Leistevuo 2001: Amalgam Fillings Raise Organic Mercury in Human Saliva

Why this study sits in the SMART reference list

Reference #9 in the IAOMT Safe Mercury Amalgam Removal Technique (SMART) materials is a peer-reviewed Caries Research paper: Leistevuo and colleagues measured organic and inorganic mercury in human saliva and compared adults with dental amalgam fillings to adults without. The finding that matters for mercury education is direct: people with amalgam had significantly higher organic and inorganic mercury in paraffin-stimulated saliva, and the authors state that their results are compatible with amalgam as a continuous source of organic mercury—the form they note is more toxic than inorganic mercury and almost completely absorbed by the human intestine.

That is the story. Amalgam is not only an elemental-mercury vapour source. This study places organic mercury in saliva on the exposure map for people who still carry “silver” fillings.

What the researchers measured

The team studied 187 adult subjects. They quantified mercury in whole saliva, focusing on paraffin-stimulated samples, using cold-vapor atomic absorption spectrometry.

They compared:

• subjects with dental amalgam fillings (n = 88);
• two nonamalgam study groups (n = 43 and n = 56).

The design question was straightforward: do people who have amalgam in their mouths show higher salivary organic and inorganic mercury than people who do not?

The core result: significantly higher organic and inorganic mercury with amalgam

Both organic and inorganic mercury amounts in paraffin-stimulated saliva were significantly higher in the amalgam group than in the nonamalgam groups (p < 0.001).

That is not a soft trend. Under the study’s own reporting, the difference between amalgam and nonamalgam saliva mercury—organic and inorganic alike—cleared a high significance threshold.

The abstract also reports a linear relationship (on the natural-log scale) between organic and inorganic mercury: log_e(organic mercury) related linearly to log_e(inorganic mercury) with r² = 0.52. Salivary organic mercury tracked with salivary inorganic mercury across the measured samples; about half the variance in log organic mercury was associated with log inorganic mercury in that fitted relationship.

Dose-related signal with amalgam surface count

The authors further correlated mercury concentrations with the number of amalgam-filled tooth surfaces:

Both coefficients are positive. More amalgam surface area associated with higher salivary inorganic mercury, and also—though more modestly in the reported Spearman coefficients—with higher salivary organic mercury. That pattern fits a filling-burden relationship: more amalgam surface, more mercury measured in saliva.

Why “organic mercury in saliva” changes the conversation

Public debate often narrows amalgam risk to inhaled elemental mercury vapour. Leistevuo et al. put another exposure compartment on the table: saliva, and within it, organic mercury.

The authors’ own interpretation is unambiguous in direction. Their results are compatible with the hypothesis that amalgam fillings may be a continuous source of organic mercury, which they describe as more toxic than inorganic mercury and almost completely absorbed by the human intestine.

Keywords associated with the article include methyl mercury, organic mercury, and inorganic mercury—underscoring that the organic fraction is central to how this paper frames amalgam-related salivary mercury.

For readers evaluating SMART-style education: if organic mercury is present in saliva at higher levels among amalgam wearers, then swallowing saliva is a plausible ongoing intake route for a highly absorbable, more toxic mercury form—alongside vapour pathways documented elsewhere in the SMART reference set. This paper measures the salivary organic mercury difference and states the continuous-source hypothesis as compatible with the data.

What this paper establishes from the abstract

Use these facts—no invented concentrations:

1. 187 adults studied; amalgam n = 88; nonamalgam n = 43 and n = 56.
2. Method: cold-vapor atomic absorption spectrometry on whole / paraffin-stimulated saliva.
3. Organic and inorganic salivary mercury were significantly higher with amalgam (p < 0.001).
4. Log–log linear link between organic and inorganic mercury (r² = 0.52).
5. Spearman correlations with amalgam-filled surfaces: inorganic 0.46, organic 0.27.
6. Authors’ conclusion: results compatible with amalgam as a continuous organic mercury source; organic mercury more toxic; nearly complete intestinal absorption.

Absolute mean/median concentrations (µg/L or ng/mL) and a full methylmercury percentage breakdown are not stated in the abstract text used for this draft. Those omissions do not erase the central result that is reported: amalgam presence and amalgam surface burden associate with higher salivary organic mercury. This paper is exposure biology evidence—not a SMART removal-protocol methods paper.

How IAOMT SMART materials use Reference #9

SMART is named and detailed in IAOMT materials; this 2001 Caries Research study does not use the SMART name. Its role in the reference list is scientific support for amalgam-related organic mercury in saliva.

Practical takeaways

1. Amalgam raises salivary mercury—organic included. The amalgam group’s organic and inorganic saliva mercury levels were significantly higher than nonamalgam groups (p < 0.001).
2. Organic mercury is not a side note. The paper’s title, keywords, and conclusion center organic mercury as the toxicologically important finding.
3. More amalgam surfaces, more salivary mercury signal. Spearman correlations with filled surfaces were 0.46 (inorganic) and 0.27 (organic).
4. Organic and inorganic track together. The reported log–log relationship (r² = 0.52) ties the two fractions in saliva.
5. Authors frame amalgam as a continuous organic mercury source. That is their stated compatibility conclusion.
6. Intestinal absorption matters. The authors note organic mercury is almost completely absorbed by the human intestine, so salivary organic mercury is an exposure pathway worth treating as real.

Bottom line

Leistevuo J, Leistevuo T, Helenius H, Pyy L, Österblad M, Huovinen P, and Tenovuo J (Caries Research, 2001; 35(3):163–166) measured organic and inorganic mercury in saliva from 187 adults and found significantly higher levels of both forms in people with dental amalgam fillings compared with nonamalgam groups (p < 0.001). Organic mercury tracked with inorganic mercury (log–log r² = 0.52), and both forms correlated positively with the number of amalgam-filled tooth surfaces (Spearman 0.46 inorganic; 0.27 organic). The authors conclude their results are compatible with amalgam fillings as a continuous source of organic mercury—more toxic than inorganic mercury and almost completely absorbed by the intestine. For IAOMT SMART Reference #9, that is the evidence point: amalgam puts measurable organic mercury into saliva, and that finding stands on the study’s own statistics and wording.

Citations

1. Leistevuo J, Leistevuo T, Helenius H, Pyy L, Osterblad M, Huovinen P, Tenovuo J. Dental amalgam fillings and the amount of organic mercury in human saliva. Caries Res. 2001;35(3):163-166. doi:10.1159/000047450. PMID:11385194.
   Abstract (Karger): https://karger.com/cre/article-abstract/35/3/163/84921/Dental-Amalgam-Fillings-and-the-Amount-of-Organic
   Legacy abstract URL cited by IAOMT: http://www.karger.com/Article/Abstract/47450
   DOI: https://doi.org/10.1159/000047450
   PubMed: https://pubmed.ncbi.nlm.nih.gov/11385194/
2. International Academy of Oral Medicine and Toxicology (IAOMT). The Safe Mercury Amalgam Removal Technique (SMART) reference list (Leistevuo et al. 2001 as Reference #9).

Source note: Numeric claims are from the published abstract (sample sizes, p < 0.001, r² = 0.52, Spearman 0.46 / 0.27, and the authors’ continuous-source / toxicity / absorption wording). Full-text concentration tables were not available for this draft (publisher full text is paywalled); no unstated statistics were invented.