Preformed metal crowns Flashcards

1
Q

What is another name for preformed metal crowns

A

Stainless steel crowns (but they are actually made of nickel chrome)

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2
Q

What are preformed metal crowns?

A

For children (deciduous and permanent teeth)
No impressions, no lab stage
Pre-contoured and pre-crimped

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3
Q

How many sizes (3M ESPE)

A

6 different sizes per tooth
Sizes 2-7
Size located on buccal aspect

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4
Q

When to use PMC on primary teeth

A

Teeth with large or multi-surface carious lesions (most common)
Pulp treated teeth (full seal, big hole, brittle because no fluid in dentinal tubules)
Trauma (rare: big fractures)
Enamel and dentine defects
Abutment for crown-loop space maintainer
Infraoccluded teeth (sinking) to maintain mesial/ distal space
Teeth with severe wear (if you can get crown on)

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5
Q

Abutment

A

Structure built to support the lateral pressure of an arch or span

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6
Q

When not to use PMC on primary teeth

A
Unrestorable tooth (too broken down or dead)
Failed pulp therapy
Soon to exfoliate
Pre-cooperative
Severe space loss
Poor motivation?
Multiple grossly carious teeth
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7
Q

When to use PMC on permanent teeth

A
Hypomineralised molars
Amelo- and dentinogenesis
Temporary restoration
Severe erosion
To keep space for ortho
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8
Q

Advantages of PMCs

A

Straightforward technique
Quick and cheap
Evidence of excellent longevity, low failure rates, compare well with other materials
Failure, if occurs, if easily corrected

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9
Q

Disadvantages of PMCs

A

Poor aesthetics
May impede eruption of adjacent teeth if too big
May cause gingival inflammation if cement not removed completely
Theoretical nickel allergy risk

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10
Q

Evidence for PMCs: Einwag and Dunninger (1996)

LEARN ONE

A

Longitudinal study of 66 pxs

  • PMC paired with amalgam restorations on contralateral teeth
  • 4.5 year survival rate was >90% for PMCs but <40% for amalgam
  • only 6% of PMCs required replacement, but 58% of amalgams
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11
Q

Evidence for PMCs: Randall, Vrijhoef and Wilson (2000)

LEARN ONE

A

SR, 10 studies from 1975-1997, duration 1.6-10 years
Failure rate 1.9-30.3% for PMCs vs 11.6-88.7% for amalgam
PMCs had greater longevity, reduced retreatment need
All studies favoured treatment with PMCs

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12
Q

Barriers

A

Lack of training, esp. undergrad
Reluctance to administer LA to children
Difficulties in prep in young children
Perceived reaction by parents

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13
Q

Selling them

A
Parent's often don't like the look of them
Children love them
-princess/ Barbie teeth
-tooth jewellery
-pirate tooth
-iron man tooth
-bling
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14
Q

Things to tell px/ parent

A

They stay on until tooth falls out
Need to be brushed like normal teeth
Glue tastes like lemons/ salt and vinegar crisps
They feel a bit funny to bite on to start with

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15
Q

Conventional technique: you will need

A
Pointy bur (Xmas tree)
Whole box of crowns
Topical/ LA
Diamond burs 
Cement
Dental tape - knotted
Maybe:
-rubber dam
-crown scissors
-crimping pliers
-ortho band seater
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16
Q

Conventional technique: airway protection

A

Child sitting slightly upright
Rubber dam
Gauze
Adhesive handle

17
Q

Conventional technique

A
  1. Topical / LA
  2. Remove caries
  3. Pulpotomy/ pulpectomy if needed
  4. Prepare tooth
  5. Select crown
  6. Adapt crown or modeify prep
  7. Cementation
18
Q

Adapt crown/ modify prep

A
Coping with:
poorly adapted crown margins - crimp
space loss - modify shape or use crown from opposite side and arch
gingival blanching - will resolve
occlusal discrepancies - will resolve
19
Q

Cementation

A
Glass ionomer (Aquacem)
Clotted cream consistency
Enough to fill crown
Remove excess with gauze and knotted floss
Apply crown from lingual to buccal
20
Q

The Hall technique

A
No tooth prep
No local analgesia
No try-in
Not for extensively carious teeth
Caries not removed, but sealed into tooth to isolate from mouth
Tooth asymptomatic
Child not at risk of endocarditis
Pre-op radiograph
\+/- separators
Airway protection
Occlusion
21
Q

Innes N, Evans DJP, Stirrups DR (2007)

A
Split mouth RCT
132 children, aged 3-10
17 GDPs in Tayside, Scotland
Hall technique vs normal 
Clinical and radiographic follow-up
Hugely in favour of Hall technique
5 year results: Major failures 3% Hall, 16.5% controls, minor failure 5% Hall, 42% controls
22
Q

Technique for Hall

A
If necessary place separators 1 week before
Topical (optional)
Choose crown
Airway protection
Try crown to contact point only
Fill crown with GIC
Push down as far as possible
Allow child to bite on band seater/ cotton wool roll
Remove excess cement with wet gauze
Get child to bite together
Remove further cement with gauze, excavator or probe
Knotted floss between contact points
23
Q

Px instructions Hall technique

A

May be a little uncomfortable afterwards
Advice about analgesia
Occlusion will be propped open but will settle