Background. Possible adverse health effects due to mercury released by amalgam fillings have been
discussed in several studies of patients who attribute various symptoms to the effects of amalgam
fillings. No systematic relation of specific symptoms to increased mercury levels could be established
in any of these studies. Thus, a psychosomatic aetiology of the complaints should be considered and
psychological factors contributing to their aetiology should be identified.
Methods. A screening questionnaire was used to identify subjects who were convinced that their
health had already been affected seriously by their amalgam fillings (N = 40). These amalgam
sensitive subjects were compared to amalgam non-sensitive subjects (N = 43). All participants were
subjected to dental, general health, toxicological and psychological examinations.
Results. The two groups did not differ with respect to the number of amalgam fillings, amalgam
surfaces or mercury levels assessed in blood, urine or saliva. However, amalgam sensitive subjects
had significantly higher symptom scores both in a screening instrument for medically unexplained
somatic symptoms (SOMS) and in the SCL-90-R Somatization scale. Additionally, more subjects
from this group (50% versus 4·7%) had severe somatization syndromes. With respect to
psychological risk factors, amalgam sensitive subjects had a self-concept of being weak and unable
to tolerate stress, more cognitions of environmental threat, and increased habitual anxiety. These
psychological factors were significantly correlated with the number and intensity of the reported
Conclusions. While our results do not support an organic explanation of the reported symptoms,
they are well in accord with the notion of a psychological aetiology of the reported symptoms and
complaints. The findings suggest that self-diagnosed ‘amalgam illness’ is a label for a general
tendency toward somatization.