https://orcid.org/0000-0003-3663-530X
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Abstract
Objective
A prospective cohort study on changes of health complaints after removal of amalgam restorations was carried out at the request of the Norwegian Directorate of Health. The aim was to provide and evaluate experimental treatment to patients with health complaints attributed to dental amalgam fillings.
Methods
Patients (n = 32) with medically unexplained physical symptoms (MUPS), which were attributed to dental amalgam restorations had all their amalgam restorations removed and replaced with other dental restorative materials. Samples of blood were collected before and 1 year after removal of the fillings, and concentration of inorganic mercury (I-Hg), methylmercury (MeHg), silver (Ag) and selenium (Se) in serum was determined by inductively coupled plasma–sector field mass spectrometry. The comparison groups (one with MUPS but without attribution to amalgam [n = 28] and one group of healthy individuals [n = 19]) received no treatment. The participants responded to questionnaires at baseline and at follow-up after 1 and 5 years.
Results
Concentration of I-Hg and Ag in serum decreased significantly after removal of all amalgam restorations. Concentration of MeHg and Se in serum were not changed. Intensity of health complaints was significantly reduced after amalgam removal, but there were no statistically significant correlations between exposure indicators and health complaints.
Conclusions
Removal of all amalgam restorations is followed by a decrease of concentration of I-Hg and Ag in serum. The results support the hypothesis that exposure to amalgam fillings causes an increase of the daily dose of both I-Hg and Ag. Even though intensity of health complaints decreased after removal of all amalgam restorations there was no clear evidence of a direct relationship between exposure and health complaints. Trial registration: The project is registered at Clinicaltrials.gov (NCT01682278).
Acknowledgements
Merete Allertsen is gratefully acknowledged for excellent help with the project administration and Randi Sundfjord is gratefully acknowledged for excellent technical assistance. We are grateful for statistical advice from prof. Stein Atle Lie regarding use of linear mixed models.
Author contributions
HH, FM, TA, ELW and LB were all involved in the study conception and design. LB and ELW were involved in acquisition of data. LB, FM, TA, ELW and HH were involved in the analysis and interpretation of data. LB was involved in drafting of the manuscript. LB, FM, TA, ELW and HH were all involved in the critical revision of the manuscript. All authors approved the final manuscript.
Disclosure statement
No potential conflict of interest was reported by the author(s).LB is employed by the Norwegian Dental Biomaterials Adverse Reaction Unit, which is funded by the Norwegian Ministry of Health and Care Services; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.