Translated from Den norske tannlegeforenings Tidende, 112th year, No. 01 - January 2002 (The journal of the Norwegian Dental Association)

 
Norwegian Dental Biomaterials Adverse Reaction Unit, November 2001

Advice to dentists regarding removal of amalgam fillings

The Dental Biomaterials Adverse Reaction Unit has prepared guidelines for dentists regarding the removal of amalgam fillings. The aim is to keep mercury exposure at the lowest possible level for both patients and dental personnel. The Patients Rights Act gives the patient the right to participate in choosing between available and justifiable examination and treatment methods.

Amalgam contains approximately 50% mercury. When working with amalgam, exposure to mercury should be as low as possible for both patients and dental personnel. All handling of mercury and mercury compounds should be done in such a way that both individual exposure and contamination of the environment is reduced and kept at the lowest possible level.

It is scientifically documented that both dental personnel and patients are exposed to mercury when amalgam fillings are removed. Mercury concentrations in air increase for a short period of time when amalgam fillings are polished or removed.1-3 In connection with drilling without a high volume suction, momentary measurements of mercury levels many times the administrative standard have been measured.3 Polishing and drilling amalgam should always be done using water cooling and a high-suction vacuum, to reduce mercury exposure to a minimum.

Some patients report symptoms in conjunction with removal and grinding of amalgam. It is known that the mercury concentration in blood increases for a short period of time after removal of amalgam, but it is not shown that this exposure is the cause of the symptoms. There is, however, a published case report where high mercury exposure in connection with amalgam work was documented, and it was also suspected that this had caused considerable adverse reactions.4

Today the average occupational exposure to mercury for dental personnel is considerably lower than the administrative standard for mercury (at present 50 µg/m3).5 Well-functioning ventilation is a prerequisite for good indoor environment. Air from the suction should not be recirculated to the workplace because this could contribute to increasing air pollution in the workplace or spread pollution to other rooms.6

 

Practical advice

The following advice can contribute to minimizing the patients as well as dental personnel’s’ exposure to mercury in connection with removal of amalgam fillings.

High-volume suction and water cooling

High-volume suction (‘vacuum-suction’ which is normally found in modern dental clinics) and water cooling shall be used in close proximity to the polishing and drilling of amalgam. The effect of the suction is dramatically reduced in relation to distance. Use of the high-volume suction gives a considerable and important reduction in concentration of mercury in air when polishing and drilling amalgam.

Remove the filling in chunks – use sharp drill

Avoid 'pulverizing' large amalgam fillings when removing them. Large restorations are to be removed in chunks. A sharp hard-metal drill should be used. Avoid using a worn drill or a diamond drill.

Remove the whole filling

When an amalgam filling is replaced with another material, the whole amalgam filling should ideally be removed. If this is not possible for some reason, it should be noted in the journal and the patient should be informed.

Rubber dam

Use of a rubber dam can in addition contribute to reducing mercury exposure.7,8 This can be indicated when treating patients who have lichenoid contact reactions to amalgam or who are allergic to mercury. The effect of additional equipment (such as extra point-suction, nose-mask or extra fresh-air supply) is not satisfactorily documented.

Pace of removal

Some recommend an interval of approximately six weeks between removal of each filling.9 This practice is not scientifically documented. Since the biological half-life for inhaled mercury vapor is approximately 60 days,10 avoiding a number of removals within short intervals of time is reasonable when one wishes to avoid additional mercury exposure from amalgam.

Supplements

It is claimed that the use of food supplements/antioxidants (for example in the form of vitamins and minerals) should be recommended in connection with amalgam removal.9, 11 A deficiency can reduce the natural defense against toxic metals.12 It is not documented that taking antioxidants when ill gives significant preventive effect.13 This is not scientifically documented in connection with amalgam removal either.

Consent and participation in choice of treatment

Most patients who suspect that they have become ill due to amalgam, do not experience discomfort beyond that normally expected during dental treatment.14 In cases where the patient experiences discomfort beyond that which is usual during dental treatment, a reasonable recommendation would be to do the planned removal according to the above mentioned guidelines. The patient has, according to the Patients Rights Act 15, a right to participate in choosing between available and justifiable treatment methods. The patient shall, according to this law, also be informed about possible risks and adverse effects.

Report adverse reactions

All suspected adverse reactions are to be reported to the Dental Biomaterials Adverse Reaction Unit. The report form can be ordered from the Unit (at Årstadveien 17, 5009 Bergen) or may be downloaded from internet (http://www.uib.no/bivirkningsgruppen/, a draft English version may be downloaded at http://www.uib.no/ood/advrep/ReportSys/NrepformEng.pdf).

References:

  1. Molin M, Bergman B, Marklund SL, Schutz A, Skerfving S. Mercury, selenium, and glutathione peroxidase before and after amalgam removal in man. Acta Odontol Scand 1990; 48 (3): 189-202.

  2. Sandborgh-Englund G, Elinder CG, Langworth S, Schutz A, Eskstrand J. Mercury in biological fluids after amalgam removal. J Dent Res 1998; 77 (4): 615-24.

  3. Pohl L, Bergman M. The dentist’s exposure to elemental mercury vapor during clinical work with amalgam. Acta Odontol Scand 1995; 53 (1): 44-8.

  4. Taskinen H, Kinnunen E, Riihimaki V. A possible case of mercury-related toxicity resulting from the grinding of old amalgam restorations. Scand J Work Environ Health 1989; 15 (4): 302-4.

  5. Direktoratet for Arbeidstilsynet. Veiledning om administrative normer for forurensning i arbeidsatmosfære. 1996-02-01 nr 0361. (Guidelines on administrative standards for pollution in the working atmosphere)

  6. Direktoratet for Arbeidstilsynet. Veiledning om klima og luftkvalitet på arbeidsplassen. 1991-03-01 nr 0444. (Guidelines on climate and air quality in the workplace).

  7. Berglund A, Molin M. Mercury levels in plasma and urine after removal of all amalgam restorations: the effect of using rubber dams. Dent Mater 1997; 13 (5): 297-304.

  8. Kremers L, Halbach S, Willruth H, Mehl A, Welzl G, Wack FX, et al. Effect of rubber dam on mercury exposure during amalgam removal. Eur J Oral Sci 1999; 107 (3): 202-7.

  9. Brodén G, Grönquist S-O, Hanson M, Molius M, (eds.) ABC for amalgamskadede: Forbundet Tenner og Helse, 2000. [ABC for the amalgam injured, published by The Norwegian Dental Patient Association. This was a translation from a publication in 1997 by the Swedish Dental Patient Association – Tandvårdsskadeförbundet – which was updated and adjusted for Norwegian conditions].

  10. Hursh JB, Cherian MG, Clarkson TW, Vostal JJ, Mallie RV. Clearance of mercury (Hg-197, Hg-203) vapor inhaled by human subjects. Arch Environ Health 1976; 31 (6): 302-9.

  11. IAOMT-Sweden. Anvisninger för avlägsnande av amalgam i allmänhet, samt behandling av patienter med misstänkt materialpåverkan. In: http://www.iaomt.f.se/sanprtkl.htm; 1997 (downloaded 28.06.01). (Directions for removal of amalgam in general, and treatment of patients with suspected material reactions. The website was downloaded on June 28, 2001).

  12. Goyer RA. Nutrition and metal toxicity. Am J Clin Nutr 1995; 61(3 Suppl): 646S-50S.

  13. Isaksson B, Andersson C, Asplund K, von Bahr C, Borgström B, Boström H, et al. Att förebygga sjukdom med antioxidanter. Stockholm: SBU – Statens beredning för medicinsk utvärdering; 1997. Report No: Vol 1 135/1.

  14. Bjerner B, Hjelm H. Sjuk av amalgam? LEK-studien. Medicinsk-odontologisk 3-årsstudie av 234 patienter. Skriftserie nr 31 1994; Landstinget Dalarna.

    15.

  15. Pasientrettighetsloven, § 3–1. Pasientens rett til medvirkning, § 3–2. Pasientens rett til informasjon. I: Lov 1999-07-02 nr 63: Lov om pasientrettigheter. Kapittel 3. Rett til medvirkning og informasjon. (Patients Rights Act, § 3-1. The patient’s right to participation. § 3–2. The patient’s right to information. In: Law of 1999-07-02 no. 63: Law on patient rights. Chapter 3. Right to participation and information).

 
Translated by Maryanne Rygg (mrygg@online.no), revised 10/08/02 by Lars Björkman (lars.bjorkman@odont.uib.no) 

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             10/08/2002