Tooth filling materials

Amalgam is a combination of mercury with other metals and has been used as a tooth filling material since early in the 19th century.

Alternative tooth-coloured materials are increasingly used because they look better and require less intervention.

How safe are different tooth filling materials? Are they equally effective in ensuring dental health?

1. Sourcedocument:
Toothfillingmaterials
SCENIHR/SCHER(2008)
Summary &Details:
GreenFacts(2008)
Dentalamalgams&alternative
materials
Context-Amalgamisacombinationof
mercurywithothermetalsandhasbeen
Introduction.........................................31.
Howaredentalamalgamsmade?............32.
Howcandentalpatientsandworkersbe
exposedtomercuryfromamalgams?.......3
3.
usedasatoothfillingmaterialsince
earlyinthe19
th
century.
Whathealtheffectscouldbelinkedtothe
formofmercurycontainedindental
amalgams?...........................................4
4.
Alternativetooth-colouredmaterialsare
increasinglyusedbecausetheylook
betterandrequirelessintervention.
Whatarethepossiblehealtheffectsof
alternativetoothfillingmaterials?............4
5.
Conclusiononhealtheffectsofdental
amalgamsandtheiralternativesonusers...
5
6.
Howsafearedifferenttoothfilling
materials?Aretheyequallyeffectivein
ensuringdentalhealth? Whatistheenvironmentalriskoftheuseof
dentalamalgamsandalternativematerials?.
5
7.
AnassessmentbytheEuropean
CommissionScientificCommitteeson
Howseriousaretherisksofindirectexposure
tomercuryfromdisposaldental
amalgams?...........................................6
8.
EmergingandNewlyIdentifiedHealth
Risks(SCENIHR)andonHealthand
EnvironmentalRisks(SCHER).
Whatfurtherinformationisneededon
environmentalrisksofdentalamalgams?...
6
9.
Theanswerstothesequestionsareafaithfulsummaryoftwoopinionsproducedin2008byscientificcommittees
oftheEuropeanCommission:"Thesafetyofdentalamalgamandalternativedentalrestorationmaterialsfor
patientsandusers"bySCENIHR(ScientificCommitteeonEmergingandNewlyIdentifiedHealthRisks)and“The
environmentalrisksandindirecthealtheffectsofmercuryindentalamalgam"bySCHER(ScientificCommittee
onHealthandEnvironmentalRisks).
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2. Thefullpublicationisavailableat:http://copublications.greenfacts.org/en/dental-amalgam/
andat:http://ec.europa.eu/health/opinions/en/dental-amalgam/
ThisPDFDocumentistheLevel1ofaGreenFactsCo-Publication.GreenFactsCo-Publicationsarepublished
inseverallanguagesasquestionsandanswers,inacopyrighteduser-friendlyThree-LevelStructureof
increasingdetail:
•EachquestionisansweredinLevel1withashortsummary.
•TheseanswersaredevelopedinmoredetailinLevel2.
•Level3consistsoftheSourcedocument,theinternationallyrecognisedscientificopinionwhich
isfaithfullysummarisedinLevel2andfurtherinLevel1.
AllGreenFactsCo-Publicationsareavailableat:http://copublications.greenfacts.org/
andat:http://ec.europa.eu/health/scientific_committees/policy/opinions_plain_language/index_en.htm
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3. 1.Introduction
Amalgamfillings
Dentalamalgamisacombinationofmercurywithothermetalsand
hasbeenusedforover150yearsforthetreatmentoftoothcavities
becauseitisverystronganddurable.Moreover,itissoftenoughto
adapttothesizeandshapeofthetoothcavity,yethardens
sufficientlyfasttomakeitpractical.However,concernshavebeen
voicedaboutpossibleharmfuleffectsofthemercurypresentin
dentalamalgams.
Thoughitmaystillbeconsideredamaterialofchoiceforsomefillingsinthebackteeth,
theuseofamalgamshasbeendecreasinginrecentyears,becauseitisnottooth-coloured
anddoesnotadheretothesurfaceofthetooth.
Alternativetooth-colouredfillingmaterialshavebecomeincreasinglypopular.Notonlydo
thesematerialslookbetter,buttheyrequirethedentisttoremovelesstoothmaterial.In
additiontheydonotcontainmercury.Asaresult,theteachingoftheuseofamalgamshas
eitherbeenreducedordiscontinuedinmanydentalschoolsinEuropeinfavourofalternative
materials.
2.Howaredentalamalgamsmade?
ConventionalDental
Amalgam
[seeAnnex1,p.7]
Mercuryisaheavymetal,sometimesknownasquicksilver,that
occursnaturallyintheenvironmentindifferentchemicalforms.The
pureform,elementalmercury,isliquidatroomtemperatureand
slowlyformsavapourintheair.
Dentalamalgamsaremadebymixingonepartofliquidmercury
withonepartofamixtureofothermetals:mainlysilver,butalso
tin,somecopperandsmallamountsofzinc.Thesettingamalgamhastheconsistencyof
apasteandispressedfirmlyintothepreparedtoothcavitytomakethefillingasstrongas
possible.Duringthisprocess,someexcessmercuryrisestothesurfaceandisremovedby
thedentist.Theamalgambecomessolidquicklyandgraduallyhardensoverafewhours
toformastrongrestorationthatcouldlastmanyyears.
Setamalgamrestorationsreleasemercuryvapourbutmuchlesssothanliquidmercury.
Amalgamscorrodeovertimeveryslowly,whichmaycontributetooverallexposureofthe
patienttomercury,buttheexactlevelofthisisnotknown.
3.Howcandentalpatientsandworkersbeexposedtomercuryfrom
amalgams?
Patientsaremainly
exposedwhenfillingsare
placedorremoved©
ThereseChase
Thegeneralpublicisforinstanceexposedtomercurywheneating
contaminatedfish,usingcosmetics,medicinalproductsandmedical
devicesthatcontainmercury–includingdentalamalgams–orat
certainworkplaceswheremercuryisused(seequestion8).
Themainexposureofpatientstomercuryfromdentalamalgam
happenswhentheyarehavingfillingsplacedorremoved.
Toreduceexposuretomercuryofdentalpatients,itisbettertoleaveamalgamfillingsin
placeunlessthereisamedicalreasontoremovethem.However,itmaybeadvisableto
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4. removefillingsinpatientswhoaresuspectedtohaveallergicreactionstooneofthemetals
intheamalgam.
Whileamalgamfillingsareinplace,patientsareexposedtomercurythatisreleasedthrough
normalwear,buttheexposureismuchlowerthanduringplacementandremoval.
Dentalworkersareconsiderablymoreexposedtomercurythanthegeneralpopulation.
Theirmainsourcesofexposurearevapoursreleasedwhenplacingorremovingfillingsand
theexhaustairfromdentalvacuumsystems.However,dentalworkerstodayareexposed
tomuchlessmercurythaninthepastbecauseofimprovementsintechniqueandinhygiene
measures,andbecauseofthesteadydeclineintheuseofamalgams.
4.Whathealtheffectscouldbelinkedtotheformofmercurycontainedin
dentalamalgams?
Dentalworkersaremore
exposedthanthegeneral
population
©MarceloTerraza
4.1Peoplearemainlyexposedtoelementalmercurybybreathing
initsvapour,sincecontactwiththeskinoringestionleadstovery
littleabsorptionintothebody.Mercuryvapourisabsorbedinthe
lungs,spreadstotheentirebodyandisthenslowlyexcreted.
Breathinginextremelyhighconcentrationsofmercurymayproduce
bronchitisandpneumoniaandaffectthecentralsystem,forinstance
leadingtomuscletremors.Long-termexposuretohighlevelsmay
affectthekidneysandtheinsideofthemouthandgums.Sucheffectshavebeenobserved
insomeworkersemployedinindustriesusingmercury.
However,theamountreleasedbydentalamalgamsismuchlowerthanthelimitsallowed
forexposureatwork.Thereisnoevidencethattheothermetallicelementsinamalgams
presentahealthrisk,apartfromallergicreactions.
4.2Dentalamalgamfillingsoccasionallycauselocaleffectsinthemouth,suchasallergic
reactionsofthegumsandoftheskininsidethemouth,butthishappensonlyrarelyand
isnormallyeasytomanage.Therehavebeenclaimsthatdentalamalgamfillingsmight
harmthekidneysorhaveeffectsonthenervoussystemorthemind.Butstudiesonhuman
populationshavenotfoundsuchlink.
Itisconcludedthatthecurrentuseofdentalamalgamsdoesnotposeahealthriskbeyond
occasionallocaleffects.
5.Whatarethepossiblehealtheffectsofalternativetoothfillingmaterials?
Compositesaretypically
hardenedusinglight
©Stockxpert
5.1Inmoderndentistry,restorationsareincreasinglymadewith
alternative,tooth-colouredmaterials.Theyvaryincompositionand
propertiesandincludecomposites,cements,andsealants.
Composites,forinstance,containmanycomponents,includinga
resinbaseandaceramicfiller.Compositesareappliedasapaste
tothetoothcavityandtypicallyhardenedusingvisiblebluelight.
Someofthealternativematerialsarechemicallyverycomplexandnotnecessarilywithout
anyhealtheffects.Thesubstanceswithinthematerialreactinsidethetoothandwiththe
surroundingsofttissue.Inthelaboratory,ithasbeenshownthatcertainresinsthatcould
remainpresentinthefillingmaterialcanaffectgumandpulpcellsandcausemutations
althoughthismaynothaveanymedicalsignificance.
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5. 5.2Certainresinsusedinalternativematerialscan,inrarecases,leadtoallergicreactions
inpatientsordentalworkers.Thelightusedtohardenresinsseemstobesafeformost
patientsandusers,whenappliedproperly,butcanoccasionallycauseadversereactions.
Alternativematerialshavenowbeeninmedicaluseformorethanthirtyyearswithlittle
evidenceofadversehealtheffects.Overthattimethematerialsthemselveshavebeen
modified,improvedandmadelessharmful.However,theirfullchemicalcompositionis
rarelydisclosedandishardtodetermine,andinformationonexposureisscarceanddifficult
toobtain.Therefore,itmaynotbepossibletoconfirmonthebasisofscientificevidence
thatallalternativetoothfillingmaterialsaresafe.
6.Conclusiononhealtheffectsofdentalamalgamsandtheiralternatives
onusers
6.1Bothdentalamalgamsandvariousalternativematerialsareconsideredeffectiveand
safetouse.Theyareassociatedwithaverysmallproportionoflocaleffectsinthemouth
andthereisnoevidencethattheycancausedisease.Therelativerisksandbenefitsof
usingdifferenttoothfillingmaterialsshouldbeexplainedtopatientsandthepublicatlarge.
6.2Dentalamalgamfillingscan,inrarecases,causelocalallergicreactionsandrelated
conditions.However,currentevidencedoesnotsupportanylinkbetweendentalamalgams
anddiseases–neitherdiseasesoftheurinary,neurological,reproductiveandimmune
systemsnoranypsychologicalconditions.
Amalgamisasafematerialtousefordentalrestorations.Aswithanyothermedical
intervention,cautionshouldbeexercisedwhenconsideringtheplacementoftoothfillings
inpregnantwomen.Mercuryexposuremaybehigheramongdentalpersonnelthaninthe
generalpopulation,butthereareveryfewreportsofanyadverseeffectsforthatparticular
group.
6.3Somecomponentsusedinthepreparationofalternativetoothfillingmaterialscan
causelocalallergicreactions,bothinpatientsandindentalworkers,althoughthenumber
ofcasesisverylow.Thereisnoevidenceofanylinkbetweentheuseofalternativetooth
fillingmaterialsandanyneurologicalorotherhealthdisorders.However,dataaresparse
andcautionshouldbeexercisedbeforeintroducingnewvariationsofthesematerialsinto
themarket.
7.Whatistheenvironmentalriskoftheuseofdentalamalgamsand
alternativematerials?
Methylmercurycan
accumulatealongthefood
chain©AurileideAlves
7.1Mercuryoccursnaturallyintheenvironmentindifferentchemical
forms.Elementalmercuryistheformusedindentalamalgams.
Formsmorecommonlyfoundinnatureareinorganicmercuryand
organicmercury.Naturalevents(e.g.weatheringofrocks)and
humanactivities(e.g.fuelandwastecombustionand,toalesser
extent,useanddisposalofdentalamalgams)cancausereleasesof
thesedifferentformsofmercuryintotheenvironment.
Wastewaterreleasedbydentalclinicscouldincreasetheconcentrationofinorganicmercury
inwaterbodies.Theaddedriskforaquaticorganismsofthissourceofinorganicmercury
isconsideredlow.Sludgefromplantsthattreatsuchwastewaterpresentalowriskfor
soil-dwellingorganisms.Inaddition,thecremationofindividualswithdentalamalgam
fillingsalsoleadstoreleasesintoairanddepositiononsoil.
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6. Themainenvironmentalconcernrelatestomethylmercury,anorganicformofmercury,
becauseitcanaccumulateinorganisms.Thelevelsofmethylmercuryincreasealongthe
foodchainandwithage.Someofthemercuryreleasedbytheuseofdentalamalgamswill
beconvertedintomethylmercury.Thoughestimatesareavailableoftheamountsofmercury
releasedbytheuseanddisposalofdentalamalgamsintheEuropeanUnion,itisnotpossible
tosaywhatproportionoftheriskassociatedwithorganicmercurypresentintheenvironment
isduetoreleasesfromamalgams.
7.2Foralternativetoothfillingmaterials,potentialeffectsonanimalsareknownforcertain
components.However,availableinformationistoolimitedtoassesstheenvironmentalrisk
andcompareittodentalamalgams.
8.Howseriousaretherisksofindirectexposuretomercuryfromdisposal
dentalamalgams?
Mercurypresentintheenvironment–includingthatreleasedbytheuseanddisposalof
dentalamalgams–canbetakenupbythehumansthroughair,waterandfood.Thegeneral
publicismainlyexposedtomethylmercurythroughthediet(particularlyfish),andto
elementalmercuryvapoursatcertainworkplacesandfromtoothfillings.Methylmercuryis
particularlypoisonoustothenervoussystem.
Theindirectexposuresofhumanstomethylmercuryfromdentalamalgamsarewellbelow
tolerablelimitsandtheriskforserioushealtheffectsislow.
9.Whatfurtherinformationisneededonenvironmentalrisksofdental
amalgams?
Toenableafullassessmentofenvironmentalrisks,moreinformationisneededonregional
variationsacrosstheEUintheuseofdentalamalgamaswellastherelatedreleaseand
fateofmercury,includingemissionsfromcrematoria.Itisalsonecessarytocompiledata
ontheeffectsofdifferentformsofmercuryonhumansandontheenvironmentaswellas
areviewofthewaymethylmercuryaccumulatesinorganismsunderdifferentEUconditions.
Therelativecontributionofdentalmercurytotheoverallmercurypoolintheenvironment
needstobedetermined.
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7. Annex
Annex1:
ConventionalDentalAmalgam(contentbyweight)
Source:GreenFacts
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EuropeanCommission.
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8. TheThree-LevelStructureusedtocommunicatetheSCENIHR&SCHEROpinionsis
copyrightedbyCogenerissprl[seehttp://www.greenfacts.org/]
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