Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS2 Clinical > Clinical Application of Amalgam > Flashcards

Clinical Application of Amalgam Flashcards

1
Q

what is amalgam

A

“an alloy of mercury with another metal or metals”

Dentistry use silver amalgam (one of many)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

3 direct restorative materials

A
  • Amalgam
  • Composite Resin
  • Glass Ionomer & RMGI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

4 indirect restorative materials

A
  • Gold
  • Other metals
  • Ceramic
  • Composite Resin - Ceromeric
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

2 possible indications for amalgam

A
  • A direct restoration in 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

Amalgam is predominately on posterior teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

amalgam contra-indications (4)

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
- Build up sub-structure, base material

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

10 advantages of amalgam

A

Durable

Good long term clinical
performance

Long lasting if placed under ideal conditions
- median survival 12 – 15 years (nothing beats, bar gold)

Long-term resistance to surface corrosion

Shorter placement time than composite
- Ultimately easier than composite, shorter placement time (1/4)

Corrosion products may seal the tooth restoration

Interface

Radiopaque

Colour Contrast

Economical

Less professional time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

12 disadvantages of amalgam

A

Poor aesthetic qualities

Does not bond easily to tooth substance

Thermal diffusivity high (1.7cm2 /sec vs 0.0026cm2 /sec for dentine)

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

  • Ditching around edges
  • Water more likely to penetrate lead to secondary caries

Local sensitivity reactions

Lichenoid lesions

Galvanic response can occur

tooth discoloration

amalgam tattoo

concern about possible mercury toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

lichenoid lesions due to amalgam

A

Type IV hypersensitivity reaction

- Remove amalgam and replace with Gold or composite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

galvanic response to amalgam

A

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

Complain tingling in mouth - rare

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

tooth discolouration due to amalgam

A

Corrosion products migrate into tooth surfaces which is porous (stain dentine) → Darkened tooth

When replace with tooth coloured restoration see a dark line where amalgam was previously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is amalgam tattoo

A

Fine amalgam particles migrate into soft tissues

Differential diagnosis
- Biopsy, X-ray (seldom helpful)

Need to be sure it’s amalgam tattoo
- Been there for a long time
Suddenly appeared could be intra myeloma - rare

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why has amalgam been in use for 100s of years (^)

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 (less professional time)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

restoration sequence for amalgam

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

2 things to remember for cavity design for amalgam

A

retention form

resistance form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

retention form in amalgam cavity design

A

Features that prevent the loss of the restoration in any direction
- Prevent the restoration being lost – straight up and down

In an occlusal direction significant undercut is not required, parallel or minimal undercut is all that is necessary.
- Caries is naturally wider in dentine than in enamel – so natural to have undercuts usually

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

resistance form in amalgam cavity design

A

Features that prevent loss of the material due to distortion or fracture by masticatory (occlusion) forces
- Bite on it – amalgam prone to move as not bonded to tooth

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)

  • Moves to dips in cavity floor
  • Place lining in particularly deep parts of floor – don’t cut even
  • Want smooth, so no deficit areas

The gingival floor of an interproximal box should be approximately 90o to the axial wall. If it is greater this→ a sloping inclined plane which makes the filling liable to slide out of the cavity.
- Need gingival box at 90 degrees so amalgam doesn’t slide/gradually creep out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

should amalgam be used in pit and small fissure caries?

A

no

there is improved composite and glass ionomer with clinical evidence to suggest their use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

can amalgam be used in moderate/large occlusal cavities?

A

yes, will last well

If caries involves most of the fissure system removal of the caries will result in a roughly parallel sided cavity of adequate depth for either composite or amalgam.
- May cut less tooth

silver amalgam is not first choice for occlusal caries generally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

2 amalgam cavity design for interproximal caries

A

Self-retentive box preparation (minimal preparation box)

Proximo-occlusal preparation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

amalgam interproximal cavity: self-retentive box preparation

A

Similar to composite
- Difference - inside edges taper out slightly (usually there from caries progression)

Don’t remove natural undercuts for composite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

3 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

2 disadvantages of 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

when should proximo-occlusal amalgam cavity preparation be used

A
  • Not fall out
  • Caries on occlusal dealt with
  • But More tissue removed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

3 advantages of proximo-occlusal amalgam cavity 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

disadvantages proximo-occlusal amalgam cavity preparation

A

Destruction of tooth tissue for retention • Increased risk of weakening of the tooth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

how to create additional mechanical retention for amalgam

A

Include grooves or dimples within the cavity design

Dentine Pin placement - titanium / stainless steel

  • Pin use is controversial
  • Used to increase retention in large non-retentive cavities.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

dentine pins for mechanical retention

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.

  • Place a hole with drill, smaller in diameter than pin, pin goes in half in half out, parallel to the long axis of the tooth
  • Hard to place

Never in enamel or at the ADJ
- Fracture the enamel
Dentine can bend with screw

Avoid the pulp and periodontal ligament

Pack amalgam around the pin

old fashioned

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

initial problems with dentine pins

A

Stress in tooth around the pin.

Cracking of dentine,

Sensitivity of tooth due to temperature transference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

long term problems with dentine 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

Caused by direct route from external silver amalgam into core of tooth
- May have a lining elsewhere but pathway at pin

never use pins with composite resins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

adhesive technology for additional amalgam retention

A

Sealing (resin) + bonding restorations
- ScotchbondTM
- Prime&Bond®NT
Must be dual curing bonding agent

Bonding – Resin Cement e.g. PANAVIA®21 EX

Resin Modified GIC e.g. Vitrebond

Bond amalgam in
- Amalgam Bonds to dentine bonding agents with MDP
- Can pack in top of bonding agent
low strength 4-5MPa compared to 20MPa to enamel
Can use when wet

Ultimately no evidence for bonded amalgam survival over non-bonded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

finishing of amalgam preparation

A

Ensure all caries is removed

Smooth and round internal line angles

Check and finish cavo-surface angles

Smooth cavity margins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

5 concerns of moisture contamination in amalgam

A

Reduces Strength

Increases creep

Increases corrosion

Increases porosity

Critical but not as critical as in bonded composite restorations

  • Can be used under water - cannot for composite
  • Better to be dry - better strength, less creep, corrosion, less porosity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

why do we need to seal dentine in amalgam

A

Because amalgam transmits temperature need to place a liner

34
Q

ways to seal dentine for amalgam

A
  • Cavity Varnishes
  • Normally with RMGIC
  • Can use DBA but this complicates the process
    (Need to keep cavity dry – would composite be more appropriate?)
35
Q

microleakage

A

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

36
Q

what 3 things can microleakage result in

A
  • Pulpal irritation and infection
  • Discolouration
  • Secondary Caries
37
Q

what can lead to microleakage

A

mechanical loading and thermal stress

Composite more dentine margins
Amalgam both dentine and enamel margins

38
Q

how does micoleakage effect composite more than amalgam

A

Composite more dentine margins

Amalgam both dentine and enamel margins

39
Q

3 roles of matrices

A 
Recreate wall(s) of the cavity
- Need to get smooth walls of restorations joining to tooth

Allows creation of proximal form and adequate condensation
- Pressure need to compact can cause filling of gap - impossible to clean

Confines amalgam to the cavity

40
Q

4 properties of matrices

A

Should be < 0.05mm thick (better contact area)

Smooth and strong

Allow close adaptation especially at the cervical margin

Allow good contact with adjacent tooth

41
Q

5 functions of wedges

A

Essential to produce adaptation of the matrix at the cervical margin, Buccal or lingual approach

Temporary tooth separation

Prevents excess amalgam gingivally

Aids proximal wall contour

Prevents movement of matrix band

(Wizard wedges, Anatomical wedges)

42
Q

what does mixing time of amalgam effect (4)

A

Handling characteristics

Working time

Amalgam microstructure

Restoration longevity

43
Q

what is condensation (with amalgam)

A

Vertical and lateral pressure needed (packing the amalgam)

very important

44
Q

importance of good condensation of amalgam (4)

A

Expels excess mercury bringing it to the surface where it will be carved off
- Weakest form

Adapts material to cavity walls

Reduces layering (homogenous) 
- Sufficient force to avoid distinct layers between gunfulls – prevents voids

Eliminates voids

45
Q

how to achieve optimal condensation (3)

A

Require correct size of instruments

  • Easier to control initial increment with a large plugger (keep material in cavity) Smear into the cavity;
  • Smaller plugger (if use initially will end up stuck to and removing from cavity); Overlapping axial strokes

Lateral as well as axial condensation

Spherical alloys require less force for condensation

46
Q

inadequate amalgam condensation (4)

A

Lack of adaptation to cavity
- Spaces round the edge - food and plaque lead to secondary caries

Poor bonding between layers
- Weak due to voids

Inadequate mercury expression and consequently removal during carving

Inferior mechanical properties

47
Q

where is the weakest form of amalgam

A

at the top, where it is expressed

48
Q

what should you always do when placing amalgam

A

overfill the cavity

49
Q

how do you remove the higher mercury content amalgam

A

carving
burnishing/finishing

use high volume aspiraion

50
Q

carving amalgam

A

Recreate anatomical contour

  • Marginal Ridge
  • Inter-proximal contact areas
  • Fissure Pattern
  • Cusps and cuspal inclines
  • Re-establishes occlusal contacts
51
Q

finishing amalgam

A

Only if required to adjust anatomical contour after amalgam has set
- Amalgam finishing burs with water spray
Aspiration
Adverse effects of heat
Mercury risk?

Polishing considered unnecessary

  • Free up mercury in material - greater risk.
  • Head shakes - unpleasant procedure
52
Q

corrosion

A

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

Associated with Gamma 2 phase (hardly any Gamma 2 phase amalgams on market most are Cu enriched) – but can be already placed in patient

53
Q

corrosion in amalgam can cause

A

marginal breakdown with creep and ditching

54
Q

how can corrosion of amalgam occur

A

Expansion of amalgam during corrosive process may assist in the development of a marginal seal

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

55
Q

creep

A

“slow internal stressing and deformation of amalgam under stress”

Apply smaller force over a long period of time - material moves away

56
Q

creep in amalgam

A

Copper incorporated to decrease creep
- Ag-Sn-Cu phase stronger (therefore less of an issue)

The greater the amount of creep the weaker the amalgam

Reduced creep should maintain marginal integrity

Correct cavo-surface angle is essential

57
Q

why would you remove amalgam (3)

A
  • Secondary caries
  • Bulk fracture
  • Removal of an amalgam core within an extracoronal restoration
58
Q

how to remove amalgam

A

need: Dental dam, High volume aspiration

Minimal and selective cutting

  • Don’t want to grind out like power
  • Cut mesial to distal and then cross ways - bits will pop out as not bonded to tooth

Hand instruments

Operator and assistant protection

Easy to see that you have removed due to colour difference

59
Q

when is the greatest amount of mercury released in dentistry

A

During Insertion
- Amount is proportional to the restorations` free surface area

During removal
- Vapour + particles

60
Q

5 methods of mercury absorption

A

Vapour into lungs

Contact with skin

Gastro-intestinal tract

Gingiva and mucosa

Dentine and Pulp as metal ions (?)

61
Q

how much mercury is absorbed from a filling?

A

Inorganic mercury vapour is released

  • very slowly from an amalgam
  • about 0.5 microgrammes/surface/day

490 amalgam surfaces would be required in a mouth to reach the exposure dose limit set by the WHO.
- Not possible to overcome safe dose in reality from dental care

Only about 15% of the mercury released is absorbed (0.08 microgrammes) from the lungs and GI tract.

Organic Mercury in food (tuna) is absorbed much more easily (About 90% of that ingested)

62
Q

mercury hygiene

A

Usual protection for dental personel

Dental dam

High Volume aspiration

Amalgam traps – separators Spillage Kit (prevent Hg going into water system)

Correct disposal of waste amalgam Correct disposal of unused amalgam

63
Q

where is 50% of mercury derived from

A

natural sources

  • ocean evaporation
  • geothermal activity
  • rock erosion

in the USA 80% of mercury pollution is from burning fossil fuels for energy
<1% is from dentistry (small part)

64
Q

mercury toxicity

A

Dental Amalgam can produce delayed hypersensitivity contact reactions on the skin and mucous membrane

Higher levels than found in dentistry can cause:
- Neuro-toxicity (mad hatter effect (used in top hats))
- Kidney dysfunction
- Reduced immunocompetence
- Effects on the oral and intestinal bacterial flora
- Effects on general health
- Foetal and birth effects
Can kill

65
Q

how can dental amalgam effect human body

A

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

66
Q

what is the Minamata convention of mercury

A

global treaty to protect human health and the environment from the adverse effects of mercury

  • Governs use of all mercury containing products.
  • Global treaty 128 countries signed up.

agreed in Geneva, Switzerland on Saturday, 19 January 2013 and adopted later that year on 10 October 2013 at a Diplomatic Conference held in Kumamoto (Minamata), Japan.
Ratified in June 2017

‘Regulation on Mercury’ is the EU plan for reducing mercury in the environment

67
Q

what is the objective of the Minamata convention of mercury

A

to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds.

Trying to get rid of amalgam use
- Limit and phase out mercury use throughout world

68
Q

implications of Minamata convention of mercury

A

15 Years Post Ratification (2032) There will be no mining for new Mercury

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

69
Q

what does the Minamata convention of mercury govern

A

Governs use of all mercury containing products.
- Known as Mercury-added products
After 2020 it will be illegal to manufacture or export any of these products:
• Batteries
• Switches
• Fluorescent lights
• Some cosmetics
• Antiseptics
• Barometers, thermometers, manometers etc. (can be replaced with LED)

Dental Amalgam is different it is subject to a phase down
Nowhere in the regulations does it suggest phase out

70
Q

European Commission Regulation (EU) 2017/852 adopted when

A

May 2018

EU guidelines on Mercury use

71
Q

what does Minamata convention mean for dentistry

A

Dental Amalgam is different it is subject to a phase down

Nowhere in the regulations does it suggest phase out

72
Q

European Commission Regulation (EU) 2017/852 mean for dentistry in UK

A

Encapsulated Amalgam
- From January 2019

Already in use in the majority of practices in uk

Amalgam Separation

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

All amalgam waste must be authorised waste management establishment

From July 2018 Silver amalgam should not be used in:
- Children under 15
- Pregnant Women
- Breastfeeding Women
Unless there is an appropriate reason for it’s use.

Essentially the decision to use the material will still be based on the dentist’s clinical judgement and the informed consent of the patient.

73
Q

SDCEP guidelines June 2018 in regards to amalgam

A

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

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

limited itself to article 10(2)
From July 2018 Silver amalgam should not be used in:
- Children under 15
- Pregnant Women
- Breastfeeding Women
Unless there is an appropriate reason for it’s use.
Unless there is an appropriate reason for it’s use.
- Read “Unless there is a specific Dental Reason for it’s use.”

74
Q

2 dental reasons for placing amalgam

A
  • Lack of cooperation
  • Inadequate moisture control

Dental reasons e.g.
14 year old MOD in upper 6 and cannot get dry as subgingival or cannot keep dam on long enough - use amalgam

It doesn’t matter how good you are at doing composite restorations. If it’s not dry, they don’t work

75
Q

amalgam use in adult

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
- similar scheme in Ireland, England has nothing in place currently

76
Q

Black Cavity Classification

A

Class I: Pit and fissure caries (occlusal)
Class II: Approximal caries (posterior teeth) (MO/DO)
Class III: Approximal caries (anterior teeth)
Class IV: Approximal caries involving incisal angle
Class V: Caries affecting cervical surfaces
Class VI: Caries affecting cusp tips (rare)

Arranged in how often they occur

77
Q

Class I

A

Pit and fissure caries (occlusal)

78
Q

Class II

A

Approximal caries (posterior teeth) (MO/DO)

79
Q

Class III

A

Approximal caries (anterior teeth)

80
Q

Class IV

A

Approximal caries involving incisal angle

81
Q

Class V

A

Caries affecting cervical surfaces

82
Q

Class VI

A

Caries affecting cusp tips (rare)

BDS2 Clinical (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions