Clinical Amalgam Flashcards
What are possible indications for amalgam
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
what are the contra-indications for amalgam
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.
what are the advantages of amalgam
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
what is the median survival for amalgam
median survival 12 – 15 years
what are the disadvantages of amalgam
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
what is the thermal diffusivity of amalgam vs dentine
1.7cm2 /sec vs 0.0026cm2 /sec for dentine
what are lichenoid lesions
type IV hypersensitivity reactions
what do you do if there is a lichenoid lesion
remove the amalgam and replace with either gold or composite
what is the galvanic response
Battery effect from 2 different amalgams or more likely amalgam and a cast metal restoration
how does tooth discoloration occur
Corrosion products migrate into tooth surfaces which is porous results in a darkened tooth
what is an amalgam tattoo
Fine amalgam particles migrate into soft tissues
not harmful, only issue is differential diagnosis
could be an intra oral melanoma
why is amalgam so popular
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
what is the restoration sequence
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
what is the retention form in cavity design
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.
what is the resistance form in cavity design
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)
what should the resistance form be in an interproximal restoration
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.
is amalgam first choice for occlusal caries
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
what are the cavity designs to treat inter proximal caries
self retentive box preparation (minimal preparation box)
proximoocclusal prepararon
what are the advantages of self-retentive box preparation
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
what are the disadvantages of a self-retentive box preparation
• Can be more technically demanding than proximo-
occlusal preparation
• Further treatment of any pit and fissure caries may be
required
what are the advantages of a proximo-occlusal preparation
• (Should be) Very retentive
Also treats any caries in pits and fissures
• Less or no opportunity for future caries in
pits and fissures
what are the disadvantages of proximo-occlusal preparations
Destruction of tooth tissue for retention
• Increased risk of weakening of the tooth
what can be done for additional mechanical retention
- Include grooves or dimples within the cavity design
* Pin placement - titanium / stainless steel
what are pins used for
to increase retention in large
non-retentive cavities.
describe pin use
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
what are initial problems with pins
Stress in tooth around the pin.
Cracking of dentine,
Sensitivity of tooth due to temperature transference
what are long term problems with pins
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
what can be used for additional retention (adhesive)
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
what did the cochrane review say in terms of bonding amalgam
‘There is no evidence to claim or refute a difference in survival between bonded and non-bonded amalgam restorations’
what should be done in the finishing of a restoration
- Ensure all caries is removed
- Smooth and round internal line angles
- Check and finish cavo-surface angles
- Smooth cavity margins
what does moisture contamination do
Reduces Strength
- Increases creep
- Increases corrosion
- Increases porosity
- Critical but not as critical as in bonded composite restorations
how can you seal dentine
Cavity Varnishes
• Normally with RMGIC
• Can use DBA but this
complicates the process
why does using DBA complicate the process
cavity must be dry
what happens in microleakge
Passage of fluid and bacteria in micro gaps (10 microns) between restoration and tooth
what does micro leakage result in
Pulpal irritation and infection
• Discolouration
• Secondary Caries
what can cause micro leakage
Over time; mechanical loading and thermal stresses
may lead to microleakage
what are the different matrixes you can use
kerrhawe matrixes
omnimatrix
what do matrixes do
- Recreate wall(s) of the cavity
- Allows creation of proximal form
- Allows adequate condensation
- Confines amalgam to the cavity
what should matrixes be
- Should be < 0.05mm thick
* Smooth and strong
what should matrices allow
- Allow close adaptation especially at the cervical margin
* Allow good contact with adjacent tooth
what are wedges essential for
Essential to produce adaptation of the matrix at the cervical margin
what are the different types of wedges
Wizard wedges
• Anatomical wedges
what are the wedges for
Temporary tooth separation
• Prevents excess amalgam gingivally
• Aids proximal wall contour
• Prevents movement of matrix band
what does mixing time affect
- Handling characteristics
- Working time
- Amalgam microstructure
- Restoration longevity
what does condensation require
vertical and lateral pressure
what is the point in condensation
- Expels excess mercury bringing it to the surface where it will be carved off
- Adapts material to cavity walls
- Reduces layering (homogenous)
- Eliminates voids
what is required for optimal condensation
correct size of instruments
what kind of instrument makes it easier to control initial increments
large plugger
once large plugger is used what is done
smeared into cavity
smaller plugger is used
overlapping axial strokes
what type of alloy requires less force during condensation
spherical
what does inadequate condensation result in
- Lack of adaptation to cavity
- Poor bonding between layers
- Inadequate mercury expression and consequently removal during carving
- Inferior mechanical properties
why do we overfull the cavity
Higher mercury content in surface amalgam
how do we remove the excess mercury
Carving
what does carving allow
recreate anatomical contour
• Marginal Ridge
- Inter-proximal contact areas
- Fissure Pattern
- Cusps and cuspal inclines
- Re-establishes occlusal contacts
when is finishing required
to adjust anatomical contour after amalgam has set
Amalgam finishing burs with water spray
Aspiration
why is polishing considered unnecessary
there is an increased risk of ingestion
what is corrosion
“detrimental change in the character of amalgam due to reactions in the mouth”
what is corrosion associated with
Gamma 2 phase
what can corrosion lead to
Can cause marginal breakdown
with creep and ditching
how can corrosion be beneficial
Expansion of amalgam during corrosive process
may assist in the development of a marginal seal
why is corrosion less of a problem now
Most amalgam is now non-gamma 2, high copper, so less of a problem.
what is creep
“slow internal stressing and deformation of
amalgam under stress”
what is incorporated to decrease creep
Copper incorporated to decrease creep
• Ag-Sn-Cu phase stronger
what is essential to preventing creep
correct cavo surface angle
what are common causes for removal
Secondary caries
• Bulk fracture
• Removal of an amalgam core within an
extracoronal restoration
how do you remove amalgam
Dental dam High volume aspiration • Minimal cutting • Selective cutting • Hand instruments
how is mercury released
The greatest amount of mercury is released during the insertion and removal of amalgam restorations
how is mercury released during insertion
Amount is proportional to the restorations` free
surface area
how is mercury released in removal
Vapour + particles
how can mercury be absorbed
- Vapour into lungs
- Contact with skin
- Gastro-intestinal tract
- Gingiva and mucosa
- Dentine and Pulp as metal ions?
is mercury absorption a worry for fillings
Inorganic mercury vapour is released very slowly from an amalgam
very little is absorbed in GI tract
what is mercury hygiene
Dental dam
High Volume aspiration
Amalgam traps – separators
Spillage Kit
Correct disposal of waste amalgam
Correct disposal of unused amalgam
what can amalgam cause
Can produce delayed hypersensitivity contact reactions on the skin and mucous membrane
what can mercury toxicity lead to
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
what is the evidence regarding amalgam
• 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
what is the minamata convention
The Minamata Convention on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury
what is the 15 year post ratification
by 2032
There will be no mining for new Mercury
There will be no import or export of Mercury or Mercury containing compounds
what is amalgam subjected to in terms of minamata
subject to a phase down
what are the 9 provisions from minamata in terms of amalgam
(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.
what is required form a country to comply with the convention
must implement at least two of the provisions of article 4 paragraph 3.
how many of the provisions is scotland complying with
5
what are the EU rules on amalgam
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.
what is required in terms of amalgam for the law
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
who should silver amalgam not be used in
children under 15
Pregnant Women
Breastfeeding Women
Unless there is an appropriate reason for it’s use.
what will the decision to use amalgam be based on
the dentist’s clinical judgement and the informed consent of the patient.
what is the feature for dental amalgam
The EU regulations require each member state to outline measures intended to reduce amalgam use by July 2019
what does the SDCEPguidance state
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.
what are the main limitations for placement of amalgam according to SDCEP
Lack of cooperation
Inadequate moisture control
what is the future for amalgam fillings in adult patients
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
what is G V Black classification
Stated classification of
CAVITY
what is blacks cavity classification class I
• Class I: Pit and fissure caries
what is blacks cavity classification class II
• Class II: Approximal caries (posterior teeth)
what is blacks cavity classification class III
• Class III: Approximal caries (anterior teeth)
what is blacks cavity classification class IV
• Class IV: Approximal caries involving incisal angle
what is blacks cavity classification class V
• Class V: Caries affecting cervical surfaces
what is blacks cavity classification class VI
• Class VI: Caries affecting cusp tips
