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BDS2 CLINICAL Operative Dentistry > Clinical Amalgam > Flashcards

Clinical Amalgam Flashcards

1
Q

What are possible indications for amalgam

A

a direct restoration that is moderate and large sized cavities in posterior teeth
core build ups when the definitive restoration will be an indirect cast restoration such as a crown or bridge retainer

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2
Q

what are the contra-indications for amalgam

A

If aesthetics are paramount to patient

The patient has a history of sensitivity to mercury
or other amalgam components

Where the loss of tooth substance is such that a retentive cavity cannot be produced

Where excessive removal of sound tooth substance would be required to produce a retentive cavity.

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3
Q

what are the advantages of amalgam

A

Durable
Good long term clinical performance
Long lasting if placed under ideal conditions
Long-term resistance to surface corrosion
Shorter placement time than composite
Corrosion products may seal the tooth restoration
interface
Radiopaque
Colour Contrast
Economical

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4
Q

what is the median survival for amalgam

A

median survival 12 – 15 years

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5
Q

what are the disadvantages of amalgam

A 
Poor aesthetic qualities
 Does not bond easily to tooth substance
 Thermal diffusivity high 
 Cavity preparation may require destruction of sound
  tooth tissue
 Marginal breakdown
Long-term corrosion at tooth restoration interface may result in "ditching" leading to replacement or repair
Local sensitivity reactions 
 Lichenoid lesions
Galvanic response can occur
Tooth discolouration
 Amalgam Tattoo
Concern about possible mercury toxicity
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6
Q

what is the thermal diffusivity of amalgam vs dentine

A

1.7cm2 /sec vs 0.0026cm2 /sec for dentine

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7
Q

what are lichenoid lesions

A

type IV hypersensitivity reactions

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8
Q

what do you do if there is a lichenoid lesion

A

remove the amalgam and replace with either gold or composite

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9
Q

what is the galvanic response

A

Battery effect from 2 different amalgams or more likely amalgam and a cast metal restoration

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10
Q

how does tooth discoloration occur

A

Corrosion products migrate into tooth surfaces which is porous results in a darkened tooth

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11
Q

what is an amalgam tattoo

A

Fine amalgam particles migrate into soft tissues
not harmful, only issue is differential diagnosis
could be an intra oral melanoma

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12
Q

why is amalgam so popular

A

Quick and Easy

Self-hardening at mouth temperature

Can be used in load-bearing areas of the mouth

Good bulk strength and wear resistance

Usually placed at one visit

Economical
vs gold (historically)
vs composite or indirect restorations

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13
Q

what is the restoration sequence

A

Caries risk, assessment and diagnosis

Likely material choice (in these examples: amalgam)

Informed consent

Caries access and removal

Cavity Design

Removal of deep caries

Cavity Toilet

Restoration placement

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14
Q

what is the retention form in cavity design

A

Features that prevent the loss of the restoration in any direction

In an occlusal direction significant undercut is not required, parallel or minimal undercut is all that is necessary.

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15
Q

what is the resistance form in cavity design

A

Features that prevent loss of the material due to distortion or fracture by masticatory forces

Ideally the cavity floor should be approximately parallel to the occlusal surface with sufficient depth of the cavity to give adequate mechanical strength (approx 1.5 – 2mm)

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16
Q

what should the resistance form be in an interproximal restoration

A

The gingival floor of an interproximal box should be approximately 90o to the axial wall. If it is greater a sloping inclined plane which makes the filling liable to slide out of the cavity.

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17
Q

is amalgam first choice for occlusal caries

A

no
unless moderate or large occlusal cavities
if the caries involves most of the fissure system then removal of caries will rseult in a rough parallel sided cavity of adequate depth for either composite or amalgam

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18
Q

what are the cavity designs to treat inter proximal caries

A

self retentive box preparation (minimal preparation box)

proximoocclusal prepararon

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19
Q

what are the advantages of self-retentive box preparation

A

Less tooth tissue removed than with a proximo-
occlusal preparation

• Reduced amount of amalgam placed

• Sound tooth tissue retained between proximal box and
any occlusal cavity

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20
Q

what are the disadvantages of a self-retentive box preparation

A

• Can be more technically demanding than proximo-
occlusal preparation

• Further treatment of any pit and fissure caries may be
required

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21
Q

what are the advantages of a proximo-occlusal preparation

A

• (Should be) Very retentive

Also treats any caries in pits and fissures

• Less or no opportunity for future caries in
pits and fissures

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22
Q

what are the disadvantages of proximo-occlusal preparations

A

Destruction of tooth tissue for retention

• Increased risk of weakening of the tooth

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23
Q

what can be done for additional mechanical retention

A
  • Include grooves or dimples within the cavity design

* Pin placement - titanium / stainless steel

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24
Q

what are pins used for

A

to increase retention in large

non-retentive cavities.

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25
Q

describe pin use

A

Can work well in large restorations and for cores beneath crowns.

Pins are self tapping screws

Place pin into dentine in the greatest bulk of the tooth.

Never in enamel or at the ADJ

Avoid the pulp and periodontal ligament

Pack amalgam around the pin

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26
Q

what are initial problems with pins

A

Stress in tooth around the pin.
Cracking of dentine,
Sensitivity of tooth due to temperature transference

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27
Q

what are long term problems with pins

A

filling can leak but will not fall out because of the pin  secondary caries which can progress further into the tooth because of the pin

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28
Q

what can be used for additional retention (adhesive)

A

adhesive technology:
sealing + bonding restorations (scotch bond, prime and bond). has to be a dual curing bonding agent.
bonding - resin cement e.g panavia(R) 21 EX
resin modified GIC e.g vitrebond

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29
Q

what did the cochrane review say in terms of bonding amalgam

A

‘There is no evidence to claim or refute a difference in survival between bonded and non-bonded amalgam restorations’

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30
Q

what should be done in the finishing of a restoration

A
  • Ensure all caries is removed
  • Smooth and round internal line angles
  • Check and finish cavo-surface angles
  • Smooth cavity margins
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31
Q

what does moisture contamination do

A

Reduces Strength

  • Increases creep
  • Increases corrosion
  • Increases porosity
  • Critical but not as critical as in bonded composite restorations
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32
Q

how can you seal dentine

A

Cavity Varnishes

• Normally with RMGIC

• Can use DBA but this
complicates the process

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33
Q

why does using DBA complicate the process

A

cavity must be dry

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34
Q

what happens in microleakge

A

Passage of fluid and bacteria in micro gaps (10 microns) between restoration and tooth

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35
Q

what does micro leakage result in

A

Pulpal irritation and infection
• Discolouration
• Secondary Caries

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36
Q

what can cause micro leakage

A

Over time; mechanical loading and thermal stresses

may lead to microleakage

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37
Q

what are the different matrixes you can use

A

kerrhawe matrixes

omnimatrix

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38
Q

what do matrixes do

A
  • Recreate wall(s) of the cavity
  • Allows creation of proximal form
  • Allows adequate condensation
  • Confines amalgam to the cavity
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39
Q

what should matrixes be

A
  • Should be < 0.05mm thick

* Smooth and strong

40
Q

what should matrices allow

A
  • Allow close adaptation especially at the cervical margin

* Allow good contact with adjacent tooth

41
Q

what are wedges essential for

A

Essential to produce adaptation of the matrix at the cervical margin

42
Q

what are the different types of wedges

A

Wizard wedges

• Anatomical wedges

43
Q

what are the wedges for

A

Temporary tooth separation
• Prevents excess amalgam gingivally
• Aids proximal wall contour
• Prevents movement of matrix band

44
Q

what does mixing time affect

A
  • Handling characteristics
  • Working time
  • Amalgam microstructure
  • Restoration longevity
45
Q

what does condensation require

A

vertical and lateral pressure

46
Q

what is the point in condensation

A
  • Expels excess mercury bringing it to the surface where it will be carved off
  • Adapts material to cavity walls
  • Reduces layering (homogenous)
  • Eliminates voids
47
Q

what is required for optimal condensation

A

correct size of instruments

48
Q

what kind of instrument makes it easier to control initial increments

A

large plugger

49
Q

once large plugger is used what is done

A

smeared into cavity
smaller plugger is used
overlapping axial strokes

50
Q

what type of alloy requires less force during condensation

A

spherical

51
Q

what does inadequate condensation result in

A
  • Lack of adaptation to cavity
  • Poor bonding between layers
  • Inadequate mercury expression and consequently removal during carving
  • Inferior mechanical properties
52
Q

why do we overfull the cavity

A

Higher mercury content in surface amalgam

53
Q

how do we remove the excess mercury

A

Carving

54
Q

what does carving allow

A

recreate anatomical contour
• Marginal Ridge

  • Inter-proximal contact areas
  • Fissure Pattern
  • Cusps and cuspal inclines
  • Re-establishes occlusal contacts
55
Q

when is finishing required

A

to adjust anatomical contour after amalgam has set
Amalgam finishing burs with water spray
Aspiration

56
Q

why is polishing considered unnecessary

A

there is an increased risk of ingestion

57
Q

what is corrosion

A

“detrimental change in the character of amalgam due to reactions in the mouth”

58
Q

what is corrosion associated with

A

Gamma 2 phase

59
Q

what can corrosion lead to

A

Can cause marginal breakdown

with creep and ditching

60
Q

how can corrosion be beneficial

A

Expansion of amalgam during corrosive process

may assist in the development of a marginal seal

61
Q

why is corrosion less of a problem now

A

Most amalgam is now non-gamma 2, high copper, so less of a problem.

62
Q

what is creep

A

“slow internal stressing and deformation of

amalgam under stress”

63
Q

what is incorporated to decrease creep

A

Copper incorporated to decrease creep

• Ag-Sn-Cu phase stronger

64
Q

what is essential to preventing creep

A

correct cavo surface angle

65
Q

what are common causes for removal

A

Secondary caries

• Bulk fracture

• Removal of an amalgam core within an
extracoronal restoration

66
Q

how do you remove amalgam

A 
Dental dam
 High volume aspiration 
• Minimal cutting
• Selective cutting
• Hand instruments
67
Q

how is mercury released

A

The greatest amount of mercury is released during the insertion and removal of amalgam restorations

68
Q

how is mercury released during insertion

A

Amount is proportional to the restorations` free

surface area

69
Q

how is mercury released in removal

A

Vapour + particles

70
Q

how can mercury be absorbed

A
  • Vapour into lungs
  • Contact with skin
  • Gastro-intestinal tract
  • Gingiva and mucosa
  • Dentine and Pulp as metal ions?
71
Q

is mercury absorption a worry for fillings

A

Inorganic mercury vapour is released very slowly from an amalgam
very little is absorbed in GI tract

72
Q

what is mercury hygiene

A

Dental dam

High Volume aspiration

Amalgam traps – separators

Spillage Kit

Correct disposal of waste amalgam

Correct disposal of unused amalgam

73
Q

what can amalgam cause

A

Can produce delayed hypersensitivity contact reactions on the skin and mucous membrane

74
Q

what can mercury toxicity lead to

A

Higher levels than found in dentistry can cause:

  • Neuro-toxicity
  • Kidney dysfunction
  • Reduced immunocompetence
  • Effects on the oral and intestinal bacterial flora
  • Effects on general health
  • Foetal and birth effects
75
Q

what is the evidence regarding amalgam

A

• No credible scientific evidence to support
suggestions of ill-health caused by dental
amalgam in patients
• No evidence to suggest correct use of dental
amalgam has adverse biological effects on dental
personnel
• Similar level of evidence to support ill health
following use of Bis-GMA containing materials

76
Q

what is the minamata convention

A

The Minamata Convention on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury

77
Q

what is the 15 year post ratification

A

by 2032

There will be no mining for new Mercury

There will be no import or export of Mercury or Mercury containing compounds

78
Q

what is amalgam subjected to in terms of minamata

A

subject to a phase down

79
Q

what are the 9 provisions from minamata in terms of amalgam

A

(i) Setting national objectives aiming at dental caries prevention and health promotion, thereby minimizing the need for dental restoration;
(ii) Setting national objectives aiming at minimizing its use;
(iii) Promoting the use of cost-effective and clinically effective mercury-free alternatives for dental restoration;
(iv) Promoting research and development of quality mercury-free materials for dental restoration;
(v) Encouraging representative professional organizations and dental schools to educate and train dental professionals and students on the use of mercury-free dental restoration alternatives and on promoting best management practices;
(vi) Discouraging insurance policies and programs that favour dental amalgam use over mercury-free dental restoration;
(vii) Encouraging insurance policies and programs that favour the use of quality alternatives to dental amalgam for dental restoration;
(viii) Restricting the use of dental amalgam to its encapsulated form;
(ix) Promoting the use of best environmental practices in dental facilities to reduce releases of mercury and mercury compounds to water and land.

80
Q

what is required form a country to comply with the convention

A

must implement at least two of the provisions of article 4 paragraph 3.

81
Q

how many of the provisions is scotland complying with

A

5

82
Q

what are the EU rules on amalgam

A

dental amalgam will only be used in pre-dosed form

dental amalgam shall not be used for dental treatment of deciduous teeth, of children under 15 years and of pregnant or breastfeeding women, except where deemed strictly necessary by the dental practitioner on the specific medical needs of the patient

a requirement for a national plan, by 1/7/19, on measures to phase down the use of amalgam

a requirement for dental facilities to be equipped with an amalgam separator.

83
Q

what is required in terms of amalgam for the law

A

Encapsulated Amalgam
From January 2019
Already in use in the majority of practices in uk

Amalgam separation mandatory from 2021
All amalgam separators installed from June 2017 must retain at least 95% of amalgam particles

All amalgam waste must be collected by an authorised waste management establishment

84
Q

who should silver amalgam not be used in

A

children under 15
Pregnant Women
Breastfeeding Women

Unless there is an appropriate reason for it’s use.

85
Q

what will the decision to use amalgam be based on

A

the dentist’s clinical judgement and the informed consent of the patient.

86
Q

what is the feature for dental amalgam

A

The EU regulations require each member state to outline measures intended to reduce amalgam use by July 2019

87
Q

what does the SDCEPguidance state

A

Acknowledges that there is no justification on health grounds for not placing amalgam restorations.

There is no justification for removal of sound amalgam restorations except in patients with a proven allergic reaction to constituents of the material.

From July 2018 Silver amalgam should not be used in:
Children under 15
Pregnant Women
Breastfeeding Women

Unless there is a specific medical reason for it’s use.

88
Q

what are the main limitations for placement of amalgam according to SDCEP

A

Lack of cooperation

Inadequate moisture control

89
Q

what is the future for amalgam fillings in adult patients

A

As we stand there are no restrictions to the use of dental amalgam in the bulk of the adult population.

There is no prospect of a phase out of amalgam.

There is a natural phase down happening.

In Scotland the main Phase down action is continuation of a preventative programme

90
Q

what is G V Black classification

A

Stated classification of

CAVITY

91
Q

what is blacks cavity classification class I

A

• Class I: Pit and fissure caries

92
Q

what is blacks cavity classification class II

A

• Class II: Approximal caries (posterior teeth)

93
Q

what is blacks cavity classification class III

A

• Class III: Approximal caries (anterior teeth)

94
Q

what is blacks cavity classification class IV

A

• Class IV: Approximal caries involving incisal angle

95
Q

what is blacks cavity classification class V

A

• Class V: Caries affecting cervical surfaces

96
Q

what is blacks cavity classification class VI

A

• Class VI: Caries affecting cusp tips

BDS2 CLINICAL Operative Dentistry (12 decks)

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