Module 4.2 Understanding Amalgam PDH Project 2011(2)

8/6/2019 Module 4.2 Understanding Amalgam PDH Project 2011(2)

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4.2 Understanding Amalgam

Abstract

In an effort to determine the place of dental amalgam in restorative

dentistry over the next number of years, this study investigated the

current opinion and level of knowledge of the general public on the use

of dental amalgam as a restorative material, taking into account

patient satisfaction with information materials about the subject. The

opinions and teaching rationale of restorative staff in dental institutes

across Europe with respect to dental amalgam were also explored.

The study found that the general public appears to have a limited level

of knowledge about dental amalgam. Concerns about its appearance

and its alleged health risks were reported as reasons to avoid its use.

A high proportion of participants were not aware of its environmental

effects, in spite of the fact that this has been the sole reason for the

banning of amalgam in Scandinavian countries. The study

recommends that a public awareness campaign addressing commonmisconceptions about dental amalgam would be of benefit. Further

research is needed into the environmental mercury load in Ireland.

The findings of the European study show that the teaching of dental

amalgam has declined across Europe. However it was noted by a

number of respondents that, in practice, the use of the material may in

fact increase in the current economic climate, as alternatives to dental

amalgam are often more costly for the patient. A European Union

decision regarding the future of dental amalgam is necessary to

standardise restorative practices across Europe.

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Acknowledgements

We would like to extend our many thanks to the following:

Prof Nunn, Mr. Brian Murray and Dr. Michael OSullivan for their

permission to use the A&E department of the Dental Hospital for our

questionnaires.

Dr. Siobhn Davis, Dr. Anne Brazil and Dr Michael O Sullivan who

kindly participated in our pilot questionnaire and offered us some

useful tips.

Ms. Majella Giles for her endless support in contacting the European

dental schools. Without her it would have been impossible!

To the many patients in the A&E department who gave up their time to

help us in spite of the fact that more often than not they were in pain!!

To all the participants of our European questionnaire who took time out

of their busy schedules to complete our questionnaire, we are very

grateful.

Dr. Jacinta McLoughlin for her advice and expertise on the practical

aspects of the project.

Finally, we would like to thank Dr. Feleena Tiedt, our supervisor, for her

hard work and patience with us every Tuesday morning.

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Table of Contents

Abstract page1Acknowledgements

page 2

Contents page3List of figures

page 5List of tables

page 5

Chapter 11.1: Introduction page61.2: Aims page71.3: Objectives page7

Chapter 2:Literature Review

2.1: History of dental amalgampage 82.2: Composition of dental amalgam

page 102.3: Dental amalgam properties page 132.4: Environmental issues regarding amalgampage 142.5: Dental amalgam and the environment

page 182.6: Health effects of dental amalgampage 202.7: International policies regarding use of dental amalgam

page 282.8:The influence of economic incentives on treatment patterns in athird-party

funded dental servicepage 322.9: Economic impact regulating the use of amalgam

page 342.10: Repair vs replacement of amalgam restorations-the ethicaldebate page 35

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2.11: Teaching rationales and public attitudes regarding dentalamalgam page 39Chapter 3:Materials and Methods

3.1: Preparatory workpage 433.2: Sample selectionpage 433.3: Formulating questionnairespage 443.4: Pilot questionnairespage 453.5: Carrying out questionnaires and analysispage 45

Chapter 4:Results

4.1: Public Attitudes and Concerns regarding Dental Amalgampage 47

4.1.1: Breakdown of subjects by age and gender page 47

4.1.2: Reported dental amalgam experience of subjects page 484.1.3: Attitudes of subjects to dental amalgam

page 49 4.1.4: Knowledge subjects had about dental amalgam

page 514.2: Dublin Dental Hospital Amalgam Information Leaflet

page 534.3: European dental teaching hospitals opinions

page 55Chapter 5:Discussion

5.1: Understanding Amalgam Patient Questionnairepage 58

5.2: Opinion on Dental Amalgam Leaflet questionnaire

page 635.3: European dental schools survey

page 65

Chapter 6:Conclusionspage 73

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Chapter 7:Recommendationspage 76Chapter 8:Appendices

Appendix 1: Letter asking for permission to conduct study

page 78Appendix 2: Ethical Approval page 79

Appendix 3: Participant Information leafletpage 80

Appendix 4: Understanding Amalgam questionnaire page 81

Appendix 5: Current DDUH Dental Amalgam Information Leaflet page 83

Appendix 6: Opinion on Dental Amalgam Leaflet questionnaire page 85

Appendix 7: Letter to European dental schoolspage 86Appendix 8: Dental Amalgam Study European questionnaire

page 87Appendix 9: Proposed amended Dental Amalgam Patient InformationLeaflet

page88

Chapter 9:Bibliography

page 90

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Chapter 1:

1.1: Introduction

Dental amalgam has been a popular dental restorative material in use

around the world for over a century. It is widely acknowledged to be

the most suitable material to use in posterior cavities due to its load-

bearing capability and durability. However, in recent years, its use has

become more controversial, for reasons including alleged adverse

health effects and the known environmental risks associated with the

mercury content of the material. The development of newer, adhesive,

tooth-coloured filling materials, such as resin-based composites and

glass ionomer cements, has strengthened the argument against its

use. The future of dental amalgam as a restorative material will be

influenced not only by the opinions of the dental professionals

responsible for the restoration of teeth, but perhaps just as importantly

by those patients seeking treatment.

As information on an endless variety of topics is increasingly available

via the internet and other media sources to members of the public, it

was acknowledged that the topic of dental amalgam is no different. It

was decided to investigate whether or not the general public had any

concerns about its use, and also to consider the level of knowledge of

the general public around the subject. There appears to be little

information already available at present on the public perception of theuse of the material, so it was hoped that, in conducting this study,

some light would be shed on the subject, and that greater insight

would be gained into the thoughts of members of the public on the

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matter. The study also hoped to investigate public satisfaction with

information materials available on the topic.

Bearing in mind the controversy surrounding dental amalgam, and the

fact that in certain countries its use has been banned completely, it

was decided to also investigate the current teaching rationale in dental

schools across Europe with respect to dental amalgam. It was felt that

an international comparison to the teaching practices here in the

Dublin Dental University Hospital would be worthy of note, and would

help with efforts to propose what place, if any, dental amalgam would

hold in restorative dentistry in the next decade.

1.2: Aims

To investigate the public awareness and perception of dental

amalgam.

To investigate the use of dental amalgam in dental institutes

throughout Europe.

To question what the future of dental amalgam in restorative

dentistry will be.

1.3: Objectives

Identify and evaluate the current attitudes and concerns

amongst the general public towards dental amalgam.

Gain an understanding of the current teaching rationale in

relation to the use and future of amalgam in international dental

schools.

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Ascertain patients perceptions of the current DDSH dental

amalgam information leaflet.

Amend the DDSH amalgam information leaflet using the

patients feedback.

Highlight areas in need of further investigation.

Extrapolate from the results of the study if there is a future for

dental amalgam in restorative dentistry.

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Chapter 2: Review of the Literature

2.1: History of Dental Amalgam

Dental amalgam has been in use as a restorative filling material since

the early 1800s. (Yip and Cutress, 2003) During this time period, many

changes in its composition and manipulation have taken place. The

first available amalgam, entitled Darcets Mineral Cement, consisted

of an alloy of bismuth, lead and tin with mercury. It was plasticised at

100oC and poured directly into the cavity at this temperature. In 1818,

Rignzrt slightly reduced the torture experienced by patients when the

restoration was placed by developing an amalgam that only needed a

plasticising temperature of 68oC. (Wilson et al, 1998)

The first room-temperature amalgams were developed by Bell in

England and Taveau in France in 1819 and 1826 respectively. These

amalgams more closely resemble what is in use in practice today.

(Eley 1997(a))

In the 1830s, the Crawcour brothers were driven from the USA because

they had placed many inadequate amalgam restorations due to their

poor knowledge of the material. This led to the first major amalgam

debate occurring, and as a consequence, the American Society of

Dental Surgeons banned its use. (Mackert et al, 1991) However, in

1850 the policy was reconsidered because the adverse health effects

that had been reported were not occurring and so amalgam then

become widely accepted as a useful restorative material. Work carried

out by J.F. Flagg and G.V. Black in the years following this, mostly

concentrated on the properties of amalgam, strengthened the debate

for its clinical use. (Mackert et al 1991)

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In the 1900s, amalgam was mainly supplied as a tablet form. It was

heated to the correct temperature until beads of mercury started to

appear and it was then transferred to a mortar and pestle. It was then

manipulated into a soft, mushy paste which was shown to release large

quantities of mercury vapour. (Anusavice, K.J 2003)

A second amalgam debate erupted in the late 1920s. This was

primarily due to the writings of Dr. Alfred Stock, a chemistry professor.

His writings included the harmful effects that can occur when one is

exposed to mercury vapour for long periods of time, having been

exposed to it himself for 25 years in a laboratory. His writings received

so much attention that a medical committee was appointed to

investigate the alleged problem in 1950. The committee concluded

that there was no reason to remove the silver-tin amalgams that were

in clinical use then. (Eley 1997(a))

The 1970s saw the third amalgam debate occurring. This time it was

mainly due to the work of H.A. Huggins and Dr. Olympio Pinto. Their

writings made strong suggestions that certain medical conditions suchas leukaemia and bowel disease were caused by exposure to mercury.

(Eley 1997(a)) However, several reports carried out by recognised

bodies such as the British Dental Association (BDA), UK Department of

Health, American Dental Association (ADA) and Canadian Dental

Association (CDA) render these claims insignificant and encouraged

the use of amalgam. (Eley 1997(a))

More recently, the Panorama programme in the UK and the 60

minutes programme in US have raised concerns over amalgams

safely as a restorative dental material. These, along with the recent

advancement of adhesive tooth-coloured materials could see a

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diminished use of amalgam in the future. However, at the moment it

is still very popular.

Nowadays dental amalgam is no longer mixed manually using a mortar

and pestle, but rather it is contained in a capsule (encapsulated) and

mixed in a triturator. The capsule is divided in half by a membrane.

The alloy powder is contained on one side of the membrane and the

liquid mercury is contained on the other side. The capsule must be

activated by means of pressing down on a tab to collapse the

membrane, allowing the powder and liquid to mix. The capsule is then

placed in a high-speed triturator for several seconds to be mixed

completely. This process of encapsulation was introduced in order to

minimise dental health professional exposure to the mercury released

during the mixing of dental amalgam. (Cutress et al, 1997)

2.2: Composition of Dental Amalgam

An amalgam consists of a mixture of two or more metals, one of

which is mercury. Dental amalgam consists of mercury combined witha powdered silver-tin alloy (McCabe, 2008).

Amalgamation describes the reaction between mercury and alloy and

results in the formation of a hard silver-grey material. As mercury is a

liquid at room temperature, when mixed with the alloy, it readily forms

a workable mass. (Mc Cabe, 2008)

The powdered alloy used in the traditional dental amalgams consists of

silver, tin, copper, zinc and sometimes small quantities of other metals

such as indium or palladium. (Van Noort 2007)

Silver is the main constituent. Current guidelines state that a

minimum of 40% silver needs to be included in the alloy. Tin is usually

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present in quantities of approximately 29-32%. The silver and tin

need to be present in sufficient quantities to ensure that the inter-

metallic compound Ag3Sn, or the gamma phase (), is present.

phase can readily undergo amalgamation with mercury but it is only

present over a small composition range. (Van Noort, 2007)

Most conventional alloy powders contain approximately 5% copper. Its

role is to increase the strength and hardness of the material. (Van

Noort, 2007) More modern, copper-enriched amalgam alloys employ a

copper content of 10-30%.

Zinc is present in small amounts in most amalgam alloys and its role is

to act as a scavenger. During amalgamation, oxidation occurs when

the metals melt together at high temperatures. Zinc reacts readily

with the available oxygen to form zinc-oxide, to stop oxygen reacting

with other metals. If oxygen is allowed to react with the other metals,

it has a negative effect on the properties of the amalgam. (Mc Cabe,

2008)

The majority of amalgam alloy powders contain no mercury. However,

some do contain a small amount, approximately 3%. These arereferred to as pre-amalgamated alloys and they react more rapidly

when mixed with the liquid amalgam than those with no mercury do.

(Mc Cabe, 2008)

Products vary in terms of the size and shape of the alloy powder

particles. Two methods are used to produce the particles. The first

lathe-cut alloy powders result from cutting a pre-homogenised ingot

of alloy and vary in size from fine grain to coarse grain. The second,

spherical alloy particles are produced by atomisation and the

particles are generally of equal size.

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The majority of alloy powders produced result from mixing particles of

different sizes. The aim of this is to increase the packing efficiency of

the alloy so that it requires less mercury to form a workable mass. (Mc

Cabe, 2008)

When a powder is triturated (mixed) mercury diffuses into the silver

and tin in the outer portions of the alloy powder and crystals of Ag2Hg3

(1) and Sn7-8Hg (2) start to form. Mercury had a limited solubility for

silver and tin. Because the solubility of silver in mercury is much lower

than that of tin, the 1 phase precipitates first and the 2 phase later.

1 and2 crystals grow as the remaining mercury dissolves in the alloy

particles. As the mercury disappears the amalgam hardens.

(Anusavice, K.J 2003)

The setting reaction for conventional amalgams is as follows:

Ag3Sn + Hg Ag2Hg3 + SnxHg + Ag3Sn

+ Hg 1 + 2 +

Considerable amounts of un-reacted alloy ( -phase) remain

unconsumed. Research has shown that by increasing the copper

content of amalgam many of the properties are improved. This has led

to newer amalgams that contain a high copper content (10-30%).

These copper-enriched alloys have been shown to have highercompressive strengths, decreased creep, reduced corrosion

susceptibility and a quicker set to full strength than the conventional

amalgams. (Anusavice, K.J, 2003) These copper-enriched alloys can

either be single composition, if they have the same size particles as

conventional amalgams with just a higher copper content, or

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dispersion modified, also called admixed alloys if they result from

particles of different alloys are blended together. (McCabe, 2008)

The setting reaction for copper-enriched alloys is as follows:

Ag3Sn + Cu + Hg Ag2Hg3 + Cu6Sn5 + Ag3Sn

+ Cu + Hg 1 + Cu6Sn5 ()/Cu3Sn () +

It is the replacement of 2 phase with the copper-tin phase that has

shown to have a profound effect on the amalgam properties.

In dispersion-modified, copper-enriched materials, it is thought that the

particles of conventional lathe-cut alloy react to form 1 and2 phases.

The 2 phase then reacts with copper from the silver-copper alloy to

form a copper-tin phase. Hence, the 2 phase exists as an intermediate

reaction product for only a short time during setting.

2.3 Dental Amalgam Properties

The dimensional changes of dental amalgamare dependent on the

type of alloy used, the shape and size of the particles and manipulative

variables such as proportioning, dispensing, trituration, condensation,

carving and polishing. (Van Noort, 2007) Approximately half an hour

after placing an amalgam, there is a small contraction because the

mercury is still diffusing into the alloy particles. After this there is a

small expansion and overall there is a small expansion of theamalgam. (McCabe, 2008)

Strength is needed to resist fracture from forces during mastication. It

is developed slowly over a period of 24hours, at which time maximum

strength is achieved. The values of compressive strength, hardness

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and modulus of elasticity for amalgam lie somewhere between those

values for enamel and dentine. It is also able to resist intra-oral

abrasion adequately and so provides a relatively good replacement

material for these tooth structures. However amalgam is weak in thin

sections and adequate preparation of the tooth surface needs to be

carried out so it does not fracture. (Anusavice, K.J, 2003)

Creep or plastic deformation will occur to a certain degree when

amalgam is exposed to the oral conditions. Creep leads to flow of the

amalgam and if this occurs excessively, amalgam will protrude out of

the cavity margins and result in ditch formation. It is the 2 phase of

the alloy that is primarily responsible for high creep values. Therefore,

coper-enriched alloys will have less creep as the 2 phase is only

present for a short period as an intermediate reaction product.

(McCabe, 2008)

Corrosion is the process in which a metal reacts with a non-metallic

element in the environment to produce a chemical compound. (Eley

1997(a)) Amalgam is prone to corrosion. The 2 phase breaks down togive tin-containing corrosion products along with mercury. This may

have a significant affect on the mechanical properties and strength of

the amalgam. Corrosion gives a poor appearance to the restoration.

The corrosion products are thought to collect around the margins

between the tooth and the restoration. The chances of ditching

occuring are significantly increased if creep has also occurred.

However, the corrosion products will eventually form a seal which

helps to prevents microleakage. The level of corrosion can also be

diminished by polishing the surfaces of the amalgam. (Eley 1997(a))

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There is noadhesive bond formed between tooth structure and the

amalgam restoration. Therefore the dental amalgam is relying

completely on the cavity design for retention.

Dental amalgam has a high value of thermal diffusivity, in other

words, it is a poor insulator. Therefore the cavities need to be lined

with for example calcium hydroxide before the amalgam is placed. The

co-efficient of thermal expansion of amalgam is three times that of

dentine. This, together with the high value of thermal diffusivity

results in greater expansion and contraction occurring in the amalgam

than occurs in the surrounding tooth structure when the patient drinks

something hot or cold. This may lead to microleakage around the

margins of the restoration.

Biological properties refer to concerns about the levels of mercury

released during placement, contouring and removal of amalgam.

Reports show that alloys that do not contain 2 phase have better

corrosion resistance so less mercury is released. Reports also show

that allergies to the material are rare. (Van Noort, 2007)

2.4: Environmental Issues regarding mercury

As previously described, dental amalgam contains small amounts of

mercury. This is a highly toxic element and for this reason many

concerns have been raised regarding its safety from an environmental

point of view.

Mercury occurs naturally in the environment in many different forms. It

is usually found within compounds and as salts. It is commonly found

in the environment in forms such as metallic mercury, mercuric sulfide,

mercuric chloride and most often in the form of methylmercury. (UN

Global Mercury Report, 2001)

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Methylmercury is of great concern to environmentalists due to its

bioaccumulation in many fish species, and also in birds and mammals

that feed on these affected fish. (AMAP, 1998) The increased

concentrations of methylmercury have a very important impact on

animals and humans, because fish bind methylmercury very strongly,

and methylmercury accounts for almost all of the mercury that

accumulates in fish. (US EPA, 2001) Inorganic mercury can also build

up, but it is taken up less efficiently than methylmercury.

Methylmercury is mostly bound to protein sulfhydryl groups, which

leads to a long half-life of approximately two years (Wiener and Spry,

1996). Given that water mercury levels remain constant, mercury

concentrations in fish will increase over time.

Methylmercury is mainly formed in the environment by microbial

metabolism of certain bacteria, primarily methylating bacteria such as

sulfate reducers, but also by natural abiotic processes. (Ullrich et al.,

2001)

The severe neurological effects of methylmercury were reported in

animals long before it was known that methlymercury was a danger to

humans. Birds experienced severe difficulty in flying and other grossly

abnormal behaviour as a result of exposure to methylmercury (US EPA,

1997). Significant effects on reproduction are also attributed to

mercury, because methylmercury can cross the placental barrier into

the developing foetus. Adverse effects of mercury can appear at egg

concentrations as low as 0.05 to 2.0 mg/kg and critical limits have

been set at 0.07-0.3mg/kg for total mercury content in soil (Pirrone et

al., 2001)

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Mercury concentrations are lowest in the smaller non-predatory fish

and can increase many times on the way up the food chain. At the top

of the aquatic chain are humans, seabirds, seals and otters. The larger

the species the more likely they are to feed on fish species that are

close to the top of the food chain (salmon, trout) and the more

vulnerable they are to consuming unsafe amounts of mercury. The

species with the highest tissue levels of mercury are otter, mink,

osprey and bald eagle (US EPA, 1997).

The levels of mercury in Arctic ringed seals and beluga whales are

thought to have increased 2-4 times in the last 35 years, (Muir et al.,

2001) in the Arctic Circle and Greenland, and mercury has been

identified as a particular health threat to the hump-backed dolphin.

(Parsons, 1998) It is possible that global warming and the resulting

increasing water levels may increase the rate of mercury methylation

because of greater water bodies, which are an ideal environment for

methylating bacteria (UN Global Mercury Report, 2001).

Natural releases of mercury include volcanic activity and weathering ofrocks, (Lamborg et al., 2002) and Figure 1 below displays common

anthropogenic releases of mercury into the environment.

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Table 1: Examples of important sources of anthropogenic releases of

mercury.

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dental surgery should always be well ventilated to reduce the build up

of mercury vapour in the air. (ADA, 1999)

Solid amalgam particles can be incinerated by waste disposal

companies which results in the release of mercury vapour into the

atmosphere or it can leach into ground water from landfills. To prevent

this, waste amalgam should be carefully collected, and stored in a

sealed container, along with its packaging (capsule covers). Waste

dental amalgam should be given to a specialized recycler. Amalgam

can be separated into silver and mercury by a process called retorting.

Retorting consists of distilling off the mercury from the amalgam and is

carried out in a cast iron retort or steel retort. This is a vessel which is

closed so tightly that no fumes of mercury escape, except by the

condenser, which leads from the cover to a vessel containing water.

Here, the fumes of mercury are condensed to a metallic state. (US

Environmental Protection Agency, 2001)

Mercury in effluent water is channeled directly into the domestic water

system and should be treated by the local water treatment plant.Unfortunately many water treatment plants do not efficiently remove

mercury from waste water. (Drummond et al, 2003)

Correct disposal of waste amalgam in the dental practice would serve

to reduce the proportion of the worldwide environmental mercury load

attributable to dental amalgam. The American Dental Association

(ADA) in 2007 introduced its Best Management Practices for Amalgam

Waste, advising practitioners that recycling dental amalgam to distill

out the mercury for reuse in other products is safe and would reduce

the environmental mercury load. The ADA recommends the use of

good dental hygiene practices (e.g. use of personal protective

equipment and waste amalgam containers), chair-side traps, amalgam

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separators that comply with ISO11143, and also the use of line-

cleaners that will not dissolve amalgam, minimising the potential for

release of mercury into the dental unit water lines.

Amalgam separators work via a combination of the following

mechanisms filtration, sedimentation, or ion exchange. Batchu et al

in 2006 conducted a study to investigate the efficacy of different types

of amalgam separators available. The ISO11143 specifies that

amalgam separators must have an amalgam-removal efficiency of over

95%. The research carried out by Batchu et al showed that each

amalgam separator they tested exceeded the requirements of

ISO11143.

However these measures are of limited success, and despite amalgam

separators being used and specialized amalgam waste disposal

systems being put in place, mercury in dental amalgam still reaches

the waterways and so has a negative effect on the environment. As a

result of this, the use of dental amalgam has been curtailed in certain

countries, such as Sweden, Norway and Germany. (Norwegian Ministryof the Environment, 2007)

It must be acknowledged however, that in Sweden and the USA, the

entire environmental mercury load cannot be attributed solely to that

mercury from waste dental amalgams. Other sources include mercury

vapour released from munitions factories, of which there are a large

number in Sweden particularly, combustion of ordinary fuel, and

medical waste incinerators, among others. It has been estimated that

the mercury in dental amalgam accounts for only 0.4% of all mercury

emission; interestingly, mercury released from medical waste

incinerators accounts for 10.1% of all mercury emissions. (US EPA,

1997)

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2.6: Health Effects of Dental Amalgam

In recent decades, the safety of dental amalgam has been questioned

from a public health perspective. When amalgam alloy powder is

triturated with the liquid mercury it consists of about 50% mercury and

50% other metals (Bailer et al, 2001; Mutter et al 2004). Concerns

have been raised about both the systemic toxic potential of the

mercury contained in the amalgam, and the possibility of allergic

reactions occurring in the oral mucosa as a result of contact

sensitisation. (Thornhill et al, 2003; Wong and Freeman, 2003; Pang

and Freeman, 1995) It must be considered whether the health

benefits balance the potential health risks of using dental amalgam as

a restorative material. (Yip & Cutress, 2003)

According to Reinhardt (1988) the absorption of mercury in the body

depends on the form it is in. Elemental mercury and inorganic mercury

(Hg++) both pass through the gastrointestinal tract without being

absorbed, or else being minimally absorbed. Methylmercury,however, is almost completely absorbed in the gastrointestinal tract.

Inhalation of elemental mercury vapour results in a 74% absorption

and retention in the bloodstream. After a few minutes in the

bloodstream, it can cross the blood brain barrier, where it can be

oxidised and retained. This is a major cause for concern. Inorganic

compounds do not easily enter the bloodstream, whereas the organic

mercury compounds (methylmercury) can accumulate in red blood

cells and plasma and in this form can cross the placenta. (Reinhardt,

1988)

According to Huggins, mercury can be released from dental amalgam

in a number of ways, including via mechanical compression during

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eating and trauma; electrochemical reactions facilitated by the

electrolytic nature of saliva; setting up of electrical currents between

dissimilar metals resulting in the release of mercury vapour; and

temperature-induced release of mercury the higher the temperature,

the greater the amount of mercury released. Mercury can then mix

with foods and be swallowed, or else mercury vapour can be inhaled

into the lungs and thence directly enter the bloodstream. (Huggins,

2007)

Reinhardt (1988) acknowledged that the amount of mercury released

from dental amalgams is estimated to be about 3mcg/cm3 of surface

area of the amalgam. However he noted that these results were

acquired by measuring intraoral air levels of mercury, which can be

difficult to achieve accurately.

The estimated exposures to mercury on a daily basis from the various

sources are as follows:

Table 2: Estimated average daily intake (retention) of inorganic

mercury.

Source: World Health Organisation Elemental Mercury and Inorganic

Mercury Compounds Human Health Aspects (2003).

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Mercury is released from dental amalgams during certain procedures,

including placement, removal and polishing. Average figures are

shown in the table below.

Table 3: Mercury exposure during dental procedures.

Trituration 1-2mcgPlacement of amalgam 6-8mcgDry polishing 44mcgWet polishing 2-4mcgRemoval of amalgam restorations

under water spray and high

volume suction

15-20mcg

Additional evacuation for 1 minuteto remove residual amalgam dust 1.5-2.0mcgSource: The future of dental amalgam: a review of the literature. Part

2:Mercury exposure in dental practice. (Eley 1997(b))

Dental personnel are undoubtedly exposed to higher levels of mercury

as a result of constant exposure to mercury on a regular basis while

placing and removing amalgams. Poor amalgam hygiene such as

incorrect storage and disposal of residual amalgam also results in

increased exposures (Eley, 1997(b)). However, a study carried out by

Karahalil et al (2005) on dentists in Turkey found that there was very

little evidence of any association between mercury exposure due to

use of dental amalgam and adverse health effects. It must also be

acknowledged that in recent decades with the advent of improved

amalgam hygiene practices that blood and urinary mercury levels have

reduced in dental personnel due to a reduction in exposure to mercury.

(Eley 1997(b))

Mercury can have a number of damaging effects at both cellular and

tissue levels. At a cellular level its effects include damage to DNA,

mitochondria, cell membrane permeability, among others. (Huggins,

2007) It has also been suggested that it would have a specific effect

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neuropsychological and renal function of 534 children between the

ages of 6 and 10. The children had carious teeth restored with either

amalgam or composite, depending on which group they were randomly

assigned to. Their IQ scores were monitored at baseline and for 5

years following placement of restorations as a test of

neuropsychological function, along with other tests of memory,

attention, and visual state, among others. Their renal function was

assessed via measurements of creatinine-adjusted albumin in urine.

They found no statistically significant differences in measurements

between the two groups, concluding that there was no reason to

assume that it is dangerous to place amalgams in children.

An investigation by Kingman et al (2004) into the effects of dental

amalgams on neurological function among adults found no

associations between exposure to amalgams and any clinical

neurological signs, for example abnormal tremor, coordination, gait,

etc.

Drexler et al in 1998 investigated mercury concentrations in breastmilk as a result of both dietary habits and amalgam restorations. They

found that immediately after birth, levels of mercury in breast milk

were strongly associated with number of amalgam surfaces and

frequency of meals, but after 2 months, the level was associated with

fish consumption and not with the presence of dental amalgams.

In 2007, Aminzadeh et al conducted a meta-analysis to investigate the

alleged association between dental amalgam and multiple sclerosis.

They found that there was no evidence to suggest that there was a

definite link.

These findings and others like them have led investigators to question

whether the symptoms that certain individuals attribute to the mercury

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associated with the experience of subjective symptoms associated with

amalgam restorations. They found that symptoms reduced in both

groups in spite of there having been two very different interventions

carried out, which may suggest that there may be a psychological

basis to amalgam intolerance.

A number of studies have been conducted in an attempt to determine

whether claims that allergic-type oral lichenoid reactions could be

caused by amalgam restorations are well-founded. Oral lichenoid

lesions are seen in around 2% of the population. Presentations include

a white, lacy, reticulate pattern or a red, erosive lesion. Upon

histological examination there is a characteristic appearance of basal

cell degeneration and a band of lymphocytes. (Wong and Freeman,

2003) Oral lichenoid lesions are usually of unknown origin (i.e.

idiopathic), however certain other aetiologies have been proposed,

including diseases such as lupus erythematosus, graft-versus-host

disease; hypersensitivity to certain drugs; immunological factors; and

allergic contact dermatitis associated with dental materials. (Wong and

Freeman, 2003; Pang and Freeman, 1995)

Ibbotson et al (1996) examined 197 patients with oral complaints. This

group could be further subdivided into a group of 109 patients who had

oral lichenoid reactions, a group of 22 patients with oral and

generalised lichen planus, and 66 patients who had other complaints.

All patients underwent patch testing for mercury allergy. It was found

that 19% of patients with oral lichenoid reactions tested positive for

mercury allergy on the patch test, which was significant when

compared to the 0% mercury allergy in lichen planus and the 3% in

patients with other oral conditions. Amalgam restorations were

replaced with composite resin restorations in 22 patients that had oral

lichenoid reactions adjacent to amalgam restorations. The lesions

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resolved following replacement in 16 of 17 patients that were positive

for mercury allergy, and in 3 of 4 patients that were negative for

mercury allergy. They concluded that since resolution did not occur in

all patients, the aetiology of oral lichenoid reactions in patients with

amalgam restorations could not be solely attributed to mercury allergy,

although it certainly seems to play a significant role.

A study by Pang and Freeman in 1995 showed that 13 out of 19

patients with oral lichenoid lesions adjacent to amalgam restorations,

who tested positive to mercury allergy testing, showed complete

healing of their lesions following replacement of their amalgam

restorations with alternative restorative materials. They concluded by

recommending that amalgam restorations should be replaced by other

restorative materials in patients with oral lichenoid lesions adjacent to

amalgam restorations. They also suggested that currents set up

between dissimilar metals could result in the constant release of

mercury ions, which could result in contact sensitisation of the mucosa

and the development of oral lichenoid lesions.

Similarly, Wong and Freeman (2003) examined 84 patients all of which

had lichenoid reactions beside amalgam restorations. They also

carried out patch tests on all patients and found that 33 patients (39%)

tested positive for allergy to mercury, and 61% tested negative. Thirty

of the patch test-positive patients opted to have their amalgams

replaced. Twenty eight of these experienced a relief of symptoms,

with all but one of these having complete healing of their oral lichenoid

lesion. They concluded that mercury in dental amalgams must play a

contributory role in the aetiology of lichen planus. They also

acknowledged that, in the majority of their patients, the amalgam

restorations in question had been in place for a number of years. From

this they hypothesised that age-related corrosion of the restoration

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leading to release of mercury ions may be a source of added irritation

of the mucosa, resulting in oral lichenoid lesions.

Laiejendecker et al in 2004 conducted a similar study in which 80

patients in four separate groups were examined. Group A comprised

patients with oral lesions closely contacting the amalgam restorations.

Group B comprised patients with lesions extending 1cm beyond the

area immediately adjacent to the restorations. Group C comprised

patients with oral lesions not found adjacent to the restorations. All

patients were patch tested for mercury allergy. Replacement of

amalgams with alternative materials was recommended for all patients

testing positive for mercury allergy. Thirteen patients from group A, 8

patients from group B, and 2 patients in group C had their amalgams

replaced. Significant improvement was seen in all of these patients

except one patient from group C. Laiejendecker et al also discussed

the possibility of metal ions released from amalgam due to corrosion

producing T-cell mediated type IV hypersensitivity reaction in the

mucosa, resulting in mucosal changes leading to oral lichenoid lesions.

Thornhill et al in 2003 suggested that the fact that amalgam

restorations are directly contacting the oral mucosa may result in

changes in the antigenicity of the basal cells due to mercury released

as a corrosion product. So, in certain individuals, this may produce

contact hypersensitivity lesions in response to amalgam that resemble

lesions seen in oral lichen planus (i.e., oral lichenoid lesions). Their

investigations showed that removal of amalgam restorations in

individuals that tested positive for mercury allergy in a patch test

resulted in resolution of the oral lichenoid lesions in 93% of cases.

From the above studies, it is clear that oral lichenoid lesions directly

adjacent to dental amalgam restorations may resolve upon

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replacement of the restorations with alternative restorative materials

in patients testing positive for mercury allergy. This is the only

documented indication for replacement of amalgam restorations.

2.7 International Policies regarding use of dental amalgam

International policies regarding the use of dental amalgam have

changed dramatically over the last 30 years. Dental amalgam remains

a very topical subject with many countries expressing very different

opinions in relation to its use.

In 1986 the Canadian Dental Association (CDA) guidelines on amalgam

use stated that, whilst waiting for new dental materials to become

available, amalgam was to remain in use as a dental material. That

same year, with the assistance of the Board of Health and Welfare, the

CDA advised the avoidance of placement or removal of amalgams in

pregnant women. (Policies on Dental Amalgam, 1992)

In 1988, the National Board of Health and Welfare in Sweden

announced that there would be no change to the use of amalgam indentistry due to a lack of evidence that amalgam is harmful to health.

In October 1990, the Food and Drugs Administration (FDA) also

reported that there should be no cause for public concern regarding

dental amalgam. In December 1990, the American Dental Association

(ADA) declared that the only health risk regarding dental amalgam was

to those who are hypersensitive to certain components of the material.

In March 1991, the US Public Health Service stated that replacement of

amalgam restorations was not justified unless the restoration had

failed or the patient had had a hypersensitivity reaction to the

material.

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The World Health Organisation (WHO) consensus statement on dental

amalgam was approved by the FDI (World Dental Federation) General

Assembly in September 1997. It confirms the safety of amalgam as a

dental restorative material and denies that the small amount of

mercury released from dental amalgams is a health risk. The health

risks for occupational personnel along with the importance of adhering

to strict mercury vapour monitoring and hygienic requirements are

highlighted in this statement.

Norway announced a ban on the use of mercury, including dental

amalgam, which took effect on January 1st 2008. Sweden announced

a similar ban which took affect from 1st June 2009. Dentists in

Denmark were no longer allowed to use mercury in restorative fillings

after April 1, 2008. (MercOut International, 2008) The reasoning

behind the Norwegian ban was due to mercurys role as an

environmental toxin. The Swedish authorities listed both

environmental and health risks as reasons behind their ban. Danish

officials backed their new policy with the fact that resin based

composites have greatly improved and can now be used in many moredifferent situations in comparison to a few years ago.

The CDA made clear in February 2005 their support for the Federal

Governments continued research regarding dental amalgam. They

affirm their plans to continue using amalgam as it has clear

advantages in many applications over other restorative materials,

especially in relation to the average duration of restorations.

(Canadian Dental Association, 2005)

The final notice of the CDA waste protocol was published on May 8th

2010. It states that the best waste management protocol for amalgam

includes the installation of an ISO 11143 certified amalgam separator

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in the practice and the use of a certified hazardous waste carrier for

the recycling or disposal of amalgam waste. (Canadian Dental

Association, 2005)

The ADA revised their statement regarding dental amalgam in August

2009, quoting from the WHO 1997 consensus as follows: Dental

amalgam is considered a safe, affordable and durable material that

has been used to restore the teeth of more than 100 million

Americans. Dental amalgam has been studied and reviewed

extensively, and has established a record of safety and effectiveness.

(American Dental Association, 2009) In 1998, the ADAs Council on

Scientific Affairs reported that there currently appears to be no

justification for discontinuing the use of dental amalgam. In addition,

the ADA quotes a 2003 paper published by the New England Journal of

Medicine: patients who have questions about the potential relation

between mercury and degenerative diseases can be assured that the

evidence available shows no connection. (American Dental

Association, 2008)

In May 2008, a Scientific Committee of the European Commission

addressed safety issues for both patients and professionals, and

discussed the use of alternative restorative materials. The committee

concluded that amalgam is safe and that the alternative materials

available are not without their own clinical limitations and toxicological

hazards. (EC Scientific Committee, 2008)

The ADA continues to support the use of amalgam and classes it as a

useful, safe, and viable material. (American Dental Association, 1998)

The British Dental Association (BDA) released a Dental Amalgam Fact

File in March 2008, following the Scientific Committee on Emerging and

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Newly Identified Health Risks (SCENIHR) report. The BDA states

dental amalgam is a safe material to use in restorative dentistry. In

relation to the removal of amalgam restorations, they verify that no

health benefits have been found. They state there is no clinical

justification for removing clinically satisfactory amalgam restorations,

except in those patients suspected of being allergic reactions to one of

the amalgam constituents. (British Dental Association, 2008)

The UK Committee on Toxicity recommends the avoidance, where

clinically reasonable, of the removal or placement of amalgam fillings

during pregnancy. This is due to the known fact that mercury can cross

the placenta from mother to foetus. (Committee on Toxicity of

Chemicals in Food, Consumer Products and the Environment-

Statement on the Toxicity of Dental Amalgam 1986)

The UK Department of Environment, Food and Rural Affairs (DEFRA)

issued a new guideline in December 2005 which stated that amalgam

separators should be fitted in all dental practices in England where

amalgam is to be used, and also advised separate waste policies foramalgam to be put in place. (UK Department of Environment, Food and

Rural Affairs, 2005)

The Australian Dental Association Amalgam Waste Policy was amended

by the ADA Federal Council in November 2007. It is a policy on the

management of amalgam waste disposal, emphasising the importance

of training dental staff adequately so they know how to dispose of it

properly. Waste items to be disposed of following the use of dental

amalgam were listed as: used amalgam capsules; excess amalgam not

placed in restorations; amalgam retained in chairs traps, suction filters

and amalgam separators; and extracted teeth with amalgam

restorations. It also instructs that amalgam separators which comply

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with ISO 11143 are to be installed in all dental clinics. (Australian

Dental Association, 2007)

In July 2009, the U.S FDA issued its most recent decision regarding

dental amalgam, categorizing it as a Class two (moderate risk)

substance, thereby placing it in the same category as gold and tooth-

coloured resin-based composite restorations. (Gamba, J 2009)

The Irish Dental Association (IDA) states that No government or

reputable scientific, medical or dental body anywhere in the world

accepts, on any published evidence, that dental amalgam is a hazard

to health. This indicates that dental amalgam will continue to be used

in Ireland for the foreseeable future. (Irish Dental Association, 2010)

2.8: The influence of economic incentives on treatment patterns in a

third-party funded dental service

When choosing a restorative material, different factors influence both

patient and operator decision as to which material is most appropriate.

For patients, common concerns include aesthetics, amalgam toxicity

and environmental factors. For the dentist placing the restoration,

their decision is based more on clinical evidence, taking into account

factor such as cavity size, shape, tooth position in arch etc. (Mjor et al,

2002)

The Dental Treatment Services Scheme (DTSS) is a national scheme in

Ireland set up for medical card holders. The scheme is operated by the

Health Services Executive (HSE) and entitles these patients to avail ofcertain dental treatments free of charge. The treating dentist can then

make a claim to the Primary Care Reimbursement Services to be

reimbursed for the treatments provided. Previously, a wider range of

treatments were covered by the scheme, but since cuts were

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implemented in early 2010, the treatments covered are more limited.

Up to two restorations are covered by the scheme. However, dentists

can only claim for composites if placed in an anterior tooth. The HSE

will reimburse up to and including two (2) restorations (from Items A3A

or A3C) per eligible person, as part of emergency treatment. (HSE

Circular 008/2010, 2010) Item A3A refers to an amalgam restoration

and Item A3C refers to composite restorations on anterior teeth only.

(HSE National Shared Services Primary Care Reimbursement Service,

2006) This may be a factor for a dentist in deciding which material to

use when restoring a posterior tooth.

In December 1999 a fee increase of 62% for amalgam restorations was

implemented in Ireland as part of the DTSS. (Woods et al, 2010) Data

regarding the frequency of placement of restorations versus extraction

between June 1996 and April 2005 were collected by the HSE.

Following analysis, it was observed that after the fee increase was

introduced, there was an 18% increase in the amount of amalgam

restorations being placed. This suggested that the behaviour patterns

of dental operators in Ireland within the DTSS had been directlyaffected by the amalgam fee increase of December 1999. Woods et al

suggest however that the 18% increase could also be a result of no

longer having to gain permission from the Principal Dental Surgeon

before providing treatment for medical card patients, which had

previously been required.

In the same report, it was noted that the DTSS had once been a

scheme based mainly on extractions or emergency care, but that these

principles seem to have now changed, with more emphasis being

placed on a restorative or preventive approach. This was one of the

first goals of the Dental Health Action Plan (1994).

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Donaldson and Gerard (2005) state thatProvider moral hazard is most

often associated with systems of payments where dentists are

remunerated based on fee for service as it rewards dentists according

to the amount of work carried out bringing about a scenario where

services are being overused This implies that, if dentists are paid on

the basis of the number of restorations placed, this will give them more

of an incentive to restore teeth rather than extract or monitor them.

Parkin and Yule (1988) carried out a similar study in Scotland in 1988.

However, they found that a reduction in dental charges had limited

effect on trends of placing restorations.

2.9: Economic Impact of Regulating the Use of Amalgam Restorations

Beazoglou et al (2007) investigated the potential economic impact of

an amalgam ban, both in certain population subgroups and in the

entire population. This study found that, if the use of amalgam as a

restorative material were to be banned for the entire population, the

average price of restoring a tooth would increase, implying that fewerrestorations would be placed overall.

The increased cost may be due to a number of reasons. Firstly,

according to Bogacki et al (2002), the materials used in the place of

amalgam may be more expensive, resulting in increased cost per

restoration. Secondly, resin-based composites have been shown to

have decreased longevity compared to amalgams, due to their need

for more maintenance and monitoring, and so may need to be replaced

more often. (Mjor et al 1998). Beazoglou et al noted that a more

indirect expenditure increase would be associated with patient time

and travel costs due to an increased number of patient visits. These

increased expenditures would affect those in lower socioeconomic

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groups most, so families with a lower income would most likely

experience a reduction in access to dental treatment.

From the above it can be seen that a ban on amalgam as a restorative

material would have economic implications for the provision of dental

care.

2.10: Repair vs Replacement of amalgam restorations - the ethical

debate

Amalgam still continues to be the most commonly-used material for

restoring posterior teeth, in spite of a decline in popularity in recent

decades, with a corresponding increase in the use of direct resin-based

composite restorations noted. . As with any restorative material,

amalgam has a limited life span and regular maintenance is often

required . Recurrent caries and fracture of the restoration are the

most common reasons for failure of amalgam restorations.

Traditionally, replacement was the recommended treatment option for

posterior teeth; however now repair is considered to be a moreconservative approach .

Repair of an amalgam restoration is defined as the removal of only

the defective part of the restoration, and/or adjacent tooth tissue,

followed by the placement of a new partial restoration, whereas,

replacement is defined as the removal of the entire restoration,

including any bases, liners, secondary caries and tooth tissue where

appropriate, followed by the placement of a new restoration .

One of the main reasons for repairing and replacing restorations is due

to secondary caries in the tooth. However, it is widely know that

secondary caries is very difficult to diagnose. In a study by Kidd et al.

(1995), marginal ditching and staining were investigated as predictors

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of secondary caries around amalgam restorations. The authors

concluded that, where amalgam margins showed wide ditches or

carious lesions, these restorations should be replaced, as plaque

samples collected from these sites were shown to contain more

S.mutans and Lactobacilli. (Kidd et al, 1995) A further study by Kidd

et al (1996) investigated marginal ditching and staining as predictors

of secondary caries around tooth-coloured restorations. They found

that these criteria could not be used as reliable indicators of the

presence of caries-infected dentine. The study stated that to suggest

that all tooth-colored fillings with stained margins should be removed

because they may have soft dentin beneath would constitute gross

over-treatment. The study concluded that only obvious carious

lesions at the margin of the restoration can give a diagnosis of

secondary caries around an existing tooth-coloured restoration. (Kidd

et al, 1996) Therefore, it is more difficult to diagnose the presence of

secondary caries under tooth-coloured restorations and this may lead

to more unnecessary repair and replacement being carried out than if

amalgam restorations are placed.

Shariff et al, 2010a, suggested that both the beneficial and detrimental

effects regarding replacement and repair need to be taken into

consideration when deciding how to restore defective amalgam

restorations. They reported that unnecessary replacement will result

in more tooth substance loss and this may lead to pulpal insult,

development of clinical symptoms, catastrophic fracture and

compromised prognosis.

They have also suggested that repair is a more conservative treatment

option and may increase the long term survival of the tooth. They

reported that it is cheaper and quicker compared to replacement, and

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can be performed without the use of local anesthesia, which may be

less distressing for patients.

Gordon et al, 2006 stated that each clinician has their own subjective

opinion regarding replacement versus repair of a defective restoration,

and their study raised concern over quality of care being delivered to

patients given the differing opinions of dental practitioners when

presented with the same clinical conditions.

Wilson et al 1999, and Forsetlund et al 2009, both reported that

treatment decisions may be influenced by funding systems, traditional

teaching methods and lack of knowledge of repair technique. All which

have favoured replacement over repair.

A recent Cochrane review evaluated the effectiveness of replacement

versus repair in the management of defective amalgam restorations in

permanent molars and premolars. The search study retrieved 145

studies. However, after examination, all but three studies (Moncada

2006, Moncada 2008, Moncada 2009) were excluded due to failure torandomize patients into treatment groups. None of the included

studies fully adhered to the inclusion criteria; Moncada (2006) and

Moncada (2008) included the same set of patients but during different

follow up periods. The patients were randomly allocated to treatment

groups but the method of randomization was not reported. Moncadas

2009 study was eliminated because the patients were not randomly

allocated to treatment groups; they were assigned into groups

dependent on defect type instead .

Although current evidence seems to favour repair as the treatment of

choice regarding the restoration of defective amalgam restorations, as

its short-term survival rates are similar to those of total replacement,

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Following discussion with the patient about the advantages and

disadvantages of amalgam, and the reasons for which amalgam would

be best used in a particular situation, the patients wishes and any

concerns they may have must be taken into account. Should they

choose an alternative restorative option, the dentist must remember

that it is the patients right to do so. (Gamba, 2009).

Should the situation arise that the patient wishes to completely avoid

amalgam on the basis of its mercury content, the dentist must ensure

that a note is made in their chart regarding this; especially if the

dentist feels that the material chosen is not the most suitable. (Gamba

2009) This report also suggested that if the patient is insistent on a

different material, they should be advised to seek a second opinion

before treatment begins.

If a patient returns requesting treatment which may be detrimental to

their health the dentist must bear the concept of nonmaleficence in

mind and ensure that they do not compromise their professional

integrity. In this case the dentist could inform the patient that, forethical reasons, they are not comfortable carrying out the treatment

desired by the patient. (Gamba 2009)

Gamba emphasizes that discussions with patients regarding treatment

options must always be unbiased and based on valid scientific

evidence. Patients have a right to this information but most

importantly have the final say in decision making regarding their teeth.

2.11: Teaching rationales and public attitudes regarding dental

amalgam

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McComb et al (2005), carried out a questionnaire to determine the

approach of teaching dental undergraduates about dental amalgam in

a number of Canadian dental schools. Eight of the ten restorative

faculties responded. Approximately half of these schools reported

spending 50% or more time devoted to teaching amalgam with two

schools stating that more than 75% of curriculum time is devoted to

teaching amalgam.

Six of the schools surveyed had clinical competency tests for class II

restorations in both amalgam and resin-based composite.

Students are taught that dental amalgam is contraindicated if it will

come in contact with dissimilar metals; when patients are concerned

about mercury contained in dental amalgams; and in pregnancy. In

the paedodontic programmes, for almost all of the schools surveyed,

dental amalgam seemed to be the material of choice for class I and

class II restorations in primary molar teeth (McComb et al, 2005).

Most schools did not expect any great change in the curriculum

regarding amalgam and its teaching over the next few years. It was

also stated that the choice of material seems to be a decision basedmore so on the patients desires than scientific evidence. Overall, this

study showed that there was still a lot of emphasis on amalgam in

curricula.

However, Ottenga et al carried out a study in a US dental school

comparing the curriculum time (lectures and laboratory sessions)

devoted to teaching of dental amalgam and resin based composite

with the clinical time spent by 3rd and 4th year students restoringposterior teeth with either material. The curriculum in the dental

school in the University of Florida spent more time teaching about

amalgam, compared to resin based composite. However, in clinical

situations the only instance where amalgam was favoured over

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composite was in four-surface posterior restorations. Clinically, resin

based composite was being used for posterior restorations 2.3 times

more often than amalgam.

This study by Ottenga et al also showed that from 2003 to 2006, there

was a gradual decline in the use of amalgam. The authors felt that the

curriculum should be updated so that graduates are competent in the

use of resin based composite. There reasoning for this was that this

material was being used more frequently for posterior restorations.

The Nijmegen dental school in the Netherlands has been amalgam

free since 2001, when it ceased teaching of amalgam to its

undergraduates. Resin based composite has instead replaced it. The

reasons given relate to preservation of tooth structure with adhesive

materials. A step-by-step transition phase from amalgam to resin

based composite was initiated in 1990 when it was realised that the

frequency of amalgam being placed in clinics in the dental school were

declining. (Roeters et al, 2004)

Lynch et al (2010), used an online questionnaire sent to 17 dental

schools in Ireland and the UK to assess the teaching programmes in

relation to resin based composite. It was interesting to note that 10

schools were teaching to place posterior composites before amalgams,

indicating that resin-based composites are gaining priority over

amalgam in the dental schools surveyed. However they still devoted

50% of their teaching time to dental amalgam. Also, 44% of

restorations placed by students over the period 2004 to 2009 wereamalgams. In the previous survey carried out by Lynch et al (2004),

the figure was 67% showing a decline in the use of amalgam by

students.

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In todays world the internet is a highly significant source of

information for the general public and everything and anything is only

a click away. It gives the public an opportunity to research treatment

options before entering the dental surgery. It was decided to include

some internet sites and anti-amalgam websites in the literature

review to gain an insight into what information is available to the

public in relation to dental amalgam.

One of the websites against the use of amalgam, Shirleys wellness

cafe claimed that amalgam contained high levels of mercury which

can slowly leak into the body over time causing a number of conditions

such as multiple sclerosis, Alzheimers, autism and many auto-immune

diseases.

Another website, mercury talk, claimed that mercury is a potent

neurotoxin. There are also numerous real life stories written by

various people who describe how their illnesses were cured after

getting their amalgams replaced.

In 2000, the Guardian published an article entitled Toxic Debate in

which the reporter talks to a dentist who believes that the mercury in

amalgam is the cause of many conditions ranging from gum disease,

migraine, headaches, depression, chronic fatigue, eczema and asthma

to rheumatism, Alzheimer's, Parkinson's, kidney disease and multiple

sclerosis. The reporter also explains the views of many other anti- and

pro-amalgam campaigners he approached.

The same article also details the experiences of a lady who decided to

get her amalgam fillings removed. Her dentist offered to remove her

amalgam restorations under high volume suction and rubber dam.

Intravenous Vitamin C was used as a detoxifying agent. The dentist

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also offered to prescribe vitamins, homeopathic remedies, and saunas

to help remove the reservoir of mercury that has built up in the body

over the years. The cost of this treatment was 1500.

Conversely, the Center for Disease Control and Prevention provides anonline fact sheet about amalgam, which cites various studies that have

shown that amalgam has little health risk.

The American Dental Association issued a statement about amalgam,

describing it as a safe, affordable and durable material that has been

used to restore the teeth of more than 100 million Americans.

In conclusion, the internet contains many sources of informationregarding pro- and anti-amalgam debates. The public has access to

these sources and the information accessed would play a part in their

opinion on dental amalgam.

It can be concluded from this literature review that there appears to be

a considerable amount of misleading and untrue information regarding

dental amalgam available to the general public. There is also a lack of

valid information available regarding the opinion of the general public

regarding amalgam. In particular, there is a shortage of evidence

based resources. It has been decided that a study to investigate

current attitudes and concerns amongst the general public towards

dental amalgam should be conducted. From the findings of this study,

the future of dental amalgam in restorative dentistry will be

questioned.

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Chapter 3: Mat erials and Methods

3.1: Preparatory work:

A letter requesting permission to conduct the study was sent to the

Dean of the Dublin Dental University Hospital (DDUH), Professor June

Nunn; to the Clinical Director of the DDUH, Dr. Michael OSullivan; and

to the CEO of the DDUH, Mr. Brian Murray. (Appendix 1) Permission

was granted in early October 2010.

An ethical approval form was submitted to the Trinity College Dublin

Health Sciences Ethics Committee in September 2010. Approval to

proceed with the study was granted via e-mail on 4/11/10. This was

confirmed in writing on 13/1/11. (Appendix 2)

A Microsoft Excel spreadsheet with contact details of European dental

institutes was obtained from Ms. Majella Giles (Association for Dental

Education in Europe Administrator). This was used as a basis for

sending e-mails to these various institutes as part of the study.

3.2: Sample selection

Public Questionnaires:

An unconditioned sample of the population was required for this

questionnaire as it was believed that they would have an unbiased

view of issues regarding dental amalgam and so a true representation

of public opinion would be obtained. As permission was not sought to

approach people outside the hospital i.e. street surveys, it was thought

that patients in the Accident and Emergency Department (A&E) of the

Dental Hospital would be the most appropriate people to survey.

Existing patients of the Dental Hospital were not surveyed as dental

amalgam is routinely used here and so these patients could be more

educated than the general public about dental amalgam.

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The group compiled a series of questions which would provide the

desired information regarding the teaching of dental amalgam in

Europe and a professional opinion on the future of dental amalgam. A

SurveyMonkey account was created and the questions entered into it.

A letter (Appendix 7) was devised to be sent via e-mail to each school

containing details of the study, along with a link to the SurveyMoney

questionnaire. Attached to the e-mail was a copy of the questionnaire

in Microsoft Word format. (Appendix 8) Each e-mail was personally

addressed to the Dean and to the Head of Restorative Dentistry in

each dental institute.

3.4 Pilot Questionnaires:

It was believed that piloting each questionnaire on a small number of

people would be beneficial for the following reasons:

To ensure that the questions were easily understood by

participants, and that no questions would be misinterpreted.

To determine how much time would need to be allocated per

questionnaire. This would give an indication of how many A&Esessions would be required to gather enough responses.

To obtain feedback as to the relevance and wording of the

questions in order to achieve an optimal valid response rate, and

to avoid the introduction of any bias into the investigation.

To help decide the manner in which the information would be

recorded and analysed.

The Understanding Amalgam and Opinion on Dental Amalgam

Information Leaflet questionnaires were piloted during one session in

A&E. Ten responses were obtained. These questionnaires were

analysed and the group decided that no amendments to either

questionnaire were required.

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The questionnaire for the European dental schools was piloted on three

members of the restorative teaching staff at the DDUH. Again, no

amendments were required.

It was then decided to proceed with the study with the definitive

questionnaires.

3.5 Carrying out questionnaires and analysis:

Public questionnaire (Understanding Amalgam):

The group spent 12 sessions in the A&E department. People sitting in

the waiting area were approached and asked if they would be willing to

participate in the survey. Those that agreed to participate were given

the Participant Information Leaflet to read prior to completing the

Understanding Amalgam questionnaire. Any queries were clarified

and they then completed the questionnaire. In total, 115 responses

were collected. The survey was analysed by entering the results of

this questionnaire into SurveyMonkey and from this, charts of the

results were generated.

Public questionnaire (Opinion on dental amalgam leaflet):

Upon completion of the first questionnaire, participants were then

given the existing Dublin Dental Hospital Dental Amalgam Information

Leaflet to read. Having read it, the participants then completed a short

questionnaire asking their opinion of various aspects of the leaflet, and

if they had any suggestions on ways in which it could be improved.

This information was also entered into SurveyMonkey and analysed.

The results were to form the basis of an amended Dental Amalgam

Information Leaflet which the group would later compile. (Appendix

10)

European questionnaire:

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One hundred and forty-five individually addressed e-mails were sent to

the Dean and the Head of each restorative department in dental

schools across Europe (obtained from the Microsoft Excel

spreadsheet), with the link to an electronic survey on the website

SurveyMonkey attached. A copy of the questionnaire in Microsoft

Word document format was also attached, which could be completed

and returned to the group if the recipients were unable to access the

electronic survey. Twenty-two of these emails returned

undeliverable and 10 others responded explaining that they were not

suitable candidates for our study. Reminder e-mails were then sent to

the remaining 113 recipients. Despite our efforts to personalise the e-

mails only 35 responses were received; a response rate of 30.97%.

These results were then entered into Microsoft Excel spreadsheets and

graphs of the data were generated and presented in the results

section.

Chapter 4: Results

4.1: Public Attitudes and Concerns Regarding Amalgam

4.1.1: Age Group and Gender Breakdown of Participants

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The relative proportion of males and

females in the study is shown in

Figure 1.

The age distribution of participants is

shown in Figure 2.


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55

0

5

10

15

20

25

30

35

40

45

50

18-25 26-35 36-50 51-60 60+

Fig 2. Age Distribution of Participant

No . ofSubjects

Age Group


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4.1.2: Reported Dental Experience of Participants

2.79

5.39 5.23

8.27

4.85

0

1

2

3

4

5

6

7

8

9

18-25 26-35 36-50 51-60 60+

Fig 3. Mean Number of Restorations per Age Groupin

Age Group

Figure 3 shows the mean number of restorations per age group. The

highest number of restorations was reported in the 51-60 age group,

with the average being 8.27 restorations. The lowest number of

restorations was reported in the 18-25 age group.

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Mean no.

of restor-

ations

Figure 4 shows the

distribution of

restorative materials

used, as reported by the

participants. An even

distribution of the

common direct

restorative materials

was observed.


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0 20 40 60 80

They Will Break

Damage to the

Appearance

Health Effects

Other

Fig 5: Concerns Regarding Existing Dental Amalgam

Restorations

No. Of Participants


4.1.3: Public Concerns and Attitudes towards Dental Amalgam

Figure 5 displays the various concerns that participants had regarding

dental amalgam. Appearance and health were reported as the main

concerns.

Twenty three percent of the subjects questioned reported having

asked for their dental amalgam restorations to be replaced with tooth-

coloured fillings or crowns. A variety of reasons for this were given, as

displayed in Figure 6, with appearance being the predominant factor.

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71

55

29

45

0

10

20

30

40

5060

70

80

Own Mouth Child's Mouth

#subjects

Fig . 7: Participants willing to have dental amalgam placed in themselvesand their children

Yes

No

22

17

23

00

5

10

15

20

25

Health Appearance Breakage Other Environment

ResponseCount

Reason

Fig. 8: Reaons participants gave for not having a dental amalgam

placed.


Figure 7 shows that 71% of all participants questioned would be willingto have a dental amalgam filling placed on a posterior tooth if they

knew that it would last longer. However, only 55% of participants

would be willing to have a dental amalgam placed in the posterior

region of their childs mouth.

Figure 8 shows the reasons given by participants who would not accept

placement of an amalgam restoration in a posterior tooth. Again,

health and appearance were the predominant reasons given.

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4.1.4: Knowledge of Participants regarding Dental Amalgam

Table 4: Breakdown of subjects according to age and gender,

associated with awareness of mercury content in dental amalgam.

Aware UnawareNumber of Subjects 67 48Percentage 56% 44%Gender Ratio M:F = 1:1 M:F = 2:3

Table 4 shows that 56% of participants were aware of the mercury

content of dental amalgam and women were slightly less likely to be

aware than men.

Table 5: Awareness of mercury content of dental amalgam vs. reported

existing dental amalgam restorations.

No. ofsubjects

% of totalsample

% reportingexistingsilver

colouredfillings

Reported havingexisting silver colouredfillings

68 60% 100%

Aware of mercurycontent of theiramalgams

63 55% 93%

Willing to consider asilver coloured fillingon a back tooth if itwould last longer.

33 29% 51%

Table 5 shows that 60% of the total sample reported to have silver-

coloured fillings. Of these, 93% were aware of the mercury content of

dental amalgam and 51% of these would be willing to have another

dental amalgam filling placed.

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33

7 6

15

1

0

5

10

15

20

25

30

35

Dentist Internet Newspaper etc Family/Friends Homeopath

Responsecount

Source of Information

Fig 9. Participant's Source of Information on Dental Amalgam


content. Thirty four per cent of participants who are aware of the

mercury content are also aware that dental amalgam is not being used

in other EU countries versus 0% of those who are not aware of the

mercury content.

Participants had learned their information about dental amalgam from

five main sources and the breakdown is given in Figure 9

4.2: Dublin Dental University Hospital Amalgam Information Leaflet

Seventy two percent of participants found the DDUH Dental Amalgam

Information Leaflet interesting. Fifty five percent of participants found

the leaflet easy to read. Eighty percent of participants felt better able

to make a decision regarding having a dental amalgam placed after

reading the leaflet, implying that the leaflet was informative.

Participant suggestions on how to

Module 4.2 Understanding Amalgam PDH Project 2011(2)

Documents

Transcript of Module 4.2 Understanding Amalgam PDH Project 2011(2)