky Mountain)
• neither trimmed nor
contoured
• longer
• lot of adaptation
• time consuming
Pre trimmed crowns (e.g.
Unitek stainless steel
crowns, 3M and Denovo
crowns)
• straight, non-contoured
sides
• but shorter
• festooned
• require contouring
11. Pre contoured crowns (e.g.
Ni-Cr Ion 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
Preveneered SSC
• Aesthetic posterior
crowns
• Resin based composite
bonded to the buccal and
occlusal surfaces
• Allow only minimal
crimping
11
12. AUSTENITIC V/S FERRITIC
• Increased ductility and ability to be cold worked without
fracturing
• Strengthening during cold working
• Greater ease of welding
• Ability to overcome sensitization (> 6500C)
12
13. AVAILABILITY
3M
Crown Shape Number of sizes Width range
available mm
Upper 1st primary molars 6 7.2 to 9.2
Upper 2nd primary molars 6 9.2 to 11.2
Lower 1st primary molars 6 7.3 to 9.3
Lower 2nd primary molars 6 9.4 to 11.4
Sizes 4 & 5 are most often used
supplied in kit form with user
needing to reorder only those
sizes frequently used.
13
14. DENOVO Stainless Steel Crowns- Pretrimmed
•1st Primary Molar Kit & 2nd Primary Molar Kit
•Total of 56 Crowns (2 crown per size, 7 sizes per quadrant)
•1st Permanent Molar Kit
•Total of 64 Crowns (2 crowns per size, 8 sizes per quadrant)
14
18. INDICATIONS
1.Restoration of carious primary molars where more than
two surfaces are affected, or where one or two surface
carious lesions are extensive.
2.If restoration is needed to last >2 yrs
18
19. 3. Child < 6yrs SS crown preferrable to restorations
4. Following pulpotomy or pulpectomy procedures.
(Kindelan 2008)
19
20. 5.Localized or generalized developmental problems,
e.g.:Enamel hypoplasia,
Amelogenesis imperfecta,
Dentinogenesis imperfecta
6. Restoration of fractured primary molars.
20
21. 7. Extensive tooth surface loss due to
Eg : Attrition
: Abrasion/erosion
: Bruxism
8. In patients with a
high caries susceptibility
9. As an abutment for certain
appliances, such as
space maintainers.
21
22. 10. In patients where routine oral hygiene measures
are impaired.
11.In patients undergoing restorative care under
general anaesthesia if two or more surfaces are
involved
12. In patients with infra-occluded primary molars
13. Single tooth cross bite
22
23. 14. As an “emergency” measure to reduce the sensitivity of
these teeth
15. For :temporary restoration of permanent teeth
:fractured permanent anterior teeth and
:young permanent molars following endodontic
treatment.
16. Recurrent caries around existing restorations
23
24. CONTRAINDICATIONS
1. If the primary molar is close to exfoliation with more than
half the roots resorbed or exfoliation within 6-12 months
2. Clinical or radiographical evidence of radicular pathology
3. Tooth exhibits excessive mobility
24
25. CONTRAINDICATIONS
4. Primary posterior teeth - conservative amalgam
restorations can be placed
5. Partially erupted teeth
6. Esthetically unappealing
7. Where conservative restorations can be placed
25
26. CONTRAINDICATIONS
8. In a patient with a known nickel allergy or sensitivity
-ESPE SSC consists of a chromium-nickel
steel of surgical quality.
- Incidence of Ni allergy due to orthodontic
treatment 1 in 100 (Hensten& Petersen 1992)
-Conventional SS crowns do not aggravate
hypersensitivity (Janson 1998)
26
27. ARMAMENTARIUM
Burs and stones
Burs no 169L OR no 69L F.G
Tapered diamond F.G.
No 6 or No 8 R.A
Green stone or heatless stone
Rubber wheel
27
29. CLINICAL PROCEDURE
A) Evaluate pre-operative occlusion
B) Administer LA
C) Place rubber dam
D) Crown selection
E) Tooth preparation
F) Evaluation of tooth preparation
G) Crown adaptation
H) Crown finishing & polishing
I) Crown cementation
J) Post operative instructions
29
34. CROWN SELECTION
Before preparation : Boley gauge
After preparation : trial & error
Smallest crown selected
Friction to be felt when crown slips gingivally
34
35. TOOTH PREPARATION
Aim of tooth preparation :
To provide sufficient space for SSC
To remove complete caries
To have sufficient tooth for retention of crown
35
36. OCCLUSAL REDUCTION
36
Humphery
1950
• All sides
reduced
• Retain
crown
structure
Rapp 1966
• Occlusal
reduction to
keep atleast
4 mm from
gingival
margin
Mink &
Bennett 1968
• Uniform
occlusal
reduction 1-
1.5 mm
• Troutman &
Kennedy
support it
38. OCCLUSAL REDUCTION
Evaluation of occlusal reduction
Forrester 1981 : Wax sheet
Visual examination
Mathewson : Use of explorer
38
39. OCCLUSAL REDUCTION
Occlusal anatomy preservation
Crown retentive potential
Less chances of pulp exposure
Preservation of tooth structure
39
Maxillary molars Mandibular molars
40. PROXIMAL REDUCTION
Wooden wedge inter proximally
69L or 169L bur moved buccolingually
Begin at the marginal ridge & at 10 degree converging
towards occlusal surface
Do not overtaper
Feather edge finish line 40
42. PROXIMAL REDUCTION
Contact with adjacent teeth must be broken gingivally &
buccolingually.
Proximal slices converge slightly towards the occlusal &
lingual (Meyers 1976)
42
Proper slice Improper slice
43. PROXIMAL REDUCTION
Proximal slice must be extended below gingival crest to
avoid leaving a ledge
Ledge may cause:
Obstructed crown placement
Popping out of crown
Stress area
43
44. PROXIMAL REDUCTION
Evaluation :
Pass explorer through proximal areas
Broken contacts
44
45. CONTROVERSIES
Mathewson, Pinkham and Mink & Bennet :
First proximal reduction followed by occlusal
Stewart, Welbury, Forrester & Brocre :
First occlusal reduction followed by proximal
45
47. BUCCAL & LINGUAL REDUCTION
Pinkham :
Large mesiobuccal bulge : both buccal & lingual
Using Preveneered crown : both buccal & lingual
47
48. EVALUATION OF TOOTH PREPARATION
Occlusal clearance 1 – 2mm
Proximal slices converge towards occlusal & lingual
Explorer can be placed between the prepared tooth &
proximal tooth
48
49. EVALUATION OF TOOTH PREPARATION
Buccal & Lingual surface if required reduced 0.5 mm with
feather edge margin
Buccal & Lingual surface converge slightly towards the
occlusal
All line & point angles rounded
49
50. CROWN SELECTION
Can be selected before or after crown preparation
Crown should have :
Tight snap fit
Restore original contour & occlusal anatomy
Choose smallest crown that well fits
Usually No 4 & No 5 sizes are commonly used.
50
51. THREE MAIN CONSIDERATIONS
*A) -Adequate M-D width
-Light resistance to seating
-Proper occlusal height
*B)Crown :larger : tooth to be adapted,
especially when the gingival part of the crown is
trimmed & crimped.
*C)Too large crown will rotate on the tooth preparation.
52. CROWN ADAPTATION
Try crown on tooth : lingual to buccal
Mark scratch line
Cut 1 mm below it with scissors
Place the crown again :
If blanching seen : rescribe & retrim
If doesn’t seat completely : reduce occlusal surface
52
53. CROWN CONTURING
Gingival Contours
Buccal gingival contour of E : Smile
Buccal gingival contour of D : Stretchout ‘S’
Proximal contour of primary molars : Frown
Lingual contours of all molars : Smile
53
54. CROWN CONTOURING
Contouring pliers used :
# 112 Ball & Socket Plier
#137 Gordan plier
# 114 Johnson plier
Used for initial contouring in middle third : Belling effect
54
55. CROWN CRIMPING
Inward movement of margins
#137 Gordan plier
# 114 Johnson plier
Crown crimping plier
After crimping : Snap into
position with firm finger pressure
55
56. CROWN CRIMPING
Evaluation :
Check with explorer
If margins open : recrimp
If overextended : start again
Blanching : Johnson 1987
Bitewing radiograph : More & Pink 1973
56
57. CROWN CRIMPING
Tight fit of crown aids in:
Mechanical retention
Protection of cement from exposure to oral fluids
Maintenance of gingival health
57
58. FINAL TRIAL
Resistance in seating without blanching
Check for ledges
Resistance to seating with blanching
Crowns too wide
Crowns too long
Tissue caught in margin
58
59. CROWN FINISHING & POLISHING
If Unpolished : accumulation of plaque & gingivitis
Large green stone : Knife edge finish cervically
Rubber wheel : to smoothen the margins
Wire brush : to polish entire crown
Rouge : to give fine lusture
59
60. CROWN FINISHING & POLISHING
Burs shavings : spun inside of crown
Wheel run slowly : Light brush movements towards centre
of crown
Allows metal closer to the tooth without reducing crown
height
60
61. CROWN FIT
Spedding 1984:
Principle 1
View from proximal surface : B-L surfaces converge occlusally
Any point above greatest diameter: visible
Any point below greatest diameter : not visible clinically
61
62. CROWN FIT
Spedding 1984:
Principle 2
Correct contours of buccal &
lingual gingival margins of
crown to gingival tissues
Margins apical to the greatest diameter : good adaptation
62
63. CROWN CEMENTATION
Crown & tooth has to be cleaned
Vital tooth : cavity varnish {Meyers 1983}
Cements :
ZnOE
Polycarboxylate
ZnPO4
GIC
Reinforced ZOE
Silicophosphate
Most commonly used : GIC 63
64. Mathewson (1979) : retention of S.S.Crown is due to
cementing medium rather than due to mechanical
adaptation.
Savide et al (1979)
Conducted study to compare the retention capabilities in
5 different types of tooth preparation.
Concluded that non-cemented preparations
demonstrated only little mechanical retention.
Following cementation : retention values increased.
65. CROWN CEMENTATION
65
Place 2 X 2” gauze
posteriorly to
tooth
Tooth & crown
cleaned
Isolation
mandatory
Apply vaseline to
contact areas
Mix luiting cement
till 1 ½” strings
are formed
66. CROWN CEMENTATION
66
Place the cement
in crown to fill
approx 2/3rd
All inner
surfaces covered
with cement
Seat crown from
lingual to buccal
Cement should
be expressed out
from sides
Ask to chew in
centric occlusion
67. CROWN CEMENTATION
67
Excess cement
removed with
scaler or explorer
Floss moved
buccolingually
Support the
mandible during
the procedure
68. CLINICAL EVALUATION OF CROWN
CEMENTATION
1. The crown & its margins are smooth & polished
2. Properly adapted to the prepared tooth
3. The proximal contacts are
established properly
68
69. CLINICAL EVALUATION OF CROWN
CEMENTATION
4. Crown is in proper occlusion
5. Crown margins extended 0.5 -1mm into gingival
crevice
6. Excess of cement is
removed completely
69
70. RADIOGRAPHIC EVALUATION OF CROWN
CEMENTATION
Crown margins should be adapted to proximmal
surface
They should not be too long
Proximal contours are well reproduced
70
71. POST OPERATIVE INSTRUCTIONS
Atleast for 1 hour avoid :
Sticky foods like caramel, gum, toffes
Hard candies
Chewing on ice
Popcorn kernels
Any other hard substances
71
72. CLINICAL MODIFICATIONS
Adjacent S.S.C
Adjacent S.S.C with amalgam restoration
Adjacent S.S.C with arch length loss
Undersized tooth / oversized crown
Oversized tooth / Undersized crown
Deep subgingival caries
Open contacts 72
73. ADJACENT S.S.C( NASH,1981)
73
Both placed at same time
Posteriormost prepared 1st
Then crown adjusted over it &
fitted into occlusion
Crown reduction of adjacent
crown done
For broad contacts : # 110
Howe’s plier used
75. ADJACENT S.S.C WITH ARCH LENGTH
LOSS(MC EVOY, 1977)
75
Crowns not
prepared at
same time
More reduction
in M-D
dimension
Flattening
Mesial & Distal
areas
76. UNDERSIZED TOOTH/OVERSIZED CROWN
(MINK & HILL,1971)
Due to longstanding mesial & distal caries
76
V cut made on
buccal surface
from gingival
to occlusal
surface
Cut edges
reapproximate
d to overlap
one another
Crown tried
on tooth &
amount of
overlap
necessary
marked
Overlapped
edges spot
welded &
78. OVERSIZED TOOTH/UNDERSIZED CROWN
Try the crown
on tooth
Cut V on buccal
or lingual side
as needed
Again Try
crown on tooth
Place ortho
band and spot
weld it 78
79. OVERSIZED TOOTH/UNDERSIZED CROWN
#114 plier : to adapt band
Scratch the band where it adapts to tooth
Reposition the scratch & band , spot weld, solder &
finish it
79
81. DEEP SUBGINGIVAL CARIES
81
• Amalgam/GIC
restoration
substitute the
tooth structure
Routine
crown
preparation
• Solder an
extension on
interproximal area
of crown
Band
82. OPEN CONTACT
Leads to food packing, plaque retention & gigivitis
Larger crown selected
Interproximal contour exagerated with #112 plier
Or addition of solder interproximally
82
84. COMMON ERRORS
Lack of feather edge
Failure to round all line angles
Incorrect crown size
Excessive reduction of tooth
Ledges formation
84
85. GINGIVITIS
Goto et al : 33% gingivitis
Crowns with defective margins / excessive cement
retention : supra gingival plaque accumulation
85
86. GINGIVITIS
Durr et al and Checchio et al
Poor Oral hygiene
Improperly contoured S.S.C
Salma & Meyers
Reduced : careful polishing of crown margins
86
87. FULL CORONAL RESTORATION FOR
ANTERIOR TEETH
Indicated when:
1.Mulitsurface caries
2.Incisal edge is involved.
3.Extensive cervical decalification
4.Pulp therapy is indicated
5.High caries risk patient
6.Child behaviour makes moisture control diffiicult for
class III restr’n.
88. PREFORMED AND HELD ON TO TOOTH BY
LUTING CEMENT
1. S.S.Crowns
2. Facial cutout S.S.Crowns
3. Resin veneered S.S.Crowns
4.Polycarbonate crowns
THOSE BONDED TO THE TOOTH
1.Strip crowns/Celluloid crowns
2.Pedo jacket crowns
3.New millenium crowns
4.Art Glass crowns
89. FACIAL CUT OUT S.S.C
Composite material on labial fenestration
Time consuming
Metal margins still visible
Difficult to control hemorrhage
Increased chairside time
Gradual deterioration in appearance 89
90. FACIAL CUT OUT S.S.C
Technique :
Allow cement to set completely
Cut window- just short of incisal edge
- gingivally till the height of gingival crest
- mesiodistally till line angles
90
91. FACIAL CUT OUT S.S.C
Remove cement
undercuts at each margin with ½ no. round bur
GIC liner to mask color of tooth structure
Etching, bonding & composite placement
Polishing always from resin to metal-prevents metal
particles from incorporating 91
92. VENEERED S.S.C
Merits -decrease chair time & less moisture sensitive
compared to strip crowns
Disadvantages
- include sterilization
- high costs(5 to 8 times as much as a plain stainless steel
crown or strip crown)
- If the facing chips or breaks after placement, esthetic repair
is difficult and usually requires replacement of the crown.
92
93. ARTGLASS
Multi-functional methacrylate matrix – 3 D molecular
networks with a highly cross-linked structure
75% filler (55% microglass and 20% silicafiller)
Available in 6 sizes for every primary tooth A-T and every
Vita shade
93
94. ARTGLASS
Merits
One appointment placement
Provide greater durability and esthetics than strip crowns.
Easily adjusted or repaired intraorally
Color stable
Wear of polymer glass similar to enamel, kind to opposing
dentition- feels natural to the patient
94
95. ARTGLASS
Seating instructions :
Preparation similar to S.S.C with more reduction
Fits passively
Place artglass liquid for 1 min inside crown
Then place flowable composite in crown and
then place on tooth
Finish with carbide bur
95
97. Waggoner and Cohen [1995] reported
Cheng Crowns
Kinder Crowns
NuSmile Primary Crowns have resin composite
facings
Whiter Biter Crown II has a flexible thermoplastic
veneer.
98. NUSMILE CROWNS
Merits
Single appointment
Easy placement technique
Reduces operatory time
Less technique sensitive
98
99. NUSMILE CROWNS
Demerits
More tooth preparation due to their greater bulk.
Avoid crimping - facing susceptible to fracture, so the tooth
is prepared to fit the most appropriate crown.
Single-use only-sterilization is recommended
99
100. NUSMILE CROWNS
Selecting a Crown
approx 1-2 sizes smaller than the stainless steel
IMP in cases with: tight interproximal contacts,
: crowded dentition/mesial-distal space
loss.
Very short clinical crowns and crowded dentitions may
not be ideal for beginning case selections.
100
101. Preparation of the Tooth
crown fits the tooth passively:
flexing of metal substructure from pressure during
fitting or seating can cause micro-fractures
102. NUSMILE CROWNS
Anterior teeth
Reduce the incisal length of the tooth by approximately
2mm and open the interproximal contacts.
feather-edge margin
tapered diamond burs : proceed from coarse to fine as the
preparation is completed.
102
103. NUSMILE CROWNS
Posterior teeth:
The tooth should be reduced by approx 30%
More preparation : buccal and occlusal aspects
(at least 2mm)
Crimping not necessary
Do not crimp excessively or near the facing
Minimally on lingual aspect of crown
103
104. CHENG CROWNS
Peter Cheng Orthodontic Laboratory-1987
anterior crowns faced with a high quality composite
(mesh-based with a light cured composite.)
104
105. CHENG CROWNS
Merits
chore of cutting windows in stainless steel crowns
completed in one patient visit (and with less patient
discomfort)
natural looking
stain resistant
doesn’t cause wear of opposing teeth
Demerits
fracture of veneers during crimping
expensive.
105
106. CHENG CROWNS
106
Anterior Crowns
Centrals Laterals Cuspids
left & right
left & right
sizes (1-6)
sizes (1-6)
upper& lower
sizes (1-6)
Posterior Crowns
First primary molar Second primary molar
upper and lower - left and right
sizes (2-7)
upper and lower - left and
right
sizes (2-7)
108. PEDO PEARLS
Heavy gauge aluminum crowns coated with FDA food
grade powder coating and epoxy-resin.
108
109. PEDO PEARLS
Merits
Universal anatomy-use on either side
Easy to cut and crimp, without chipping or peeling.
Non bulky & fits easily
Disadvantages
less durability and the crowns are relatively soft
self-cured or dual-cured composite is recommended for
repairing
109
110. DURA CROWNS
White-Faced Crowns
Crowns can be crimped labialy and lingually,
can be easily trimmed with crown scissors,
easily festooned and has got a full-knife edge
Starter Kit includes: 24 Crowns.
Centrals, left and right sizes 2,3,4 two of each.
Laterals, left and right sizes 3,4,5 two of each
110
111. KINDER KROWNS
1988 by pediatric dentists
natural shades and contour available
Great depth and vitality from the lifelike composite
111
112. PEDO JACKET
It is a tooth colored copolyester material which is filled
with resin and left on tooth after polymerization instead of
being removed.
Anterior crown jackets & primary 1st molar
112
113. PEDO JACKET
Merits
It does not split, stain or crack.
Crowns can be easily trimmed with scissors.
Thin yet strong interproximal wall allows multiple
adjacent restorations with a minimum amount of tooth
reduction.
113
114. PEDO JACKET
Using a plastic primer, they can either be bonded into place
with composite resin or cemented with a glass ionomer
cement
Demerits
Only one size is available.
114
115. NEW MILLENIUM CROWNS
This is similar in form to the pedo jacket and strip
crown,
except that it is lab enhanced composite resin
material.
Like others, this is also filled with resin material and
bonded to the tooth
116. PEDO CHEMPU CROWNS
Sizes 2-4
Color : White
Color stable, plaque resistant,
match natural pediatric shades.
Available for the right and left central and lateral as well as
cuspids.
Kit includes
-centrals, left and right sizes 2,3,4 (2 of each)
-laterals, left and right sizes 2,3,4 (2 of each)
116
117. POLYCARBONATE CROWNS
Provisional crown should be easy to adapt to the prepared
tooth and easy to remove when needed.
Made of a polycarbonate resin incorporating microglass
fibers
117
118. POLYCARBONATE CROWNS
Merits
good durability and strength.
easy to trim with dental burs or crown scissors, and can
then be easily adjusted with pliers
smooth surface finish
universal shade
118
119. POLYCARBONATE CROWNS
Demerits
Do not resist strong abrasive forces thus leading to
occasional fracture, hence it is contraindicated in cases of
Severe bruxism
deep bite
abrasion
crowding
decreased space between teeth
119
121. STRIP CROWNS
Automatically contours restorative material to match the
natural dentition
Thin interproximal walls
Sufficient strength for easy handling
Ideal for chemical or light-cured composites
Simple to fit & trim
Removal is fast & easy
Easily matches natural dentition
121
122. STRIP CROWNS
Leaves smooth shiny surface
Easy shade control with composite
Superior esthetic quality
Ideal for photo cure
Crystal clear and thin
Large selection of size
Easy to repair
122
123. STRIP CROWNS
Demerits
technique sensitive
adequate tooth structure is required
moisture and hemorrhage
control
123
124. STRIP CROWNS
Contraindications
grossly decayed teeth with inadequate structure for
retention
extensive caries with no intact enamel left
impinging deep overbite
presence of periodontal disease.
124
125. STRIP CROWNS
STEPS
Cleaning
Select an appropriate crown form
Reduce the mesial and distal proximal surfaces
125
126. STRIP CROWNS
Tooth Preparation
Reduce the incisal edge approximately 1 mm.
Remove all caries with a spoon excavator or a #4 round bur.
Trim crown with fine scissors & try it
126
127. STRIP CROWNS
Place a vent on the lingual surface of the crown on
mesial & distal corner of incisal edge
Seat the filled crown form carefully 1 mm below the
gingival margin after filling with composite
Remove excess soft composite resin
127
128. STRIP CROWNS
Remove the cellulloid sheet
Trim & polish if necessary
128
129. PUSH CROWNS
"Hall technique”
Basis : If the environment of an actively cariogenic plaque
biofilm can be altered, for example by sealing in the caries with
a restoration and so isolating it from nutrients from the oral
cavity, then the caries process could arrest.
No local anaesthesia needed
Useful for fearful children
Consider how long the tooth needs to be preserved in the
mouth before exfoliating.
Norna Hall 2009
129
130. Charles R, Jessica Y, Timothy W
Parental satisfaction high with pre-veneered crowns
High fracture rate & Loss of resin facing maximum
Ped Dent 2001
130
131. Sean Beattie et al
Regardless of the type esthetic SSC are able to resist
occlusal forces over a short clinical periods.
J Cand Dent Assoc 2011
131
132. Omar Meligy
S.S.C might impede the exfoliation of primary molar
Int J Ped Dent 2010
132
133. Champagne C, Waggoner W, Ditmer M
Parental satisfaction with preveneered SSC was more
than only SSC
Ped Dent 2008
133
134. A Khatri, B Nandlal, Srilatha 2007
Nano composite resin used along with sandblasted
SSC had more shear bond strength than conventional
composite resins.
JISPPD 2007
134
136. N Sue Seale
SSC is superior in durability & longevity to Class II
amalgam in primary teeth
Pediatr Dent 2002
136
137. W F Waggoner
Crown doesn’t matter for retention of preformed crowns
It depends upon technique & precision
Eur Archives Pediatr Dent 2006
137
138. Guelmann M
Compared Dura crowns, Kinder Krowns, NuSmile
crowns & SSC for retention
Group I : crown only crimped {SSC most retentive}
Group II : crown only cemented {NuSmile least}
Group III : cemented & crimped : Kinder krowns most
retentive
Pediatr Dent 2003
138
139. Lee Y K
NuSmile crowns more resistant to # than Kinder
Krowns & Cheng crowns
Kinder krowns had more facing loss
Houston Biomed Research 2004
139
140. Yual Yilmaz
Polycarbonate crowns showed lowest tensile bond
strength as compared to open face SSC & NuSmile
crowns
J Dent Child 2004
140
141. Dustin James
NuSmile crowns withstand higher loads than Kinder
Krowns & Cheng crowns
Pediatr Dent 2007
141
142. Monica Gupta
Veneer resistance to fracture was more with the
crimped crowns than non-crimped crowns
JISPPD 2008
142
143. Y Yilmaz, G Guter
Sterilization & disinfection results in crazing, contour
alterations and vestibular surface changes of pre-veneered
SSC.
Chemical disinfection in an ultrasonic bath is
preferred for preveneered crowns
JISPPD 2008
143
144. GT Wickersham
NuSmile crowns exhibited higher fracture resistance
with chemiclav & autclav sterilization
Chemiclav sterilization caused negative color changes
Autoclav sterilization had no effect on fracture
resistance & color changes
Pediatr Dent 1998
144
145. CONCLUSION
Preservation of tooth for natural space maintainer
Esthetics
Phonetics
Mastication
Overall development of child
145
1950- Humphrey and Engel recommended stainless steel crowns for the restoration of badly broken down primary molars and also as space maintainers
Unitek-california, , 3M-minneapolis, rocky mountain-denver//NICKEL BASE –already work hardened while AUSTENTIC soft and malleable & harden when adapted with pliers… Ni base fit easily& require least adjustment(stephen wei)
Untrimmed -THESE ARE CROWNS WITH STRAIGHT SIDES & MARGINS THAT FOLLOW THE GINGIVAL CONTOUR. THE GINGIVAL MARGINS CAN BE TRIMMED WHERE NECESSARY & ALSO NEED CONTOURING & CRIMPING TO ENSURE GINGIVAL ADAPTATION TO THE PREPARED TOOTH. Pre trimmed -Parallel crown walls saves chair time, minimizing the need for buccal, lingual, and mesial tooth reduction.
Consistent wall thickness helps prevent bite through and minimizes trial fitting distortion.
The Molar Crowns have shallow occlusal anatomy which reduces rocking during mastication, with minimal occlusal interference.
Pre contoured –more rounded..POSSESSS MORE DIFFICULTY IN ADAPTATION SINCE TRIMMING WILL RESULT IN REMOVAL OF MANUFACTURERS GINGIVAL CRIMP & inc dimensiond os cervical margin
Chromium oxidizes and forms a thin surface film of chromium oxide (Cr2O3), known as “passivating film” which protects against corrosion.
Austenitic stainless steel is used extensively for the fabrication of dental appliances and is composed of chromium (11.5-27%), nickel (72.2%.),and carbon (0.25%). Nickel-Base Crowns Inconel 600 alloy 72% nickel 14% chromium 6-10% Fe 0.04% carbon 0.35% manganese 0.2% silicon
Primary Molars
3M-There are 48 crown sizes available in the 3M ESPE stainless steel primary molar crown range.//. A size 7 is available for extra large teeth.
Stephen wei.. ½ round bur-markin margins//No.4 round burs- caries removal//polishin Rubber wheel//No.114 Pliers (Johnson contouring pliers) & No.137 pliers (Gordon contouring pliers)- general contourin in occlusal & middle region//No. 17 crown pliers (Unitek corp,) for crimpin i.e. marked curvature in cervical region.// No.112 ball and socket pliers – produce convexity to simulate contact pt.
Stephen wei.. ½ round bur-markin margins//No.4 round burs- caries removal//polishin Rubber wheel//No.114 Pliers (Johnson contouring pliers) & No.137 pliers (Gordon contouring pliers)- general contourin in occlusal & middle region//No. 17 crown pliers (Unitek corp,) for crimpin i.e. marked curvature in cervical region.// No.112 ball and socket pliers – produce convexity to simulate contact pt.
Occlusal reduction -1.5 mm reduction
- avoid significant occlusal prematurity
- should follow the contours of the tooth
slightly premature or high occlusal contact up to about 1.0 mm is normally well tolerated in children-capacity for dentoalveolar
compensation, with the occlusion adapting to any prematurity
within a few weeks.
Occlusal reduction -1.5 mm reduction
- avoid significant occlusal prematurity
- should follow the contours of the tooth
slightly premature or high occlusal contact up to about 1.0 mm is normally well tolerated in children-capacity for dentoalveolar
compensation, with the occlusion adapting to any prematurity
within a few weeks.
Proximal reduction
- achieved by using a tappered diamond bur at 10 to 15 ˚
-to allow the crown to be seated beyond the max bulbosity of
the crown.
-avoid creation of ledges/steps
- distal surface of second primary molars
Where a primary molar has no adjacent tooth important to avoid producing an excessive marginal overhang particularly on the distal surface of second primary molars : can impede the eruption of the first permanent molar//A DENTAL EXPLORER MAY BE FREELY PASSED BETWEEN THE f a step or ledge is present (fig. 5), the operator will have difficulty seating the crown and may be tempted to trim it unnecessarilyADJACENT TEETH & The best precaution is either to place a wooden wedge between teeth before the proximal reduction is attempted .//
B)Crown should be somewhat larger than the tooth to which it is being adapted, especially when the gingival part of the crown is trimmed & crimped
The crown wic doesn’t adhere to this will be ill adaptedAny point above greatest diameter
Several factors can influence the decision of choosing cement, MOST IMP of all is Status of Pulp.
Znpo4: zinc phosphate
S.S. CROWN is used as a guide in reproducing the anatomy and morphology of the silver amalgam restr’n.