Evidence map›Paper›PMID 40831375›Full record

ArticleJournal of oral rehabilitation2025

A Five-Year Follow-Up Study on the Removal of Dental Amalgam Restorations (Bergen Amalgam Trial): Examining Potential Confounding Factors and Effect Modification.

Lars Björkman, Frauke Musial, Terje Alræk, Harald J Hamre, Wolfgang Weidenhammer

Abstract read
In one paragraph

Article in Journal of oral rehabilitation, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Lars BjörkmanDental Biomaterials Adverse Reaction Unit, NORCE Norwegian Research Centre AS, Bergen, Norway.ORCID https://orcid.org/0000-0003-3663-530X
Frauke MusialDepartment of Community Medicine, Faculty of Health Sciences, the National Research Center in Complementary and Alternative Medicine (NAFKAM), UiT the Arctic University of Norway, Tromsø, Norway.ORCID https://orcid.org/0000-0003-0074-343X
Terje AlrækDepartment of Community Medicine, Faculty of Health Sciences, the National Research Center in Complementary and Alternative Medicine (NAFKAM), UiT the Arctic University of Norway, Tromsø, Norway.ORCID https://orcid.org/0000-0001-6876-1699
Harald J HamreInstitute for Applied Epistemology and Medical Methodology, University of Witten/Herdecke, Freiburg, Germany.ORCID https://orcid.org/0000-0003-1098-1079
Wolfgang WeidenhammerRetired, formerly: Centre for Complementary Medicine and Naturopathy, University Hospital Rechts der Isar, Technical University Munich (TUM), Dorfen, Germany.ORCID https://orcid.org/0009-0003-1552-2813

Funding

The Norwegian Ministry of Health and Care Services funded the project via the Norwegian Directorate of Health
6 · The paper itself

Abstract

backgroundThis government-funded project comprised experimental treatment aimed at improving health and quality of life for individuals with health complaints attributed to dental amalgam.

objectivesThe objective was to evaluate long-term changes in health complaints and health-related quality of life (HRQoL) after amalgam removal in individuals attributing health issues to dental amalgam, while also assessing effect modification and confounding factors.

methodsThe project was designed as a prospective cohort study. Three cohorts were followed over time: an Amalgam cohort (treatment group, n = 32), a cohort of patients with medically unexplained physical symptoms (MUPS cohort, n = 28) and a cohort of healthy volunteers (Healthy cohort, n = 19). The Amalgam cohort included patients with MUPS attributed to amalgam seeking amalgam removal, while the MUPS cohort had no such symptom attribution. Amalgam cohort participants had their fillings replaced with alternative materials. Questionnaires were completed at baseline (Q1), 1-year follow-up (Q2) and 4 years later (Q3). Changes over time were analysed using linear mixed-effects models.

resultsIn the Amalgam cohort, general health complaints significantly decreased after amalgam removal, while HRQoL significantly improved. No major changes were observed over time in the other cohorts. The differences in change scores between the Amalgam and MUPS cohorts were statistically significant, indicating better health outcomes in the Amalgam cohort. Adjusting for potential confounders did not substantially alter the effect estimates. Stratified analyses suggested that baseline indicators of health might act as effect modifiers.

conclusionImprovement of health was consistent over time even after adjustment for potential confounders. Baseline indicators of health could be effect modifiers.

Indexed as

Dental AmalgamDental Restoration, PermanentQuality of LifeAdultFemaleFollow-Up StudiesHumansMaleMiddle AgedProspective StudiesSurveys and QuestionnairesDental Amalgamdental amalgamdental caredental materialshumansprospective studiessubjective health complaint

Identifiers

PMID40831375
PMCPMC12624185

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.