Import
Dental amalgam has been the most commonly used filling material to restore teeth affected by caries/caries for over 100 years. Due to environmental concerns, mercury-containing products, including amalgam, have been banned in Norway since 2008. However, the material also has many positive qualities: it is durable, long-lasting, affordable and technically simple to produce. The most common alloy used in Norway consisted of mercury mixed with an alloy where the main ingredients were silver and tin. Most people with amalgam fillings do not experience any health problems. However, some people report health problems they believe can be attributed to amalgam fillings, such as fatigue, dizziness, pain, and psychological symptoms. One measure to alleviate these health complaints has been to remove amalgam fillings and replace them with composite resin or other filling materials.
Purpose
This systematic review summarizes research on the health effects of amalgam filling removal (either tooth extraction or filling replacement) compared with no removal in people with subjective health complaints attributable to amalgam fillings.
Method
We searched databases and other resources for controlled studies. Two investigators independently assessed the studies against the inclusion criteria, assessed the risk of bias in the included studies, extracted data and assessed the certainty of the evidence using the GRADE approach.
Results
We included a Norwegian before-and-after controlled trial, published in 2011, and a German randomized controlled trial, published in 2008. Both studies included subjects with subjective health complaints attributed to amalgam fillings, without other medical or psychological findings that would could you explain the symptoms
In the Norwegian study, there were 20 people in the intervention group who had their amalgam fillings removed and replaced with other materials. The control group, also consisting of 20 people, received no treatment. The authors randomized an additional 10 subjects to serve as replacements in case of dropouts from the intervention group. The follow-up period was a total of 3 years, with measurements taken at baseline, after 3 months, 1 year and 3 years.
The main findings of the Norwegian study at 3-year follow-up and our assessment of certainty of results (GRADE):
|
Result after 3 years* |
Result* |
Absolute result |
# participants (# studies) |
Certainty in assessment (GRADE) |
|
|
Amalgam removal Average difference (95% CI) |
No amalgam removal Average difference (95% CI) |
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|
Intraoral index (numeric rating scale 0-60, lower is better) |
3.5 (0.4 to 6.6) |
-0.6 (-6.4 to 5.2) |
6.9 index score (1.3 to 12.4) |
40 |
⨁◯◯◯ VERY LOW a |
|
Extraoral index (numeric rating scale 0-50, lower is better) |
2.0 (-2.2 to 6.2) |
-0.6 (-4.8 to 3.6)
|
4.3 index score (-1.6 to 10.3) |
40 |
⨁◯◯◯ VERY LOW a |
|
General health index (numeric rating scale 0-120, lower is better) |
10.1 (5.0 to 15.2) |
-2.3 (-13.1 to 8.5) |
14.2 index score (2.4 to 26.0) |
40 |
⨁◯◯◯ VERY LOW a |
|
CI: Confidence interval. The absolute outcome is calculated using an analysis of covariance (ANCOVA) and shows changes in index scores in the intervention group and the control group, adjusted for sex, age and health complaints from baseline. *Difference between questionnaire 1 (baseline) and 3-year follow-up. Positive values indicate a decrease in health complaints, while negative values indicate increased complaints. **Results presented from an intention-to-treat analysis. |
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Rationale for GRADE ratings: a It was downgraded due to challenges with outcome measures, differences in outcome measurement methods between groups, relatively high dropout rates and a small number of participants. |
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Explanation: Intraoral index: intraoral burning sensation, intraoral pain ⁄ sensitivity, taste disturbances, intraoral stiffness ⁄ paresthesia, dry mouth and increased salivation ⁄ mucus. Extraoral index: extraoral burning sensation, extraoral pain ⁄ tenderness, extraoral stiffness ⁄ paresthesia, extraoral skin problems and jaw joint pain. General health complaints: musculoskeletal problems, gastrointestinal problems, cardiovascular problems, skin problems, eye and vision problems, ear and hearing problems, nose and throat problems, fatigue, dizziness, headaches, memory problems, concentration difficulties and anxiety and depression. |
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- It is uncertain whether removal of amalgam fillings affects subjective health complaints compared to no removal of amalgam fillings.
In the German study, 30 people were randomized to have their amalgam fillings removed (Group A), 29 people to have their amalgam fillings removed and receive a biological detoxification intervention (Group B), and 31 people to participate in a lifestyle program without amalgam fillings removed (Group C, control). The detoxification program consisted of a series of vitamins given over 12 weeks, starting 4 weeks before the amalgam removal. The control group participated in a health-related lifestyle program consisting of 14 consultations with two-hour group sessions. The follow-up period was 1.5 years, with measurements taken at baseline, as well as after 1, 2, 6, 12, and 18 months. The primary outcome, from which the results were reported, was the 12-month follow-up.
The main findings of the German study at 12-month follow-up, together with our assessment of the certainty of the evidence (GRADE):
|
Result after one year* |
Result |
its p-value adjusted ANOVA |
# participants (studies) |
Certainty in assessment |
|
|
A: Amalgam removal, B: Amalgam removal + detoxification Mean difference (SD) |
Lifestyle program without removal of amalgam fillings (Control) Mean difference (SD) |
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|
Main outcome: Change in weighted sum score of the three chief complaints (0-9, lower values are better) |
A –3.5 (SD 2.2) B –3.5 (SD 2.2) |
-2.5 (2.4) |
0.091* |
90 |
⨁◯◯◯ VERY LOW a, b |
|
Health complaints: Total symptom score (0-150, lower is better) |
A -21.8 (17.6) B -24.0 (16.5) |
-16.3 (12.2) |
0.230 |
90 |
⨁◯◯◯ VERY LOW a, b |
|
Number of complaints (0-50, lower is better) |
A -9.7 (8.4) B -10.5 (9.2) |
-2.5 (2.4) |
0.091 |
90 |
⨁◯◯◯ VERY LOW a, b
|
|
Physical health: SF-36 (0-100, higher is better) |
A 3.9 (8.5) B 2.4 (11.5) |
1.0 (6.9) |
0.546 |
71 |
⨁◯◯◯ VERY LOW a, b
|
|
Mental health: SCL-90-R Global Severity Index (90 items, 0-4 each item, lower is better) |
A –5.5 (7.4) B –4.9 (8.9) |
-6.9 (5.4) |
0.633 |
74 |
⨁◯◯◯ VERY LOW a, b
|
|
Internal locus of control, KGG (Stanin values) |
A –0.2 (9.3) B 2.3 (7.8) |
4.1 (7.2) |
0.197 |
74 |
⨁◯◯◯ VERY LOW a, b
|
|
ANOVA: analysis of variance (ANOVA); KKG: The Health Center Control Scale. SCL-90-R: SCL-90-R Symptom Checklist; SD: standard deviation; SF-36: The Brief Health Survey 36 items. The absolute effect is calculated as ANOVA adjusted for baseline values and based on the intention-to-treat population. * P value for ANCOVA (analysis of covariance) between groups, adjusted for baseline values. See Appendix 6 for effect estimates calculated in different ways, none of the analytical methods produced statistically significant differences. For stannin values, scores of 4-6 are average, scores less than or equal to 3 are below average, and scores of 7 or higher are above average. |
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Rationale for GRADE ratings: a Two-level downgrading due to challenges with lack of blinding of patients, therapists and outcome assessors combined with subjective outcome measures, relatively high dropout and lack of reporting of outcome measures in the protocol. b Downgraded one level due to small number of participants. |
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- It is uncertain whether amalgam removal (removal alone or removal plus biological detoxification) affects subjective health complaints compared to a lifestyle program without amalgam removal.
Discussion
We included a Norwegian before-and-after controlled study and a German randomized controlled trial that examined the health effects of amalgam fillings removal. The small number of participants and challenges associated with outcome measures resulted in a high risk of systematic bias in the studies, weakening our confidence in the evidence base. Therefore, there is considerable uncertainty about whether amalgam removal affects health outcomes in people with subjective health complaints attributable to amalgam fillings. This is consistent with findings from a previous systematic review. Conducting controlled studies that can provide reliable or stronger evidence of the health effects of amalgam removal in individuals reporting health complaints attributable to amalgam fillings is challenging, as blinding is not possible and outcome measures consist of subjective complaints. for health.
Conclusion
This systematic review summarizes the existing research on the health effects of amalgam removal compared with no amalgam removal in people with health complaints attributable to amalgam. Our confidence in the evidence is very low, and therefore it is not possible to draw any definitive conclusions about the outcome.
